Diagnosis: Garra allostoma is an insectivorous Garra with a terminal or subterminal mouth and curved or crescentic mouth opening superficially resembling a generalized Barbus; cheek below eye laterally expanded; rostral cap reduced, smooth; mental disc smooth, non tuberculate, posterior border bound to isthmus; upper and lower lips well developed; lower lip non-tuberculate, divided into distinct, lateral and medial portions by a constriction; medial portion of lower lip constricted near symphysis, so that it is bilobate; horny sheaths of upper and lower jaws not greatly enlarged, without trenchant cutting edge; pharyngeal teeth in two rows, 2 or 3,5 (Ref. 96454). Absence of rostral fimbriae distinguished Garra allostoma from all other Garra, and having only two instead of three pharyngeal tooth rows distinguished it from all others for which the number of rows has been reported (Ref. 96454).
Description: mouth terminal to subterminal, crescent-shaped; mental disc poorly developed and non-tuberculate, without free marginal membrane; lips well developed, the lower consisting of two lateral sectors and a bilobed central part; rostral lobe poorly developed and smooth-edged; upper and lower jaws somewhat horny, but without cutting edges; two rows of pharyngeal teeth (2-3/5) (Ref. 2940, 81282). Between 36 and 37 scales in a longitudinal series; 16-18 scales around caudal peduncle; no scales on back before dorsal fin (Ref. 2940, 81282). Dorsal fin with iii,7 rays; anal fin with iii,5 rays; pectoral fin with ii,12-14 rays; pelvic fin with 8 rays (Ref. 2940, 81282).
Colouration: back black, sides marbled, belly pale; first scale in the longitudinal series dark or black, preceded (at upper angle of gill cover) by a small pale area which is red in live specimens (Ref. 2940, 81282). Basal area of dorsal fin with four oblique, black marks, other fins colorless (Ref. 2940, 81282).