Characterization of sperm morphology in two species of Neotropical bats: Artibeus planirostris and Sturnira erythromos (Phyllostomidae, Chiroptera)

Sperm morphology is considered the best indicator of male fertility. In Neotropical bats, important aspects of sperm morphology have been scantly studied. The aim of the present study was to characterize and compare the sperm morphology and morphometry of Artibeus planirostris and Sturnira erythromos. A total of 11 specimens were analyzed from the Colección de Mamíferos Lillo: five A. planirostris and six S. erythromos. The fixed epididymis were extracted and macerated in Farmer's solution, followed by the routine cytological procedure with different stains. To carry out the description and morphometric analysis, microphotographs were taken under an optical, epifluorescence and scanning electron microscope. A total of 50 sperm from each individual were measured for morphometric analysis. The percentage of normal/abnormal spermatozoa was estimated and the sperm abnormalities were classified. Both species showed morphologically simple spermatozoa with a spatulate head, a short neck, a helical midpiece and a tail that tapers at the final end, similar to other species of Phyllostomidae. The differences observed were: apex of the head was conical in A. planirostris and was oval in S. erythromos; longer head and midpiece in S. erythomos and longer sperm in A. planirostris. Both species showed a high percentage of sperm with normal appearance: 65% for A. planirostris and 72% for S. erythromos. The main sperm abnormalities were: scattered tails and heads, coiled tails, folded midpieces and presence of cytoplasmic droplets. The present work will improve the understanding of their reproductive biology. Research Highlights Morphological descriptions and morphometric analyses of the sperm of Artibeus planirostris and Sturnira erythromos were carried out with optical, epifluorescence and scanning electron microscopy. Artibeus planirostris and Sturnira erythromos have morphologically simple spermatozoa similar to other Phyllostomidae species. Both species showed: 65% normal sperm for A. planirostris and 72% for S. erythromos. Sperm abnormalities were: scattered heads, coiled tails, folded midpieces and the presence of cytoplasmic droplets.