Nomenclatural note

Polypodiopsis Carrière, typified by P. muelleri Carrière from New Caledonia, may be synonymous with Retrophyllum, or it could be a member of the Proteaceae, such as Beauprea balansae Brongn. & Gris, as was suggested by Hutchinson (Reference Hutchinson1920). Polypodiopsis Carrière, an earlier homonym of the fern genus Polypodiopsis E.B.Copel., is now a nomen rejiciendum and cannot be used at genus rank (Mill & Weston, Reference Mill and Weston2004; Brummitt, Reference Brummitt2006 [‘2005’]; Barrie, Reference Barrie2006). However, when Bertrand (Reference Bertrand1874) apparently reduced Carrière's name to Podocarpus sect. Polypodiopsis, he designated a different name, Podocarpus vitiensis (now Retrophyllum vitiense), as type of the section, the name of which should therefore be attributed to Bertrand, not Carrière.

Etymology

Retrophyllum is derived from Latin, retro (‘backwards’), and Greek, phyllon, Latinised as phyllum (‘leaf’), on account of the orientation of the leaves, which are twisted so that along one side of the stem axis all the abaxial surfaces face uppermost, while along the other side of the axis all the adaxial surfaces are turned uppermost. The gender is neuter.

Trees or shrubs; dioecious. Trunk buttressed or not. Bark exfoliating in short vertical strips or small pieces (Pacific species: Groups A and B), or as large plates (South America: Group C). Vegetative shoots dimorphic with either both foliage and scale leaves or only scale leaves (Groups A and B) or monomorphic with foliage leaves only (Group C), heterofacially flattened at least in juvenile phase, in adult phase sometimes not fully so (New Caledonian species: Group B). Terminal buds developed on shoots, these either protected in some way (Groups A and B) or naked (Group C); bud scales present (Fiji and Malesia: Group A) or absent (Groups B and C). Leaves of juvenile phase always ± distichous, heterofacially turned at base so that all leaves along one side of the axis present their abaxial surface to the light and all those along the other side present the adaxial surface; those of adult phase either distichous and flattened in 2 ranks (Groups A and C) or wholly or partly in 4 ranks that show only minimal heterofacial turning (Group B). Adult leaves subsessile with bases decurrent and ± crossing over to a departure point on the opposite side and so creating a ± zigzag pattern along the branch (all groups, but particularly prominent in Group C); blades bifacially flattened, coriaceous, relatively thin (Groups A and C) or thick to very thick (Group B), with or without a visible midrib; resin canals 1 median below the vascular bundle (Groups A and B) or (1)3(5) below the vascular bundle plus 2–6 lateral bundles around the leaf margin (Group C); transfusion tissue present; accessory transfusion tissue absent. Pollen cones usually lateral but sometimes terminal in Retrophyllum vitiense, 1–8 together, potentially arranged in racemose inflorescences (Groups A and C) or groups (Group B) borne on a common peduncle; individual pollen cones ± pedicellate (Groups A and C) or sessile (Group B), cylindrical, ellipsoid or ovoid; microsporophylls imbricate, decussate (Group B: appearing spirally arranged) or spirally arranged (Groups A and C), triangular or ovate (Groups A and B) or lanceolate (Group C). Pollen 2-saccate. Female cones borne on current growth, as part of specialised reproductive shoots (Groups A and C) or terminating foliage shoots (Group B); cones sylleptic (Groups A and C) or proleptic (Group B), pedunculate; peduncle broadened distally (Group C) or not (Groups A and B), in the vegetative portion bearing adpressed scales (Group A) or spreading bracts (Groups B and C); carpophore absent; cone axis with either 1 or 2 (Group B) or 6–8 (Groups A and C) sterile bracts below the fertile bract; fertile bract free from the epimatium (Groups A and B) or with its basal half firmly adnate to it (Group C), distally navicular (Group C) or flat (Groups A and B). Prophylls absent. Receptacle vestigial, formed from the fertile bract and sometimes the last sterile bract (Groups A and C) or from 1 or 2 peduncle bracts plus the last sterile bract and fertile bract (Group B), cylindrical (Groups A and C) or obovoid (Group B). Ovule inverted. Epimatium present. Seed distally crested or not, with a beak at the micropylar end (Groups A and B) or lacking a beak (Group C). Germination epigeal (Group B) or hypogeal (Group C). Seedling phyllotaxis decussate (Group B), spiral (Group C) or currently unknown (Group A).

Present diversity and distribution

Six living species in three very distinct morphological lineages occurring respectively in: (A) Fiji, Solomons and eastern Malesia west to the island of Morotai in the Moluccas; (B) New Caledonia; and (C) tropical South America (eastern slopes of the Andes and extending into the Amazon Basin in Brazil).

Past diversity and distribution

Two (or more?) fossil species have also been included in the genus as traditionally circumscribed: †Australasia (New Zealand, Western Australia and Tasmania [undescribed material]) and southern South America (Argentina and ?Chile). There is apparently no record of the genus having occurred in Antarctica, which might be expected given the disjunct distribution of the living and known fossil species between the Australasia/Southwest Pacific area and South America.

Chromosome number and genomics

Diploid chromosome number: 2n = 20 (3 species cytologically known, from Groups A and B only). The karyotype of all known species comprises 10 pairs of metacentric chromosomes. The genome size is known only for Retrophyllum rospigliosii (of which the chromosome number is not yet known); at 12 pg, it is small for conifers but average within the Podocarpaceae, most species of which have small genome sizes of 8–18 pg, with only Falcatifolium (22 pg in F. taxoides) and Manoao colensoi (28 pg) being larger within the family (Zonneveld, Reference Zonneveld2012). Vieira et al. (Reference Vieira, Rogalski, Faoro, Fraga, dos Anjos, Picchi, Nodari, Pedrosa, de Souza and Guerra2016) have very recently published the complete plastome sequence of Retrophyllum piresii, based on material cultivated at the Museu Paraense Emílio Goeldi in Belém; I have seen herbarium material of this plant as well as photographs kindly sent by Chad Husby, and have verified the identification.

Note on typification

Gray (Reference Gray1962: 73) indicated that the Kew example of Seemann 576 was the ‘holotype’ of Podocarpus vitiensis (basionym of Retrophyllum vitiense), with an isotype (not so indicated) at GH. This was incorrect because, as was noted by Smith (Reference Smith1979), Seemann (Reference Seemann1862: 366; Reference Seemann1863: 33) cited two syntypes in both the original protologue and in another publication the following year; the first of these was collected by W.G. Milne on the voyage of HMS Herald, and the second was Seemann 576. (Smith, Reference Smith1979: 101 in fact cites two Milne collections of this species, both unlocalised, one without number and the other Milne 33). However, de Laubenfels (Reference de Laubenfels1969: 344) repeated the designation of Seemann 576 at K as ‘holotype’ of Podocarpus vitiensis, with specimens at A and BM indicated as ‘isotypes’. These specimens should be regarded as lectotype (K) and isolectotypes (A, BM, GH) respectively, following Smith (Reference Smith1979: 100) and the more precise lectotypification by Farjon (Reference Farjon2010). The choice of a Kew specimen as lectotype by both the above authors is difficult to understand, because it is one of the two BM sheets, not either of the K sheets, that bears Seemann's drawings that were used in his two publications (1863, 1868). However, there is no controversy over the identity of any of these sheets, and Farjon's recent designation, which supersedes the earlier ones by de Laubenfels (Reference de Laubenfels1969: 342) and Smith (Reference Smith1979: 100), must therefore stand. Both latter authors independently chose Seemann 576 at K but without realising that there are two sheets of that number at K, one of them (annotated ‘1/2’, i.e. sheet 1 of 2) being a seedling and the other (‘2/2’) a branch from a young tree, and they could not have come from the same plant. Sheet ‘1/2’ at Kew is therefore not an isolectotype.

Iconography

Seemann, J. Bot. 1: t. 2 (Reference Seemann1863).

Etymology

Derived from Viti, alternative name for Fiji.

Vernacular names

ailumu (Solomon Is., Kwara'ae language: Mauriasi et al. BSIP 17025 in sched., K, L); dakua salusalu (Fiji: Parham, Reference Parham1964, Reference Parham1972; Damanu R10 in sched., K), ndakua salusalu or salu-salu (Fiji: Mead, Reference Mead1928; Smith, Reference Smith1979); ngapiru [Vanikoro (Solomon Is.: Nambalua – Piaito BSIP 7061 in sched., L); ?kau solo (Fiji: Seemann, Reference Seemann1862, Reference Seemann1863, Reference Seemann1868); tau solo (Fiji: Seemann, Reference Seemann1868, possibly a misprint for kau solo) Seemann's use (Reference Seemann1862 etc.) of the name kau solo in fact refers to Dacrycarpus imbricatus var. patulus, according to Smith (Reference Smith1979), who also said that the most frequently used name for Retrophyllum vitiense is ndakuua salusalu.

Distinguishing features

Retrophyllum vitiense is most closely allied to R. filicifolium (N.E.Gray) R.R.Mill (see below) from New Guinea and the Moluccas. Both have ± flat, distichous adult leaves, female cones borne laterally near the base of an ultimate foliage shoot, and dimorphic shoots bearing either foliage leaves or small decussate scale leaves. The dimorphic shoots separate both these species from the two South American species of Retrophyllum, which have monomorphic shoots. The flat, distichous, non-imbricate adult leaves and lateral female cones separate the two Papuasian species from the New Caledonian species Retrophyllum comptonii and R. minus, both of which have terminal female cones and adult leaves more or less in 4 ranks and ± imbricate (although juvenile and transitional shoots are distichous). Vegetative material of Retrophyllum vitiense is best separated from its nearest ally R. filicifolium by its tapered leaves widest close to the base, not near the middle. For differences in reproductive characters between these two species, see under Retrophyllum filicifolium.

Tree, 15–47 m, dbh 25–450 cm. Trunk sometimes spur-buttressed at base on large trees, bole straight and when adult unbranched except near top. Bark smooth, finally with faint vertical fissures, flaking into small longitudinal crumbly pieces, fissured, greyish-brown or (Solomons) dark brown, whiter in mature trees; inner bark yellowish-brown or (Solomons) reddish-brown; wood cream-coloured. Crown compact but much branched, pyramidal and finally rounded, with pendulous branchlets and twigs. Buds ovoid or obovoid; bud scales present, in 2 series, decussate, all equal, ovate and keeled, acute, brownish with narrow paler entire margin, initially persistent but later slowly caducous, not leaving scars. Ultimate juvenile shoots alternate, subopposite or opposite, 130–280 mm, with 23–72 (usually 35–60) pairs of foliage leaves, occasionally biramulate. Juvenile foliage leaves 4–11 mm apart, opposite-distichous, heterofacially turned at base, diverging at 60–80°, shortly petiolate, the petiole 0.2–0.5(–1.5) mm, lamina lanceolate or narrowly lanceolate, those near middle of branchlet 18–35 × (3.8–)4–6(–7) mm. Adult trees with dimorphic shoots, most shoots bearing foliage leaves but leader shoots bearing scale leaves; shoot flattening heterofacial with the decurrent leaf bases running straight down the internodes. Primary adult branches opposite-decussate or alternate. Penultimate adult branches erecto-patent with respect to subtending branch (although topographically deflexed-patent), straight or slightly curved with flexuous internodes, alternately bearing axillary decussate lateral foliage shoots and decussate ovate to orbicular bracts c.2 mm. Ultimate adult foliage shoots (70–)100–230 mm with (7–)11–60 pairs of leaves, straight or curved with slightly flexuous internodes. Leaf scars absent. Adult foliage leaves 4–8 mm apart, opposite-distichous, not imbricate, heterofacially twisted, shortly petiolate; petiole decurrent straight along length of internode, free part 0.2–1.7 mm; lamina of most leaves spreading but not forming a shallow ‘V’ along branch, widely erecto-patent, diverging at 45–70(–80)°, deep green, narrowly lanceolate to lanceolate (widest just above the base), those near middle of branchlets (12–)16–27(–32) × 3.2–6(–7) mm but lowest ones shorter and more ovate, all straight, coriaceous but relatively thin and flexible; margin not thickened, narrowly hyaline; surfaces equally amphistomatic, lacking a raised central area but with longitudinal vein-like striae between the rows of stomata; midrib evident, raised beneath, obscure throughout or at least distally above; apex subacute or obtuse, never mucronate; base rounded, obtuse or cuneate.

Pollen cones terminal or lateral, subtended by a bract, foliage leaf or (when terminal) pair of foliage leaves, solitary or 1–3 together, occasionally in a compound ‘inflorescence’ of 2 pairs of cones and a terminal cone, the individual cones when more than one present each subtended by a bract and shortly pedicellate; cones linear-cylindrical to narrowly cylindrical when terminal, cylindrical to ovoid when lateral; microsporophylls 44–80 per cone, in 11–15(–20) whorls; lamina triangular to ovate or somewhat wedge-shaped with buff-coloured scarious margin; microsporangia reniform, equalling the microsporophyll; pollen with hyaline body and whitish to hyaline sacci.

Female cones lateral, arising from near the base of an ultimate foliage shoot, 1 or 2 per shoot, pedunculate. Peduncle unbranched (bearing 1 cone axis) or forked at apex (bearing 2 cone axes), 2–12 mm, equalling or shorter than cone, longer than vestigial receptacle, erect or erecto-patent when young, with 3–5 pairs of bracts below the cone axis; distal part of peduncle not shed with cone. Peduncle bracts adpressed or subadpressed, ovate, c.1 × 0.5 mm, scarious-margined. Cone axis formed of 6–8 sterile bracts and 1 or 2 fertile bracts. Sterile bracts persisting till resting phase and then slowly caducous, narrowly ovate or ovate-elliptic, subacute, larger than peduncle bracts, at first horizontally spreading, later deflexed and finally caducous. Receptacle cylindrical. Fertile bract initially erect and longer than the epimatium, free from the epimatium and last sterile bract, with a narrowly wedge-shaped, prominently keeled proximal portion and free, ovate-elliptic, acute, non-keeled distal portion. Cones obovoid or pyriform, 15–23 × 10–12 mm; epimatium initially blackish-violet, later turning bright magenta and finally becoming bluish-red when ripe, not crested, with a conical, slightly hooked beak at micropylar end; micropylar beak with two short prongs that point ± vertically downwards towards the last sterile bract.

Taxonomic notes

Seemann was convinced that he was dealing with a new genus allied to Podocarpus (see Seemann, Reference Seemann1863: 33 as well as his annotation on the type, and Wasscher, Reference Wasscher1941: 424), although he nevertheless provisionally placed the species in Podocarpus. His perceptive taxonomic insight has since proved to be correct, because there is no doubt that Retrophyllum, in whatever sense it is defined, is distinct from Podocarpus.

Podocarpus filicifolius N.E.Gray, based on material from Morotai in the Moluccas, has usually been regarded as a synonym of this species, but examination of ample material both from Fiji and from New Guinea and Morotai has demonstrated that the plants from the latter areas are taxonomically distinct from Fijian material. They are treated below as Retrophyllum filicifolium.

Seeds of a fossil species allegedly closely allied to Retrophyllum vitiense were found in Pliocene beds in New Zealand by Evans (Reference Evans1937: 192, note; quoted by Florin, Reference Florin1940: 47). The fossil was not named, and the only other New Zealand fossil that has been definitely assigned to Retrophyllum is the Miocene species R. vulcanense M.Pole (Pole, Reference Pole1992). The possibility that Evans's seeds may have belonged to an extinct allied genus, such as Smithtonia or Willungia, should not be discounted.

Nomenclatural notes

Page (Reference Page1989) used Seemann (Reference Seemann1863) as the basionym reference, being presumably unaware of the earlier Bonplandia one (Seemann, Reference Seemann1862).

Linden [1869, nomen nudum (see Mill, Reference Mill2010); in Thurber (Reference Thurber1870, nomen nudum); Linden ex K. Koch (Reference Koch1871)], described Torreya bogotensis from Bogotá, Colombia; this was considered to be synonymous with Podocarpus vitiensis (Retrophyllum vitiense) by Bertrand (Reference Bertrand1874), but this is surely incorrect. If it really is a Retrophyllum at all (and there is some doubt), it is far more likely to be R. rospigliosii, which grows in Colombia. Linden's name was proposed for rejection under Art. 56 of the ICBN (McNeill et al., Reference McNeill, Barrie, Burdet, Demoulin, Hawksworth, Marhold, Nicolson, Prado, Silva, Skog, Wiersema and Turland2006) by Mill (Reference Mill2010), and this was unanimously recommended by the Nomenclature Committee for Vascular Plants (Brummitt, Reference Brummitt2011). Reveal (Reference Reveal2012) considered that the 1869 French description by Linden validated the name but Mill (Reference Mill2010) did not, and Brummitt (Reference Brummitt2011) reported that even the more detailed descriptive matter given by Koch (Reference Koch1871) was “just sufficient to validate the name”.

Phenology

Fl. Mar–Dec; fr. Jun–Feb (Smith, Reference Smith1979: 99).

Distribution

Southwest Pacific: Solomon Is. (Santa Cruz group), Vanuatu (only Banks Islands, Prov. Torba: absent from the main archipelago), Fiji. The Santa Cruz group (Solomons) and Banks Islands (Vanuatu) are adjacent. TDWG: 60 FIJ SCZ VAN. Map: Fig. 2.

Fig. 2.

Global distribution of Retrophyllum vitiense.

Bioregions: Oceania; New Guinea & Melanesia (only the Santa Cruz and Vanuatu populations)

Ecoregions: OC0105 Fiji tropical moist forests, AA0126 Vanuatu rain forests.

Ecology

Dense lowland wet zone rain forest, montane rain forest or ridge forest, where it typically grows as scattered trees on slopes and in gullies in areas with rainfall of approximately 5000 mm per annum; 50–915 m. According to Mead (Reference Mead1928), this rain forest develops on the southeastern or ‘weather’ sides of the mountains. Associates include species of Agathis Salisb., Calophyllum vitiense Turrill, Gironniera celtidifolia Gaudich. (in the understorey), Parinari insularum A.Gray, Semecarpus vitiensis (A.Gray) Engl. and Pagiantha thurstonii (Horne ex Baker) A.C.Sm. (Keppel, Reference Keppel2005; Mead, Reference Mead1928, gives additional rain forest components). It can form a unique community in which it and Calophyllum vitiense are codominant (Keppel et al., Reference Keppel, Tuiwawa, Naikatini and Rounds2011).

Chromosome number: 2n = 20 (Hair & Beuzenberg, Reference Hair and Beuzenberg1958, as Podocarpus vitiensis)

Phytochemistry

The wood of Retrophyllum vitiense contains podocarpic acid, totarol, 19-hydroxytotarol and 4β-carboxy-19-nortotarol (Cambie et al., Reference Cambie, Cox, Croft and Sidwell1983), a unique combination of phenolics among the 10 species of Podocarpaceae studied.

Plant–animal interactions

The beetle Xyleborus rameus Schedl is known to bore into the seeds of Retrophyllum vitiense in Fiji (Greenwood, Reference Greenwood1977). The drywood termite Cryptotermes domesticus (Haviland) is known to attack timber of Retrophyllum vitiense in Fiji (Gray, Reference Gray1974).

IUCN conservation assessment (global: IUCN 3.1)

The most recent assessments are as LC (Farjon, Reference Farjon2010: 943; Thomas, Reference Thomas2013), but these both referred to the species in a wide sense, including what is here recognised as the separate species Retrophyllum filicifolium. Doyle (Reference Doyle, Farjon and Page1999), using an earlier IUCN grading system, evaluated the species as circumscribed here as LRlc on both Fiji and the Solomon Islands, also equivalent to IUCN 3.1: LC. Therefore it is considered that an assessment of LC is appropriate for the species as more narrowly circumscribed here, although it should be noted that Farjon commented that, in the wider geographical area of his circumscription, the species was subject to logging throughout its range.

Uses

Retrophyllum vitiense is one of the most highly prized timber trees of Fiji, being used for high-quality furniture, etc. and for flooring, exterior work and construction (Damanu 15 in sched., K). Mead (Reference Mead1928) commented that in his time it was one of the commonest and most important timber trees of Fiji. He also mentioned its use in boat-building. However, use of the species today should be avoided, because most imports are from non-sustainable forests (Rainforest Information Centre, no date, accessed 16 September 2015). Moreover, the wood is not very decay-resistant and is therefore unsuitable for use in some situations, such as ground contact (Osborne, Reference Osborne1967). The resin is inflammable and is used by Fijians to start fires (Degener 14483 in sched., A, NY and Degener & Degener, Reference Degener and Degener1953).

2. Retrophyllum filicifolium (N.E.Gray) R.R.Mill, comb. nov. – Podocarpus filicifolius N.E.Gray, J. Arnold Arbor. 43: 74 (15 Jan. 1962) quoad descr. foliorum tantum. – Lectotype designated here: Moluccas, Morotai, “tree, 15 m”, 1949, A. Kostermans s.n. (lecto L, foliage shoots only – image, originally determined by van Steenis as Podocarpus vitiensis Seem.; isolecto A, K). The lectotype specimen at L is a mixture of juvenile foliage of Retrophyllum filicifolium and detached fruits of Nageia wallichiana; the latter are here excluded as a result of lectotypification by the foliage element. The isolectotypes cited comprise foliage only. Epitype designated here: New Guinea, Northern District, ridge above Doma, 1500 m, 14 xi 1962, P.J.B. Woods 345 (epi E, barcode E00094518: comprising adult foliage, several attached young female cones, one attached older female cone and another in packet; isoepi K–database). Figs 1A, G, K, 3A–J.

Fig. 3.

Retrophyllum filicifolium. A, Branching arrangement (Woods 345). B, Juvenile foliage shoot (Woods 241). C, Adult male shoot (Carr 15666). D, Young male cones (Carr 15666). E, Mature male cone (Carr 15666). F, Microsporophyll and microsporangia, adaxial view (Carr 15666). G, Microsporophyll and microsporangia, abaxial view (Carr 15666). H, Adult female branch (Woods 345). I, Young female cone (Woods 345). J. Mature female cone (Woods 345). Magnifications: A, B, × 0.67; C, H, × 1.5; D, E, I, J, × 3; F, G × 15. Scale bars: A, B, 6 cm; C, H, 2 cm; D, E, I, J, 1 cm; F, G, 1 mm. Drawn by Claire Banks.

Podocarpus vitiensis sensu Wasscher (Reference Wasscher1941: 425–427), Gray (Reference Gray1962: 72–74), p.p. quoad pl. novoguineensis, non Seemann (Reference Seemann1862).

Decussocarpus vitiensis sensu de Laubenfels (Reference de Laubenfels1969: 342) p.p. excl. typ., quoad syn. Podocarpus filicifolius N.E.Gray (p.p.).

Nageia vitiensis (Seem.) Kuntze sensu de Laubenfels (Reference de Laubenfels, van Steenis and De Wilde1988: 394–395) p.p. excl. typ., quoad syn. Podocarpus filicifolius N.E.Gray (p.p.).

Nageia vitiensis sensu Takeuchi (Reference Takeuchi2010: 20) non (Seem.) Kuntze (1891).

Retrophyllum vitiense sensu Li (Reference Li and Marshall2007: 346), Abdillahi et al. (Reference Abdillahi, Stafford, Finnie and Van Staden2010: 7) p.p. quoad pl. novoguineensis.

Etymology: filicifolium, Latin from filix, ‘a fern’, and folium, ‘a leaf’

“The name refers to the fern-like appearance of the pinnately leaved twigs, reminiscent of the royal fern, Osmunda regalis” (Gray, Reference Gray1962: 74).

Vernacular names: lehil (New Britain: Frodin NGF 26292), moegò (New Guinea – Wissel Lakes, Kapaukoe language, Vink & Schram BW8730 as Retrophyllum vitiense)

Distinguishing features. Retrophyllum filicifolium has for long been confused with and included within R. vitiense, as explained in the Taxonomic Problems section of this paper

Male material of Retrophyllum filicifolium can be distinguished from R. vitiense by its pollen cones with fewer microsporophylls (typically 20–32 in 5–8 whorls as opposed to 44–80 in 11–20 whorls). Terminal pollen cones, which occur in some examples of Retrophyllum vitiense, including its type specimen, have not so far been observed in R. filicifolium. Material with young female cones can be separated from Retrophyllum vitiense by the fewer sterile bracts on the female cone axis (about 4, not 6–8) that are ephemeral and quickly caducous, not persisting till the cones reach resting phase, by the fertile bract with the proximal half lacking a keel, and by the obovoid, not cylindrical, receptacle. The ripe cones also appear to be slightly larger on the basis of the few that have been seen, being c.26 × 17 mm rather than 15–23 × 10–12 mm, although this may not hold when additional material is examined. Vegetative differences include the more quickly caducous bud scales that leave pale scars on the branchlet, the typically shorter juvenile and adult ultimate foliage shoots with fewer pairs of leaves (although there is overlap) and especially the broadest point of both adult and juvenile leaves being near the middle of the lamina rather than towards the base as in Retrophyllum vitiense. There is no geographical overlap between the two species, so if the provenance is known, identification is automatic.

Tree, 27–60 m, dbh 50–130 cm. Trunk sometimes spur-buttressed at base, when adult unbranched except near top. Bark smooth, flaking, fissured, dark brown or blackish on mature trees, light or medium brown on juveniles; inner bark reddish-brown, salmon or pink; wood pale orange, straw-coloured, yellow or white. Crown not widely spreading. Terminal buds on primary branches globose or ovoid; bud scales present, in 4 series, decussate, the lowest pair longer and slightly wider than the other three pairs, all ovate or ovate-rhombic and slightly keeled, acute, brownish with very narrow paler entire margin, caducous, leaving cream, transversely narrowly rhombic scars much paler than the branchlet; those on foliage shoots usually remaining dormant, ovoid. Ultimate juvenile shoots alternate, subopposite or opposite, 65–210 mm, with 7–35 (usually 11–20) pairs of foliage leaves, occasionally biramulate or sending off a lateral scale-bearing shoot. Juvenile foliage leaves 4–7 mm apart, opposite-distichous, heterofacially turned at base, diverging at 60–85°, shortly petiolate, the petiole 0.2–1 mm, lamina lanceolate or narrowly lanceolate with the lowest ones elliptic, oblong-elliptic, ovate or narrowly ovate and considerably smaller, those near middle of branchlet 18–40 × 4.2–6 mm, the apex often indistinctly mucronate. Adult (and juvenile) trees with dimorphic shoots, most shoots bearing foliage shoots but leaders bearing scale leaves; shoot flattening heterofacial with the decurrent bases running straight down the internodes. Primary adult branches not observed. Penultimate adult branches erecto-patent to widely patent with respect to subtending branch, straight or slightly curved, bearing opposite-decussate axillary lateral foliage shoots interspersed with remote pairs of decussate subadpressed to spreading ovate scales. Ultimate adult foliage shoots 20–90 (–120) mm with 4–18(–25) pairs of leaves, straight or curved, internodes slightly flexuous. Leaf scars absent. Adult foliage leaves 2–7 mm apart, opposite-distichous, pectinate, not imbricate, heterofacially twisted, subsessile to shortly petiolate; petiole decurrent straight along whole length of internode, free part 0.2–1.5(–2) mm); laminas spreading and at least sometimes forming a shallow ‘V’ along the branchlet (cf. label of epitype), widely erecto-patent, diverging at (45–)50–80(–90)°, mid to deep green, narrowly elliptic to elliptic or oblong (widest just below the middle), those near middle of branchlets 7–25(–30) × 3–4.5(–5) mm but lowest ones shorter, all straight, coriaceous and moderately thick; margin not thickened, very narrowly hyaline; abaxial surface flat to ± convex, adaxial surface ± flat, both equally amphistomatic, lacking a raised central area but with vein-like striae alternating with the stomatal rows; midrib evident, raised beneath but obscure throughout or at least distally above; apex subacute, obtuse or sometimes broadly rounded, usually not mucronate, the base rounded, obtuse or cuneate.

Pollen cones terminal on lateral shoots arising just above bud scales of previous season, subtended by a bract, 1–several together in groups that sometimes form a raceme-like inflorescence, ellipsoid or ovoid; microsporophylls 20–32(–40) per cone, in 5–8(–10) whorls; lamina triangular to ovate with buff-coloured scarious margin; microsporangia reniform; pollen hyaline.

Female cones borne laterally from near the base of an ultimate foliage shoot of the previous year's growth, the reproductive shoot subtended by a bract. Peduncle 5–10 mm, equalling or shorter than unripe cone and always shorter than ripe cone, longer than vestigial receptacle, erect or erecto-patent when young, becoming pendulous, with 3–5 pairs of bracts below the cone axis. Peduncle bracts adpressed or subadpressed, ovate to ovate-rhombic, c.1.5 × 0.3–0.5 mm, very narrowly scarious-margined. Cone axis formed of c.4 sterile bracts and 1 or 2 fertile bracts. Sterile bracts ephemeral, present at receptivity but then quickly caducous, elliptic, obtuse to rounded, larger than peduncle bracts, at first spreading but soon becoming deflexed and falling. Receptacle obovoid, purplish-brown, glaucous. Fertile bract initially erect, its proximal half fused to the epimatium and lacking a keel. Cones obovoid or pyriform, c.26 × 17 mm; epimatium green when young becoming red when ripe, glaucous when unripe, not crested, with conical, slightly hooked beak at micropylar end.

Distribution

Malesia: Moluccas (Morotai: type locality of Podocarpus filicifolius), New Guinea, Bismarck Archipelago (New Ireland, New Britain). Morotai marks not only the westernmost limit of this species, but also of the genus Retrophyllum in Asia. TDWG: 42 MOL 43 BIS NWG-IJ NWG-PN. Map: Fig. 4.

Fig. 4.

Global distribution of Retrophyllum filicifolium.

Bioregions: Wallacea; New Guinea & Melanesia

Ecoregions: AA106 Halmahera Rain Forests, AA0112 New Britain–New Ireland Montane Rain Forests, AA0116 Northern New Guinea Montane Rain Forests.

Ecology

According to field notes on specimen labels, Retrophyllum filicifolium is a typical species of tall primary montane rain forest or ridge forest, associated with Dacrycarpus (Endl.) de Laub., emergent palms such as Gulubia Becc. and other trees including Agathis, Podocarpus L'Hér. ex Pers., Serianthes Benth., Syzygium R.Br. ex Gaertn., Casuarina rumphiana Miq., and sometimes in shade among bamboos. It occurs at altitudes of 300–1800 m, mostly between 900 and 1500 m. It would seem to occur chiefly at higher altitudes than Retrophyllum vitiense which, in Fiji and the Solomon Islands, grows mainly between 100 and 900 m.

Provisional IUCN conservation assessment: LC

This species is here reinstated for the first time after a lapse of more than 40 years (when it was synonymised with Podocarpus vitiensis by de Laubenfels, Reference de Laubenfels1968), and there has therefore been no previous conservation assessment for it as a separate species. The species appears to be widespread on New Guinea, and it is therefore regarded as Least Concern, although it is, or has been, subjected to logging.

Uses

None have been recorded. However, they are likely to be similar to those of Retrophyllum vitiense.

Group B. Bark exfoliating in short strips or pieces. Vegetative shoots dimorphic. Terminal buds protected by reduced foliage leaves; true bud scales absent. Leaves heterofacially flattened in both juvenile and adult phases. Adult leaves in 4 ranks, thick to very thick; juvenile ones distichous. Resin canal 1, situated below vascular bundle. Pollen cones in groups at branch tips, on a common peduncle (sometimes ± sessile), individual cones sessile, subtended by scale-like bracts and the lower ones in the group axillary to leaves; microsporophylls decussate (appearing spirally arranged), triangular or ovate. Female cones terminating ordinary foliage shoots, proleptic; peduncle not broadened distally, in its vegetative portion bearing spreading bracts; cone axis with 1 or 2 sterile bracts below fertile bract. Fertile bract free from epimatium, flat. Receptacle formed from 1 or 2 peduncle bracts plus the last sterile bract and the fertile bract, obovoid. Seed beaked at micropylar end. Germination epigeal. Seedling phyllotaxis decussate. – New Caledonia.

Iconography

De Laubenfels, Fl. Nouv. Caléd. 4: 51, pl. 11 f. 1–8 (1972), as Decussocarpus comptonii.

Etymology

This species is named after Robert Harold Compton (1886–1979), Cambridge botanist who, after the First World War, became director of Kirstenbosch Botanical Garden (South Africa) in 1919. Compton collected Retrophyllum comptonii several times during a field expedition to New Caledonia in 1914, although he was not the first to do so; a much earlier collection by Vieillard has been seen.

Vernacular names: palissandre (Chevalier, Reference Chevalier1957: 114; Suprin, Reference Suprin2011b)

Distinguishing features

Retrophyllum comptonii in most of its wide range has the capacity to become a tall tree up to at least 30 m, although in the far south of the island it tends to be much shorter. It is rarely if ever an aquatic. The adult foliage is mostly opposite decussate, with only the leaves in the upper part of the tree in 4 ranks. The adult leaves have a raised central area that is always narrower than the leaf margins and when dried is marked either by two (not three) parallel ridges or longitudinal wrinkles. The surface of the seed is scalloped and ridged, these low and not prominent.

Tree or shrub, 2.5–30 m tall, 12–80 cm dbh. Trunk apparently not buttressed, the bole straight and lacking branches for 10 m or more in large trees. Bark smooth when young, ± rough on older trees, peeling in short vertical strips or ragged pieces, fissured, dark grey, greyish-brown, tan or reddish-brown; inner bark brownish; wood cream or whitish. Crown pyramidal, finally rounded. Buds ovoid, protected by very reduced foliage leaves; true bud scales absent. Juvenile shoots with 1 or 2 very small leaves at base and 22–35 pairs of foliage leaves in up to 3 growth increments. Juvenile leaves 5–7 mm apart, opposite, distichous and pectinate, heterofacially turned at base, diverging at 55–65°, sessile or subsessile, lamina narrowly lanceolate or linear-lanceolate, 20–35 × c.2.5 mm on seedlings, somewhat smaller on older saplings, gradually tapered to a subacute, narrow and frequently slightly mucronate tip. Adult trees with dimorphic shoots, most shoots bearing foliage leaves but a few leader shoots bearing scale leaves and these either emitting lateral foliage shoots or terminating in foliage shoots; shoot flattening fully heterofacial on juvenile and transitional shoots but only partly so on adult branches. Primary adult branches irregularly arranged, divaricate or widely spreading, opposite, alternate or in whorls of 3. Penultimate adult branchlets erecto-patent to divaricate, ± curved, initially clad with distant, alternate, small, elliptic-ovate subadpressed scales with decurrent bases, their free laminas finally deciduous. Ultimate adult foliage shoots ± clustered at tips of penultimate branches, erecto-patent to suberect, flexuous, 40–70 mm with 8–15 pairs of leaves, subtended by 1 or 2 pairs of very reduced scale-like foliage leaves. Leaf scars absent. Lowest true adult foliage leaves smaller and relatively broader than the others; adult leaves in 4 ranks or some (on transitional shoots) opposite-decussate and distichous, crowded, 3–4 mm apart, sessile with partly twisted bases, most showing heterofacial twisting, scarcely or not imbricate, erecto-patent to suberect, mid to dark green; lamina of leaves in middle of shoot elliptic, oblong-elliptic, narrowly lanceolate or lanceolate, 6–15 × 2–5 mm, straight, thick and coriaceous; margin not thickened, narrowly hyaline; surfaces unequally amphistomatic, with more stomata on adaxial surface; midrib not visible on either surface but both surfaces with a raised, narrowly elliptic central area narrower than the margins and either longitudinally wrinkled or marked by two parallel ridges when dried; apex obtuse or broadly rounded; base obtuse or cuneate.

Pollen cones lateral (axillary) or terminal on lateral shoots of current growth, subtended by a leaf or scale-leaf, 1–5 together, pedunculate (individual cones sessile when > 1 together); peduncle shorter than cone(s), erecto-patent, bearing 1 pair of ± adpressed scales; peduncle scales greenish, keeled, ovate with decurrent base, acute, with very narrow, buff scarious margin; cones ellipsoid or ovoid, 4–6(–12) × 2.5–3 mm, straight, reddish, or greenish with a pink tinge; microsporophylls decussate but appearing spirally arranged, 16–20(–28) per cone in 4 or 5 short/3 or 4 long ‘spirals’; lamina greenish sometimes tinged pink or red, broadly triangular or deltate and abruptly narrowed to an acute, apiculate apex, with very narrow whitish hyaline margin, longer than the microsporangia; microsporangia pinkish, elliptic; pollen white or cream.

Female cones terminal on lateral foliage shoots of current growth, shortly pedunculate. Peduncle in line with shoot or erecto-patent, shorter than remainder of cone but longer than receptacle, bearing 1 (occasionally 2) cone(s), bearing 8–10 bracts in 4 or 5 decussate pairs; distal part of peduncle shed with cone. Peduncle bracts light green turning brownish green, not keeled but convex abaxially, elliptic or ovate-elliptic, 1.5–4 × c.1–1.5 mm, subacute to obtuse. Proximal sterile bracts (cone axis) absent other than the one subtending the fertile bract. Cone subtended by a non-fleshy receptacle formed from 1 or 2 peduncle bracts plus either one sterile and one fertile bracts or two fertile (or part-fertile) bracts. Receptacle narrowly obovoid or narrowly pyriform, light green at first becoming orange. Sterile bract normally 1, light green becoming pale orange, stiffly spreading to erecto-patent, elliptic to ovate-elliptic, obtuse, with scarious margin. Fertile bract light green becoming pale orange, initially erect, with median longitudinal groove, wholly free from epimatium, with reflexed, ovate free tip with acute apex. Cones pyriform, 20–25 × 13–20 mm; epimatium green becoming scarlet or deep red when ripe (occasionally blue-black, fide Munzinger et al. 1680 in sched., P), with short conical apical crest; seed beaked at micropylar end, the beak usually straight, occasionally curved. Seed surface with two ridges leading to the micropylar beak, not porous and not adapted to water dispersal.

Germination epigeal. Seedlings with two brown, erect, soon deciduous cataphylls that envelop the base of the stem and have greenish linear lanceolate tips that protect the first leaves; initial leaves of main axis cotyledon-like, c.6 pairs, separated by short, naked internodes, widely spreading and the lowest pair becoming recurved, their blades linear, 21–28 × 1.5–2 mm, longer than the leaves on the initial branchlets, basally not twisted, opposite-decussate, amphistomatic.

Distribution

New Caledonia (throughout the island except the northern half of the western coast). TDWG: 60 NWC. Map: Fig. 5.

Fig. 5.

Global distribution of Retrophyllum comptonii.

A specimen collected by Bernard Suprin (in herb. MacKee, no. 46368, P, barcoded P001655140) very closely resembles Retrophyllum minus (treated below) in branching pattern but is from a high-altitude locality in the north of New Caledonia and belongs to R. comptonii, with which it agrees in leaf characters. Vieillard 1265 from Balade (extreme NE New Caledonia) also has to belong to Retrophyllum comptonii on geographical and habitat grounds, although it was determined as Podocarpus minor Parl. by Guillaumin in 1943 – this was 6 years before Podocarpus comptonii (now Retrophyllum comptonii) was segregated from P. minor (now R. minus). The later annotation slip “= Nageia minor Carrière cf. de Laubenfels, Blumea 32: 211, 1987” is misleading and represents an uncritical up-dating of the nomenclature on the 1943 determinavit slip rather than a new determination; this is also a feature of several other specimens in the P herbarium. The specimen not unexpectedly has the characteristics of Retrophyllum comptonii. On the other hand, a specimen from Port Boisé (Le Mont-Dore) that de Laubenfels in 1972 determined as Decussocarpus comptonii has in this revision been reassigned to Retrophyllum minus, along with others from the same locality that had previously been identified as Decussocarpus minor. Gray (Reference Gray1962: 75) cited an example of Vieillard 1275 from Mt. Mou at P under Podocarpus comptonii, but I have not seen such a specimen and it is not among those imaged in the P database: all examples of Vieillard 1275 that I have seen are from low-lying localities and are Retrophyllum minus. It is possible that the specimen Gray (Reference Gray1962) cited is the one now barcoded P00188118, which is an unnumbered Pancher collection but was given the number Vieillard 1275 and mentions Mt. Mou among several collecting localities, which may not all relate to that number.

Veillon 2962 from Ouégoa is currently determined at P as Decussocarpus comptonii, but the corresponding sheet at NOU is indicated as having been identified as Falcatifolium taxoides (Brongniart & Gris) de Laub. by Veillon on the date of collection. After examining images of both sheets, on account of its leaf and pollen cone morphology I concur with Veillon's determination.

Bioregion: New Guinea & Melanesia

Ecoregion: AA0113 New Caledonia Rain Forest.

Ecology

Dense humid rain forest, moss forest or dry montane forests on mountain slopes and by rocky riverbanks; chiefly on ultrabasic rocks but also occurring on gneiss (Mt. Ignambi, Mt. Colnett) and limestone (Mt. Panié); 150–1600 m. The lower altitudinal range was given as 600 m by Farjon (Reference Farjon2010), even though de Laubenfels (Reference de Laubenfels, Aubreville and Leroy1972) had cited numerous collections from locations such as Mois de mai that are at much lower altitudes; more recent collections from as low as 150 m in the Plaine des Lacs area have also been made, and the species descends to near sea level at Baie des Pirogues in the extreme south of Grande Terre. In these low-lying locations, the species grows together with Retrophyllum minus and some individuals are very difficult to separate from it. Indeed, it is possible that some plants of Retrophyllum minus, including the epitype collection, with female cones maroon-red or greenish red, are in fact fertile hybrids between R. comptonii and the lacustrine form of R. minus, equivalent to Buchholz's Podocarpus palustris, although there is as yet no evidence to support this hypothesis other than their intermediate morphology. Associates of Retrophyllum comptonii in its more typical montane forest habitats include other gymnosperm trees such as Acmopyle pancheri Pilg., Araucaria humboldtensis J.Buchholz, A. laubenfelsii Corbasson, A. montana Brongn. & Gris, A. muelleri (Carrière) Brongn. & Gris, Austrotaxus spicata Compton, Falcatifolium taxoides (Brongn. & Gris) de Laub., Podocarpus sylvestris J.Buchholz and various angiosperm trees such as species of Nothofagus Blume.

Little or nothing is known about the dispersal of this species. The attractively coloured red ripe female cones suggest an adaptation to dispersal by vertebrates such as birds, as postulated by Farjon (Reference Farjon2010), although the flesh has been described as tasteless (McPherson 2191 in sched.). Pigeons such as Ducula goliath (Gray), the New Caledonian Imperial Pigeon, might act as dispersers, although no fruits of Podocarpaceae were recorded in the diet of that species in one limited study in the months of March and April (Barre et al., Reference Barre, Wichatitsky, Lecoq and Maillard2003).

Chromosome number: 2n = 20 (Hair & Beuzenberg, Reference Hair and Beuzenberg1958, as Podocarpus comptonii)

Phytochemistry

Cambie et al. (Reference Cambie, Cox and Sidwell1984) recorded the presence of the phenolics totarol and 19-hydroxytotarol in the wood of Retrophyllum comptonii. These were the only two phenolic compounds isolated; podocarpic acid and 4β-carboxy-9-nortotarol were both absent, in contrast to their earlier report on Retrophyllum vitiense (Cambie et al., Reference Cambie, Cox, Croft and Sidwell1983).

Mycological associations

The ascomycete fungus Caliciopsis podocarpi Huguenin was first described from two specimens; the host of the holotype was Retrophyllum minus and that of the other collection was R. comptonii (Huguenin, Reference Huguenin1969: 300). This was the first instance of Caliciopsis Peck occurring on Retrophyllum or indeed any member of ‘Podocarpus sensu lato’ (in the sense of Buchholz & Gray, Reference Buchholz and Gray1948), although the genus was later recorded from Podocarpus nubigenus (Butin, Reference Butin1970).

IUCN conservation assessment: LC (Farjon, Reference Farjon2010: 938; Jaffré et al., Reference Jaffré, Munzinger and Lowry2010: 1489; Thomas, Reference Thomas2010a)

The species is one of the most widespread of all New Caledonia's conifers, occurring throughout the island.

Uses

According to Farjon (Reference Farjon2010), the species has been extensively logged, especially at lower altitudes, for its high-quality wood used locally for flooring, furniture and similar purposes.

Iconography

De Laubenfels, Fl. Nouv. Caléd. 4: 51, pl. 11 f. 9–15 (1972), as Decussocarpus minor.

Etymology

Retrophyllum minus was originally described by Carrière (Reference Carrière1867) in the genus Nageia as N. minor Carrière. The other six species that he enumerated in that genus all had leaves measuring 40–160 mm in length, whereas he gave the length of the leaves of Nageia minor as 12–17 mm. The epithet minor (Latin for ‘smaller’; minus when neuter) therefore most probably alludes to the much smaller leaves of Retrophyllum minus compared with the leaves of the other six Nageia species, although there are no clues in his protologue as to why the epithet was chosen. Although less likely, it might also refer to the smaller stature of Retrophyllum minus compared with those six Nageia species, for which Carrière only gave actual height details for two. The epithet has nothing whatever to do with Retrophyllum minus being the smallest species in the genus Retrophyllum, as stated by Farjon (Reference Farjon2010: 938) and implied also by Gray (Reference Gray1962: 76), because, with the exception of R. vitiense (1863), of which Carrière was apparently unaware as he gave no treatment of it under any genus, all other species of Retrophyllum were first described between 1923 and 1983, long after Carrière described Nageia minor. Buchholz's epithet palustris alludes to the fact that the species is very frequently aquatic.

Vernacular name: bois bouchon (Jaffré, Reference Jaffré1988; Suprin, Reference Suprin2011a) – French for ‘cork wood’, referring to the very light, corky texture of the wood (an adaptation to its aquatic habitat)

Distinguishing features

Retrophyllum minus is a low shrub or small tree that is typically aquatic. The adult foliage is all in 4 ranks. The very thick adult leaves have a raised central area that when dried is marked by longitudinal wrinkles or by three (not two) ridges, and is typically wider than the leaf margins, although this is variable and plants with a narrower central area can be confused with Retrophyllum comptonii unless other characters are also examined. The seed surface is rough, porous and very buoyant, an adaptation to the aquatic habitat.

Small tree or shrub, frequently aquatic, normally 0.9–3.5 m tall but rarely attaining 8 m; 20–50 cm diam. at water-line. Trunk rapidly tapering from a wide, buttressed base, sometimes split from near base. Bark rough when old, peeling in short vertical strips or ragged pieces, fissured, dark grey, greyish brown or tan (colour often masked by ferruginous silt); inner bark brownish or reddish-brown; wood cream or whitish, very light. Crown open, irregular. Buds shortly ovoid to shortly ellipsoid, protected by very reduced foliage leaves; true bud scales absent. Primary branches irregularly arranged, divaricate, widely spreading or ascending; foliage branches clustered at tips of branches, erecto-patent to erect, straight, curved or flexuous. Shoots dimorphic but appearing mostly monomorphic, with only occasional scale-bearing shoots that soon pass into foliage shoots. Shoot flattening heterofacial on juvenile shoots but adult shoots ± lacking flattening. Juvenile foliage shoots with (1–)2–4 small leaves at base and 17–35 pairs of foliage leaves in 2–3 growth increments. Juvenile leaves (3.5–)4.5–6(–7.5) mm apart, opposite, distichous and pectinate, heterofacially turned at base, diverging at (40–)50–60(–70)°, sessile or subsessile, lamina narrowly lanceolate, linear-lanceolate or lanceolate-elliptic, 25–33 × 2.8–4 mm, gradually tapered to a narrow, obtuse tip. Adult foliage shoots subtended by 1–3 pairs of very reduced scale-like foliage leaves, the lowest true foliage leaves smaller and relatively broader than the others; leaves opposite-decussate in 4 ranks, crowded, sessile with bases not twisted and all with abaxial surfaces outermost, the upper leaves of each shoot partially imbricate, erecto-patent to erect, either yellow- to mid-green or grey-green; lamina of leaves in middle of shoot narrowly elliptic, elliptic, narrowly lanceolate-elliptic, lanceolate-elliptic or narrowly lanceolate, straight, very thick and coriaceous; margin thickened, extremely narrowly hyaline; midrib not visible on either surface but both surfaces with a raised elliptic central area as wide as or wider than the margins and either longitudinally wrinkled or marked by three longitudinal lines when dried; apex obtuse, broadly rounded or occasionally subacute; base cuneate or shortly attenuate.

Pollen cones lateral (axillary) or terminal on lateral shoots of current growth, subtended by a leaf or scale-leaf, 1–7 together, pedunculate (individual cones sessile when > 1 together); peduncle shorter than cone(s), erecto-patent, bearing 1–3 decussate pairs of spreading scales; peduncle scales green or grey-green, not keeled, ovate or ovate-lanceolate with ± long decurrent base and ± patent free part, subacute, with or without a narrow scarious margin; cones ellipsoid, ovoid or subglobose, 4–8 × 2–3 mm, straight; microsporophylls decussate but appearing spirally arranged, 24–40 per cone, the lamina green, ± heavily tinged violet, broadly triangular, deltate or triangular-ovate, abruptly narrowed to an acute, apiculate apex, with extremely narrow whitish hyaline margin, shorter than the microsporangia; microsporangia free, pinkish, elliptic or semicircular, stomium longitudinal, abaxial; pollen white to hyaline.

Female cones terminal on lateral foliage shoots of current growth, shortly pedunculate. Peduncle in line with shoot or erecto-patent, shorter than remainder of cone but longer or shorter than receptacle, bearing either 8–10 or 4 bracts in 4–5 or 2 decussate pairs respectively; distal part of peduncle shed with cone. Peduncle bracts light green or grey-green, keeled, elliptic, ovate-elliptic or ovate-rhombic, subacute to obtuse. Cone subtended by a non-fleshy to slightly fleshy receptacle formed from 1 or 2 peduncle bracts plus the sterile and fertile bracts. Receptacle narrowly obovoid, narrowly pyriform, narrowly obconical or cylindrical, light green or greyish-violet. Sterile bract normally 1, stiffly spreading to erecto-patent, oblong-elliptic, ovate-elliptic or elliptic, obtuse or subacute, with very narrow scarious margin. Fertile bract light green or greyish-violet, initially erect, with median longitudinal groove, wholly free from epimatium, with spreading, ovate free tip with acute apex. Cone obovoid (sometimes shortly so), ellipsoid or pyriform; epimatium either green at first, then blushing red and finally maroon-red when ripe, or grey-green and not turning red, with a shortly conical (sometimes indistinct) apical crest; seed beaked at micropylar end, the beak straight or curved. Seed with rugulose, porous texture, adapted to floating in water. Germination epigeal. Seedlings: initial leaves of main axis c.5 pairs, linear, 15–18 × c.1.5 mm excluding decurrent base, basally not twisted, opposite-decussate in a spiral arrangement, amphistomatic, separated by short, naked internodes, the youngest ones narrowly linear, apiculate and 23–31 × 1.5–2.2 mm, older ones becoming opposite in one plane, linear-elliptic or narrowly elliptic, shorter (11–20 × 1.9–3.0 mm) and bluntly mucronate at tip.

Taxonomy

Retrophyllum minus is a variable species. Some states, including the type, have ascending branches, leaves yellow- to mid-green when fresh, and female cones initially green turning red or finally maroon, as in Retrophyllum comptonii. Other states, including virtually all the aquatic material assigned by Buchholz to Podocarpus palustris and collected since, have more widely divaricate or patent branches, leaves grey-green, and female cones that are grey-green or whitish and apparently not turning red when ripe. Such plants also appear to have more microsporophylls per pollen cone (30–40) compared with plants at the other end of the spectrum of variation, which have only about 25 microsporophylls per cone. The plants with almost white, extremely glaucous ripe female cones are very distinct and easily recognisable in the field as belonging to Retrophyllum minus. This is not the case with the state having pinkish-green to red ripe cones, which often shows Retrophyllum comptonii-like characteristics. The variation within the species clearly influenced Buchholz to describe one extreme, that with cones not turning red when ripe, as Podocarpus palustris. Plants assignable to this and to typical Retrophyllum minus often occur together at the same site, however. The two states appear to be very distinct, especially when reproductive organs are present, and the fact that many of the distinguishing features are reproductive rather than vegetative also makes the case for recognising varieties within the species stronger than it might otherwise be. Matters are complicated, however, by the occurrence of low-altitude populations of Retrophyllum comptonii sympatrically with R. minus in the Plaine des Lacs area, and it is therefore possible that hybridisation may occur. Indeed, as mentioned under Retrophyllum comptonii, the morphological characters of ‘typical’ Retrophyllum minus (i.e. including its type material) are intermediate between those of Podocarpus palustris and Retrophyllum comptonii, and a hybrid origin of those populations of R. minus agreeing with its type therefore needs testing. For this reason, varieties are not here recognised within the species.

Material from the Port Boisé area (hb. MacKee 19303, 19304, 19305) was determined at Paris as both Decussocarpus minor and D. comptonii by de Laubenfels in 1972. All three sheets seem identical in foliage characters and are more similar to Retrophyllum comptonii than they are to R. minus. However, plants from the same population were analysed using RAPD by Herbert et al. (Reference Herbert, Hollingsworth, Gardner, Mill, Thomas and Jaffré2002), who found that the Rivière Trou Bleu population, coded by them as RTB, grouped with Retrophyllum minus, not R. comptonii, using this technique. Hence, all the specimens from this locality are here assigned to Retrophyllum minus.

Distribution

New Caledonia (Grande Terre, Province Sud: Prony, Baie du Sud, Lac en Huit, Rivière des Lacs, Plaine des Lacs). Map: Fig. 6.

Fig. 6.

Global distribution of Retrophyllum minus.

In the Rivière des Lacs area Retrophyllum minus coexists with plants that are assignable to Retrophyllum comptonii and as noted above some plants possess characters intermediate between the two species, suggestive of hybridisation. Most of the area of the two lakes forming Lac en Huit, one of the classic localities for Retrophyllum minus, is in Yaté commune, but the southern third of the eastern lake is in Le Mont-Dore, as well as the RM9 road (‘Route de l'Aérodrome’) along the south side of both lakes and all of the CR7 road (‘Route du Déversoir’ – the Nouméa–Yaté main road). Records from this area have therefore been assigned to one or other commune, or an unassignable boundary zone, depending on field notes and their accuracy. The whole of Grand Lac (Lac Arnaud) is in Yaté.

Bioregion: New Guinea & Melanesia

Ecoregion: AA0113 New Caledonia Rain Forest.

Ecology

Retrophyllum minus as delimited here, and by de Laubenfels (Reference de Laubenfels, Aubreville and Leroy1972), is exclusively a low-altitude species. It grows along lake and shallow river margins in areas subject to seasonal flooding, from near sea level up to 350 m but typically below 170(–250) m, very often as a swamp tree. The observation in the protologue, “Habite dans la Nouvelle-Calédonie, au sommet de très-hautes montagnes. . .” presumably applies to material of Retrophyllum comptonii, which does inhabit mountain summit habitats as well as lowlands. Before the separation of Podocarpus comptonii from P. minor by Buchholz (Reference Buchholz1949), the name Podocarpus minor was applied indiscriminately to New Caledonian plants of Retrophyllum from both lowland swamps and high mountains. Retrophyllum minus grows in single-species stands or with other tall shrubs, such as Dacrydium araucarioides Brongn. & Gris. Retrophyllum comptonii also occurs at some localities, especially in the Plaine des Lacs. Plants from lowland swamp habitats (true Podocarpus minor, = Retrophyllum minus) were often given the informal designation “type lacustre”, especially on labels of specimens collected by Bernier, while plants later segregated as Podocarpus comptonii (= Retrophyllum comptonii) were labelled “type sylvestre”. This species has been regarded as a rheophyte by van Steenis (Reference van Steenis1981: 168), and its seeds float, aided by their porous epimatium (Carlquist, Reference Carlquist and Carlquist1974: 223). Jaffré (Reference Jaffré1988) described an association in which the two dominant species were Retrophyllum minus and Dacrydium guillauminii J.Buchholz, which are otherwise two of the rarest plant species of New Caledonia. Retrophyllum minus was, according to Jaffré (Reference Jaffré1988), found on unstable soil in small coves in the 1- to 5-m-wide alluvial zone along the riverbanks. Other associates include Cloezia aquarum (Guillaumin) J.W.Dawson, Homalium kanaliense Briq., Melaleuca brongniartii F.Muell., Neocallitropsis pancheri (Carrière) de Laub., Pancheria communis Baker f. and Xanthostemon aurantiacus Schltr. Fruiting periods of Retrophyllum minus tend to coincide with periods of high water levels (Cornu et al., Reference Cornu, Sarrailh and Marion2001).

Analysis of late Quaternary sediment cores from Lac Xere Wapo in the eastern Plaine des Lacs region has revealed the presence of Retrophyllum minus pollen and wood as far back as 120,000 years ago, but that there have been some marked fluctuations in abundance; the species was abundant in the earliest zone, XW-4 (120,000–90,000 years ago), but there was an abrupt rise and fall in abundance in zone XW-3 (90,000–80,000 years ago) and a dramatic decline in zone XW-2 (80,000–45,000 years ago) that is countered by a rise in Araucaria pollen. In the most recent zone (XW-1, 45,000 years ago to present), Retrophyllum again becomes one of the dominant species but Dacrydium is the most dominant (Stevenson & Hope, Reference Stevenson and Hope2005).

Chromosome number: 2n = 20 (Hair & Beuzenberg, Reference Hair and Beuzenberg1958, two separate counts as Podocarpus minor and P. palustris)

Mycological associations

See under Retrophyllum comptonii.

Conservation status: EN B1ab(iii,v)+2ab(iii,v); C2a(i) (Thomas, Reference Thomas2010b)

At the Madeleine site, which has been subjected to much trampling by the public, who have used the rare trees as diving platforms (Province Sud, 2012), there has been extensive planting since 1999 of Retrophyllum minus (1200 trees: Province Sud, 2012) and other rare gymnosperms, such as its associates Dacrydium guillauminii and Neocallitropsis pancheri. Germination success of Retrophyllum minus there has been very good (Cornu et al., Reference Cornu, Sarrailh and Marion2001; Province Sud, 2012).

Uses

No uses of Retrophyllum minus are reported in recent literature. Sebert (Reference Sebert1874), however, commented that, among the New Caledonian Podocarpaceae, Podocarpus minor was “l'espèce la plus interessante sous le rapport industriel”; this opinion of course also embraced Retrophyllum comptonii, which at that time was included in a broad concept of Podocarpus minor as previously stated.

Group C. Bark exfoliating as large plates. Vegetative shoots monomorphic. Terminal buds naked. Adult leaves distichous and heterofacially flattened in 2 ranks, relatively thin. Resin canals (1)3(5) median plus 2–6 lateral ones round leaf margin. Pollen cones in racemose inflorescences subtended by leaves, the raceme branches opposite, individual cones ± pedicellate, subtended by leaf-like bracts; microsporophylls spirally arranged, lanceolate. Female cones borne on specialised lateral reproductive shoots, sylleptic; peduncle broadened distally, in its vegetative portion bearing small spreading bracts that may or may not resemble reduced leaves; cone axis with 6–8 sterile bracts below fertile bract. Fertile bract with its basal half firmly adnate to epimatium, navicular. Receptacle formed from fertile bract and last sterile bract, cylindrical. Seed not beaked at micropylar end. Germination hypogeal. Seedling phyllotaxis spiral. – South America.

5. Retrophyllum rospigliosii (Pilg.) C.N. Page, Notes Roy. Bot. Gard. Edinburgh 45: 380 (22 Feb. 1989 [‘1988’]). – Podocarpus rospigliosii Pilg., Notizbl. Bot. Gart. Berlin 8: 273 (1 Feb. 1923). – Decussocarpus rospigliosii (Pilg.) de Laub., J. Arnold Arbor. 50: 347 (15 Jul. 1969). – Nageia rospigliosii (Pilg.) de Laub., Blumea 32(1): 211 (3 Feb. 1987). – Type: Peru, Oxapampa, N. Esposto 556 (holo B–extant, images seen; photos of holo at A, F [negative #11579, and a second duplicate photo of the B holotype mounted on a herbarium sheet], GH, NY); iso S (2 sheets: SBT W 430–image, S–Regnell 7799–image, both fragments ex Berlin) and S spirit collection–database). Farjon (Reference Farjon2010: 941) indicated that the holotype was at USM (Universidad Nacional Mayor de San Marcos, Peru) but, if there is a duplicate there, it is highly improbable that Pilger saw it and, if it exists, it will be another isotype. Figs 1C, F, J, M, 7A–H, 9D, E.

Fig. 7.

Retrophyllum rospigliosii. A, Branching arrangement (Pennington 1433). B, Juvenile foliage shoot (Roldán et al. 3168). C, Adult male shoot (Pennington 1433). D, Young male cones (Pennington 1433). E, Mature male cone (Pennington 1433). F, Microsporophyll and microsporangia, adaxial view (Carr 15666). G, Microsporophyll and microsporangia, abaxial view (Pennington 1433). H, Adult female branch (Bunting 4939). Magnifications: A, B, × 0.67; C, H, × 1.5; D, E, × 3; F, G, × 15. Scale bars: A, B, 6 cm; C, H, 2 cm; D, E, 1 cm; F, G, 1 mm. Drawn by Claire Banks.

?Torreya bogotensis [Linden, Cat. n. 25 (1870) et ex Thurb. in Bull. Torrey Bot. Club 1: 7 (1870) nom. inval.]; Linden ex K.Koch, Wochenschr. Vereines Beförd. Gartenbaues Königl. Preuss. Staaten 14(25): 199 (1871), nom. utique rej. (Mill, Reference Mill2010; Brummitt, Reference Brummitt2011: 1207). – Type not indicated.

Podocarpus montanus sensu Knuth in Fedde, Repert. Spec. Nov. Regni Veg. Beih. 43: 95 (1926) non (Humb. & Bonpl. ex Willd.) Lodd. (1836).

Etymology

Podocarpus rospigliosii is named after Dr Carlos Rospigliosi Vigil, who led the first expedition sent out in May 1918 by the newly founded Museo de Historia Natural in Lima, of which Rospigliosi was the inaugural director, and in which both Nicolás Esposto (collector of the type of P. rospigliosii) and Rospigliosi participated. In 1922, Rospigliosi sent specimens of Podocarpus rospigliosii to Pilger in Berlin, who described it as new some months later.

Vernacular names: pino, pino hayuelo, pino de montaña, pino colombiano (Colombia: Villamizar & Suevara 63, UDBC), pino hembrito (Colombia, Santander: Cardenas & Oliveros 198, COL–database), chaquiro crespo and chaquiro colorado (Colombia: Vásquez Correa, Reference Vásquez Correa2010), pino negro (Colombia: Villamizar & Suevara 63, UDBC), diablo fuerte (Cajamarca, Peru: Vicuña-Miñano & León, Reference Vicuña-Miñano and León2003), pino romerón, pino silvestre (throughout Colombia); pino de Pacho (Cundinamarca, Colombia); romerillo macho (Becerra-Montalvo & Zevallos-Pollito, Reference Becerra-Montalvo and Zevallos-Pollito2014), romerillo blanco, diablo fuerte, alcumano, ulcumano, utcumanu (NW Peru: Vicuña-Miñano & León, Reference Vicuña-Miñano and León2003; Vicuña-Miñano, Reference Vicuña-Miñano2005), pino criollo (Mérida, Venezuela: Aranguren & Márquez, Reference Aranguren and Márquez2011)

Some of the above, such as diablo fuerte and ulcumanu, are shared with other species of Podocarpaceae.

Distinguishing features

Retrophyllum rospigliosii is distinguishable from the only other currently known South American species of its genus, R. piresii, by its more lanceolate leaves that are acute to shortly acuminate and frequently abruptly narrowed just below the tip, and by its more shortly ellipsoid to subglobose female cones that are narrowed at the base. The foliage shoots are at all stages arranged ± alternately, whereas in Retrophyllum piresii the adult shoots (the only state known) are opposite. The peduncle of the female cone bears reduced leaves, not scales as in Retrophyllum piresii. Several of these characters were not noted when the original description of Retrophyllum piresii was drawn up and serve as additional justification for the recognition of two separate species. Eckenwalder (Reference Eckenwalder2009), however, reduced Retrophyllum piresii to synonymy within R. rospigliosii on the grounds that, in his opinion, the specimen known to him fell within the range of variation of the latter species. Retrophyllum rospigliosii can be distinguished from the Fijian R. vitiense and the New Guinea R. filicifolium (the only other species in the genus that have all leaves not imbricate) by its bark exfoliating in large plates (not small pieces), the naked buds (in R. vitiense and R. filicifolium protected by bud scales), the foliage shoots lacking scale leaves, the blade of the microsporophyll longer than the microsporangia (not equalling or shorter than them), the more acute female cone peduncle bracts that lack even a narrow scarious margin, the much more pronounced zigzag arrangement of the decurrent leaf bases (which in fresh material are bright green and contrast strongly with the brownish colour of the rest of the branchlet) and the ellipsoid to subglobose (not obovoid) female cones. Prumnopitys montana (Humb. & Bonpl. ex Willd.) de Laub., which has in the past been confused at least once with Retrophyllum rospigliosii (Knuth, 1926: see synonymy), has spirally arranged leaves that appear alternate-distichous and the shoot flattening is homofacial, not heterofacial, so that the leaves along both sides of the shoots are turned with their abaxial surfaces uppermost; the laminas are also almost all obovate, rather than lanceolate as in R. rospigliosii.

Evergreen tree 20–45 m; dbh to 250 cm (Vicuña-Miñano & León, Reference Vicuña-Miñano and León2003). Trunk of mature trees buttressed at base, unbranched for up to 28 m although branching in young trees begins at c.3 m. Bark of trunk smooth, bluish-black, exfoliating in large plates; wood reddish-yellow. Crown ovoid or umbrella-shaped, much branched. Branchlets of last two orders erecto-patent, straight or slightly curved; ultimate branchlets usually alternate, adult ones 25–140(–210) mm with 5–32(–50) pairs of leaves, juvenile ones up to 270 mm (perhaps more) with up to at least 40 pairs of leaves. Leaf scars absent. Buds naked. Leaves on last two orders of branching all of one type (scale leaves absent). Leaves on penultimate axes soon caducous except when subtending branch bases or when branch does not develop further branching, arranged in 2 stepped opposite-distichous parallel ranks; decurrent bases crossing over to opposite side of branchlet and forming a green zigzag pattern that contrasts strongly with the dark brown bark when fresh; lamina larger than those of ultimate shoots, ± ovate-elliptic. Juvenile leaves of ultimate shoots unequally amphistomatic, 4–5 mm apart, opposite-distichous, pectinate, subsessile; lamina horizontally spreading, mid to deep green, narrowly lanceolate or lanceolate, 15–23 × 3–6 mm, straight, coriaceous, initially dorsally keeled when unfolding but both surfaces becoming flat, with vein-like striae between rows of stomata, midrib slightly raised on both surfaces, apex subacute or obtuse, base obtuse. Adult leaves equally or unequally amphistomatic, 3–5 mm apart throughout on most foliage shoots but up to 10 mm apart on leader shoots and sometimes in lower 1/3 of foliage shoots, opposite-distichous, pectinate, not imbricate, subsessile (free part of petiole 0.3–0.5 mm); lamina spreading and forming a shallow ‘V’ along branch, erecto-patent, diverging at 45–60(–70)°, mid to deep green, elliptic, lanceolate, ovate, ovate-elliptic, obovate-elliptic or obovate, 7–14 × 3–5 mm, straight, thinly coriaceous, the margin only slightly thickened, both surfaces flat with vein-like striae alternating with the stomatal rows, midrib only slightly raised but distinct on both surfaces, the blade frequently (but not always) abruptly narrowed distally below the acute or shortly blunt-acuminate apex that is never mucronate, the base obtuse or cuneate, the petiole decurrent along the whole length of the internode.

Pollen cones subtended by a foliage leaf, lateral in leaf axils of current growth, solitary or in groups or primary clusters of up to 3, often with an opposite pair of cones below; common peduncle present when cones in clusters but otherwise absent, individual cones shortly pedicellate and subtended by a pair of bracteoles; peduncle (when present) with 4–6 decussate, ovate, acute scales; cones greenish brown when young turning pinkish brown, ovoid when young becoming cylindrical, straight or curved from base, 8–12 mm when shedding pollen; microsporophylls 28–36, decussate in 7–9 whorls of 4, lamina longer than microsporangia, triangular-lanceolate, narrowly lanceolate or lanceolate, with entire or finely crenulate whitish hyaline scarious margin, the apex acute and incurved; microsporangia reniform; pollen snow-white or cream.

Female cones borne on current year's growth, terminal on specialised lateral reproductive shoots bearing reduced, ovate, acute leaves. Peduncle deflexed-patent to pendulous, its lower portion bearing 1 or 2 pairs of ovate-elliptic, leaf-like peduncle bracts and passing into the cone axis which bears 3 or 4 pairs of decussate, elliptic to obovate leaf-like sterile bracts (sometimes with interspersed small scales) with acute apex and glaucous on adaxial surfaces; apical part of cone axis (above last pair of sterile bracts) forming an indistinct cylindrical receptacle that becomes violet when ripe and is often shed with the cone together with the fertile bract. Fertile bract initially erect, with its basal part adnate to epimatium, distal part navicular and free. Female cone shortly ellipsoid to subglobose, 16–30 × 12–18 mm (the seed proper c.15 × 11 mm); epimatium violet and ± glaucous especially when not fully ripe, somewhat asymmetrical with the adaxial side rather more convex than the abaxial, with a narrowed base and very short conical distal crest that sometimes breaks off and with a straight, conical beak at micropylar end; micropylar beak with two short prongs that point slightly obliquely (towards the abaxial side) downwards towards the last sterile bract; cone resiniferous within; seed proper rounded at the distal end, narrowed to a conical spine at the micropylar end.

Germination apparently hypogeal (first foliage shoot emerging at soil level, cotyledons not visible). Seedlings with alternate-spiral phyllotaxis, the main axis with relatively long internodes and rather widely spaced, alternate-spiral leaves similar to those of the foliage shoots; foliage shoots with 12–25 pairs of leaves (the lower ones with fewer pairs than the upper), the leaves in 4 ranks (2 sets of 2) that are flattened distichously to form a shallow ‘V’ along the shoot with the largest leaves near the middle of the shoot.

Notes

Adult foliage shoot length (and consequently number of leaves) is very variable, being dependent at least partly on position on the tree and reproductive condition; individual ultimate foliage shoots in the upper or fertile regions of the tree are much shorter than those lower down (which also have longer leaves than those higher up). Neill & Salinas 7202 and Morales et al. 867, both from Ecuador, are atypical in having adult foliage leaves diverging from the axis mostly at angles greater than 65°, with many almost at a right angle especially in the former specimen. The adult foliage shoots of Neill & Salinas 7202 are also unusually long (to > 20 cm, with up to 50 pairs of leaves), whereas those of Morales et al. 867 are much shorter. The habitat and altitude (tropical forest at 600–675 m) of these two gatherings are also atypical for Retrophyllum rospigliosii. The habitat and foliage angle of both specimens are more characteristic of Retrophyllum piresii, which has not been recorded from Ecuador. However, Neill & Salinas 7202 has the alternate branching and lanceolate, acute leaves that are typical of Retrophyllum rospigliosii and consequently it is assumed to be a slightly divergent form of that species. In Morales et al. 867 most branches are opposite as in Retrophyllum piresii, but a few are alternate. Another specimen [Peru. Puno: Río Candamo, fila at mouth of Río Guacamayo, ridge top forest with cloud forest aspects, 13°30′S 69°50′W, 870 m, 28 v 1992, Gentry et al. 77310 (MO)] is also problematic. It is again from a rather low altitude for Retrophyllum rospigliosii, and the branches are opposite as in R. piresii. Unfortunately, it is sterile so it is not known whether it would have the distinctive long ellipsoid female cones that are so characteristic of Retrophyllum piresii. It was determined as the latter species [on the field label, as Nageia piresii (Silba) de Laub.] by de Laubenfels in 1994, which remains the current determination, but its true status remains uncertain.

Distribution

Northern and Western South America. W Venezuela (Táchira, Mérida, Trujillo), E Colombia (Antioquia, Cundinamarca, Magdalena, Norte de Santander, Santander del Sur), Ecuador (Napo, one collection; also see Jørgensen & Léon-Jánez, 1999), NW & C Peru (Gray & Buchholz, Reference Gray and Buchholz1948: 120; Torres-Romero, Reference Torres-Romero, Pinto and Lozano1988; Brako & Zarucchi, Reference Brako and Zarucchi1993: 2; Vicuña-Miñano, Reference Vicuña-Miñano2005: 286), NE Bolivia (Dpto. La Paz: Prov. Bautista Saavedra and Prov. Franz Tamayo, 3 collections: Zenteno-Ruiz, Reference Zenteno-Ruiz2007 and more recently collected specimens cited below). Andean Region (Northern Andean Province). TDWG: 82 VEN 83 BOL CLM ECU PER. Map: Fig. 8.

Fig. 8.

Global distribution of Retrophyllum rospigliosii.

Bioregions: Northern Andes, Central Andes

Ecoregions: NT0105 Bolivian Yungas, NT0109 Cauca Valley Montane Forests, NT0118 Cordillera Oriental Montane Forests, NT0121 Eastern Cordillera Real Montane Forests, NT0136 Magdalena Valley Montane Forests (in which it and Podocarpus oleifolius D.Don are two of the most dominant trees), NT0153 Peruvian Yungas, NT0159 Santa Marta Montane Forests, NT0175 Venezuelan Andes Montane Forests (where again it is one of the most dominant trees along with Prumnopitys montana and Podocarpus oleifolius together with assorted dicot trees).

Ecology

Montane forests, cloud forest; (600–)1500–3750 m (generally at higher altitudes than Retrophyllum piresii; the three records from below 1000 m relate to the three atypical specimens from Ecuador and Peru discussed above, all of which have some features of Retrophyllum piresii). Retrophyllum rospigliosii grows best on slightly sloping ground, fertile river beds and small depressions, on wet, deep, fertile acid clay or clay/sand soils with good to slow drainage; it is not tolerant of either swampy or drought conditions. It requires constant humidity and cloudy conditions with an annual rainfall of 1500–2500 mm and an annual average temperature of 10–18°C (Nieto & Rodriguez, Reference Nieto, Rodriguez and Vozzo2003). It plays an important role in intercepting rainfall: a Retrophyllum rospigliosii plantation at La Mucuy (Mérida, Venezuela) intercepted 42% of precipitation, almost the same percentage as the 45% intercepted by nearby montane cloud forest (Ataroff, Reference Ataroff2002). The seeds of Retrophyllum rospigliosii are recalcitrant, with a viability in storage at 12°C of 3–6 months but with a drastic drop in viability after 4 months (Ceballos-Freire & López-Ríos, Reference Ceballos-Freire and López-Ríos2007).

In Cajamarca, Peru, Retrophyllum rospigliosii occurs in undisturbed and fragmented primary forest together with Cecropia polystachya Trécul, Cinnamomum triplinerve (Ruiz & Pav.) Kosterm., Heliocarpus americanus L., Ladenbergia magnifolia (Ruiz & Pav.) Klotzsch, Otoba parvifolia (Markr.) A.H.Gentry, Piptocoma discolor (Kunth) Pruski, Ruagea insignis (C.DC.) T.D.Penn., Virola calophylla Warb., etc. (Vicuña-Miñano & León, Reference Vicuña-Miñano and León2003).

Phytochemistry

Ninety-one compounds have been isolated and identified from the essential oil of the ‘fruits’ of Retrophyllum rospigliosii (Quijano-Celis et al., Reference Quijano-Celis, Gaviria, Vanegas-López, Ontiveros, Echeverri, Morales and Pino2010). The essential oil from the leaves yielded 68 compounds (Quijano-Celis et al., Reference Quijano-Celis, Gaviria, Vanegas-López, Ontiveros, Echeverri, Pino and Morales2013). In both cases, limonene (38% in ‘fruits’, 43% in leaves) and α-pinene (16% in ‘fruits’, 18% in leaves) comprised the largest fractions. Retrophyllum rospigliosii contains several norditerpene dilactones that were previously known only in Podocarpus and/or Nageia, including nagilactones E, F and G, β-sitosterol and a derivative of the latter (Amaro-Luis & Carroz, Reference Amaro-Luis and Carroz1988), as well as a unique compound, rospiglioside (Amaro Luis et al., Reference Amaro Luis, Amesty, Montealegre and Bahsas2006). As well as rospiglioside, Amaro Luis et al. (Reference Amaro Luis, Amesty, Montealegre and Bahsas2006) isolated ferruginol, sugiol, sugiol acetate, totarol, totarol acetate, 4β-carboxy-19-nortotarol and 16-hydroxy-4β-carboxy-19-nortotarol from the leaves of Retrophyllum rospigliosii, but the phenolics of the wood do not appear to have been studied. Its biflavones are similar to those found elsewhere in Podocarpaceae and include sciadopitysin, podocarpusflavone A, podocarpusflavone B, amentoflavone, 7,4′,7′′,4′′′-tetra-O-methyl-amentoflavone, 7,4′,7′′-tri-O-methyl-amentoflavone, 7,7′′-di-O-methyl-amentoflavone, sequoiaflavone and heveaflavone (Chaabi et al., Reference Chaabi, Antheaume, Weniger, Justiniano, Lugnier and Lobstein2007; Amaro-Luis et al., Reference Amaro-Luis, Amesty, Bahsas and Montealegre2008). The biflavones act as phosphodiesterase inhibitors and may therefore have potential as therapeutic drugs for a wide variety of medical conditions (Rahimi et al., Reference Rahimi, Ghiasi, Azimi, Fakhari and Abdollahi2010 and work cited therein). However, the biflavones and other compounds of Retrophyllum rospigliosii assayed were found to lack any antimycotic activity against three pathogenic fungi (Niño et al., Reference Niño, Espinal, Mosquera and Correa2007).

Plant–animal interactions

In Colombia, the seeds of Retrophyllum rospigliosii are eaten by the endangered yellow-eared parrot or loro orejiamarillo, Ognorhynchus icterotis (Massena & Souanc) (Botero-Delgadillo & Páez, Reference Botero-Delgadillo and Páez2011). Whether this activity effects dispersal is not known.

Retrophyllum rospigliosii is the one of the hosts of at least three members of the wood-boring beetle family Scolytidae, namely Araptus impensus (Wood), Platypus secus Wood (Wood & Bright, Reference Wood and Bright1992, as Podocarpus ‘raspigliosii’) and Thamnophthorus impensus Wood (Schedl, Reference Schedl1965). Some of the paratypes of Platypus secus were collected from Retrophyllum rospigliosii logs at the beetle's type locality in La Carbonera Experimental Forest, Mérida, Venezuela (Wood, Reference Wood1971, as Podocarpus ‘raspigliosii’).

Mycological associations

Retrophyllum rospigliosii is the only known host of Tripospora venezuelensis E.Müll. (Coryneliales), which is known only from the type collection from Mérida, Venezuela (Müller & Dennis, Reference Müller and Dennis1965; Benny et al., Reference Benny, Samuelson and Kimbrough1985). The mycorrhiza of Retrophyllum rospigliosii have been investigated by Furman (Reference Furman1970) and Guerrero Forero & Hodson de Jaramillo (Reference Guerrero Forero and Hodson de Jaramillo1988). The latter team found that Retrophyllum rospigliosii had a mixture of vesicular arbuscular mycorrhiza that included several species of Acaulospora Gerdemann & Trappe (Acaulosporaceae) and Glomus Tul. & C.Tul. (Glomeraceae).

Conservation status (global): VU (A2acd) (Gardner & Thomas, Reference Gardner and Thomas2013)

Logging of this valuable timber tree has reduced or fragmented most of the formerly rather extensive stands of this species. Whole mountainsides of the species in Peru were clear-felled in the 1980s for timber, and the species is there now reduced to scattered individuals (M. Gardner, Royal Botanic Garden Edinburgh, pers. comm., 7 Feb. 2012). Yaguana et al. (Reference Yaguana, Lozano, Neill and Asanza2012) have commented that the forest at Numbala (Ecuador), at the edge of Podocarpus National Park, is one of the last remnants of its type. Retrophyllum rospigliosii is regarded as NT in Colombia (Barragan Bedoya & Valdés Torres, Reference Barragan Bedoya and Valdés Torres2011).

Uses

The fruits are reported as edible (Gray & Buchholz, Reference Gray and Buchholz1948; Buchholz & Gray, Reference Buchholz, Gray and Steyermark1957; and several specimen labels). The tree is often cultivated in gardens and parks in Colombia (Nieto & Rodriguez, Reference Nieto, Rodriguez and Vozzo2003) and Peru (Brako & Zarucchi, Reference Brako and Zarucchi1993), and is used in forestry in Colombia (Nieto & Rodriguez, Reference Nieto, Rodriguez and Vozzo2003, who also give details of recommended practices for seed harvesting and silviculture) as well as in Venezuela (Ruiz Terán 918 in sched., K, MO). The wood is of very good quality and is widely used in construction in Venezuela and Colombia. It is easily worked and is used to make furniture, boxes, cabinets, veneer, pencils, paper pulp and other items (Nieto & Rodriguez, Reference Nieto, Rodriguez and Vozzo2003). It is also used to make handcrafted decorative objects (Feuillet Hurtado et al., Reference Feuillet Hurtado, Macias Pinto and Chito Cerón2011). Its characteristics have been described recently by Vásquez Correa & Alcántara Vara (2009) and Vásquez Correa et al. (Reference Vásquez Correa, Alcántara Vara and Herrera Machuca2010). The logging cycle for the species was estimated at 109 years by Becerra-Montalvo & Zevallos-Pollito (Reference Becerra-Montalvo and Zevallos-Pollito2014).

6. Retrophyllum piresii (Silba) C.N. Page, Notes Roy. Bot. Gard. Edinburgh 45: 380 (22 Feb. 1989 [‘1988’]). – Decussocarpus piresii Silba, Phytologia 54: 461, t. 1 (10 Dec. 1983). – Nageia piresii (Silba) de Laub., Blumea 32(1): 211 (3 Feb. 1987). – Type: Brazil: Território de Rondônia, Serra Pacas Novos, Seringal S. Luiz, 50 km east of Rio Pacas Novos, 14 viii 1976, N.A. Rosa, J.M. Pires, W. Rodriques, S. Barros 856 [misprinted in protologue as ‘Rosa & Pires 586’] (holo US, iso K–database, L–image, MG–image, MO, NY, R–2 sheets, images, RB–image). Fig. 9A–C.

Fig. 9.

Retrophyllum piresii. A, Branching arrangement (Rosa et al. 856). B, Adult female branch (Rosa et al. 856). C, Mature female cone (Rosa et al. 856). Retrophyllum rospigliosii. D, Young female cone (Vasquez et al. 20459). E, Mature female cone (Bunting 4939). Magnifications: A, B, × 0.67; C, × 1.5; D, E, × 3. Scale bars: A, 6 cm; B, 2 cm; C, D, E, 2 cm. Drawn by Claire Banks.

Etymology

Retrophyllum piresii is named after João Murça Pires (1917–1994), Brazilian botanist, who published (with C. Mainieri) a revision of Podocarpus in Brazil (Silvic. Sao Paulo 8: 1–24, 1973) and who was one of those who collected both the type and the only two other currently known specimens of wild origin, made a few days earlier and on the same day.

Vernacular name: pinheiro-da-amazónia (Secco et al., Reference Secco, Silva do Rosário, Rodrigues, Giulietti, Rapini, Gomes de Andrade, de Queiroz and Cardano da Silva2009)

Distinguishing features

This species shares many characters with its South American congener Retrophyllum rospigliosii but, as was noted in the protologue, it can be distinguished by its elliptic (not lanceolate) leaves with ± parallel sides, and the more ellipsoid female cones that are not narrowed at the base. Additional characters not described by Silba that distinguish it from Retrophyllum rospigliosii are the bracts on the female peduncle all very reduced and scale-like (not foliar), the obtuse leaf apices (misleadingly described in the protologue as ‘bluntly acute’) and the leaves never abruptly narrowed just below the apex (normally so in Retrophyllum rospigliosii). The opposite branching with leaves on penultimate branches opposite and not forming stepped ranks also separates Retrophyllum piresii from the vast majority of specimens of R. rospigliosii, although a few specimens of the latter approach R. piresii in these features, as noted above. Further differences may become apparent when more material is collected (male and juvenile collections of Retrophyllum piresii are particularly desirable to complete the description). The two species also appear to be ecologically separated, with Retrophyllum piresii inhabiting lowland swamp forest at altitudes of less than 1000 m and R. rospigliosii normally occurring in montane and cloud forests, nearly always above 1500 m, although there are one or two low-altitude records as discussed under that species.

Evergreen tree c.30 m tall and up to 2.5 m dbh, adult tree branching at c.15 m above base. Trunk (fide Farjon, Reference Farjon2010) straight and erect, in large trees lacking branches for 15 m or more. Bark (imperfectly known) medium to dark brown outside, purplish to dark brown inside, smooth on branchlets; wood reddish brown. Crown rounded (fide Farjon, Reference Farjon2010: 940). Branchlets of last two orders erecto-patent, slightly curved; ultimate branchlets usually opposite, 50–130 mm with 24–38 pairs of leaves, penultimate ones 180–210 mm. Leaf scars absent. Buds obconical, naked. Leaves on last two orders of branching all of one type (scale-leaves absent). Leaves on penultimate axes normally soon caducous although persistent when subtending branch bases and when axis has not developed further branching, opposite and spreading or orientated so that both leaves of each pair are suberect, not forming stepped ranks. Juvenile foliage not known. Adult foliage leaves unequally amphistomatic, 4–5 mm apart, opposite-distichous, pectinate, not imbricate, subsessile (petiole 0.2–0.5 mm); lamina spreading and forming a shallow ‘V’ along branch, erecto-patent, diverging at 65–80°, mid to deep green, elliptic, oblong-elliptic or obovate-elliptic (never lanceolate), 9.5–11 × 2–2.5 mm in middle of shoot and 5–6 × 1.7–2.5 mm near base, straight, thinly coriaceous, the margin only slightly thickened, both surfaces flat with vein-like striae alternating with the stomatal rows, midrib only slightly raised on both surfaces or not at all, sometimes obscure distally on abaxial surface, the apex obtuse and the blade never abruptly narrowed below it, usually with an indistinct mucro, the base obtuse, the petiole decurrent along the whole length of the internode. Pollen cones unknown. Female cones borne on previous year's growth, terminal on specialised lateral shoots bearing very reduced scale-leaves or bracts. Peduncle c.15–16 mm, about 2/3 length of cone, deflexed-patent to pendulous, its lower portion bearing at least 3 pairs of decussate scale-like, shortly ovate or elliptic bracts, its apical part together with the fertile bract forming an indistinct, cylindrical receptacle that is shed with the cone. Fertile bract with basal part adnate to epimatium, distal part free and navicular. Female cone with epimatium pecan-brown turning reddish when mature, 19–22 × 11–14 mm, distinctly ellipsoid with a shortly conical distal crest, not narrowed at the base, the seed proper slightly smaller.

Taxonomic notes

Silba's protologue, and later description (Silba, Reference Silba1986: 78), are both very brief and give little detail concerning many aspects of its morphology, but no other taxonomic account of this species appears to have been published until now except that of Farjon (Reference Farjon2010), which added some details of trunk and habit. Further collections of the species from the type locality are badly needed, particularly of the unknown juvenile stages and male cones.

Distribution

W Brazil (SW Rondônia: Serra dos Pacaás Novos), near the border with lowland NE Bolivia. More recently recorded from Bolivia and Peru in similar habitats (D.J. de Laubenfels, pers. comm., 24 October 2005). These records require confirmation; one problematic sterile specimen, determined as Retrophyllum piresii by de Laubenfels, is discussed above under R. rospigliosii. For the time being, the species is regarded as endemic to Brazil and known from the two wild gatherings (both female) and one sterile cultivated collection cited here. Map: Fig. 10.

Fig. 10.

Global distribution of Retrophyllum piresii.

Bioregion

Amazonia. Ecoregion: NT0135 Madeira-Tapajós moist forests; perhaps also in NT0166 Southwest Amazon moist forests.

Ecology

Lowland tropical swamp forest; 250–300 m.

Phenology

Reputedly fertile in January (de Oliveira, Reference de Oliveira2012).

Conservation status (global, IUCN 3.1): DD (two independent assessments: de Oliveira, Reference de Oliveira2012; Gardner, Reference Gardner2013)

The only confirmed locality from which wild material has been gathered is within a National Park. Insufficient is known about the extent and area of occurrence, or of potential threats, to award an assessment other than DD and this will not change until further research can be done on the species in the field. The species is in cultivation (see cited specimens).

Uses

None have been reported although it is likely to have wood of high quality similar to that of R. rospigliosii.