Abstract

Intra- and inter-specific morphometric variation between Odontophrynus populations (Anura: Cycloramphidae) of central Argentina. Morphometric analyses are particularly important, and for many years they have supported evolutionary and ecological phenomena, and have been useful for the classification of new species, mainly to the lowest taxonomic levels. In order to assess the degree of sexual dimorphism, the intra-specific morphometric variation and the inter-specific morphological differences, we performed morpho- metric analyses of two morphologically cryptic species, Odontophrynus cordobae (diploid) and O. americanus (tetraploid). For this, we measured 15 morphometric variables on 211 individuals from 18 localities of Córdoba province. We found sexual dimorphism in six and three parameters in O. cordobae and O. americanus, respec- tively. Diploid and tetraploid males significantly differed in six morphometric variables. Discriminant Function Analysis (DFA) including all populations correctly classified a 76.37% of individuals within their respective species. DFA based on four groups (1- allopatric O. cordobae, 2-syntopic O. cordobae; 3- allopatric O. ameri- canus; 4- syntopic O. americanus) accurately classified a 73.45% of individuals within their respective groups. Allopatric individuals of each species and, allopatric and syntopic individuals within each species were clearly segregated. Syntopic individuals of O. cordobae and O. americanus showed the lowest percentages of correct classification. Morphometric differences between sympatric diploids and tetraploids were not greater than those observed in allopatry. These findings deviate from the expected results under the hypothesis of character displacement, and they suggest that external morphological characters would not have a major influence on the recognition and choice of conspecific males by females.
Keywords: odontophrynus, morphological measures, diploid, tetraploid, cryptic species