Un "índice de caracteres" para la diferenciación taxinómica en peces siluriformes de las familias <i>Pygidiidae</i> y <i>Diplomystidae</i>

Abstract

The Character-Index applied to genus Hatcheria (Pygidiidae) from Argentina, is useful for differentiation of specific and infraspccific units. Combines the predorsal distance, the preventral distance, the dorsal base and head length (all in thousands of standard length) with the interocular distance (in thousands of head Iength) and the peduncle depth. For Diplomystidae or "otunos" the Character-Index combines head depth + body depth + adipose length + peduncle length, divided by 0.1 mouth breadth + peduncle depth. Its application is significative for Diplomystes viedmensis viedmensis Mac Donagh (Cl: 13 in both holotype and topotype) and for a new suspecies, in press, from Mendoza and San Juan (CI: 11.0 and 11.4).