| Diagnose |
Brachyhypopomus arrayae can be distinguished from other species of the genus Brachyhypopomus by the following combination of characters: presence of prominent pale uninterrupted middorsal stripe from occipital region to base of caudal filament (vs. absence in all congeners except B. beebei, B. belindae, B. flavipomus, B. gauderio, B. pinnicaudatus, and B. verdii); anal-fin with 174-212 rays (vs. 214-230 in B. beebei; precaudal vertebrae 20-23 (vs. 24-26 in B. belindae and B. verdii); pectoral fin with 16-19 rays, mode 16 (vs. 12-15, mode 13 for B. gauderio (except populations from Uruguay drainages) and vs. 13-15, mode 14 for B. pinnicaudatus (except populations from coastal French Guiana). It has similar pigmentation and overlapping meristic counts and morphometric proportions with some populations of B. gauderio and B. pinnicaudatus from which it can be distinguished by the contact of a small ascending process on the endopterygoid (mesopterygoid of Mago-Leccia, 1978) with the orbitosphenoid (Arratia & Schultze, 1991; de Santana & Crampton, 2011), (vs. the lack of a contact between the ascending process on the endopterygoid and the orbitosphenoid in B. gauderio and B. pinnicaudatus (Ref. 116763). |