Taxonomic status ofMicronycteris homezi(Chiroptera, Phyllostomidae)

Abstract

There are currently six species ofMicronycteris(sensu stricto) recognized in Venezuela, of which three have pale venters:M. homezi,M. minutaandM. schmidtorum. Since the original description ofM. homezias a subspecies ofM. megalotis(based on the presence of a cutaneous fossa in the interauricular region), this taxon has not appeared in checklists for Venezuelan mammal inventories due to confusion and uncertainty related to the original description. However, it was recently reconsidered as a valid taxon on the basis of an additional series of males collected in French Guiana, Guyana, and Brazil. The examination of a larger number of specimens ofMicronycteriscollected in Venezuela (73 of them within the pale venter group), allows us to reject the cutaneous fossa as a valid character to diagnoseM. homezi, suggesting that the namehomezirepresents a junior synonym ofM. minuta. Among the arguments supporting this statement are: 1) the discovery of a cutaneous fossa in two congeneric forms (M. megalotisandM. microtis); 2) the existence of histological evidence verifying the presence of this structure (incipiently developed) in specimens assignable toM. minuta; 3) the development of the fossa only in adult males (associated with a hypertrophy of the interauricular band); and 4) the similarity, in both chromatic and morphological features of Venezuelan specimens assignable to eitherM. minutaorM. homezi. The presence of a developed cutaneous fossa only in some adult males, as well as its correlation with the growth of the interauricular band and the modification of histological components could be the result of hormonal effects influenced by social rank or reproductive condition. Both structures are elements of a coordinated system, whereby the interauricular band is responsible for the production of sebaceous substances associated with the cutaneous fossa.