MORPHOLOGICAL VERSUS CHROMOSOMAL AND MOLECULAR DIVERGENCE IN 2 SPECIES OF ELIGMODONTIA

Karyotypic and mtDNA variation support the presence of at least two di stinct species of Eligmodontia in the Patagonian region of Argentina. No diagnostic morphological characters are available to identify these species reliably, and few data are available to assess reliably the d egree of morphological difference between them. We used univariate and multivariate analyses of external morphological and cranial character s in a sample of Eligmodontia collected at 15 localities across northe rn Patagonia to test the hypothesis that these presumed species (Eligm odontia typus and E. morgani) also are morphologically distinct. No si ngle diagnostic morphological character was identified based on specim ens for which independent identifications were available through mtDNA sequence and species-specific diploid numbers. However, discriminant function analyses were able to assign specimens reliably to correct sp ecies as independently determined. Cluster analyses based on various c ombinations of morphological characters showed some congruence with th e other data sets, but specimens of known mtDNA haplotype did not clus ter together exclusively. These patterns suggest that although the gen etic and karyological differences are substantial and potentially repr esent a deep divergence, these changes are not mirrored by equivalent morphological divergence.