A new species of Cambeva (Siluriformes, Trichomycteridae) from the Rio Iguaçu basin, Paraná State, Brazil and redescription of Cambeva stawiarski (Miranda Ribeiro 1968)

Abstract

This work aimed to describe Cambeva cauim, sp. nov., endemic to the Rio Iguaçu basin, Brazil and redescribe Cambeva stawiarski using external and internal morphological data through the revision of specimens deposited in fish collections, including the type material.In this process, we have also added comments on the possible type locality of C. stawiarski. C. cauim, sp. nov. and C. stawiarski are mainly diagnosed by the anatomy and number of procurrent caudal-fin rays in addition to colouration and several meristic and morphometric characters. Both species are compared with other possibly related species and their synapomorphic characters are discussed. C. cauim, sp. nov. and C. stawiarski along with eight other congeners are endemic to the Rio Iguaçu basin, a high impacted freshwater region which could be considered as a biodiversity hotspot to the genus.

A new catfish species of the genus Cambeva (Siluriformes: Trichomycteridae) from the Rio Iguaçu drainage, southern Brazil, with a remarkable unique colour pattern

“…The possible sister group relationships between C. castroi and C. melanoptera supports the recent hypothesis of a local evolutionary radiation as a result of long‐term isolation of the Rio Iguaçu drainage from the remaining portion of the Rio Paraná basin by the Cataratas do Iguaçu (Iguaçu Falls) (dos Reis et al ., 2021), a hypothesis in part already advanced by Haseman (1910: 374). A total of 11 species of Cambeva are known to occur in this river drainage (dos Reis et al ., 2021; present study), a number that is presently larger than that in neighbouring drainages. Due to the relatively larger number of endemic species, dos Reis et al .…”

“…A similar condition was first described by Bockmann et al . (2004) for C. diabola and later reported to occur in other congeners (Costa et al ., 2021a; dos Reis et al ., 2021). This process was not present in C. melanoptera , as well as in the three specimens of C. diabola here examined, indicating that this condition may have a variable occurrence in species of Cambeva from southern Brazil and therefore being ambiguous for inferring relationships.…”

“…1080 km, the Rio Iguaçu is one of the largest tributaries of the Rio Paraná basin, which is the main component of the Río de La Plata hydrographic system. The landscape of the upper and middle sections of the basin is dominated by waterfalls and fast‐flowing rivers, which shelter a diversified assemblage of rheophilic catfishes of the trichomycterine genus Cambeva Katz et al ., 2018 (dos Reis et al ., 2021). This genus was recently described to comprise species of a clade sister to Scleronema Eigenmann, 1917 (Katz et al ., 2018).…”

“…120 species. Nonetheless, the number of species included in Cambeva is quickly increasing since the genus description, presently reaching 40 valid species and others waiting formal description (Costa et al ., 2021a, 2021b; dos Reis et al ., 2021).…”

“…Cambeva occurs in a broad eastern South American region between the Rio São Francisco basin in southeastern Brazil and the Lagoa dos Patos system in southern Brazil (Costa, 1992; Ferrer & Malabarba, 2013; Katz et al ., 2018), but about one‐fourth of all species of the genus occur in the Rio Iguaçu drainage (dos Reis et al ., 2021). Cambeva species endemic to the Rio Iguaçu drainage exhibit the largest morphological diversity in the genus, with some of them having unique features.…”