AUTHORS: Javier Barrio, Director of the Mammal Research Division, CORBIDI, Lima 33, Peru
ABSTRACT: The deer from South America have a complex and confusing taxonomy, caused by originally having been based only on morphology. Once genetics were used to elucidate the phylogeny, the trees became scrambled: while some problems were resolved, more questions were added. It can be said that the lack of resolution was in part due to the large number of species included in the analyses while at most a single gene or few samples from a species was used. Recent publications disentangle the problem a little but still doubts remain. The last publication by Gutiérrez et al.[1] fills up several blanks thanks to a larger sample size used, but leaves areas still unresolved, such as "How far apart are some species from others in the taxonomic tree?", a question that needs sampling using other genes to be properly answered.
One of the main unresolved areas is the taxonomy of the “Pudu” species as currently known, with the two species considered to be nested in totally separate genera-related branches with the northern species being basal to at least 6 different other genera.
“Pudu species”
The genus Pudu, as currently known, includes two species, the northern pudu (Pudu mephistophiles) from the Andean forests of Colombia, Ecuador and Peru, and the southern pudu (Pudu puda), from the Patagonian forests of Argentina and Chile. “Pudu” mephistophiles, as recognized today, has its distribution split in two geographically allopatric populations. The northern population of P. mephistophiles distributes throughout the southern two-thirds of the central Andes of Colombia to the northern tip of the Peruvian Andes, close to 5°14’S. The second population, cut off from the first one, occurs along the northern and central part of the eastern Peruvian Andes, east of the Marañón, from 5°42’30”S to 11°15’S. The gap between the two populations is caused by the Huancabamba Depression, a barrier of low elevation and drier environments along the Huancabamba and Marañón Rivers. Here I suggest a new “Pudu” taxon based on the geographically allopatric “Pudu” mephistophiles population that had never been analyzed taxonomically, not even morphologically. This separated population had already been mentioned as deserving a morphological analysis back in 1969.
The “new taxon” proposed here is distributed along the montane forests of the eastern Andean Cordillera on the central Peruvian Andes. Differences in morphology, geographic distribution, including ecological niche preferred, and probably genetics (process pending) render this allopatric population as a different species from the northern one. The collected and studied specimens come from 1800 to 3500masl in Peru, mainly from the cloud forest, as opposed to 2800-4500masl reports for Ecuador, mainly in highland Páramo [2]. A test comparing BW and ZB measures for each of the three taxa separates the eastern montane Peruvian population from the other two species (Figure 1). Its skull length of 148.2 mm (full adult female), based on the only skull with the pre-maxilla not broken, added to the ZB and BW data in a PCA puts the species skull closer to puda than mephistophiles (Figure 2), besides the different physical appearance of the skull among the three taxa.
This “new taxon” is characterized by a dark orange reddish body, sometimes with a narrow yellowish tinge on the lateral and front neck, dark brown head and legs, small white inner ears, and fawn colored underside. Overall, species currently allocated to the genus Pudu are distinguished from other Cervidae primarily by their very small overall size, a trait shared with a couple of species currently allocated to the genus Mazama, by the small size of their extremities, and the coalition of the cuboid-navicular bone and the medial and external cuneiform tarsal bones in a single element, a characteristic also present in the Asian cervids Muntiacus and Elaphodus. Additionally, cervical vertebrae in what were these 3 “Pudu” dwarf species are very short, as opposed to the relatively longer length in most deer species’ vertebrae. This and the
longer legs give the "Mazama" dwarf species an appearance of being more proportionate. I evaluated discrete and mensural morphological characters to compare the two allopatric northern populations, to define the status of the Peruvian population of the northern pudu, and will overlay this information on the molecular genetic evidence. The number of specimens available for the Peruvian population is still small, and additional specimens are needed to help elucidate the evolutionary history of this new dwarf deer.
