Psilorhynchus nudithoracicus species group

Diagnosis. Members of this species group are distinguished from congeners by the following combination of characters: pre- and postepiphysial fontanelle a long rectangular opening, similar in size and separated only by a narrow strut of frontal dorsal to the epiphysial bar; scales over anterodorsal body surface edged with dark brown pigment posteriorly, forming a strong reticulate pattern; scales in lateral line scale row (L1) marked posteriorly with a small spot, often divided by unpigmented lateral line canal, forming a double-dash line along lateral line scale row; scales in two rows directly above (L+1 & 2) and one row below (L-1) lateral line scale row marked posteriorly with a small blotch, forming a series of rows (L rows) of variable length along body side (absent in P. tenura); caudal fin moderately forked, with tips of upper and lower lobes weakly rounded.

Included species. P. melissa, P. nudithoracicus, P. ro b u s t u s and P. t e n u r a.

Remarks. This group is roughly equivalent to the P. gracilis species group proposed by Conway (2011), with the addition of P. t e n u r a. Several of the osteological characters listed as diagnostic for that group by Conway (2011), including the presence of a short mandibular sensory canal along the ventrolateral face of the anguloarticular, a prominent dorsal projection on the third pectoral radial, and a hiatus between the proximal tip of hypural one and the compound centrum define a more exclusive subgrouping of the P. nudithoracicus group (composed of P. melissa, P. nudithoracicus and P. robustus).