Species tot sunt diversae quot diversas formas ab initio creavitiv — A dialogue on species

Species tot sunt diversae quot diversas formas ab initio creavitiv — A dialogue on specie

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

Two new catfish species of typically Amazonian lineages in the Upper Rio Paraguay (Aspredinidae: Hoplomyzontinae and Trichomycteridae: Vandelliinae), with a biogeographic discussion

Two new species of particular biogeographic significance are described from the upper rio Paraguay basin, one of the genus Paracanthopoma (Trichomycteridae, Vandelliinae) and the other of the genus Ernstichthys (Aspredinidae, Hoplomyzontinae). The two species occur sympatrically in the Rio Taquarizinho, tributary of the Rio Taquari, in the upper Paraguay system. Paracanthopoma saci is distinguished from its only congener, P. parva, by a spatulate caudal peduncle; a minuscule premaxillary dentition (reduced to three delicate teeth); the supraorbital latero-sensory canals opening as two separate s6 pores; the caudal fin slightly convex or truncate with round edges; the skull roof entirely open, unossified; the origins of dorsal and anal fins approximately at same vertical; and the pelvic fin with three rays. Ernstichthys taquari is diagnosed among congeners by the narrow bony shields on dorsal and ventral series, not overlapping or contacting each other; by the presence of seven or eight serrations on the posterior margin of the pectoral spine; and by the pectoral-fin spine only slightly larger than subsequent soft rays. Both Paracanthopoma and Ernstichthys were previously unknown outside of the Greater Amazonian river systems (Amazon, Orinoco, Essequibo and smaller surrounding drainages). Their presence restricted to the Rio Taquari is unexpected and suggests a peculiar biogeographical history. Ancestral geographic distributions were reconstructed using S-DIVA and BBM methods in RASP. A majority of resulting hypotheses support that the two species reached the Paraguay from the Amazon. The alternative explanation accounts for their presence in the Paraguay by vicariant events. In no case, their presence in the Paraguay is an ancestral distribution with subsequent Amazonian dispersal. Though unusual, this pattern is also seen in a few other fish taxa, showing that the Rio Taquari is biogeographically hybrid, combining elements from both the Paraguay and Amazon drainages

A new subterranean species of Phreatobius Goeldi, 1905 (Siluriformes, Incertae sedis) from the Southwestern Amazon basin

A new species of the previously monotypic catfish genus Phreatobius is described from an artificial well in the village of Rio Pardo, located 90 km south of the city of Porto Velho, State of Rondônia, Brazil, in the drainage area of the Rio Branco (Rio Madeira system, Amazon basin). Phreatobius dracunculus n. sp. differs from its only congener, P. cisternarum, by the absence of eyes (vs. present), the lack of dark integumentary pigmentation (vs. faint dark pigment always present), the presence of five pectoral-fin rays (vs. four), ventral procurrent rays 11-13 (vs. 22 to 26), dorsal procurrent rays 29-31 (vs. 42 to 50), fewer vertebrae (52 or 53 vs. 59 to 64) and the larger pseudotympanus. The new species shows all diagnostic characters so far proposed for Phreatobius, including an unusual red coloration in life. The localities of the two species of Phreatobius are approximately 1900 km apart. That, in association with their peculiar and mostly inaccessible habitats, indicates that the genus may be widely distributed in the Amazon basin.Uma nova espécie do gênero previamente monotípico Phreatobius é descrita de um poço artificial no Povoado de Rio Pardo, localizado 90 km ao sul da cidade de Porto Velho, Estado de Rondônia, Brasil, na área de drenagem do rio Branco (sistema do Rio Madeira, bacia Amazônica). Phreatobius dracunculus sp. n. difere da única espécie congênere, P. cisternarum, pela ausência de olhos (vs. presente), ausência de pigmentação na pele (vs. algum pigmento escuro sempre presente), presença de cinco raios na nadadeira peitoral (vs. 4), menor número de raios procorrentes ventrais 11-13 (vs. 22 a 26), e menor número de raios procorrentes dorsais 29-31 (vs. 42 a 50), menor número de vértebras (52 ou 53 vs. 59 a 64) e pseudotímpano maior. A nova espécie apresenta todos os caracteres diagnósticos propostos para Phreatobius, incluindo a conspícua coloração vermelha em vida. As localidades das duas espécies de Phreatobius estão aproximadamente a 1900 km de distância. A presença desta espécie em região tão distante da ocorrência de P. cisternarum em associação com o ambiente freático peculiar, evidenciam que o grupo pode estar amplamente distribuído na bacia amazônica

Ural centrum in Siluriformes

23 p. : ill. ; 26 cm.Includes bibliographical references (p. 15-17).A well-developed second ural half-centrum is a peculiar characteristic of the caudal skeleton of certain siluriforms, not seen in other Recent ostariophysans. Although the character has been previously recorded in the literature, its exact taxonomic distribution, structure, ontogeny, and phylogenetic meaning within siluriforms are not yet determined. In this paper, the degree of development of the second ural half-centrum is surveyed across the order. The ontogeny of the relevant axial structures in the posterior region of the vertebral column is reported in representative siluriform taxa. The condition where the second ural centrum is well formed and forms a complete intervertebral joint anteriorly with the compound caudal centrum is considered derived within siluriforms, a character state homoplastic with the primitive state in more distant teleostean outgroups. Various catfishes display that derived condition, which is informative about relationships at different levels within the group. The most inclusive of those clades is the superfamily Sisoroidea, including the families Amblycipitidae, Akysidae, Sisoridae, Erethistidae, and Aspredinidae. The placement of the neotropical Aspredinidae into an otherwise exclusively Asian clade has important biogeographical implications and the structure of the second ural centrum provides additional support to that hypothesis. Based on the currently available knowledge on the relationships among catfishes, a well-developed second ural centrum is hypothesized to be a result of six different events in siluriforms