Psilorhynchus

Conway, Kevin W., Dittmer, Drew E., Jezisek, Laci E. & Ng, Heok Hee, 2013, On Psilorhynchus sucatio and P. nudithoracicus, with the description of a new species of Psilorhynchus from northeastern India (Ostariophysi: Psilorhynchidae), Zootaxa 3686 (2), pp. 201-243 : 205

Key to the species groups of Psilorhynchus

1a. Branched dorsal-fin rays 8.............................................................................. 2

1b. Branched dorsal-fin rays 9–10.......................................................................... 3

2a. Lateral line scales 33–36; unbranched pectoral-fin rays 4–5............................................. P. sucatio

2b. Lateral line scales 39–48; unbranched pectoral-fin rays 7–11............................ P. homaloptera species group

3a. Caudal fin forked, lobes weakly rounded or pointed; scales along dorsal body surface with dark posterior edge, forming strong reticulate pattern; scales in lateral-line scale row (L1) and scales in two rows directly above (L+1 & 2) and one row below lateral line scale row (L-1) marked posteriorly with a small spot, forming a series of rows (L rows) along body side; postepiphyseal fontanelle obvious, similar in size and shape to preepiphyseal fontanelle, separated by a narrow strut of frontal bone................................................................................ P. nudithoracicus species group

3b. Caudal fin weakly forked, lobes rounded; dorsal body surface without strong reticulate pattern; scales in lateral line scale row and row directly above and below lateral line scale row without obvious spot along posterior edge (scales may be marked with a spot at center); postepiphyseal fontanelle, when visible, irregularly shaped, smaller than preepiphyseal fontanelle and separated by a large gap................................................................. P. balitora species group