A taxonomic review of the vampire catfish genus Paracanthopoma Giltay, 1935 (Siluriformes, Trichomycteridae), with descriptions of nine new species and a revised diagnosis of the genus

A taxonomic revision is presented of the genus Paracanthopoma, probably the least-known vandelliine genus at present. The work is based on most of the material available in museums worldwide and includes a major expansion in the knowledge about the genus. Paracanthopoma is circumscribed as a monophyletic group on the basis of nine putatively synapomorphic characters. Evidence is provided for Paracanthopoma and Paravandellia as sister groups and the two genera are comparatively diagnosed. A total of 13 species are recognized in Paracanthopoma, of which nine are new and one is transferred from Paravandellia: Pc. ahriman, new species, Pc. alleynei (Henschel et al., 2021), Pc. carrapata, new species, Pc. cangussu Henschel et al., 2021, Pc. capeta, new species, Pc. daemon, new species, Pc. irritans, new species, Pc. malevola, new species, Pc. parva Giltay, 1935, Pc. saci Dagosta & de Pinna, 2021, Pc. satanica, new species, Pc. truculenta, new species, and Pc. vampyra, new species. Different species display a high degree of phenotypic divergence and are diagnosed on the basis of traditional as well as new morphological characters of both external and internal anatomy. Geographical distributions are mapped for each species and an identification key is provided. Preliminary evidence suggests the existence of four main subclades within Paracanthopoma. The first one includes Pc. ahriman, Pc. cangussu, and Pc. irritans. A second subclade comprises Pc. carrapata, Pc. daemon, Pc. parva, and Pc. truculenta. A third clade includes Pc. malevola and Pc. satanica and a fourth comprises Pc. alleynei and Pc. vampyra. The last clade lacks some putative synapomorphies of all other members of Paracanthopoma and seems to be the sister group to the rest of the genus. Relationships of Pc. capeta and Pc. saci are not as clear, but some evidence exists for the former being related to the first subclade and the latter to the second subclade.