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

Abstract

Cambeva melanoptera sp. nov. is described from stream tributaries of the Rio Iratim, Rio Iguaçu drainage, southern Brazil. This new species is remarkable with a colour pattern not found elsewhere among trichomycterid catfishes, consisting of a broad distal black zone in all unpaired and pectoral fins, strongly contrasting with a pale-yellow proximal zone. C. melanoptera also differs from all other trichomycterids from eastern South America by the presence of the nasal barbel about thrice longer than the maxillary and rictal barbels. Due to the presence of a similar bicolour caudal fin, the new species is tentatively considered closely related to Cambeva castroi and Cambeva diabola, as well as more closely related to C. castroi than to C. diabola, with the first two species sharing the presence of a curved lateral process of the parurohyal and a trapezoidal projection on the lateral margin of the lateral ethmoid. The great morphological diversity found in Cambeva species endemic to the Rio Iguaçu drainage, including numerous exclusive characteristics not occurring in congeners and in any other species of closely related trichomycterine genera, indicates the need for more studies focusing on possible causal factors responsible for such unique diversification pattern.

Monophyly or Homoplasy? The Relationships of a Rare New Species of Cambeva (Siluriformes: Trichomycteridae) from the Brazilian Atlantic Forest with a Bicolored Caudal Pattern

“…The new species has a peculiar color pattern on the caudal fin, comprising a lightyellowish-white bar on the caudal fin base, posteriorly edged by a black pigmented area. A similar bicolored pattern of the caudal fin has been reported for three other congeners endemic to other regions of the Rio Paraná basin: Cambeva castroi (de Pinna, 1992) and Cambeva melanoptera Costa, Abilhoa, Dalcin & Katz, 2022 from the Rio Iguaçu drainage, and Cambeva diabola (Bockmann, Casatti & de Pinna, 2004) from the Rio Paranapanema drainage [6][7][8]. Although the caudal fin color pattern is not identical in those species, varying in the extent and intensity of each color, it has been considered the main evidence of monophyly of the species sharing it [7,8].…”

Morpho-Molecular Discordance? Re-Approaching Systematics of Cambeva (Siluriformes: Trichomycteridae) from the Guaratuba-Babitonga-Itapocu Area, Southern Brazil

“…In lists of examined material specimens, geographical names correspond to Portuguese names used in the region. Comparative material appears in Costa et al [4,6,7,[9][10][11].…”

“…About half of these species belongs to a clade endemic to eastern South America that includes the genera Cambeva Katz, Barbosa, Mattos & Costa, 2018, Scleronema Eigenmann, 1917 and Trichomycterus s.s. Valenciennes, 1832, called the CST-clade [3]. In the last three years, 39 new trichomycterine species of phylogenetic lineages little or not previously known were described from eastern and central South American region [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20], demonstrating that our current knowledge about this group is still at an initial stage. Cambeva, the focus of the present study, includes over 40 species [9], many of them with restricted distribution, occurring between the Rio São Francisco basin in south-eastern Brazil and tributaries of the Lagoa dos Patos system in southern Brazil [21].…”