Cynopoecilus Regan

Cynopoecilus Regan, 1912b: 642

(type species Cynolebias melanotaenia Regan, by original designation).

Diagnosis. Differs from all other rivulid genera by the following synapomorphies: a concavity on the median portion of the posterior border of autopalatine(vs. no concavity); minutecaudal accessory cartilages(vs. caudalaccessory cartiabsent); anterior part of anal fin of male thickened(probably glandular tissue,vs. no modificationon anal-fin surface of male);eight nine anal-fin rays attached to the first proxiradial(vs. two rays);anteriorly curved sixth seventh anal-fin rays of males(vs.not distinctively curved);posteriorly curved 10th to12th anal-fin rays of males vs.not distinctively curved); five minute rays at the anterior portion anal fin(vs. one or no minuteray);a reduced pelvic fin,its tip not reaching anal-fin origin (vs. reduced,reaching anal-fin base);a bulbshaped structure on the urogenital region of male never a bulb-shaped structure);a slender urohyal(vs. deep), a broad longitudinal black from tip of lower jaw to caudal-fin base (vs. such stripe),an oblique longitudinal black from pectoral-fin base to posterior part of anal-fin base (vs. no such stripe), and a zigzag display during male courtship behavior(vs.no courtship behavior pattern).

Remarks. For a description and discussion on polarization of the above diagnostic features see Costa (1995a, 1998).

Distribution. Lagoa dos Patos system and adjacent coastal areas, southern Brazil and eastern Uruguay (Fig. 1).