Madeira River and Machado River, Brazil.

South America: known only from rio Madeira and rio Machado, a tributary of rio Madeira in Brazil.

Dorsal soft rays (total): 11; Analsoft rays: 36 - 40; Vertebrae: 38 - 39

6.1 cm SL (male/unsexed; (Ref. 75890))

Can be distinguished from Acestrocephalus boehlkei, Acestrocephalus maculosus and Acestrocephalus stigmatus by the absence of dark humeral blotch characteristic of these species. Differs from Acestrocephalus sardina and Acestrocephalus nigrifasciatus by having smaller eye and fewer maxillary teeth (30-38 vs. 40-46). Can be separated from Acestrocephalus acutus by possessing only scattered dark chromatophores instead of the typical oblong dark blotch on the caudal-fin base of that species and the first pleural rib, the cavity anterior to it and the obliquusinferioris muscle visible (vs. entirely covered by the fibers of the obliquus superioris muscle in Acestrocephalus acutus (Ref. 75890).Description: Dorsal fin ii,9; Anal fin iv,32-36; Pectoral fin i+11-15; Pelvic fin i+7 (Ref. 75890).

benthopelagic; freshwater

Not Evaluated