A new catfish of the genus Trichomycterus from the Rio Paraíba do Sul Basin, south-eastern Brazil, a supposedly migrating species (Siluriformes, Trichomycteridae)

Abstract

A new species of the catfish genus Trichomycterus is described from the Rio Paraíba do Sul, south-eastern Brazil. This species exhibits some morphological character states that are unique amongst congeners, including a robust opercle and a long interopercle with numerous odontodes (50–60 opercular and 90–100 interopercular), a black bar on the basal portion of the caudal fin and a dark brown flank with a well delimited dorsal yellow stripe. It also exhibits some morphological traits that are uncommon amongst congeners, such as the presence of nine pectoral-fin rays. The presence of a shallow hyomandibular outgrowth and a ventrally expanded pre-opercular ventral flap suggests that this species is closely related to T. melanopygius, T. pradensis and T. tete. The new species also differs from T. melanopygius, T. pradensis and T. tete by having an emarginate caudal fin and a single median supra-orbital pore S6. Anecdotal evidence suggests that T. largoperculatus and T. pradensis have migratory habits, a condition not previously reported for eastern South American trichomycterines.

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

“…Cambeva chrysornata is similar to C. cubataonis and is distinguished from C. guaratuba by the medial margin of the autopalatine exhibiting a deep concavity in its middle portion, posteriorly followed by a distinctive projection towards the mesethmoid. Cambeva chrysornata is also distinguished from C. cubataonis by having 14 vertebrae (vs. [15][16].…”

“…Cambeva guaratuba is also distinguished from C. chrysornata by having longer barbels, the tip of the rictal barbel posteriorly reaching area posterior to the orbit (vs. reaching the anterior margin of the orbit or an area anterior to it) and maxillary and rictal barbels reaching interopercular patch of odontodes (vs. not reaching), a relatively deep dorsal fin, with the longest ray longer than the dorsal-fin base (vs. longest ray shorter than the dorsal-fin base), pectoral fin subtriangular in dorsal view (vs. rounded), pelvic fin truncate, its posterior extremity reaching a vertical at the anterior half of the dorsal-fin base (vs. rounded, its posterior extremity reaching a vertical anterior to the dorsal-fin origin), more procurrent caudal-fin rays (total of 20 or 21 dorsally and 13 or 14 ventrally, vs. 16 or 17 dorsally and 11 or 12 ventrally), more vertebrae (40 or 41, vs. 38 or 39), and the absence of an irregularly shaped golden longitudinal line on the medio-dorsal portion of the flank (vs. presence). Cambeva guaratuba is also distinguished from C. cubataonis by having 14 vertebrae (vs. [15][16].…”

“…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].…”

High Endemism in an Endangered Biodiversity Hotspot: Phylogeny, Taxonomy and Distribution Patterns of Catfishes of the Psammocambeva Alpha-Clade (Siluriformes: Trichomycteridae) from the Rio Doce Basin, Brazil

“…Recent studies indicated the existence of at least 21 trichomycterine species endemic to the Rio Paraíba do Sul basin ( [12,49,50] and included references), belonging to five different subgenera (i.e., Cryptocambeva, Humboldtglanis, Paracambeva, Psammocambeva, and Trichomycterus; [10]). Contrastingly, today, there are 16 nominal species of Trichomycterus considered endemic to RDB, of which 15 belong to Psammocambeva and only one, T. argos, belongs to Cryptocambeva.…”