Hypostomus commersoni Valenciennes, 1836

Bertora, Andrea, Grosman, Fabián, Sanzano, Pablo, Cardoso, Yamila P. & Rosso, Juan J., 2018, TAXONOMIC REVISION OF THE SOUTHERNMOST POPULATION OF Hypostomus commersoni VALENCIENNES, 1836 (SILURIFORMES: LORICARIIDAE) AND COMMENTS ON DISPERSAL ROUTES, Historia Natural 8 (1), pp. 25-34 : 29

Hypostomus commersoni Valenciennes, 1836

Material examined. UNMDP 4840, 1 specimen, 325 mm SL; UNMDP 4865, 1 specimen, 280 mm SL; UNMDP 4868, 1 specimen, 280 mm SL; UNMDP 4869, 1 specimen, 300 mm SL; UNMDP 4870, 1 specimen, 175 mm SL; UNMDP 4871, 14 specimens, 72-395 mm SL; Argentina, Buenos Aires, Langueyú stream, 36°55’38.66”S, 58°56’8.70”W, Nov 2016, Bertora, Grosman, Sanzano and Rosso.

Remarks. Collected specimens of H. commersoni have their dorsal surface of body with dark grey roundish dots over a grey background, 28-29 lateral scutes, lateral keels strong, 1-3 scutes bordering the posterior margin of the supraoccipital bone, cleithral width 3.4-4.2 in standard length (SL), mandibular ramus length 2.4-4.1 in interorbital distance, pectoral length 3.1- 3.8 in SL, interdorsal length greater than 4.5 in SL, dorsal fin base greater than its distance to adipose fin and lower caudal ray 2.4-2.9 in SL ( Table 1 and Figure 3 ).

Specimens in alcohol have ground colour of dorsal surface light to dark brown, slightly lighter to whitish ventrally. All body and fins covered with small, roundish, black or dark-brown dots, smaller and closer together on head. This pattern is sometimes inconspicuous on caudal fin and ventral portion of caudal peduncle. Live specimens are darker than alcoholfixed individuals.

Figures

Figure 3 - Lateral, dorsal and ventral views of Hypostomus commersoni (UNMDP 4840, 325 mm SL) collected in Langueyú stream (36°55’38.66”S, 58°56’8.70”W).