Variação morfométrica craniana de bugios, Alouatta guariba (Primates: Atelidae), mortos durante surto de febre amarela silvestre

Abstract

The cranial morphology of Alouatta (Howler Monkey) is unique among Platyrrhini primates, due to the dorsoventral rotation of the face in relation to the neurocranium, a condition called “airorhynchy”. Howler Monkeys has positive sexual dimorphism, males have a larger body size than females. However, not much is known about sexual dimorphism related to the cranium dimensions and age variation. Between the end of 2016 and mid-2017 one of the most severe outbreaks of yellow fever affected Brazil. This outbreak affected mainly the states of Minas Gerais and Espírito Santo, causing one of the largest non-human primates deaths that science has already recorded, the Brown Howler Monkeys being the most affected. This study analyzed 155 specimens of Alouatta, guariba, which were prepared and deposited at the Instituto Nacional da Mata Altântica (INMA). The objective of this work was to analysis the cranial morphometric variation for the specie and an realize in-depth study on ontogenetic variation and sexual dimorphism of A. guariba, in addition to characterizing the demographic profile of Brown Howler Monkeys in sex and age groups and mapping the samples collected. Data analysis indicates that adult males were the most collected group during the yellow fever outbreak. The samples come from 116 locations, mainly distributed in the southern portion of Espírito Santo, in the mountain region. Sexual dimorphism in howler monkeys is present in most cranial variables before the adult age. The morpho-functional regions that showed sexual dimorphism from the sub-adult age group were: hyoid, jaw, oral, nasal and zygomatic. In contrast, the morpho-functional regions that did not present sexual dimorphism were: cranial vault, cranial base and orbit. It was possible to identify sexual dimorphism in the cranial variables regardless of the presence of the hyoid bone.