Lagidium

Abstract: Molecular phylogenetic relationships were investigated in 6 species of Chinchillidae (Chinchilla lanigera, C. brevicaudata, Lagidium peruanum, L. viscacia, L. wolffsohni, and Lagostomus maximus), 1 species of Dinomyidae (Dinomys branickii), 1 of Abrocomidae (Abrocoma cinerea), and 1 of Octodontidae (Octodon degus) using the first 548 base pairs of the mitochondrial cytochrome-b gene. Maximum-parsimony and maximumlikelihood analyses consistently showed Chinchillidae as a robust clade and confirmed a close relationship with Dinomyidae. Both Chinchilla species differed at 22 sites, and 3 were nonsilent; average genetic distances were approximately 6%. Sequences from domestic C. lanigeraand wild C. brevicaudatashowed low levels of variation. Although all topologies obtained were congruent with current taxonomy, Lagidium exhibited large genetic distances (range 5.9‐8.9%), suggesting the existence of more than the 3 species currently recognized. Chinchillids are endemic South American rodents (Rodentia, Hystricognathi, Chinchillidae) and occur along the Andes. They include chinchillas (Chinchilla), mountain viscachas (Lagidium), and pampas viscachas (Lagostomus).

Abstract: We tested whether size of habitat patches and distance between patches are sufficient to predict the distribution of the mountain vizcacha Lagidium viscacia a large, rock-dwelling rodent of the Patagonian steppe Argentina, or whether information on other patch and landscape characteristics also is required. A logistic regression model including the distance between rock crevices and depth of crevices, distance between a patch and the nearest occupied patch, and whether or not there was a river separating it from the nearest occupied patch was a better predictor of patch occupancy by mountain vizcachas than was a model based only on patch size and distance between patches. Our results indicate that a simple metapopulation analysis based on size of habitat patches and distance between patches may not provide an accurate representation of regional population dynamics if patches vary in habitat quality independently of patch size and features in the matrix alter connectivity.

Abstract: Hematocrit levels were measured on a series of Chilean mammals including PHYLLOTIS DARWINI RUPESTRIS, AKODON ANDINUS, AKODON BERLEPSCHII, LAGIDIUM VISCACIA and CHINCHILLA BOLIVIANA from high altitude; and PHYLLOTIS D. DARWINI, AKODON (ABROTHRIX) LONGIPILIS, ORYZOMYS LONGICAUDATUS, NOTIOMYS MEGALONYX, ABROCOMA BENNETTI, OCTODON DEGU, CHINCHILLA VELLIGERA and ORYCTOLAGUS CUNICULUS from near sea level. Translocation of 3 highland species to sea level for 2 months did not reduce their hematocrits. The offspring of two highland species showed no reduction in hematocrit after birth and rearing in the laboratory at sea level.Hematocrit levels by species ranged from 380 to 540 ml/l but showed no correlation with the altitude of origin. The hematocrit in “more vigorous” species at both high and low altitudes was about 20% higher than in “less vigorous” species.The erythrocyte hemoglobin concentrations ranged from 295–316 g/l for 4 highland species (plus P. D. DARWINI). Lower values (256–278 g/l) were found in 3 lowland species; and higher values were found in the larger LAGIDIUM (330 g/l) and guanaco, LAMA GUANICOE (423 g/l) from high altitudes.

Abstract: The material consists of the ovaries from a pregnant female and observations on a live female of the Patagonian species of Mountain viscacha (Lagidium boxi). The study is reported because it shows that L. boxi, like the Peruvian Mountain viscacha (JL. peruanum), appears to ovulate only from the right ovary (Pearson, 1949). Features of the material are compared with information known for other hystricomorph rodents.