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TÍTULO

POSTCRANIAL MEASURES IN THE TAXONOMY OF THE GENUS MAZAMA (ARTIODACTYLA; CERVIDAE)

Resumo

The genus Mazama is a robust example of an adaptive convergence process in mammals, presenting all the species a great morphological similarity with a small to medium body size and simple, straight, short and spit-shaped antlers. Although individual variations exist among these species, it is very difficult to identify them using corporal biometry and cranial features according to previously published studies. However, the use of post-cranial measures has not been addressed before, casting doubts about the presence of some particular characteristics that could assist in the identification of these species. Therefore, the present study was designed to evaluate different post-cranial bones measurements as a novel approach for the Mazama species identification. The work included a total of 23 post-cranial measures from different bones, such us the atlas, axis, humerus, radius, ulna, scapula, femur, pelvis and sacrum from 50 individuals belonging to the genus M. nana (3), M. gouazoubira (11), M. nemorivaga (7), M. temama (4), M. pandora (1), M. bororo (7) and M. americana (17). All of them present at the Museum of the Deer Research and Conservation Center. We carried out a Principal Components Analysis (PCA) and a cluster analysis (based on the UPGMA method) using two criteria: the first one, characterizing a single matrix with all the measurements performed and, the second one, analyzing each bone independently to be able to find possible clustering patterns. Concerning the first criterion, the results obtained from the distance tree showed two large groups associated with the body size. One of them represented by M. americana and two individuals belonging to the M. bororo species, and the other group formed by the small-sized species (M. nana, M. nemorivaga, M. gouazoubira, M. temama), M. pandora and four individuals of M. bororo species. It was not possible to separate the species within the subgroups, observing a smaller proximity among individuals from different species in comparison to individuals belong to the same one. The cluster analysis made for each measure considered separately did not discriminate the size nor differentiate the species between groups. A different result was obtained in the principal component analysis (PCA) where it was possible to visualize a pattern of morphological groups that separated each species, excepting M. temama, with 81.69% of the variance characterizing the first component  by the measured  greatest femur length and  greatest pelvis length. The 6.55% of the variation characterized the second component represented by the measurement ulna greatest length. Thus, we conclude that post-skull measurements are a promising tool in the discrimination and taxonomy of Mazama species.  

Palavras-chave

neotropical cervids, taxonomy, zoology, morphology