Histology of a Sexually Dimorphic Integumentary Gland in Macroglossus lagochilus (Chiroptera: Pteropodidae)

Abstract

A sexually dimorphic integumentary gland is described in the pteropodid bat, Macroglossus lagochilus. This gland is restricted to males from Central Province (mainland), Papua New Guinea and is not found in either males or females taken from the Bismarck Islands (Manus, New Britain, New Ireland, Duke of York). Histological examination of the glandular structure, which is readily identified externally as a crescent-shaped welt occupying the lower neck and upper chest, reveals that it is comprised of numerous hypertrophied tubular apocrine-type glands. Comparisons of the integumentary gland of Macroglossus males with those of other pteropodids that have been reported in the literature document striking differences in the organization and histology of sexually dimorphic glandular structures in Pteropodidae. The absence of the Macroglossus chest gland in individuals from the Bismarck Islands is not related to reproductive seasonality or to any apparent biological features of island and mainland populations.