Hemigrammus arua Lima, Wosiacki & Ramos, 2009
photo by Hoffmann, P. and M. Hoffmann

Family:  Characidae (Characins; tetras), subfamily: Stethaprioninae
Max. size:  3 cm SL (male/unsexed)
Environment:  benthopelagic; freshwater; depth range 1 - 2 m
Distribution:  South America: headwaters of the rio Arapiuns, rio Tapajós basin, and from the adjacent headwaters of the igarapé Juruti Grande, rio Amazonas in Brazil.
Diagnosis:  Dorsal soft rays (total): 11-12; Anal soft rays: 21-25; Vertebrae: 31-31. Distinguished from all species of the genus, except Hemigrammus stictus (Durbin), by having a large single humeral spot situated from fifth-sixth to posterior margin of eighth-tenth lateral line scales. Differs from Hemigrammus stictus by having a humeral spot roughly rectangular, higher than wide, with a pronounced upper, anteriorly-oriented extension, conferring an inverted-comma shape to the blotch (vs. humeral spot roughly rounded, not presenting an inverted-comma shape), and life color pattern presenting unpaired fins orange reddish (vs. caudal fin and caudal peduncle bright red in life, remaining fins translucent) (Ref. 81198). Description: Dorsal-fin rays ii, 9, 10, not including small ossification anterior to first unbranched ray, discernible only in c&s specimens, absent in two out of eight c&s individuals; anal-fin rays iv, 17-21; pectoral-fin rays i, 9-11; pelvic-fin rays typically i,7, a single specimen i,8 (Ref. 81198).
Biology:  Inhabits shallow marginal areas, with abundant aquatic macrophytes, both emergent and non-emergent (Ref. 81198). Gut contents of four specimens include insect larvae, winged insects and plant matter (Ref. 81198).
IUCN Red List Status: Least Concern (LC); Date assessed: 07 November 2018 Ref. (130435)
Threat to humans:  harmless


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