Skip to main content
×
×
Home

Information:

  • Access
  • Cited by 1
  • Cited by
    This article has been cited by the following publications. This list is generated based on data provided by CrossRef.

    Grillenzoni, Claudia Monegatti, Paola Turco, Elena Conti, Stefano Fioroni, Chiara Fontana, Daniela and Salocchi, Aura Cecilia 2017. Paleoenvironmental evolution in a high-stressed cold-seep system (Vicchio Marls, Miocene, northern Apennines, Italy). Palaeogeography, Palaeoclimatology, Palaeoecology, Vol. 487, p. 37.


    ×

Figures:

Actions:

      • Send article to Kindle

        To send this article to your Kindle, first ensure no-reply@cambridge.org is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about sending to your Kindle. Find out more about sending to your Kindle.

        Note you can select to send to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.

        Find out more about the Kindle Personal Document Service.

        Chemosymbiotic bivalves from Miocene methane-seep carbonates in Italy
        Available formats
        ×
        Send article to Dropbox

        To send this article to your Dropbox account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your <service> account. Find out more about sending content to Dropbox.

        Chemosymbiotic bivalves from Miocene methane-seep carbonates in Italy
        Available formats
        ×
        Send article to Google Drive

        To send this article to your Google Drive account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your <service> account. Find out more about sending content to Google Drive.

        Chemosymbiotic bivalves from Miocene methane-seep carbonates in Italy
        Available formats
        ×
Export citation

Abstract

Eleven species of chemosymbiotic bivalves are reported from middle to late Miocene methane seep deposits (‘Calcari a Lucina’) in the Italian Apennines, including seven new species and one new genus. The new species are Bathymodiolus (s.l.) moroniae and B. (s.l.) miomediterraneus among the Bathymodiolinae and Archivesica aharoni, A. apenninica, A. strigarum, and ‘Pliocardiaitalica among the Vesicomyidae; specimens from the middle Miocene of Deruta are reported as Archivesica aff. aharoni. Samiolus iohannesbaptistae new genus new species is introduced for an unusual mytilid with a commarginally ribbed surface, which might be the first non-bathymodiolin mytilid obligate to the seep environment. The two large lucinid species from which these deposits derived their informal name ‘Calcari a Lucina’ are identified as Meganodontia hoernea (Des Moulins, 1868) and Lucinoma perusina (Sacco, 1901). With Chanellaxinus sp., we report the first thyasirid from a Neogene deep-water seep deposit in Italy and the first fossil occurrence of this genus.

Introduction

Limestone deposits yielding large lucinid bivalves have been known for centuries from the Miocene deposits in Italy, and were termed ‘Calcari a Lucina’ (Manzoni, 1876; Coppi, 1877; Scarabelli, 1880; Sacco, 1901; Di Stefano, 1903). Due to their isolated occurrence in deep-water sediments and the large bivalves preserved in them, they were considered to have been transported from shallow water (Ricci Lucchi and Veggiani, 1967). This view changed after the first discovery of faunal communities at methane seeps in the deep Gulf of Mexico with similarly large bivalves (Paull et al., 1984) and the recognition that methane seep carbonates can be identified based on their distinctive, light carbon isotope signature (Hovland et al., 1987). The ‘Calcari a Lucina’ deposits throughout Italy are now considered as ancient deep-water methane seep deposits (Clari et al., 1988; Conti et al., 1993; Terzi, 1993; Aharon and Sen Gupta, 1994; Berti et al., 1994; Ricci Lucchi and Vai, 1994; Taviani, 1994; Terzi et al., 1994; Peckmann et al., 1999; Clari et al., 2004b; Conti et al., 2004, 2010). Despite this wealth of geologic literature on these deposits, modern studies on the macrofauna are relatively rare (Moroni, 1966; Taviani, 1994, 2011, 2014; Taviani et al., 2011). The purpose of the present contribution is to provide a revision of the major taxa of chemosymbiotic bivalves of the ‘Calcari a Lucina’ deposits, with exclusion of solemyids.

Materials and methods

Specimens were coated with ammonium chloride for photography. The material is from twelve seep deposits of middle to late Miocene age (Fig. 1) associated with deep-water hemipelagic marls or turbidites, mostly ascribed to the Marnoso-arenacea Formation. Their geological and stratigraphic context is described in various publications (Vai et al., 1997; Conti and Fontana, 1999; Clari et al., 2004b; Taviani, 2011). A short description of the localities is provided in the Appendix.

Figure 1 Maps showing the fossil localities discussed in the text. Left panel, general map of Italy showing all localities: 1=Abisso “Mornig”, 2=Ca’ Carnè, 3=Ca’ Cavalmagra, 4=Monticino-Limisano – Castelnuovo junction, 5=Ca’ Fornace, 6=Ca’ Pianté, 7=Case Rovereti, 8=Castelvecchio, 9=Deruta, 10=Le Colline, 11= Marmorito, 12=Montepetra, 13=Sasso delle Streghe, 14=Verzino.

Repositories and institutional abbreviations

MGGC: Museo Geologico Giovanni Capellini, University of Bologna; MSF: Museo Civico di Scienze Naturali, Faenza; MZB: Museo dell’Evoluzione (formerly Zoologia), University of Bologna; MRSN: Museo Regionale di Scienze Naturali, Torino (managing the Bellardi and Sacco collection, property of the Turin University).

Systematic paleontology

Class Bivalvia Linnaeus, 1758

Subclass Pteriomorphia Beurlen, 1944

Order Mytilida Férussac, 1822

Family Mytilidae Rafinesque, 1815

Genus Bathymodiolus Kenk and Wilson, 1985

Type species

Bathymodiolus thermophilus Kenk and Wilson, 1985, Recent, Galapagos Rift Zone, by original designation.

Remarks

Molecular phylogenetic studies have shown that species currently classified as Bathymodiolus belong to at least two clades within the bathymodiolins (Gustafson et al., 1998; Jones et al., 2006; Lorion et al., 2010, 2013; Thubaut et al., 2013), of which those related to B. childressi may be placed in a separate genus. This species group is often referred to as the ‘childressi clade’ and it is recommended to use “Bathymodiolus” only in quotation marks for these species until the taxonomic uncertainties are settled (Gustafson et al., 1998). Morphologically, the two clades can be distinguished based on muscle-scar pattern (Gustafson et al., 1998), which, unfortunately, is not preserved in any of the fossils reported here from northern Italy. Therefore, we refer to them as Bathymodiolus (sensu lato).

Bathymodiolus (s.l.) moroniae new species

Figure 2

Figure 2 Bathymodiolus (s.l.) moroniae new species from Miocene seep deposits in Italy: (1, 2) holotype (MGGC 21907) from Case Rovereti, isolated right valve; (3) paratype (MZB 27273) from Case Rovereti, internal mold of large specimen, left valve; (4) paratype (MZB 27270) from Case Rovereti, left valve with preserved shell; (5, 6) paratype (MRSN PU 40607.01) from Deruta, internal mold of articulated specimen; (7, 8) paratype (MGGC 21922) from Case Rovereti, left valve of juvenile specimen showing fine taxodont dentition on posterior side of shell; (9) paratype (MSF 2119) from Abisso “Mornig,” left valve, anterior side with shell remains, posterior side internal mold showing pallial line and adductor muscle scar; (10) paratype (MRSN PU 40607.02) from Deruta, left valve with preserved shell; (11) paratype (MSF 1100) from the Monticino-Limisano – Castelnuovo junction, large right valve with preserved shell.

1966Modiolus (Modiolus) exbrocchii exbrocchii Sacco; Moroni, p. 78, pl. 5, fig. 2, pl. 6, fig. 4.

1996Bathymodiolus exbrocchii Sacco; Taviani, fig. 2a, 4c.

2001Modiolinid Taviani, fig. 20.7a.

2011“Bathymodiolus” cf. exbrocchii (Sacco, 1898); Taviani, fig. 3c.

Type specimens

Holotype: MGGC 21907, single right valve from Case Rovereti. Paratypes: seven specimens from Case Rovereti: MZB 27218, 27268, 27270, 27272, 27273; MGGC 21921, 21922; one from Monticino-Limisano – Castelnuovo junction: MSF 1100; one from Ca’ Piantè (MSF 2135, on same large block as MSF 1360); one from Abisso “Mornig” (MSF 2119).

Diagnosis

Medium- to large-sized “Bathymodiolus” with blunt, elevated umbo at anterior 10% of total shell length; dorsal and ventral margins nearly straight, posterodorsal corner at posterior third of shell; maximum inflation just anterior to anterior third of shell.

Occurrence

Late Miocene seep carbonates in Italy.

Description

Moderately inflated modioliform shell, maximum inflation at ~27% of total shell length; blunt, elevated umbo at anterior 10% of total shell length, anterior margin narrow, convex; ventral margin straight, slightly concave in large specimens; dorsal margin straight to very slightly curved; posterodorsal corner at posterior third of shell; surface smooth except for growth increments; hinge area in juvenile specimens with row of taxodont teeth below the ligament attachment line, smooth in adults; pallial line distant from shell margin, numerous mantle muscle scars toward interior; shell composed of a calcitic fibrous prismatic outer layer and a nacreous inner layer.

Etymology

To honor Maria Antonietta Moroni, for her seminal work on the ‘Calcari a Lucina’ fauna.

Materials

Forty-four valves (including MZB 27064, 27271, 27278, 27281) from Case Rovereti; three specimens from Verzino (MGGC 21923, 21924, 21925); one from Deruta (MGGC 21926); seven articulated shells from Deruta (MRSN, under cf. Bathymodiolus exbrocchii, PU 40607); one articulated specimen from Verzino MGGC 21927; three articulated shells (MSF 1360) plus one valve from Ca‘ Piantè; and specimens from Montepetra; four valves from block from Monticino-Limisano – Castelnuovo junction, Brisighella (MSF 1106-1109); five valves from Abisso “Mornig” (MSF 1086, 1090, 1094, 1097, 2120); see Table 1 for measurements.

Table 1 Measurements of Bathymodiolus (s.l.) moroniae new species; H=height, L=length, W=width of two valves, except when indicated otherwise.

Remarks

The assignment of this species to Bathymodiolus (sensu lato) is based on its general shape, the change from a hinge with denticles in young specimen to an edentulous hinge in adults, its shell microstructure (cf., Génio et al., 2012), and its mass occurrence at seep deposits. The early juvenile shell shape and adductor and retractor muscle scars, which have been used to identify other fossil bathymodiolins (Kiel, 2006; Kiel and Goedert, 2007; Saether et al., 2010; Amano and Jenkins, 2011; Kiel and Amano, 2013) are not preserved in Bathymodiolus (s.l.) moroniae n. sp.

Nelli (1903) and Moroni (1966) had identified this species as Modiolus (Modiolus) exbrocchii exbrocchii Sacco, 1898, which was named by Sacco (1898) based on an illustration of Modiola brocchii Mayer in Hörnes, 1870 from the Vienna Basin (Hörnes, 1870, p. 345, pl. 45, fig. 13a, b). However, this species differs from B. (s.l.) moroniae by being more elongate and by having a distinct and sharp ridge running from the umbo to the posteroventral margin, whereas B. (s.l.) moroniae is smoothly convex. Furthermore, specimens of B. moroniae with the size of M. exbrocchii as figured by Hörnes (11 cm) are more compact and less elongate that M. exbrocchii.

Most similar in general shell shape are specimens of B. brevior von Cosel, Métivier, and Hashimoto, 1994 living at hydrothermal vents in the Indian Ocean (this population was formerly called B. marisindicus Hashimoto, 2001, but later synonymized with B. brevior, based on molecular data), and B. puteoserpensis von Cosel, Métivier, and Hashimoto, 1994 from the Mid-Atlantic Ridge (von Cosel et al., 1994; Hashimoto, 2001). Another similar species is B. brooksi from the Gulf of Mexico (Gustafson et al., 1998). Interestingly, these three morphologically most similar species all belong to Bathymodiolus sensu strictu and not to the childressi clade.

Unlike bathymodiolins at most other fossil seep deposits, Bathymodiolus (s.l.) moroniae n. sp. occurs mostly as disarticulated valves, especially in adult stages.

Bathymodiolus (s.l.) miomediterraneus new species

Figure 3

Figure 3 Bathymodiolus (s.l.) miomediterraneus new species from the middle Miocene seep deposit at Le Colline, northern Italy: (1) paratype (MSF 1353) with strongly concave ventral margin, right valve; (2) holotype (MGGC 21908) showing broadly arched dorsal margin, left valve; (3, 4) paratype (MSF 1352), small specimen showing right valve and in ventral view, respectively; (5) block with two paratypes (MSF 1351), view of left valves; (6) strongly arched, gerontic specimen (MSF 1190).

Type specimens

Holotype: MGGC 21908; paratypes: MSF 1351 (two articulated shells), MSF 1352 (two articulated shells, one figured), MSF 1353 (right valve), MSF 1190 (left valve); all types from Le Colline.

Diagnosis

Small- to medium-sized “Bathymodiolus” with subterminal umbo, broad anterior margin, and arched dorsal margin; maximum inflation just anterior to middle of shell; blunt ridge running from umbo to posteroventral corner.

Occurrence

Middle Miocene (early Serravallian) seep carbonates at Le Colline in northern Italy.

Description

Well inflated, moderately sized, arched modioliform shell with low, subterminal umbo; maximum inflation just anterior of center; anterior margin broad and well rounded, posterodorsal margin broadly arched in large specimens, smaller specimens with distinct posterodorsal corner, ventral margin slightly concave in small specimens, strongly concave in large ones; posterior margin gently rounded; blunt ridge running from umbo to posteroventral corner; surface smooth except for growth increments.

Etymology

Referring to the Miocene Mediterranean Basin.

Materials

Three specimens from Le Colline (MSF 2136); see Table 2 for measurements.

Table 2 Measurements of Bathymodiolus (s.l.) miomediterraneus new species, all specimens from Le Colline, northern Italy; H=height, L=length, W=width of two valves, except when indicated otherwise.

Remarks

Similar in shape is ‘Modiolapistacina Sacco, 1904 from the Burdigalian of Piedmont (Sacco, 1904, pl. 29, fig. 6a, b; Merlino, 2007, pl. 6, figs. 8, 9); the type specimen is small (~13 mm long) and has the umbo in a more posterior position and a broader anterior margin than B. miomediterraneus n. sp. ‘Modiolapistacina may be related to small bathymodiolins such as “Idas” and should be further investigated in the context of whale- and wood-fall communities in the Italian Neogene. The middle Miocene ‘Modiolaexbrocchii (e.g., the specimen illustrated as Modiola brocchii by Hörnes, 1870) and its variation M. exbrocchii var. tauroparva Sacco, 1898, a small species of ~20 mm length (Sacco, 1898, pl. 11, figs. 28, 29; Merlino, 2007, pl. 6, fig. 7), have a more elevated umbo and a more distinctive ridge running from the umbo to the posterior-ventral margin than B. miomediterraneus. The new species differs from Bathymodiolus (s.l.) moroniæ n. sp. by having the umbo in a more anterior (subterminal) position. The most similar Recent species are Bathymodiolus mauritanicus von Cosel, 2002, which occurs off West Africa and in the Gulf of Cadiz (von Cosel, 2002; Génio et al., 2008) and appears to have a broader posterior margin than B. (s.l.) miomediterraneus n. sp., and the Japanese Bathymodiolus hirtus Okutani, Fujikura, and Sasaki, 2004, which has a more elevated umbo as adult than B. (s.l.) miomediterraneus n. sp. and is broader (less slender) as juvenile (Okutani et al., 2004). A fossil species with a similar subterminal umbo is the presumably Oligocene Bathymodiolus (s.l.) palmarensis from Colombia (Kiel et al., 2010), but it differs from B. (s.l.) miomediterraneus n. sp. by being more elongate and by having almost straight anterior and posterior margins. Bathymodiolus (s.l.) miomediterraneus n. sp. is typically found with articulated valves, in contrast to Bathymodiolus (s.l.) moroniae n. sp. and Samiolus iohannesbaptistae n. gen. n. sp.

Genus Samiolus new genus

Type species

Samiolus iohannesbaptistae new genus new species, from late Miocene seep deposits in northern Italy.

Diagnosis

Small- to medium-sized modioliform shell; strong, almost angular ridge from umbo to posteroventral corner; posterior part of shell sculptured by roughly commarginal wrinkles, unlike any other mytilid.

Etymology

The name combines the name Sami, crediting the paleontologist Marco Sami, who was responsible for collecting a substantial number of valuable macrofossils from ‘Calcari a Lucina’, including this new taxon, with the mytilid genus Modiolus, which has a similar shell shape.

Remarks

Samiolus n. gen. contains presently only the type species. A similar strong and sharp ridge can be seen in Gibbomodiola taurarcuata Sacco, 1898 from the Italian Miocene (Sacco, 1898, pl. 11, figs. 34a, 35b; Merlino, 2007, pl. 6, fig. 10), but this species lacks wrinkles (own observations on Sacco’s type material housed in the Turin Museum). Another species with a similar ridge is Modiola dombraviensis Kittl, 1887 from middle Miocene ‘blue deep-water clays’ in eastern Czech Republic and southern Poland (Kittl, 1887, p. 272, pl. 9, figs. 7–11). But Modiola dombraviensis has a nearly smooth surface with only fine growth increments and lacks the wrinkled sculpture of Samiolus iohannesbaptistae n. sp. (own observation of material housed in the Natural History Museum Vienna). This wrinkled surface sculpture distinguishes Samiolus iohannesbaptistae n. gen. n. sp. also from all fossil and extant bathymodiolins (Squires and Goedert, 1991; von Cosel and Olu, 1998; Gustafson et al., 1998; von Cosel, 2002; Sasaki et al., 2005; Desbruyères et al., 2006; von Cosel and Janssen, 2008; Lorion et al., 2010; Amano and Jenkins, 2011).

Samiolus iohannesbaptistae new species

Figure 4

Figure 4 Samiolus iohannesbaptistae new genus new species from late Miocene seep deposits in northern Italy: (1–4) paratype (MSF 1073) from Ca’ Carnè, four views on right valve; (5, 6) interior of small specimen (MGGC 23010) from Ca’ Carnè, showing hinge dentition of right valve; (7–10) paratype (MSF 1120) from Ca’ Carnè, right valve; (11) large specimen (MSF 1355) from Ca’ Piantè, left valve; (12–16) holotype (MGGC 21910) from Ca’ Carnè, five views of right valve.

Type specimens

Holotype MGGC 21910 from Ca’ Carnè; paratypes: three specimens from Ca’ Carnè: MSF 1073, MSF 1120 (left valve), MZB 60090; one specimen from Ca’ Piantè: MSF 1355.

Diagnosis

Same as generic diagnosis.

Occurrence

Late Miocene (late Tortonian) seep carbonates in northern Italy.

Description

Modioliform, small- to moderately sized shell, umbo subterminal; posterodorsal margin slightly arched, posterodorsal corner at ~60% total shell length, ventral margin convex; strong ridge starting posterior of umbo, running to posteroventral corner, anterodorsal margin of ridge almost angular, followed by broad groove; shell surface anterior of ridge smooth except for growth lines, posterior side shows ribbing or wrinkles, resulting from irregular, roughly commarginal thickenings. Juvenile specimen with fine taxodont hinge teeth along entire posterodorsal margin and on oval hinge plate below beak; hinge area in adult smooth. Largest specimen 33 mm long, 17 mm high, single valve 7 mm wide; a juvenile specimen with taxodont hinge teeth measures 8.3 mm in length.

Etymology

To honor Gian Battista Vai in recognition of his leading role in the modern study of ‘Calcari a Lucina.’

Materials

Eight specimens from Ca’ Carnè; six from Ca’ Piantè; three valves from Montepetra (MZB 60095), and one valve from Case Rovereti (MSF 1356); see Table 3 for measurements.

Table 3 Measurements of Samiolus (s.l.) iohannesbaptistae new genus and species; H=height, L=length, W=width of two valves, except when indicated otherwise.

Remarks

We have found mostly disarticulated specimens of this species. One specimen has been figured by Sami and Taviani (2015, fig. 7).

Subclass Heterodonta Neumayr, 1884

Family Thyasiridae Dall, 1900

Genus Channelaxinus Valentich-Scott and Coan in Coan and Valentich-Scott, 2012

Type species

Channelaxinus oliveri Valentich-Scott and Coan in Coan and Valentich-Scott (2012), (by original designation); Recent, Bahía Santiago, Colima, México.

Channelaxinus sp.

Figure 5

Figure 5 Channelaxinus sp. from the middle Miocene (Langhian) of Ca’ Cavalmagra, northern Italy: (1, 2) left valve (MSF 2113), internal mold and counterpart with small amount of shell preserved; (3) left valve (MSF 1287), internal mold with few shell remains; (4) right valve (MSF 2112) of small specimen.

Description

Shells subrectangular, thin-shelled, reaching 20 mm in length and 16 in height, only slightly inflated, sculptured by irregular growth lines and indistinct, blunt ridge running from umbo to postero-ventral corner; beak prosogyrate, projecting slightly above dorsal margin; anterior margin straight to slightly concave, ventral margin gently convex, postero-ventral corner well rounded, posterior margin gently convex below sulcus, postero-dorsal margin slightly convex, with deep sinus at end of posterior sulcus; posterior sulcus deep, bordered by sharp ridge, area between sulcus and postero-dorsal margin narrow, with narrow submarginal sulcus; anterior adductor muscle scar thin, elongate, weakly impressed, separated from pallial line, length just over half of shell length; interior radiating striae distinct.

Materials

Three specimens from Ca’ Cavalmagra (MSF 1287, 2112, 2113).

Occurrence

Only known so far from the late Langhian of Ca’ Cavalmagra.

Remarks

A superficially similar thyasirid from the Miocene of the Turin Hills is Thyasira michelottii (Hörnes, 1875), but it clearly differs from Channelaxinus sp. reported here by having a much shorter anterior adductor muscle scar (Zuschin et al., 2001). The extant type species Channelaxinus oliveri differs from Channelaxinus sp. mainly by having a narrower angle between the anterior and dorsal margins and a blunter (less pointed) umbo (Coan and Valentich-Scott, 2012; Oliver and Frey, 2014). This is the first fossil record of Channelaxinus.

Family Lucinidae Fleming, 1828

Genus Meganodontia Bouchet and von Cosel, 2004

Type species

Meganodontia acetabulum Bouchet and von Cosel, 2004 (by original designation); Recent, in 256–472 m depth off northern Taiwan.

Meganodontia hoernea (Des Moulins, 1868)

Figures 6, 7

Figure 6 Meganodontia hoernea (Des Moulins, 1868) from the late Miocene seep deposit at Ca’ Piantè in northern Italy: (1) internal mold of left valve (MGGC 23003) showing the elongate anterior adductor muscle scar; (2) dorsal view of same specimen as Figure 6.1; (3) left valve in foreground showing posterodorsal shell margin, right valve in background showing edentulous hinge (MGGC 23004); (4) outer shell of right valve seen in the background of Figure 6.3; (5) hinge and ligament nymph in left valve (MGGC 23005).

Figure 7 Meganodontia hoernea (Des Moulins, 1868), specimens from Sacco’s collection from the Turin Hills: (1–3) left valve (MRSN BS 154.01.002) from Albugnano, with well-preserved shell material, showing hinge area and external sculpture; (4) view of left valve of internal mold (MRSN PU 40603.01) from an unknown locality, showing the elongate anterior adductor muscle scar and the internal pustules; (5, 6) right valve (MRSN BS 154.01.001) from Albugnano, showing external sculpture.

1868Lucina hoernea Des Moulins, p. 368.

1901Lucina globulosa var. hörnea Sacco, p. 67, pl. 15, figs. 31–33, pl. 16, fig. 1.

1901Lucina globulosa var. alta Sacco, p. 68, pl. 15, fig. 4.

1901Lucina globulosa var. perinaequilatera Sacco, p. 68, pl. 15, fig. 5.

1966Lucina hoernea; Moroni, p. 80, pl. 3, fig. 3.

2001Lucina Taviani, fig. 20.1.

2011“Lucina” sp. Taviani, fig. 3a.

Description

Very large, globular shells, height/length-ratio 0.9; umbones elevated, prosogyrate; external sculpture of fine, irregular, commarginal growth lines, posterodorsal sulcus shallow but distinct; lunule lanceolate, bordered by sharp, smooth ridge. Hinge plate narrow to moderately broad, edentulous, ligament nymph narrow. Anterior adductor muscle scar elongate, detached from pallial line for ~80% of its length, angle of deviation ~30°, width about half the distance to pallial line, curved in the opposite direction as shell margin, reaching below midline to ~44% of total shell height; somewhat constricted posteriorly just below the point of detachment. Interior of shell with numerous pustules, often in rows radiating form umbo; pallial blood vessel scar visible.

Materials

Eight specimens from Ca’ Piantè (MSF 1357; 2100–2104, 2110); 45 articulated shells from Deruta (as Lucina globulosa hoernea Desmoulins, Bellardi and Sacco collection in MRSN, PU 40597–40601); one articulated shell from Bersano (as Lucina globulosa [Deshayes] var hoernea, Bellardi and Sacco collection in MRSN, BS 154.01.001); one articulated shell from Albugnano (as Lucina globulosa [Deshayes] var hoernea Desmoulins, Bellardi and Sacco collection in MRSN, BS.154.01.002); two articulated shells from Pino Torinese (as Lucina globulosa [Deshayes] var hoernea Desmoulins, Bellardi and Sacco collection in MRSN, BS.154.01.003 and BS.154.01.004); one articulated shell from Pera del Gal, Turin Hills (as Lucina globulosa [Deshayes] taurofuchsi Sacco, 1901, Bellardi and Sacco collection in MRSN, BS.154.01.007); one articulated shell from Pino Torinese (as Lucina globulosa [Deshayes] alta Sacco, 1901, Bellardi and Sacco collection in MRSN, BS.154.01.008); one articulated shell from Pino Torinese (as Lucina globulosa [Deshayes] perinaequilatera Sacco, 1901, Bellardi and Sacco collection in MRSN BS.154.01.009); more than 20 articulated shells (molds) from Sasso delle Streghe (Modena), a dozen articulated shells from other localities of the Modena and Forlì Apennines; a dozen articulated shells from the Turin Hills (Sacco’s collection in MRSN); see Table 4 for measurements.

Table 4 Measurements of Meganodontia hoernea (Des Moulins, 1868), all specimens from Ca’ Piantè, northern Italy; H=height, L=length, W=width of two valves, except when indicated otherwise.

Occurrence

Middle to late Miocene seep carbonates in Italy.

Remarks

Bouchet and von Cosel (2004) considered “Lucinahoernea not to belong to Meganodontia because it has more globose and prominent umbones than M. acetabulum and because internal features of “Lucinahoernea were not known to them. Here, we show that “Lucinahoernea has an edentulous and narrow hinge plate, as well as an elongate, blade-shaped anterior adductor muscle scar just like Meganodontia acetabulum. Therefore we consider “Lucinahoernea as belonging to Meganodontia, but as distinct from M. acetabulum. In addition to the differences mentioned above, Meganodontia hoernea has a less distinctive posterior adductor muscle scar than Meganodontia acetabulum. Moroni (1966) provided an extensive synonymy for Meganodontia hoernea. In the Meganodontia species from the early Miocene of Cuba (Kiel and Hansen, 2015), the anterior adductor muscle scar deviates from the pallial line at a broader angle, as in M. hoernea. Examination of Sacco’s type material showed that his “variations” L. globulosa var. alta Sacco, 1901 and L. globulosa var. perinaequilatera Sacco, 1901 represent deformed specimens of Meganodontia hoernea and should therefore be considered as synonyms.

Taylor et al. (2011) tentatively assigned Meganodontia to their new subfamily Pegophyseminae, whose species are united by some unusual morphological characters, including thin, globular, smooth shells, a narrow edentulous hinge with an internal and laterally extended ligament in most species (Taylor et al., 2011). Meganodontia hoernea is a common and widespread species in the Miocene of Italy, associated with ‘Calcari a Lucina’ limestones and reducing deep-sea marly sediments.

Genus Lucinoma Dall, 1901

Type species

Lucina filosa Stimpson, 1851 (by original designation); Recent, northwest Atlantic.

Lucinoma perusina (Sacco, 1901)

Figures 8, 9

Figure 8 Lucinoma perusina (Sacco, 1901) from the late Miocene type locality at Deruta, northern Italy: (1–3) lectotype (MRSN BS.154.03.034), originally illustrated as “Dentilucina perusina var. pseudorotunda” (Sacco, 1901, pl. 19, fig. 15); (4) large internal mold (MRSN PU 40604.01) showing muscle scars and pallial line in right valve; (5) right valve of medium-sized specimen (MRSN PU 40604.02) with defoliated outer shell layer, giving it a smooth appearance; (6) right valve of small specimen (MRSN PU 40606.01) showing surface sculpture; (7) right valve of small specimen (MRSN PU 40606.02).

Figure 9 Lucinoma perusina (Sacco, 1901) from late Miocene seep deposits in northern Italy: (1) partial internal mold of a left valve (MGGC 23006) showing anterior adductor muscle scar, from Ca’ Piantè; (2) dorsal view of same specimen as in Figure 9.1, showing lunule; (3) internal mold of left valve (MGGC 23007) showing anterior adductor muscle scar, from Ca’ Piantè; (4) left valve (MGGC 23008) showing external sculpture, from Ca’ Piantè; (5) hinge of same specimen as in Figure 9.4; (6) hinge of a large specimen (MSF 2116) from Ca’ Fornace; (7) block from Ca’ Fornace with several specimens (MSF 2118) showing their external surfaces; (8) dorsal view showing umbones, lunule and escutcheon, middle specimen from Figure 9.7.

1901Dentilucina perusina Sacco, p. 83, pl. 19, figs. 12–14.

1901Dentilucina perusina var. pseudorotunda Sacco, pl. 21, fig. 15.

1966Phacoides (Lucinoma) perusinus (Sacco); Moroni, p. 82, pl. 5, figs. 1, 3, pl. 6, figs. 1, 2.

1996Lucinidae Taviani, fig. 4b.

Description

Medium- to large-sized Lucinoma, outline of shell oval in small specimens, becoming more round in large ones; umbones central, prosogyrate, elevated; surface sculptured by fine, irregular growth increments or commarginal ribs, posterior sulcus only weakly developed; lunule elongate, heart-shaped, moderately excavated, bordered by distinct angulation; escutcheon lanceolate, wide; anterior adductor muscle scar thin, elongate, reaching well below midline of shell, detached from pallial line for more than three-quarters of its length, deviates from pallial line by ~10°; posterior adductor muscle scar oval, dorsally pointed; hinge plate broad, two strong, radiating cardinal teeth in each valve, one anterior lateral tooth in each valve, posterior lateral teeth not seen.

Materials

Ten specimens from Ca’ Piantè and six specimens from Santa Sofia; six shells from Montepetra, all articulated; one specimen on block with articulated Archivesica sp. (MSF 2111); four articulated shells (MSF 2114–2117) and a cluster (MSF 2118) from erratic blocks in Sintria Creek, near Ca’ Fornace; 26 articulated shells from Deruta (as Dentilucina cf perusina Deshayes, Bellardi and Sacco collection in the Turin Museum, PU 40604); ten articulated shells from Deruta (as Lucina globulosa Deshayes, Bellardi and Sacco collection in the Turin Museum, PU 40602); one articulated shell from Deruta (Bellardi and Sacco collection in the Turin Museum, as Dentilucina perusina Sacco pseudorotunda Sacco, 1901, BS.154.03.034) ; see Table 5 for measurements and specimen numbers.

Table 5 Measurements of Lucinoma perusina (Sacco, 1901); H=height, L=length, W=width of two valves, except when indicated otherwise.

Occurrence

Middle to late Miocene seep carbonates, from northern Italy to Sicily.

Remarks

There is no formal description of Dentilucina perusina in Sacco (1901); he used this name in the discussion of Dentilucina barrandei (Mayer, 1871), and illustrated three specimens as D. perusina, including one as Dentilucina perusina var. pseudorotunda Sacco, 1901; all specimens are from Deruta. The figured specimens of D. perusina sensu strictu are not present at MRSN and are presumably lost; here, we illustrate the specimen previously illustrated as Dentilucina perusina var. pseudorotunda Sacco (1901, pl. 21, fig. 15) and designate it as lectotype for Dentilucina perusina. Sacco’s illustrated specimens of D. perusina sensu strictu are more oval than the rather round D. p. pseudorotunda; however, virtually all of the 37 specimens of Bellardi and Sacco collection from Deruta (housed in MRSN) are of the round shape of D. p. pseudorotunda. Hence, we consider this as the typical shape of D. perusina. Moroni (1966) provided an extensive synonymy for this species.

Externally similar is the Miocene “Dentilucina” barrandei from the Turin Hills, but its cardinal teeth are smaller than in L. perusina and they are nearly parallel, in contrast to the radiating teeth in D. perusina. Among the extant species, Lucinoma kazani Salas and Woodside, 2002 living at seeps in the Mediterranean Sea, has a similar shell but less inflated, a similarly short and well-defined lunule, and similar fine commarginal ribs, whereas the North Atlantic-Mediterranean L. borealis has a broader and more elongate lunule, and its ribs are more lamellar than in L. perusina and L. kazani (Salas and Woodside, 2002). None of the Lucinoma species known from Japan are particularly similar to L. perusina (Okutani, 2000).

Family Vesicomyidae Dall and Simpson, 1901

Genus Archivesica Dall, 1908

Type species

Callocardia gigas Dall, 1895 (by original designation); Recent, Gulf of California.

Remarks

There is currently little consensus which species belong to the genus Archivesica. While the concept of Amano and Kiel (2007), which includes middle Eocene to Recent species is probably too broad (cf., Amano and Kiel, 2012), the view of Krylova and Sahling (2010) to include only two extant species in addition to the type, may be a little too narrow. In a recent molecular phylogenetic analysis (Audzijonyte et al., 2012), a monophyletic clade called the ‘gigas group’ emerged and included 14 named and five unnamed species, including the type species of Archivesica. Because the species described below are morphologically most similar to several members of this clade—Archivesica soyoae (Okutani, 1957) A. kilmeri (Bernard, 1974), A. okutanii (Kojima and Ohta, 1997), and A. kawamurai (Kuroda, 1943)—we assign them to Archivesica. Other authors (Krylova and Janssen, 2006; Krylova and Sahling, 2010) have separated these species into the genera Archivesica, Phreagena, and Akebiconcha, but they have not consistently emerged as monophyletic groups in molecular phylogenetic studies (Audzijonyte et al., 2012; Valdés et al., 2013).

The first claim of the occurrence of large deep-water vesicomyids in the Mediterranean Miocene was based on the discovery in 1992 (Taviani et al., 1992; Taviani, 1996) of a bed containing ‘Calyptogena’ (=Archivesica) associated with turbidites in the Romagna Apennines (for details see Berti et al., 1994; Taviani, 2014). However, large vesicomyids such as those reported here are not rare in some well-studied outcrops and their occurrence could not have escaped the attention of former investigators. They most likely were identified as Lutraria or veneroideans, or, as in the case of the Bellardi and Sacco collection at MRSN from Deruta, as cf. “Tellinidae?”. In this respect, Taurotapes craverii (Michelotti, 1847) from the lower Miocene of the Turin area (Sacco, 1904) deserves special attention. Elongated bivalves were reported under this name from a putative Miocene hydrocarbon seep at Roccapalumba (Nicosia, 1956), which most likely represent Archivesica-like vesicomyids (unpublished observation, M. Taviani, 2016).

Archivesica aharoni new species

Figures 10, 11

Figure 10 Archivesica aharoni new species from Miocene seep deposit in Italy: (1) holotype (MGGC 21909), semi-articulated specimen, internal mold of left valve showing anterior adductor muscle scar, and interior of right valve, from Ca’ Pianté; (2) paratype (MSF 1048), internal view of left valve, from Ca’ Pianté; (3) paratype (MSF 1051), right valve with partially preserved shell, from Ca’ Pianté; (4) paratype (MZB 23846), internal mold of left valve, from Ca’ Rovereti; (5) paratype (MSF 1046), exterior of left valve, from Ca’ Rovereti; (6) paratype (MGGC 21928), rubber cast of right valve showing hinge and the lacking pallial sinus, from Marmorito.

Figure 11 Archivesica aharoni new species from Miocene seep deposit in Italy: (1, 2) holotype (MGGC 21909) from Ca’ Pianté, dorsal view, and close-up of hinge of right valve, respectively; (3) paratype (MSF 1048) from Ca’ Pianté, close-up of hinge of left valve; (4) paratype (MGGC 21928) close-up of hinge of right valve; (5) paratype (MGGC 23009) from Verzino, close-up of hinge of left valve.

1994Calyptogena n. sp. Taviani, fig. 3e.

1996?Calyptogena sp. Taviani, figs. 3a, b.

2001Calyptogena sp. Taviani, fig. 20.9b.

2011Calyptogena n. sp. Taviani, fig. 3e.

Type specimens

Holotype MGGC 21909 from Ca’ Piantè. Paratypes: three specimens from Ca’ Piantè (MSF 1048, 1051, 1053); one from Marmorito (MGGC 21928); two from Case Rovereti (MZB 23846, 28075); three from Verzino (MZB 28076, 28077, 23009); see Table 6 for measurements.

Table 6 Measurements of Archivesica aharoni new species; H=height, L=length, W=width of two valves.

Diagnosis

Large Archivesica with pointed posterior margin, often with posterior ridge and sulcus below; anterior adductor muscle scar large and round, right valve with three radiating, equally sized teeth.

Occurrence

Late Miocene seep carbonates in Italy.

Description

Moderately large (up to 115 mm long), elongate-veneriform shell with umbo anterior at ~28% total shell length; anterior side strongly convex, slightly pointed; ventral side evenly curved; posterodorsal margin only slightly convex, transition to posterior margin at clear angulation; posterior margin pointed at its ventral side. Beak elevated, blunt, slightly prosogyrate; external sculpture of rough growth lines only; no lunula or lunular incision, escutcheon narrow with sharp edges, length about two-thirds of posteroventral margin. Anterior adductor muscle scar distinct and round, pallial line starting at its posteroventral corner, distinct only in anterior half of shell. Hinge plate high but short; RV with three equally strong cardinal teeth that radiate anteroventrally, a distinctive inverted-V-shaped groove between hinge teeth and nymph plate forms the subumbonal pit; cardinal 1 straight, oblique to anterodorsal margin, cardinals 3a and 3b not connected, 3a subparallel to anterodorsal margin, 3b almost at right angle to it; nymph plate narrow. LV with three teeth, cardinal 2a parallel to anterodorsal margin, wedge-shaped, tapering anteriorly, 2b short, perpendicular to 2a, 4 short, wedge-shaped, nearly perpendicular to ventral shell margin.

Etymology

For Paul Aharon, Tuscaloosa, Alabama, in recognition of his relevant work on Gulf of Mexico recent cold seeps and ‘Calcari a Lucina’ fossil counterparts.

Materials

Two specimens from Ca’ Piantè (MSF 1055, 1358) and four shells from Verzino (MGGC 23002).

Remarks

The two most similar species are the extant Japanese Archivesica soyoae and A. kawamurai. The former differs from A. aharoni n. sp. mainly by having a broader nymph plate and the teeth in the left valve are more elongate (Sasaki et al., 2005). In addition to the left valve teeth of Archivesica kawamurai being more elongate than in A. aharoni n. sp., the teeth of the right valve are more slender (Sasaki et al., 2005; Amano and Kiel, 2010). The geographically close Phreagena sp. from a ca. 25,000 years old vent field on the Mid-Atlantic Ridge (Lartaud et al., 2010) differs from A. aharoni n. sp. by having the anterior onset of the pallial line in a more anterior position, cardinal tooth 3b in the right valve points posteriorly rather than ventrally as in A. aharoni n. sp., and its escutcheon is much broader. The late Miocene A. shikamai Amano and Kiel, 2010 from Japan differs by generally having straighter and more parallel dorsal and ventral margins.

Archivesica aff. aharoni Kiel and Taviani, herein

Figure 12

Figure 12 Archivesica aff. aharoni new species from the middle Miocene seep deposit at Deruta in northern Italy: (1) left valve of small specimen (MRSN PU 40611.02) showing shell outline; (2) right valve of medium-sized specimen (MRSN PU 40609.01) showing shell outline; (3) large specimen (MRSN PU 40608-01) showing muscle attachment scars and pallial line; (4–6) moderately sized specimen (MRSN PU 40608.02), (4) view of left valve showing pointed posterior end, muscle attachment scars and pallial line, (5) dorsal view showing hinge area, (6) close-up of hinge area; (7, 8) large specimen (MRSN PU 40608.03), (7) view of left valve showing anterior muscle attachment scars and pallial line, (8) dorsal view showing hinge area; (9) (MRSN PU 40609.01) detached hinge region showing fractured teeth of the right valve and molds of the teeth of the left valve.

Description

Shells up to 94 mm long, elongate-veneriform shell with umbo anterior at ~26–35% total shell length; anterior margin either pointed or truncate; ventral margin evenly curved; posterodorsal margin almost straight to slightly convex, transition to posterior margin with clear angulation in specimens with truncate posterior margin, or more rounded in specimens with pointed posterior margin. Beak elevated, blunt, slightly prosogyrate; external sculpture of rough growth lines only; no lunula or lunular incision. Anterior adductor muscle scar distinct and round, pallial line starting at its posteroventral corner, pallial sinus small, shallow; posterior adductor muscle scar large, round, with anteriorly pointed hook at dorsal margin. Hinge plate high but short; RV with three equally strong cardinal teeth that radiate anteroventrally; LV with three teeth, cardinal 2a wedge-shaped, tapering anteriorly, parallel to anterodorsal margin, 2b and 4 short.

Materials

Four lots of articulated bivalves, mostly molds, but some with preserved portions of the shell, labeled as “cf. Tellinidae (?)” in the Bellardi and Sacco collection at MRSN (N40608: 20 specimens, largest specimen L×H×W=100×54×35 mm; PU 40609: 25 specimens, largest specimen 82×38×20 mm; N40610: 30 specimens, largest specimen 79×40×24 mm; PU 40611: 16 specimens., largest specimen 45×22×6 mm); four additional specimens (MGGC 21930, 21931; MZB 60096, 60097).

Occurrence

Middle Miocene (Serravallian) seep carbonate at Deruta in northern Italy.

Remarks

These specimens share all features of A. aharoni, but are slightly smaller and consistently lack the posterior ridge and groove that can be seen in many specimens of A. aharoni from the type locality. Furthermore, the posterior part of the pallial line and the posterior adductor muscle scar can be more clearly seen than in specimens of A. aharoni from the type locality, but this might be a taphonomic artifact.

Archivesica strigarum new species

Figure 13

Figure 13 Archivesica strigarum new species from the middle to late Miocene seep deposits in northern Italy: (1) paratype (MGGC 21929) from Sasso delle Streghe, left valve showing the round anterior adductor muscle scar; (2–5) holotype (MZB 28095) from Sasso delle Streghe, internal mold; (2) left valve, (3) dorsal view, (4) close-up of hinge area, (5) silicon rubber cast of hinge area; (6, 7) paratype (MRSN PU 40611.01), small specimen from Deruta. Abbreviations: aprs, anterior pedal retractor scar; LV, left valve; RV, right valve.

2001 Calyptogena sp. Taviani, fig. 20.8a.

Type specimens

Holotype: MZB 28095, internal mold from Sasso delle Streghe (87×38×24.5 mm). Paratypes: MGGC 21929, specimen with partially preserved external features from Sasso delle Streghe; MRSN PU 40611, small specimen from Deruta (41×19×11.5 mm).

Diagnosis

Elongate Archivesica, beak situated anteriorly at ~26% of total shell length; onset of pallial line at posteroventral margin of anterior adductor muscle scar; no pallial sinus.

Occurrence

Middle Miocene seep carbonates in northern Italy.

Description

Elongate veneriform shell (max. dimensions L=95 mm, H=45 mm, W=30 mm) with beak situated in anterior third of shell; anterior margin well rounded, posterodorsal margin only slightly tapering, posterior margin broadly rounded, ventral margin gently rounded, shell surface smooth except for growth lines. Anterior adductor muscle scar broadly oval, bordered posteriorly by distinct ridge; pedal retractor scar oval, distinct from adductor muscle scar; onset of pallial line at posteroventral margin of anterior adductor muscle scar, obliquely cutting across anteroventral shell margin; pallial sinus small, shallow, pointed. RV hinge with thick cardinal 1; cardinal 3a thick, elongate; cardinal 3b thin and very long; LV hinge with cardinal 2a thick, elongate; cardinal 2b thin and close to almost equally shaped cardinal 4b.

Etymology

For the type locality at Sasso delle Streghe (the witches’ rock; Striga Latin for witch).

Materials

Slab with five decalcified shells from Sasso delle Streghe (MGGC 23000); one incomplete articulated mold (MSF 1357); one specimen from Deruta (MRSN PU 40610).

Remarks

Extant species with similar hinge dentition and pallial line include Archivesica gigas, A. kawamurai, A. kilmeri, and A. okutanii (Dall, 1895; Kuroda, 1943; Bernard, 1974; Kojima and Ohta, 1997). Among the characters used to distinguish Phreagena from Archivesica was the anterior pedal retractor scar, which is deeply impressed in Phreagena, but shallow in Archivesica (Krylova and Janssen, 2006); in A. strigarum it is deeply impressed. Archivesica strigrarum n. sp. is more elongate than Archivesica aharoni n. sp. and has a more oval (rather than round) anterior adductor muscle scar. It lacks the arched posterodorsal margin and posterodorsal ridge of A. apenninica n. sp. and its anterior adductor muscle scar is oval in contrast to the more quadrate scar of A. apenninica n. sp. Compared to the elongate specimens of A. apenninica n. sp., it has a longer anterior portion. It is also more elongate than most other species of Archivesica, except the early Miocene A. sakoi Amano et al., 2014 from southern Japan.

Archivesica apenninica new species

Figure 14

Figure 14 Archivesica apenninica new species, from the middle Miocene seep deposit at Castelvecchio in northern Italy: (1, 2, 10) holotype MGGC 23001, right valve with damaged posterior margin; view of outer shell surface, dorsal view, and close-up of hinge dentition, respectively; (3, 4, 9) paratype MSF 2125, left valve; view of outer shell surface, dorsal view, and close-up of hinge dentition, respectively; (5) paratype MSF 2123, right valve of very elongate specimen; (6) paratype MSF 2121, right valve with damaged posterodorsal margin; (7, 8) paratype MSF 2126, internal mold showing muscle attachment scars and pallial line; view of left valve and dorsal view, respectively.

Type specimens

Holotype: MGGC 23001. Paratypes: MSF 2121, 2123, 2125, 2126; all types from Castelvecchio.

Diagnosis

Large for the genus; dorsal margin broadly arched, ridge running from umbo to posterior margin; anterior adductor muscle scar oval with groove running toward umbo; no pallial sinus; three radiating and almost equally strong cardinal teeth in each valve.

Occurrence

Only known from the middle Miocene (early Serravallian) seep carbonate at Castelvecchio in northern Italy.

Description

Elongate-veneriform shell, up to 125 mm long, umbo broad, elevated, slightly prosogyrate, anterior at ~28–33% total shell length. Anterior shell margin strongly convex; ventral margin gently and evenly curved; posterodorsal margin broadly arched, transition to posterior margin indistinct, angulate only in very elongate specimens; posterior margin strongly convex and somewhat pointed. External sculpture of rough growth lines; distinct ridge or angulation from umbo to posterior margin; no lunula or lunular incision, escutcheon narrow with sharp edges, length at least half of posteroventral margin. Anterior adductor muscle scar distinct, oval, somewhat pointed anteroventrally, most deeply impressed on posterior side, with groove extending toward umbo; anterior pedal retractor scar small, oval, distinct from adductor muscle scar; pallial line starting at posteroventral corner of anterior adductor scar, running oblique toward ventral shell margin in anterior half of shell, parallel to it afterward, sharply bent upward below center of posterior adductor scar, pallial sinus small, shallow. Hinge plate high but short; RV with three equally strong cardinal teeth that radiate toward ventral margin, cardinals 3a and 3b not connected, subumbonal pit present, nymph plate narrow; LV with three widely radiating teeth, cardinal 2a weak, 2b short, wedge-shaped, not connected to 2a, 4 short, nearly perpendicular to 2a.

Etymology

For the Apennine Mountains, Italy.

Materials

All specimens from Castelvecchio; MSF 2121–2132 and several fragmentary specimens at MSF; see Table 7 for measurements.

Table 7 Measurements of Archivesica apenninca new species, all specimens from Castelvecchio; H=height, L=length, W=width of two valves, except when indicated otherwise.

Remarks

Archivesica apenninica n. sp. is variable in elongation, but the characteristic broadly arched posterodorsal margin, as well as the nearly equally strong hinge teeth are seen in all available specimens. A similar broadly arched posterodorsal margin is present in the Recent Japanese species A. solidissima (Okutani, Hashimoto, and Fujikura, 1992), A. soyoae (Okutani, 1957), and A. okutanii (Kojima and Ohta, 1997), but these species differ from A. apenninica either by having a concave ventral margin or by having more anteriorly pointing cardinal teeth (Sasaki et al., 2005). The pallial sinus is more pronounced in extant species than in A. apenninica.

Genus Pliocardia Woodring, 1925

Type species

Anomalocardia bowdeniana Dall, 1903, late Pliocene Bowden Formation, Jamaica, by monotypy.

Remarks

Pliocardia is currently a dustbin taxon used for small to moderately sized, oval and thick-shelled species with an Archivesica-like hinge dentition. Molecular phylogenetic studies indicate two separate groups among species with the general shape of Pliocardia: one includes the species Vesicomya stearnsii, Calyptogena ponderosa, C. cordata, and ‘Pliocardiakrylovata, the other includes Vesicomya kuroshimana, V. crenulomarginata, and specimens called “cf. venusta” (Kojima et al., 2004; Martin and Goffredi, 2011; Audzijonyte et al., 2012). Several additional extant species for which no molecular data are available are also included in this genus (Krylova and Sahling, 2010), as well as several fossil taxa (Amano and Kiel, 2007, 2012). As it is still unclear to which of those groups (if at all) the type species of Pliocardia belongs. The identity of this genus remains unclear and it is only used in quotation marks for the species reported below.

Pliocardiaitalica new species

Figure 15

Figure 15Pliocardiaitalica new species from the middle Miocene seep deposits at Ca’ Cavalmagra in northern Italy, holotype (MGGC 21909); (1) exterior of left valve; (2) ventral side; (3) anterior side.

Type specimens

Holotype: MGGC 21909 (cast: MSF 1277). Paratype: MSF 1275; all types from the middle Miocene of Ca’ Cavalmagra.

Diagnosis

Large, inflated Pliocardia with strong, protruding, prosogyrate beak, small anterior portion and broadly expanded posterior portion.

Occurrence

Known only from Ca’ Cavalmagra.

Description

Well-inflated specimens with large, protruding beak in anterior third of shell; anterior part of shell short, somewhat pointed, posterior part broadly expanded; anterior adductor muscle scar in ventral half of shell, broadly oval, onset of pallial line at its posteroventral corner, pallial sinus small and shallow, posterior adductor muscle scar indistinct, very close to posterior shell margin; interior of posterior part of shell with distinct radial grooves.

Etymology

Refers to the geographic area that is the source of all studied material.

Materials

One articulated specimen (MSF 1276) and nine isolated valves (MSF 1273, 1274, 1279, 2105–2109; MZB 60218); see Table 8 for measurements.

Table 8 Material of “Pliocardiaitalica new species, all specimens from Ca’ Cavalmagra; H=height, L=length, W=width of two valves.

Remarks

Most similar to “Pliocardiaitalica n. sp. are two extant species from the central Indo-Pacific Ocean: “Pliocardiasolidissima (Prashad, 1932) and “Pliocardiaticaonica (Dall, 1908). Both have a similarly large and prosogyrate umbo and broad posterior margin, but differ from the Italian Miocene “Pliocardiaitalica n. sp. by having a more convex posterodorsal margin; in addition, P. ticaonica is shorter than “Pliocardiaitalica n. sp. Among the taxa from the Caribbean Sea and the Gulf of Mexico, “Pliocardiacaribbea (Boss, 1967) has a broader anterior margin and has the anterior adductor muscle scar in a more dorsal position; “Pliocardiacordata (Boss, 1968) is shorter and has a smaller and more pointed beak; and “Pliocardiaponderosa (Boss, 1968) seems to have a steeper sloping posterodorsal margin.

Discussion

The present study is intended to provide a taxonomic baseline for future biogeographic and evolutionary studies. At first glance, the bivalve fauna of the ‘Calcari a Lucina’ seep deposits show a wide range of biogeographic links to places as distant as the Recent western Pacific (Bathymodiolus, Archivesica, and Meganodontia), the Recent Indian Ocean (“Pliocardia”), as well as the Miocene Caribbean seep faunas (Meganodontia). We identified 11 chemosymbiotic bivalve species from the middle to late Miocene ‘Calcari a Lucina’ methane-seep deposits in northern Italy, among them three mytilids, one thyasirid, two lucinids, and four or five vesicomyids.

Apart from Bathymodiolus (s.l.) moroniae n. sp. and B. (s.l.) miomediterraneus n. sp. (two species that resemble extant bathymodiolins) the taxonomic affinity of the new genus and species Samiolus iohannesbaptistae is unclear. This taxon might represent a rare case of a genus that occurs exclusively at deep-water methane seeps, but does not belong to the bathymodiolins. An interesting taphonomic aspect of the mytilids is the common occurrence of B. (s.l.) moroniae n. sp. and Samiolus iohannesbaptistae n. gen. n. sp. as disarticulated shells, which is in contrast to the articulated mode of occurrence of the vast majority of other fossil seep-associated bathymodiolins (Squires and Goedert, 1991; Amano et al., 2010; Kiel et al., 2010; Saether et al., 2010; Amano and Jenkins, 2011; Kiel and Amano, 2013). Articulated shells, including juveniles and giant specimens up to 133 mm in length, indeed occur at Ca’ Piantè, as well as in Deruta, but this is rather an exception than the rule. At the well-sampled sites at Montepetra and Case Rovereti, where disarticulated mussel shells are common, the co-occurring vesicomyids and lucinids were found as articulated or semi-articulated shells. This excludes the possibility that the mussel shells disarticulated due to transport, but suggests in-situ disarticulation, either by the force of the ligament, or perhaps due to large scavengers.

In addition to the seep-inhabiting bathymodiolins reported here, a bathymodiolin named Adipicola apenninica Danise, Bertolaso, and Dominici, 2016 was recently described from a whale bone from the middle Miocene (Langhian) Pantano Formation in the vicinity of the town of Carpineti (Reggio Emilia province, northern Italy). Adipicola apenninica was reported as being very abundant, where the associated thyasirids and lucinids were rare (Danise et al., 2016).

Most Cretaceous to extant lucinids at methane seeps belong to either the Codakiinae or the Myrteinae (Taylor et al., 2011; Kiel, 2013). Thus, if the inclusion of Meganodontia in Pegophyseminae (cf., Taylor et al., 2011, 2014) is correct, it would be the third lucinid subfamily to have a considerable fossil history at methane seeps (Taylor et al., 2014; Kiel and Hansen, 2015).

The taxonomy of the Vesicomyidae is still in flux, partially due to the frequent convergence among their few shell characters (Krylova and Sahling, 2010). Amano and Kiel (2010) recently questioned Paleogene records of Archivesica, and Amano et al. (2014) identified the early Miocene Japanese A. sakoi Amano et al., 2014 as earliest member of Archivesica sensu strictu. The middle Miocene Archivesica strigarum n. sp. introduced here is thus among the earliest Archivesica species and is, just as A. sakoi, very elongate compared to extant Archivesica species.

Acknowledgments

This paper is a tribute to the late paleontologist M.A. Moroni for her intuition in the ‘60s that the Santa Sofia ‘Calcari a Lucina’ was a peculiar habitat of its own. We are grateful to P. Aharon, S. Conti, G.B. Vai, R. Barbieri, S. Cau, L. Angeletti, G. Bini, S. Gualtieri, for their cooperative work in recognizing and sampling ‘Calcari a Lucina’ limestones and their equivalents along the Italian Apennines over more than 25 years. Above all, we warmly thank M. Sami (Museo Civico di Scienze Naturali, Faenza) for the generous access to the vast collection of fossils from the ‘Calcari a Lucina’ deposits and for comments on various aspects of stratigraphy, and the collaborators of the Museo Civico di Scienze Naturali di Faenza, A. Benericetti, M. Diversi, and V. Liverani, for collecting part of the material. Thanks to D. Ormezzano (Museo Regionale di Scienze Naturali, Torino) for access to, and help with, the collection under his care, and S. Cavagna and G. Pavia for their cooperation. Furthermore, we thank K. Amano (Joetsu) for discussions on vesicomyid systematics; A.G. Beu (Lower Hutt) for advice on the ICZN; E. Krylova (Moscow) for providing images of the subfossil vesicomyid from the Rainbow vent field; C.T.S. Little (Leeds) for donating a specimen from his collection; I. Zorn, M. Harzhauser, and O. Mandic (Vienna) for access to specimens in their care; G. Hundertmark (Göttingen) and J. Bouchal (Stockholm) for photography; and J.D. Taylor (London) for his constructive review of the manuscript. Research on the ‘Calcari a Lucina’ by MT was funded over the years by various projects supported by the Italian Ministry of Education, University and Research (MIUR), and CNR; additional financial support was provided by the Deutsche Forschungsgemeinschaft through grant Ki802/6-1 and the Alméns fund of the Kungliga Vetenskaps-Akademien to SK. This is ISMAR-CNR Bologna scientific contribution n. 1833.

References

P. Aharon , and B.K. Sen Gupta , 1994, Bathymetric reconstructions of the Miocene-age “calcari a Lucina” (Northern Apennines, Italy) from oxygen isotopes and benthic Foraminifera: Geo-Marine Letters, v. 14, p. 219230.
K. Amano , and R.G. Jenkins , 2011, New fossil Bathymodiolus (s. l.) (Mytilidae, Bivalvia) from Oligocene seep-carbonates in eastern Hokkaido, Japan—with remarks on the evolution of Bathymodiolus (s. l.): The Nautilus, v. 125, p. 2935.
K. Amano , and S. Kiel , 2007, Fossil vesicomyid bivalves from the North Pacific region: The Veliger, v. 49, p. 270293.
K. Amano , and S. Kiel , 2010, Taxonomy and distribution of fossil Archivesica (Vesicomyidae, Bivalvia) in Japan: The Nautilus, v. 124, p. 155165.
K. Amano , and S. Kiel , 2012, Two Neogene vesicomyid species (Bivalvia) from Japan and their biogeographic implications: The Nautilus, v. 126, p. 7985.
K. Amano , R.G. Jenkins , M. Aikawa , and T. Nobuhara , 2010, A Miocene chemosynthetic community from the Ogaya Formation in Joetsu: evidence for depth-related ecologic control among fossil seep communities in the Japan Sea back-arc basin: Palaeogeography, Palaeoclimatology, Palaeoecology, v. 286, p. 164170.
K. Amano , R.G. Jenkins , M. Ohara , and S. Kiel , 2014, Miocene vesicomyid species (Bivalvia) from Wakayama in southern Honshu, Japan: The Nautilus, v. 128, p. 917.
A. Audzijonyte , E.M. Krylova , H. Sahling , and R.C. Vrijenhoek , 2012, Molecular taxonomy reveals broad trans-oceanic distributions and high species diversity of deep-sea clams (Bivalvia: Vesicomyidae: Pliocardiinae) in chemosynthetic environments: Systematics and Biodiversity, v. 10, p. 403415.
F.R. Bernard , 1974, The genus Calyptogena in British Columbia with a description of a new species: Venus, v. 33, p. 1122.
M. Berti , M.G. Cuzzani , A. Landuzzi , M. Taviani , P. Aharon , and G.B. Vai , 1994, Hydrocarbon-derived imprints in olistostromes of the Early Serravallian Marnoso-arenacea Formation, Romagna Apennines (northern Italy): Geo-Marine Letters, v. 14, p. 192200.
K. Beurlen , 1944, Beiträge zur Stammesgeschichte der Muscheln: Bayerische Akademie der Wissenschaften, Sitzungsberichte, v. 1–2, p. 133145.
K.J. Boss , 1967, A new species of Vesicomya from the Caribbean Sea (Mollusca: Bivalvia: Vesicomyidae): Brevoria Museum of Comparative Zoology, v. 266, p. 16.
K.J. Boss , 1968, New species of Vesicomyidae from the Gulf of Darien, Caribbean Sea (Bivalvia: Mollusca): Bulletin of Marine Science, v. 18, p. 731748.
P. Bouchet , and R. von Cosel , 2004, The world’s largest lucinid is an undescribed species from Taiwan (Mollusca: Bivalvia): Zoological Studies, v. 43, p. 704711.
P. Clari , C. Gagliardi , M.E. Governa , B. Ricci , and G. M. Zuppi , 1988, I Calcari di Marmorito: Una testimonianza di processi diagenetici in presenza di metano: Bollettino del Museo Regionale di Scienze Naturali, Torino, v. 6, p. 197216.
P. Clari , S. Cavagna , L. Martire , and J. Hunziker , 2004a, A Miocene mud volcano and its plumbing system: a chaotic complex revisited (Monferrato, NW Italy): Journal of Sedimentary Research, v. 74, p. 662676.
P. Clari , S. Conti , D. Fontana , and M. Taviani , 2004b, Fluid expulsion and authigenic products in the Miocene foredeep and satellite basins of the Northern Apennines, Italy: Field Guide Book-Post-Congress P07, 32nd IGC, August 20–28, Florence, Italy, p. 2.
E. V. Coan , and P. Valentich-Scott , 2012, Bivalve Seashells of Tropical West America. Marine Bivalve Mollusks from Baja California to Northern Peru: Santa Barbara, Santa Barbara Museum of Natural History, 596 p.
S. Conti , and D. Fontana , 1998, Recognition of primary and secondary Miocene lucinid deposits in the Apennine chain: Memorie di Scienze Geologiche, v. 50, p. 101131.
S. Conti , and D. Fontana , 1999, Miocene chemoherms of the northern Apennines Italy: Geology, v. 27, p. 927930.
S. Conti , R. Gelmini , and L. Ponzana , 1993, Osservazioni preliminari sui calcari a Lucine dell’Appennino Settentrionale.: Atti della Società dei Naturalisti e Matematici di Modena, v. 124, p. 3556.
S. Conti , D. Fontana , A. Gubertini , G. Sighinolfi , F. Tateo , C. Fioroni , and P. Fregni , 2004, A multidisciplinary study of middle Miocene seep-carbonates from the northern Apennine foredeep (Italy): Sedimentary Geology, v. 169, p. 119.
S. Conti , D. Fontana , S. Mecozzi , G. Panieri , and G.A. Pini , 2010, Late Miocene seep-carbonates and fluid migration on top of the Montepetra intrabasinal high (Northern Apennines, Italy): relations with synsedimentary folding: Sedimentary Geology, v. 231, p. 4154.
F. Coppi , 1877, Note sul calcare a Lucina pomum Dod: Bollettino del Regio Comitato Geologico Italiano, v. 8, p. 6971.
W.H. Dall , 1895, Diagnoses of new species of mollusks from the west coast of America: Proceedings of the U.S. National Museum of Natural History, v. 18, no. 1034, p. 7–20.
W.H. Dall , 1900, Contributions to the Tertiary fauna of Florida, with especial reference to the Miocene Silex-beds of Tampa and the Pliocene beds of the Caloosahatchie River. Part 5, Teleodemacea: Solen to Diplodonta: Transactions of the Wagner Free Institute of Science, Philadelphia, v. 3, p. 9491218.
W.H. Dall , 1901, Synopsis of the Lucinacea and of the American species: Proceedings of the U.S. National Museum of Natural History, v. 23, p. 779–833.
W.H. Dall , 1903, Contributions to the Tertiary fauna of Florida, with especial reference to the Silex beds of Tampa and the Pliocene beds of the Caloosahatchie River, including in many cases a complete revision of the generic groups treated of and their American species. Part 6. Concluding the work: Wagner Free Institute of Science of Philadelphia, Transactions, v. 3, p. 12191654.
W.H. Dall , 1908, A gigantic Solemya and a new Vesicomya : The Nautilus, v. 22, p. 6163.
W.H. Dall , and C.T. Simpson , 1901, The Mollusca of Porto Rico: United States Fishery Commission, Bulletin, v. 20, p. 351524.
S. Danise , L. Bertolaso , and S. Dominici , 2016, Bathymodioline mussel dominated Miocene whale fall from Italy: Bolletino della Società Paleontologica Italiana, v. 55, p. 17.
C. Des Moulins , 1868, Descriptions et figures de quelques coquilles fossiles du terrain tertiaire et de la craie (Gironde, Dordogne, Royan): Actes de la Société linnéenne de Bordeaux, v. 26, p. 357379.
D. Desbruyères , M. Segonzac , and M. Bright , 2006, Handbook of deep-sea hydrothermal vent fauna. Second completely revised version: Denisia, v. 18, p. 1544.
G. Di Stefano , 1903, Il calcare con grandi lucine dei dintorni di Centuripe in provincia di Catania: Atti dell’Accademia Gioenia di Scienze Naturali (S. 4), v. 16, p. 171.
J.B.L. Férussac , 1822, Tableau Systématiques des Animaux Molluscques: Paris and London, J. B. Bailliere, 111 p.
J. Fleming , 1828, A History of British Animals, exhibiting the descriptive characters and systematical arrangement of the genera and species of quadrupeds, birds, reptiles, fishes, Mollusca and Radiata of the United Kingdom; including the indigenous, extirpated, and extinct kinds; together with periodical and occasional visitants: Edinburgh, Bell & Bradfute, 554 p.
L. Génio , S.B. Johnson , R.C. Vrijenhoek , M.R. Cunha , P.A. Tyler , S. Kiel , and C.T.S. Little , 2008, New record of Bathymodiolus mauritanicus Cosel from the Gulf of Cadiz (NE Atlantic) mud volcanoes: Journal of Shellfish Research, v. 27, p. 5361.
L. Génio , S. Kiel , M.R. Cunha , J. Grahame , and C.T.S. Little , 2012, Shell microstructures of mussels (Bivalvia: Mytilidae: Bathymodiolinae) from deep-sea chemosynthetic sites: do they have a phylogenetic significance?: Deep-Sea Research I, v. 64, p. 86103.
S. Gualtieri , 1998, Rilevamento e sezioni stratigrafiche al limite Miocene-Pliocene nella parte interna del bacino crotonese (gole del Vitravo e del Lese nell’alto Neto) [Master thesis]: Bologna, University of Bologna, 113 p.
R.G. Gustafson , R.D. Turner , R.A. Lutz , and R.C. Vrijenhoek , 1998, A new genus and five new species of mussels (Bivalvia: Mytilidae) from deep-sea sulfide/hydrocarbon seeps in the Gulf of Mexico: Malacologia, v. 40, p. 63112.
J. Hashimoto , 2001, A new species of Bathymodiolus (Bivalvia: Mytilidae) from hydrothermal vent communities in the Indian Ocean: Venus, v. 60, p. 141149.
M. Hovland , M. Talbout , H. Qvale , S. Olausson , and L. Aasberg , 1987, Methane-related carbonate cements in pockmarks of the North Sea: Journal of Sedimentary Petrology, v. 57, p. 881892.
M. Hörnes , 1870, Die fossilen Mollusken des Tertiär-Beckens von Wien, II, Bivalven: Abhandlungen der kaiserlich-königlichen geologischen Reichsanstalt, v. 4, p. 1479.
R. Hörnes , 1875, Die Fauna des Schliers von Ottnang: Jahrbuch der kaiserlich-königlichen Geologischen Reichsanstalt, v. 25, p. 333431.
W.J. Jones , Y.-J. Won , P.A.Y. Maas , P.J. Smith , R.A. Lutz , and R.C. Vrijenhoek , 2006, Evolution of habitat use by deep-sea mussels: Marine Biology, v. 148, p. 841851.
V.C. Kenk , and B.R. Wilson , 1985, A new mussel (Bivalvia: Mytilidae) from hydrothermal vents in the Galapagos Rift Zone: Malacologia, v. 26, p. 253271.
S. Kiel , 2006, New records and species of mollusks from Tertiary cold-seep carbonates in Washington State, USA: Journal of Paleontology, v. 80, p. 121137.
S. Kiel , 2013, Lucinid bivalves from ancient methane seeps: Journal of Molluscan Studies, v. 79, p. 346363.
S. Kiel , and K. Amano , 2013, The earliest bathymodiolin mussels: Evaluation of Eocene and Oligocene taxa from deep-sea methane seep deposits in western Washington State, USA: Journal of Paleontology, v. 87, p. 589602.
S. Kiel , and J. L. Goedert , 2007, Six new mollusk species associated with biogenic substrates in Cenozoic deep-water sediments in Washington State, USA: Acta Palaeontologica Polonica, v. 52, p. 4152.
S. Kiel , and B. T. Hansen , 2015, Cenozoic methane-seep faunas of the Caribbean region: PLoS ONE, v. 10, no. 10, p. e0140788.
S. Kiel , K.A. Campbell , and C. Gaillard , 2010, New and little known mollusks from ancient chemosynthetic environments: Zootaxa, v. 2390, p. 2648.
E. Kittl , 1887, Die Miocenablagerungen des Ostrau—Karwiner Steinkohlenreviers und deren Faunen: Annalen des Kaiserlich-Königlichen Naturhistorischen Hofmuseums, v. 2, p. 217282.
S. Kojima , and S. Ohta , 1997, Calyptogena okutanii n. sp., a sibling species of Calyptogena soyae Okutani, 1957 (Bivalvia: Vesicomyidae): Venus, v. 56, p. 189195.
S. Kojima , K. Fujikura , and T. Okutani , 2004, Multiple trans-Pacific migrations of deep-sea vent/seep-endemic bivalves in the family Vesicomyidae: Molecular Phylogenetics and Evolution, v. 32, p. 396406.
E.M. Krylova , and R. Janssen , 2006, Vesicomyidae from Edison Seamount (South West Pacific: Papua New Guinea: New Ireland fore-arc basin): Archiv für Molluskenkunde, v. 135, p. 231261.
E.M. Krylova , and H. Sahling , 2010, Vesicomyidae (Bivalvia): current taxonomy and distribution: PLoS ONE, v. 5, no. 4, p. e9957.
T. Kuroda , 1943, Akebiconcha, a new pelecypod genus: Venus, v. 13, p. 1418.
F. Lartaud , et al., 2010, Fossil clams from a serpentinite-hosted sedimented vent field near the active smoker complex Rainbow, MAR, 36°13'N: Insights into the biogeography of vent fauna: Geochemistry, Geophysics, Geosystems, v. 11, p. 117. DOI: 10.1029/2010GC003079.
C.v. Linnaeus , 1758, Systema Naturae (tenth edition): Holmiae, Laurrentii Salvii, 824 p.
J. Lorion , B. Buge , C. Cruaud , and S. Samadi , 2010, New insights into diversity and evolution of deep-sea Mytilidae (Mollusca: Bivalvia): Molecular Phylogenetics and Evolution, v. 57, p. 7183.
J. Lorion , S. Kiel , B.M. Faure , K. Masaru , S.Y.W. Ho , B.A. Marshall , S. Tsuchida , J.-I. Miyazaki , and Y. Fujiwara , 2013, Adaptive radiation of chemosymbiotic deep-sea mussels: Proceedings of the Royal Society B, v. 280, p. 20131243. http://dx.doi.org/10.1098/rspb.2013.1243.
A. Manzoni , 1876, Della posizione geografica del calcare a Lucina pomum, Mayer: Bollettino del Regio Comitato Geologico Italiano, v. 7, p. 209216.
A.M. Martin , and S.K. Goffredi , 2011, Pliocardiakrylovata, a new species of vesicomyid clam from cold seeps along the Costa Rica Margin: Journal of the Marine Biological Association of the U.K., v. 92, p. 11271137.
L. Martire , M. Natalicchio , C. Petrea , S. Cavagna , P. Clari , and F. Dela Pierre , 2010, Petrographic evidence of the past occurrences of gas hydrates in the Tertiary Piedmont Basin (NW Italy): Geo-Marine Letters, v. 30, p. 461476.
M.C. Mayer , 1871, Description de coquilles fossiles des terrains tertiares supérieurs (suite): Journal de Conchyliologie, v. 19, p. 336349.
B. Merlino , 2007, Catalogo dei tipi e degli esemplari della collezione Bellardi e Sacco: Parte 3, Turin, Museo Regionale di Scienze Naturali Torino, Cataloghi, v. 17, 271 p.
G. Michelotti , 1847, Description des fossiles des terrains miocènes de l’Italie septentrionale: Leiden, Société Hollandaise des Sciences, 408 p.
M.A. Moroni , 1966, Malacofauna del “Calcare a Lucine” di S. Sofia—Forlì: Palaeontographica Italica, v. 60, p. 6987.
B. Nelli , 1903, Fossili miocenici nel Macigno di Porretta: Bollettino della Societa Geologica Italiana, v. 22, p. 181252.
M. Neumayr , 1884, Zur Morphologie des Bivalvenschlosses: Sitzungsberichte der Kaiserlichen Akademie der Wissenschaften, v. 88, p. 385419.
M.L. Nicosia , 1956, La fauna miocenica di “La Portella” presso Roccapalumba: Bollettino del Servizio Geologico d’Italia, v. 77, p. 363373.
T. Okutani , 1957, Two new species of bivalves from the deep water in Sagami Bay collected by the R.V. Soyo-Maru : Bulletin of Tokai Regional Fisheries Research Laboratory, v. 17, p. 2731.
T. Okutani , 2000, Marine mollusks in Japan: Tokyo, Tokai University Press, 1173 p.
T. Okutani , J. Hashimoto , and K. Fujikura , 1992, A new species of vesicomyid bivalve associated with hydrothermal vents near Amami-Oshima Island, Japan: Venus, v. 51, p. 225233.
T. Okutani , K. Fujikura , and T. Sasaki , 2004, Two new species of Bathymodiolus (Bivalvia: Mytilidae) from methane seeps on the Kuroshima Knoll off the Yaeyama Island, southwestern Japan: Venus, v. 62, p. 97110.
P.G. Oliver , and M.A. Frey , 2014, Ascetoaxinus quatsinoensis sp. et gen. nov. (Bivalvia: Thyasiroidea) from Vancouver Island, with notes on Conchocele Gabb, 1866, and Channelaxinus Valentich-Scott & Coan, 2012: Zootaxa, v. 3869, p. 452468.
C.K. Paull , B. Hecker , R. Commeau , R.P. Freeman-Lynde , C. Neumann , W.P. Corso , S. Golubic , J.E. Hook , E. Sikes , and J. Curray , 1984, Biological communities at the Florida Escarpment resemble hydrothermal vent taxa: Science, v. 226, p. 965967.
J. Peckmann , V. Thiel , W. Michaelis , P. Clari , C. Gaillard , L. Martire , and J. Reitner , 1999, Cold seep deposits of Beauvoisin (Oxfordian; southeastern France) and Marmorito (Miocene; northern Italy): microbially induced authigenic carbonates: International Journal of Earth Sciences, v. 88, p. 6075.
B. Prashad , 1932, The Lamellibranchia of the Siboga expedition. Systematic part 2 (exclusive of the Pectinidae): Siboga Expeditie, v. 53c, p. 1351.
C.S. Rafinesque , 1815, Analyse de la Nature, ou Tableau de l’univers et des corps organisées: Palermo, Barraveccia, 224 p.
F. Ricci Lucchi , and G.B. Vai , 1994, A stratigraphic and tectonofacies framework of the “calcari a Lucina“ in the Apennine Chain, Italy: Geo-Marine Letters, v. 14, p. 210218.
F. Ricci Lucchi , and A. Veggiani , 1967, I calcari a Lucina della Formazione Marnoso Arenacea Romagnola: Giornale di Geologia, v. 34, p. 159172.
F. Sacco , 1898, I molluschi dei terreni terziarii del Piemonte e della Liguria. Parte 25: Torino, Carlo Clausen, 76 p.
F. Sacco , 1901, I molluschi dei terreni terziarii del Piemonte e della Liguria. Parte 29: Torino, Carlo Clausen, 217 p.
F. Sacco , 1904, I molluschi dei terreni terziarii del Piemonte e della Liguria. Parte 30: Torino, Carlo Clausen, 203 p.
K.P. Saether , C.T.S. Little , K.A. Campbell , B.A. Marshall , M. Collins , and A.C. Alfaro , 2010, New fossil mussels (Bivalvia: Mytilidae) from Miocene hydrocarbon seep deposits, North Island, New Zealand, with general remarks on vent and seep mussels: Zootaxa, v. 2577, p. 145.
C. Salas , and J. Woodside , 2002, Lucinoma kazani n. sp (Mollusca: Bivalvia): evidence of a living benthic community associated with a cold seep in the Eastern Mediterranean Sea: Deep-Sea Research I, v. 49, p. 9911005.
M. Sami , and M. Taviani , 2015, I Calcari a Lucina e i Gessi di Rontana. I Gessi di Brisighella e Rontana: Memorie dell’Istituto Italiano di Speleologia—Ser. 2, v. 28, p. 3956.
T. Sasaki , T. Okutani , and K. Fujikura , 2005, Molluscs from hydrothermal vents and cold seeps in Japan: a review of taxa recorded in twenty recent years: Venus, v. 64, p. 87133.
G. Scarabelli , 1880, Descrizione della carta geologica del versante settentrionale dell’Appennino fra il Montone e la Foglia: Forlì, Tipografia Galeati Imola, 119 p.
R.L. Squires , and J.L. Goedert , 1991, New Late Eocene mollusks from localized limestone deposits formed by subduction-related methane seeps, southwestern Washington: Journal of Paleontology, v. 65, p. 412416.
W. Stimpson , 1851, A Revision of the Synonymy of the Testaceous Mollusks of New England, with notes on their structure, and their geographical and bathymetrical distribution: Boston, Phillips, Sampson, and company, 58 p.
M. Taviani , 1994, The “calcari a Lucina“ macrofauna reconsidered: deep-sea faunal oases from Miocene-age cold vents in the Romagna Apennine, Italy: Geo-Marine Letters, v. 14, p. 185191.
M. Taviani , 1996, La scoperta delle oasi di mare profondo nel Miocene italiano: Paleocronache, v. 1996, p. 714.
M. Taviani , 2001, Fluid venting and associated processes, in Vai, G.B., and Martini, I.P., eds., Anatomy of an Orogen: the Apennines and adjacent Mediterranean basins: London, Kluwer Acadmeic Publishers, p. 351366.
M. Taviani , 2011, The deep-sea chemoautotroph microbial world as experienced by the Mediterranean metazoans through time, in Reitner, J., Quéric, N.-V., and Arp, G., eds., Advances in Stromatolite Geobiology. Lecture Notes in Earth Sciences 131: Berlin, Springer, p. 277295.
M. Taviani , 2014, Marine chemosynthesis in the Mediterranean Sea, in Goffredo, S., and Dubinsky, Z., eds., The Mediterranean Sea: its history and present challenges: Dordrecht, Springer, p 6983.
M. Taviani , P. Aharon , and G.B. Vai , 1992, Discovery of vesicomyid-faunas in the Marnoso Arenacea Formation (Miocene of Romagna Apennines, Italy): IUGS-SOG Miocene Columbia Project, Portonovo (Ancona, Italy), 11–14 November 1992, Abstracts, unpg.
M. Taviani , L. Angeletti , and A. Ceregato , 2011, Chemosynthetic bivalves of the family Solemyidae (Bivalvia, Protobranchia) in the Neogene of the Mediterranean Basin: Journal of Paleontology, v. 85, p. 10671076.
J.D. Taylor , E.A. Glover , L. Smith , P. Dyal , and S.T. Williams , 2011, Molecular phylogeny and classification of the chemosymbiotic bivalve family Lucinidae (Mollusca: Bivalvia): Zoological Journal of the Linnean Society, v. 163, p. 1549.
J.D. Taylor , E.A. Glover , and S.T. Williams , 2014, Diversification of chemosymbiotic bivalves: origins and relationships of deeper water Lucinidae: Biological Journal of the Linnean Society, v. 11, p. 401420.
C. Terzi , 1993, The “Calcari a Lucina“ (Lucina limestone) of the Tuscan-Romagna Apennines as indicators of Miocene cold seep activity (northern Apennines, Italy): Giornale di Geologia, v. 55, p. 7181.
C. Terzi , P. Aharon , F. Ricci Lucchi , and G.B. Vai , 1994, Petrography and stable isotope aspects of cold-vent activity imprinted on Miocene-age “calcari a Lucina“ from Tuscan and Romagna Apennines, Italy: Geo-Marine Letters, v. 14, p. 177184.
J. Thubaut , N. Puillandre , B.M. Faure , C. Cruaud , and S. Samadi , 2013, The contrasted evolutionary fates of deep-sea chemosynthetic mussels (Bivalvia, Bathymodiolinae): Ecology and Evolution, v. 3, p. 47484766.
G.B. Vai , M. Taviani , S. Conti , and P. Aharon , 1997, Cold-E-Vent. Hydrocarbon Seepage and Chemosynthesis in Tethyan Relic Basins: Products, Processes and Causes, in An International Field Workshop to be held in Bologna and nearby Apennines. June 23–26/1997, Abstracts with Program: Bologna, p. 30.
F. Valdés , J. Sellanes , and G. D’Elía , 2013, Phylogenetic position of vesicomyid clams from a methane seep off central Chile (~36°S) with a molecular timescale for the diversification of the Vesicomyidae: Zoological Studies, v. 51, p. 11541164.
R. von Cosel , 2002, A new species of bathymodioline mussel (Mollusca, Bivalvia, Mytilidae) from Mauritania (West Africa), with comments of the genus Bathymodiolus Kenk & Wilson, 1985: Zoosystema, v. 24, p. 259271.
R. von Cosel , and R. Janssen , 2008, Bathymodioline mussels of the Bathymodiolus (s. l.) childressi clade from methane seeps near Edison Seamount, New Ireland, Papua New Guinea (Bivalvia: Mytilidae): Archiv für Molluskenkunde, v. 137, p. 195224.
R. von Cosel , and K. Olu , 1998, Gigantism in Mytilidae. A new Bathymodiolus from cold seep areas on the Barbados accretionary Prism: Comptes Rendus de l’Académie des Sciences, Paris, v. 321, p. 655663.
R. von Cosel , B. Métivier , and J. Hashimoto , 1994, Three new species of Bathymodiolus (Bivalvia: Mytilidae) from hydrothermal vents in the Lau Basin and the North Fiji Basin, western Pacific, and the Snake Pit area, Mid-Atlantic Ridge: The Veliger, v. 37, p. 374392.
W.P. Woodring , 1925, Miocene Mollusca from Bowden Jamaica, pelecypods and scaphopods: Carnegie Institution of Washington publications, v. 336, p. 1564.
M. Zuschin , O. Mandic , M. Harzhauser , and P. Pervesler , 2001, Fossil evidence for chemoautotrophic bacterial symbiosis in the thyasirid bivalve Thyasira michelottii from the Middle Miocene (Badenium) of Austria: Historical Biology, v. 15, p. 223234.

Appendix

Details of localities (see Figure 1) of Miocene methane-seep bivalves reported in this paper. Regarding the localities from Piedmont mentioned here in the context of the Sacco collection at MRSN (Albugnano, Bersano, Pera del Gal , Pino Torinese, etc.), the reader must refer to the catalog edited by Merlino (2007). The material illustrated by Moroni (1966) was reported to have been stored in the Museo Geologico Giovanni Capellini, University of Bologna, with the S. Sofia collection (catalog numbers 121–140); however, the collection is not present in this museum and is possibly kept in the University of Palermo, but not traceable at present (G. Ruggieri, personal communication, 1996).

1. Abisso “Mornig”.—Micritic limestone blocks near the entrance of “Mornig” cave, SE of Castelnuovo, not far from Brisighella (Ravenna province), Romagna Apennine, northern Italy; coordinates: 44°13'40''N, 11°44'72''E; Tossignano marls, late Miocene (late Tortonian).

2. Ca’ Carnè.—Marly to micritic limestone deposits just S-SE of Ca’ Carnè (“Vena del Gesso Romagnola” Regional Park visit center), near Brisighella (Ravenna province), Romagna Apennine, northern Italy; coordinates: 44°13'40''N, 11°44'72''E; Tossignano marls, late Miocene (late Tortonian).

3. Ca’ Cavalmagra.—Limestone (calcarenitic) deposit SSE of Palazzuolo (Firenze province), Tuscan Romagna Appenine, northern Italy; coordinates: 44°05'78''N, 11°33'62''E; Marnoso-arenacea Formation, middle Miocene (upper Langhian).

4. Monticino-Limisano – Castelnuovo junction.—Few scattered limestone blocks near the junction between Castelnuovo street and Calbane street, not far from Brisighella (Ravenna province), Romagna Appenine, northern Italy; coordinates 44°14'03.07''N; 11°44'18.72''E; late Miocene (late Tortonian).

5. Ca’ Fornace.—Erratic limestone blocks in the Sintria Creek downstream of the bridge near Ca’ Fornace, near Brisighella (Ravenna province), Romagna Apennine, northern Italy; coordinates: 44°14'14''N, 11°44'40''E; late Miocene (late Tortonian).

6. Ca’ Pianté.—Scattered marly to micritic limestone blocks SW of Ca’ Pianté, not far from Ca’ Carnè and near Brisighella (Ravenna province), Romagna Appenine, northern Italy; late Miocene (late Tortonian); additional information can be found in Conti and Fontana (1998).

7. Case Rovereti.—Large isolated limestone block just NW of the small village of Raggio, near Santa Sofia (Forlì province), Romagna Appenine, Italy; coordinates: 43°55'38''N, 11°56'43''E; located on San Paolo Marls but not necessarily belonging to such stratigraphic unit, late Miocene (middle Tortonian–early Messinian). This deposit has previously been described in more detail (Moroni, 1966; Taviani, 1994; Terzi et al., 1994; Clari et al., 2004a).

8. Castelvecchio.—Limestone (calcarenitic) deposit just W of small village of Castelvecchio, Piancaldoli, near Firenzuola (Firenze province), Tuscan Romagna Apennine, northern Italy; coordinates: 44°11'53''N, 11°24'18''E; Marnoso-arenacea Formation, middle Miocene (early Serravallian).

9. Deruta.—Small blocks at Fosso Castelleone 2 km SE of Deruta (Perugia province), central Italy; coordinates 42°58'15.47''N; 12°26'35.48''E. Upper Miocene (Serravallian). This area was described by Clari et al. (2004b).

10. Le Colline.—Scattered marly to micritic limestone blocks outcrop NE of Salecchio, near Palazzuolo (Firenze province), Tuscan Romagna Appenine, northern Italy; coordinates: 44°06'17''N, 11°34'53''E; Marnoso-arenacea Formation, middle Miocene (early Serravallian); further information on this outcrop is provided by Conti and Fontana (1998).

11. Marmorito.—Limestone deposits near the village of Marmorito in the Monferrato hills, east of Torino in the Piedmont Basin in northern Italy; coordinates: 45°03'24''N, 08°01'11''E; late Miocene (Tortonian). This well-known deposit was described in more detail elsewhere (Clari et al., 1988; Martire et al., 2010).

12. Montepetra.—Large limestone deposit on the southeastern margin of the village of Montepetra (Forlì-Cesena province), northern Italy; coordinates: 43°55'50.67''N, 12°11'38.22''E. (late Tortonian). This deposit is well described in the literature (Taviani, 1994; Conti and Fontana, 1998; Clari et al., 2004b; Conti et al., 2010).

13. Sasso delle Streghe.—A 30 m high marly limestone peak near the village of Rocca Santa Maria (Modena province), northern Italy; coordinates: 44°28'40.02''N, 10°47'40.11''E; Termina Formation, Miocene (late Serravallian–Tortonian) (Taviani, 1994; Conti and Fontana, 1998; Taviani, 2001; Clari et al., 2004b; Conti et al., 2010). Also known in the past as ‘Sasso delle Cappe’ (Clams’ rock).

14. Verzino.—Small isolated outcrops in the Crotone basin along the steep right slope of the Vitravo river, between the villages of Verzino and Pallagorio at the localities of Maradera-Occhito (Crotone province), southern Italy; coordinates 39°31'90''N 16°87'32''E to 39°30'97''N 16°87'92''E (late Miocene: Tortonian to Messinian?). More information is reported by Gualtieri (1998).