Fig. 8
Body elongated; greatest depth contained 2.9 to 3.4 and caudal peduncle depth 8.3 to 11.2 times in SL; head length 3.3 to 4.0, predorsal distance 1.8 to 2.0 and caudal peduncle length 6.3 to 9.2 in SL; snout length 3.6 to 6.5, horizontal orbital diameter 2.1 to 3.3 and least interorbital width 2.3 to 3.3 in HL. Mouth terminal; inner row of premaxilla with 5 teeth, outer row with 3-6, dentary with 3 or 4 maxillary teeth. Lateral line incomplete, with 9-15 pored scales; longitudinal series with 31-35 scales; transverse series above lateral line with 5 or 6 scale rows and below with 4 or 5 scale rows. Dorsal fin with 10 or 11 rays, pectoral fin with 10-14 rays, pelvic fin with 7-10 rays, anal fin with 24-27 rays and caudal fin with 19 rays (Zarske et al., 2006; Jerep et al., 2011). Ground color whitish to pale; silvery to darkbrown longitudinal stripe on flank; black rounded humeral spot; dark-brown rounded blotch on last portion of caudal peduncle and caudal-fin base, reaching only base of median caudal fin rays.
Maximum standard length. 38.4 mm.
Distribution. Coastal drainages of French Guiana, upper rio Paraná, rio Tocantins-Araguaia and rio Xingu basins.
Remarks. Hemigrammus ora has been captured in the upper rio Paraná floodplain since 2011 by Nupélia staff, and this is the first record to the upper rio Paraná basin. Zarske et al. (2006) described this species from the costal drainages of French Guiana, and Jerep et al. (2011) widened its geographic distribution to the upper rio Tocantins-Araguaia and rio Xingu basins, hypothesizing the continuous distribution of this species from its typelocality to the lower Amazon tributaries. Additionally, Jerep et al. (2011) found two morphological differences: three small dentary teeth and longer snout length 7.7- 10.6% SL ( vs. 8-10 small dentary teeth and snout length 3.9-7.0% SL from the type specimens). The specimens from the upper rio Paraná floodplain present three or four small dentary teeth (in accordance with Jerep et al., 2011) and snout length 6.4-7.2% SL (23.3-28.0% HL; in accordance with Zarske et al., 2006). Hemigrammus ora is a non-native species from the upper rio Paraná basin, probably introduced from the rio Tocantins-Araguaia basin.