Comparative prenatal development and embryonic staging of neotropical fruit bats (genus Artibeus)

Systems of embryonary classification are essential tools in developmental and comparative biology. They are established in a process called staging, in which the chronology of appearance and development of morphological characters is recorded in a series of embryos, with these ontogenetic events being used to recognize stages. We examined 29 embryos of Artibeus. Then, we analyzed embryonic growth through the following parameters: Crown-rump length, uterine diameter, forearm length, and nose leaf length. We analyze morphological characters along the prenatal development of three species of Artibeus and provide a stage system based on Cretekos et al. (2005). These results are then compared to those available for other bat species staged so far, and we highlight some modifications in the characters and nomenclature adopted here in an attempt to make our staging system more generalizable in respect to the order Chiroptera. The analysis of embryonic staging in different species allowed the identification of stages that share common characteristics among species (e.g., formation of the neural tube and appearance of the pharyngeal arches and limb buds) and stages with characters that may be used to separate groups (e.g., presence or absence of noseleaf and tail). Most of the development in Artibeus corroborated the staging proposed by Cretekos et al. (2005) for Carollia perspicillata. The analysis of parameters studied here and other characteristics can set the foundation for standardization in several bat groups. We also propose adaptations to the staging system based on characteristics common to all groups.