Notes on the taxonomy of mountain viscachas of the genus Lagidium Meyen 1833 (Rodentia: Chinchillidae)

LUCERO, SERGIO O.; TETA, PABLO

Therya

Asociación Mexicana de Mastozoología

Lugar: México, Distrito Federal; Año: 2017 vol. 8 p. 27 - 33

2007-3364

Mountainviscachas of the genus Lagidium Meyen1833 are medium-to-large hystricomorph rodents (1.5 -- 3 kg) that live in rockyoutcrops from Ecuador tosouthern Argentina and Chile. Lagidium includes more than 20 nominalforms, most of them based on one or two individuals, which were first describedduring the 18th and 20th. Subsequent revisions reduced the number ofspecies to three to four, depending upon the author. Within the genus, Lagidium viscacia (Molina, 1782) is themost widely distributed species, with populations apparently extended from westernBolivia to southern Argentina and Chile. We reviewed > 100individuals of Lagidium, including skins and skulls, most of them collected in Argentina. Weperformed multivariate statistical analysis (i. e., principal componentanalysis [PCA], discriminant analysis [DA]) on a subset of 55 adult individualsgrouped according to their geographical origin, using 16 skull and toothmeasurements. In addition, we searched for differences in cranial anatomyacross populations. PCA and DA indicate a moderate overlap between individualsfrom southern Argentina, on onehand, and northwestern Argentina,western Bolivia and northernChile,on the other. The external coloration, although variable, showed a predominanceof gray shades in southern Argentinaand yellowish gray in northwestern Argentina. Specimens of southern Argentina were characterized by their biggeroverall size, nasals expanded in its front half, and narrow dorsal root of thezygomatic process of the maxillary, while those of northwestern Argentina weresmaller, with nasals lacking expansions and the dorsal root of the zygomaticprocess of the maxillary broad. Our study provides coincident results fromquantitative and qualitative morphology that allow us to clearly differentiatesouthern Argentinean populations of Lagidiumviscacia from those of northwestern Argentinaand western Bolivia.The oldest available name for the populations from southern Argentina,sometimes referred as L. boxi, is moreni, a taxon with an unclear typelocality. The status of the populations from northwestern Argentina and western Bolivia is relatively more complex,since at least eight nominal forms were described from this general area andbecause our sampling is far from being extensive. In addition, is also unclearif these populations correspond to one or more species, as well as their degreeof differentiation from L. viscacia s. s. Without analyzing topotypes of allnominal forms and adequate samples across the entire distribution range, it ispremature to put forward a formal taxonomic proposal; as such, at this momentwe prefer to maintain those populations from northwestern Argentina, western Boliviaand central Chileunder L. viscacia.