Trachycorystes, BLEEKER, 1858

GENUS TRACHYCORYSTES BLEEKER, 1858 View in CoL (CLADE 73)

Trachycorystes Bleeker, 1858b: 200 View in CoL (type species: Auchenipterus trachycorystes Valenciennes, 1840 View in CoL ; type by absolute tautonymy. Gender masculine).

Included species: Trachycorystes menezesi Britski & Akama, 2011 View in CoL and Trachycorystes trachycorystes ( Valenciennes, 1840) View in CoL .

Diagnosis: Trachycorystes is diagnosed by six morphological synapomorphies. Non-exclusive: (1) n a s a l b o n e p l a t e -l i k e, l a t e r a l l y e x p a n d e d (char. 3512: 0 → 1), convergent in Tatia boemia , Tatia brunnea , Tatia jacaratia , Tatia caxiuanensis , Tatia nigra , Trachelyopterichthys , Trachelyopterus and Spinipterus sp. ‘oncinha’; (2) lateroposterior portion of sphenotic slightly concave (char. 3552: 0 → 1), convergent in Ageneiosus (except Ageneiosus pardalis and Ageneiosus vittatus ), Liosomadoras morrowi , Trachelyichthys , Trachelyopterus lucenai , Trachelyopterus porosus and several centromochlines; (3) bony expansion in posteromedial portion of premaxilla (char. 3585: 0 → 1), convergent in Ageneiosus (except Ageneiosus intrusus and Ageneiosus uranophthalmus ) and Auchenipterus fordicei ; (4) posterior bony projection on last dorsal-fin pterygiophore absent (char. 3680: 0 → 1), convergent in Auchenipterichthys punctatus , Liosomadoras , Entomocorus , Gelanoglanis , Glanidium , Duringlanis perugiae , Tatia simplex , Pseudotatia , Tatia nigra , Tatia intermedia , Tatia caxiuanensis , Tatia sp. 2 , Balroglanis carolae , Trachelyichthys , Trachelyopterichthys and Spinipterusacsi;(5)posterior portion of basipterygium long, with process developed as wing (char. 3729: 0 → 1), convergent in Ageneiosus , Tympanopleura , Asterophysus , Centromochlus and Trachelyopterus ; and (6) basal process of pelvic-fin rays posteromedially oriented (char. 3732: 1 → 0), convergent in Epapterus , Pseudepapterus , Pseudauchenipterus , Glanidium , Gelanoglanis, Ageneiosini , Asterophysus , Trachelyopterichthys and Trachelyopterus (except Trachelyopterus insignis ).

Comparisons: Trachycorystes are medium-sized predator species with the cephalic shield well exposed on the surface of the head, and distinguished from all auchenipterines, except Asterophysus , by the uniform dark brown or greyish to black coloration of the body, lacking any colour marks (vs. distinctly marked colour patterns present, or light background with darker dorsal profile); from all auchenipterines, except Asterophysus and Trachelyopterus , by having the lower jaw prognate, slightly outward in comparison to the premaxilla (less evident in Trachycorystes menezesi ) (vs. lower and upper jaws ending in the same vertical line); and except for Trachycorystes menezesi , distinguishes from Tocantinsia , Asterophysus , Pseudepapterus , Pseudauchenipterus , Entomocorus , Auchenipterus , Ageneiosus (except Ageneiosus vittatus and Ageneiosus inermis ) and Tympanopleura by having truncated caudal fin (vs. bifurcated caudal fin). It is distinguished from auchenipterines, except Ageneiosini , Auchenipterichthys , Pseudauchenipterus , Liosomadoras , Tocantinsia and some species of Trachelyopterus ( Trachelyopterus insignis , Trachelyopterus galeatus , Trachelyopterus amblops and Trachelyopterus albicrux ) by having six branched dorsal-fin rays (vs. five, four, three or seven branched dorsal-fin rays); and, except for Auchenipterichthys , Asterophysus and Pseudepapterus , by the number of branched pelvic-fin rays, eight or nine (vs. Entomocorus , Trachelyopterus and Spinipterus with five rays, Pseudauchenipterus with seven rays, Trachelyichthys with ten or 11 rays, Auchenipterus and Trachelyopterichthys with 10–14 rays, and Epapterus with 14–16 rays). It differs from all auchenipterines, except Trachelyichthys , Trachelyopterichthys and Spinipterus acsi , by having a long posterior process of the cleithrum, approximately two-thirds or the same length as the pectoral-fin spine (vs. posterior process of cleithrum small, not surpassing the base of branched pectoral-fin rays, or moderate, approximately half of pectoral-fin spine length).