Assessing Intraspecific Variation in Rhynchonycteris (Chiroptera: Emballonuridae): An Integrative Morphological and Molecular Study

Abstract

This study investigates intraspecific variation in the neotropical bat Rhynchonycteris naso (Emballonuridae) in Ecuador. An integrative approach was employed, combining linear morphometrics based on 18 cranio-dental measurements with molecular analyses using mitochondrial genes (COI and Cytb) and nuclear loci. A total of 41 museum specimens representing populations from both sides of the Andes mountain range were examined. The results revealed three distinct morphotypes: one located west of the Andes (Morphotype 1) and two sympatric morphotypes in the Amazonian region (Morphotypes 2 and 3). Morphological analyses demonstrated significant differences in cranial dimensions, particularly zygomatic width and condyle-to-canine length, as well as variation in dental formula ranging from 32 to 36 teeth among the three morphotypes. Molecular data did not reveal a clear geographic structure corresponding to the proposed morphotypes. These findings suggest the need for more variable genetic markers to accurately detect population structure. The sympatric occurrence of Morphotypes 2 and 3 in the Ecuadorian Amazon may indicate ecological segregation or secondary contact following a period of geographic isolation. However, the small sample size and limited geographic coverage constrain the ability to draw definitive conclusions regarding their taxonomic status. These results highlight the importance of expanding sampling across the species’ entire distribution, from Mexico to Bolivia, to determine whether the observed morphological and genetic patterns represent continuous geographic variation or a process of cryptic speciation.