Relationships between extant genera of the Mustelidae (Mammalia : Carnivora)

Abstract

A comprehensive cladistic analysis of the extant genera of the Family Mustelidae was performed employing, 27 characters based on cranial and dental morphology. The analysis utilized an unrestricted parsimony computer programme (PAUP) and binary characters. A morphometric study of head shape was also performed to identify discriminators between genera. Shape similarities and differences were compared with the phylogenetic hypotheses. The phylogenetic analysis employed the outgroup method to polarize characters. Based on the data set, no autapomorphs were identified for a traditionally recognized family - the Procyonidae. Within the Mustelidae, there appears to be a number of distinct clades. Group I is proposed for the clade containing the musteline and lutrine genera. Within this group, the exact relationship of Enhydra is still_unclear, as is the internal arrangement of the three lutrine genera. The rnustelines contain a wide variety of forms, some of which may not merit separate generic rank (Poecilictis, Vormela and Ictonyx). The second major clade is Group II. The genera included are from three traditionally recoqnized subfamilies (Melinae, Mellivorinae and Mephitinae) which are no longer considered valid. The third clade is the single genus, Melogale. Formerly a part of the subfamily Melinae, it appears, rather, to be the primitive sister group to Group I. The morphornetric analys"is is somewhat inconclusive. Employing a form of discriminant analysis - Canonical Variate Analysis - plots of the "best" combinations of variables (best at discriminating) show three groups. Well separate are the lutrines, incluoing Enhydra. A loose collection of the larger-bodied forms falls in between the lutrines and the last group. The final cluster is composed of the smaller forms. It is proposed that the dense cluster of the small forms represents a small carnivore head morphology possibly constrained by mechanical requirements. Further tests of this proposal, though, are necessary.