Potamorrhaphis eigenmanni Miranda Ribeiro 1915

Most closely resembles P. guianensis from which it differs most markedly in lower numbers of dorsal and anal fin rays, vertebrae, and predorsal scales. Predorsal scales 77-113, mean 93.9.

Dorsal spines (total): 0; Dorsal soft rays (total): 27 - 33; Analspines: 0; Analsoft rays: 24 - 29; Vertebrae: 64 - 72

Oviparous (Ref. 205). Eggs may be found attached to objects in the water by tendrils on the egg's surface (Ref. 205).