Cnesterodon septentrionalis Rosa & Costa 1993

Cnesterodon septentrionalis Rosa & Costa, 1993

(Fig. 8)

Cnesterodon septentrionalis Rosa & Costa, 1993: 706, figs. 13, 18. Type -locality: Brazil, Mato Grosso, Município de Alto Araguaia, swamp near the Córrego do Rancho fountainhead.

Diagnosis. Cnesterodon septentrionalis is diagnosed by the following autapomorphies: (1) six epipleural ribs; and (2) bony style of ray 3 of gonopodium of fully developed mature males large and very curved upwards, almost describing a semicircular outline, and invested with few membranous tissue (Rosa & Costa, 1993; fig. 13). Cnesterodon septentrionalis is readily distinguished from its congeners by the branched second pelvic-fin ray in adult males [42-0]; pleural ribs not associated with haemal arches in males [60-0]; first proximal radial of dorsal fin located between neural spines of 11th and 12th vertebrae in adult males [62-6]; first proximal radial of dorsal fin in adult females located between neural arches of vertebrae 11th and 12th [63-3]; less than nine caudal-fin rays entirely lying over on hypural plate [132-0].

Furthermore, Cnesterodon septentrionalis is distinguished from C. omorgmatos and C. raddai by dark brown blotches along body sides (forming bars vs. circular or irregular, respectively). Cnesterodon septentrionalis is distinguished from C. decemmaculatus, C. brevirostratus, and C. iguape by dark bars of body very elongate reaching dorsal and ventral profiles, covering more than four scales in a transverse row (vs. dark bars on sides of body, mostly confined to midline, covering less than three scales in a transverse row, never extending to dorsal and ventral profiles). The absence of small scales covering lateral and ventral region below pectoral fin and the pointed snout also differentiates C. septentrionalis from C. brevirostratus. The absence of a longitudinal dark brown band along flank differentiates C. septentrionalis from C. hypselurus. Cnesterodon septentrionalis differs from C. carnegiei by the number of caudal fin rays (20-22 vs. 25-26, respectively), by the number of longitudinal series scales (25-26 vs. 28-31, respectively) and by the number of transverse rows between dorsal and anal fin (7 vs. 8-10, respectively).

Distribution. Upper rio Araguaia drainage (Fig. 1).