Only six species of the genus Cylindrobulla have been described anatomically. A new species from Ghizo Island, Solomon Islands, is here described. It is the first anatomically described species from the South Pacific Ocean. The new species, Cylindrobulla ghizoensis sp. nov., has a thin, semi-transparent shell 2–6 mm long and a white head and foot, which are completely retractable inside the shell. The foot is slightly longer than the head. The uniseriate radula has numerous small (6–8 µm) teeth with a short central cusp only marginally longer than the few lateral cusps. The short penis has no stylet. A comparison of all described species of Cylindrobulla permits an emended genus diagnosis including a shell with a deep, oblique apical keel with excentric nucleus, a thickened edge of body whorl, a suctorial pharynx, and numerous (80–100+) small, uniformly sized radular teeth, including several formative teeth and a poorly defined ascus. Comparing the feeding structures of Cylindrobulla with those of other sacoglossans shows a pharynx with weaker musculature and teeth unsuitable for piercing algal cell walls, indicating a different feeding method.

Arborea elegans sp. nov., a new species of the clade Arboreomorpha, is described and figured based on three specimens preserved in mudstone from the Ediacaran Mistaken Point Formation at Halfway Cove, near the town of Logy Bay-Middle Cove-Outer Cove, Newfoundland, Canada. Arborea elegans is readily attributed to the clade Arboreomorpha because of its parallel primary branches diverging orthogonally from the central stalk, and merging at their apices to form a distinct marginal rim. It is assigned to the genus Arborea because of its distally tapered petalodium, rectangular first-order branches arising orthogonally from a prominent stalk, and first-order axes exposed over the entire length of the branches. It is distinguishable from other species of the genus by its slender petalodium, reduced stem, relatively broad first-order branches, and proportionally wide basal disc.

The crustose cyanolichen Fuscopannaria frullaniae (syn. Moelleropsis nebulosa subsp. frullaniae) is a poorly understood taxon that occurs on mosses and liverworts, described from eastern Canada and reported from the Iberian Peninsula, Macaronesia and the eastern USA. Originally placed in the genus Moelleropsis, the position of the species has been debated in the absence of sexual fruiting structures and, until now, DNA sequences from the fungal symbiont. We produced nine sequences from two fungal ribosomal loci from F. frullaniae collected at five different localities in Nova Scotia, Canada and North Carolina, USA. Initial BLASTn queries against public databases revealed high similarity between these sequences and basidiomycete sequences from the Dictyonema clade in Hygrophoraceae, specifically from the genus Acantholichen. We did not obtain ascomycete sequences from any locus or specimen. Phylogenetic analyses recovered the obtained sequences within the broader Acantholichen clade. We conclude that the lichen fungal symbiont is in fact a basidiomycete and introduce for it the new combination Acantholichen frullaniae. Acantholichen frullaniae is the first species of the genus to possess a granular, crustose thallus. The species lacks the characteristic, spiny, balloon-shaped cells called acanthohyphidia that are found in other species of the genus, though it possesses similar, albeit spineless cells on the surface of thallus granules; we suggest that these structures within the wider genus are homologous and represent spiny or smooth cystidia. Numerous samples yielded evidence of basidiospores and basidia produced from thallus granules, evident only after treatment with diluted potassium hydroxide, representing the first sexual structures reported in the genus. We discuss the possible reasons for this, as well as the ecology and threats to the species across its Canadian populations.

A new species of spionid polychaete from the coastal waters of southwest India, Trochochaeta chakara sp. nov., is described and illustrated. Adults are common on Alappuzha mud banks (locally known as Chakara) off the coast of Kerala. They live in silty tubes in soft sediment and are characterized by the presence of two pairs of red eyes, caruncle extending to end of chaetiger 1, heavy falcate spines in neuropodia of chaetigers 2 and 3 (those in chaetiger 3 much stronger and darker), capillary chaetae in notopodia of chaetigers 1, 3–10, frayed heavy spines in neuropodia of chaetigers 4–13, hirsute capillaries in neuropodia from chaetiger 14, lateral interneuropodial membranes from chaetiger 14, one pair of ventral papillae on each chaetiger from chaetigers 14–16, bundles of acicular spines in notopodia from chaetigers 50–52, and small pygidium with up to six pairs of short cirri. This is the third species of Trochochaeta described and found in the Indian Ocean, including T. orissae (Fauvel, 1932) and T. cirrifera (Hartman, 1975).

This study provides the first integrative analysis of Megacoelium spinicavum Thatcher & Varella, 1981 (Digenea: Haploporidae) from the Amazon sailfin catfish Pterygoplichthys pardalis Castelnau, 1855 (Siluriformes: Loricariidae) in the Peruvian Amazon. A detailed morphological description is presented, including the first scanning electron microscopy (SEM) images of tegumental structures, which revealed two distinct types of tegumental spines: (1) small, button-like spines and (2) sharply pointed spines. Partial sequences of the 28S rDNA and mitochondrial cox1 genes were generated and analysed to investigate the phylogenetic position of Megacoelium Szidat, 1954, within the Haploporidae Nicoll, 1914. Phylogenetic analyses placed M. spinicavum within the ‘robust species’ clade of Saccocoelioides Szidat, 1954, clustering with S. bacilliformis Szidat, 1973, although with weak support. These results provide additional evidence that Saccocoelioides is not monophyletic and support restricting the genus to the ‘minute species’ clade containing the type species. The ‘robust species’ clade appears to comprise at least three divergent lineages, potentially representing distinct genera, one of which includes M. spinicavum. The absence of molecular data for M. plecostomi Szidat, 1954, the type species of Megacoelium, continues to obscure its phylogenetic placement. We highlight the need for comprehensive morphological and multilocus molecular analyses, including SEM, to clarify the taxonomic status of Megacoelium and to resolve the evolutionary relationships of chalcinotrematine digeneans in Neotropical fishes.

Avian schistosomatids are blood flukes parasitizing a wide spectrum of aquatic birds. However, its research in the Neotropics is ongoing with several putative new taxa pending description. Although waterfowl represent the most important avian hosts for these flukes, only a small proportion of these birds have been assessed for schistosomatids. This study aimed to describe avian schistosomatids from two native ducks from the Southern Cone of South America. A total of 24 Chiloe wigeon (Mareca sibilatrix) and three Cinnamon teals (Spatula cyanoptera) from different localities in Chile and Argentina were dissected to retrieve schistosomatids. The retrieved worms were described through an integrative approach considering morphology (staining and SEM) and molecular tools (PCR: COI, 28S rRNA genes). The new schistosomatid: Trichobilharzia kulfu sp. nov. was recovered from the viscera of Chiloe wigeon. It was closely related to other undescribed Trichobilharzia taxa from the United States, also from Mareca ducks. The new species was morphologically and molecularly different from other Trichobilharzia species, and it was included in the clade Q. In addition, SEM imaging proved to be an important tool to describe unnoticed traits on the tegument of worms. This new species represents the second Trichobilharzia taxon from the Neotropics described through an integrative approach. Furthermore, the Cinnamon teals harboured Trichobilharzia querquedulae. Considering there are several avian schistosomatids described only through morphological or molecular tools, there is a clear need to include a comprehensive approach in the description of avian schistosomatids, considering the remarkable richness of schistosomatids in Neotropics.

A new phylogenetic analysis of Lecanora s. lat. is presented based on a dataset of seven loci, including recently published mitochondrial markers. In this analysis, comprising 136 specimens and 572 sequences, several clades that can be circumscribed taxonomically are recovered as monophyletic with strong support. Lecanora divides into two large monophyletic subclades. The well-supported MPRPS clade sensu Medeiros et al. (2021) combines the genera Lecanoropsis, Myriolecis, Protoparmeliopsis, Rhizoplaca and the Lecanora polytropa- and L. varia-groups. The second unsupported clade contains the genera Bryonora, Palicella, Pulvinora and Vainionora, plus the Lecanora albella/subcarnea-, L. carpinea/rupicola-, L. intumescens-, L. subfusca- and L. symmicta-groups. Japewia, Lecidella, Miriquidica, Ramboldia and members of the Lecanora fuscescens-group are placed outside these two clades. Phylogenetic, morphological and chemical evidence supports the resurrection of three genera: Glaucomaria (for the Lecanora carpinea/rupicola-group), Straminella (for the L. varia-group), and Zeora (for the L. symmicta-group). Descriptions for each of the resurrected genera are provided, including new taxonomic combinations and lists of additional Lecanora species likely to be transferred to the proposed new genera pending further studies. Comments on the nomenclature of the new genera, as well as for Lecanoropsis and Myriolecis, are provided.

The first known trochurine lichid from the Lower Devonian of southern France is assigned to the genus Branikarges Basse & Müller, 2023, replacing the invalid genus Lobopyge Přibyl & Erben. Branikarges euanclarksoni sp. nov. occurs in cherty limestones of the upper Emsian middle Izarne Formation in the Cabrières klippes, in the southeast of the Montagne Noire. Among the few contemporary representatives of typical Branikarges, the new species is closest to north Gondwana related taxa. Silicified early growth stages assigned to B. euanclarksoni have been recovered from the middle Bissounel Formation, a temporal equivalent of the middle Izarne Formation in the Montagne Noire nappe succession. The material includes, besides a questionable metaprotaspis, some meraspid cranidial fragments, librigenae and hypostomes, as well as an almost complete succession of transitory pygidia. This material allows for the first establishment of the meraspid stage development of Branikarges through applying the distribution model of spine markers on alternate pleurae developed by B. D. E. Chatterton in 1971.

Cambrian trilobites from two separate allochthonous limestone blocks of La Cruz olistoliths at the Quebrada Oblicua (Precordillera of Mendoza, Argentina), originally described by the naturalist Carlos Rusconi in the 1950s, are revised herein. One of the olistoliths is dominated by the late Guzhangian cedariid Cedaria puelchana Rusconi, whereas the other block contains Pseudagnostus cf. P. idalis Öpik, Dunderbergia punctata (Rusconi) new combination, Sigmocheilus cf. S. sigmoidalis (Palmer), Litocephalus obliquoanus (Rusconi) new combination, and Onchonotopsidae? gen. et sp. indet., which indicate a late Paibian age (Dunderbergia Zone). The genera Dunderbergia Walcott (=Tabalqueia Rusconi), Sigmocheilus Palmer, and Litocephalus Resser (=Cayupania Rusconi) are reported from South America for the first time. In line with previous studies on Cambrian faunas from the Precordillera, the assemblages revised here show North American (Laurentian) affinities.