Presence of Dromiciops gliroides (Microbiotheria: Microbiotheriidae) in the deciduous forests of central Chile

Abstract

Dromiciops gliroides Thomas, 1894 (Microbiotheria, Microbiotheriidae) commonly known as ‘‘monito del monte’’ in Chile, is the sole representative of the Order Microbiotheria and considered a living fossil in the fauna of South America. The oldest fossil record for microbiotherids has been ascribed to the Early Paleocene Tiupampa fauna of Bolivia (Gayet et al. 1991). Additional fossils have been reported for the Antarctic Peninsula (Middle Eocene; Woodburne and Zinsmeister 1982, 1984) and from the Late Oligocene and Early Miocene deposits in the Argentinean Patagonia (Marshall 1982). Recent fossil findings have been reported for south – central Chile with two genera and seven species, with a single living species. Evolutionary studies at morphological and molecular levels concluded that this species is more phylogenetically related to Australian than to South American marsupials (Szalay 1982; Palma and Spotorno 1999; Palma 2003). Dromiciops gliroides is a tree climber species with nocturnal habits associated to the presence of southern beech forests of the genus Nothofagus (Fagaceae) and to the bamboo of the genus Chusquea (Bambusaceae, Graminea, Pearson 1995). Its northernmost distributional limit has been traditionally reported for Concepcion (Region VIII; 371000, 721300; Fig. 1), while to the south it has been found into the Chiloe island (Region X; ca. 441000, 721000). To the east, the distribution of the species encompasses the provinces of Neuquen and Rio Negro in Argentina (Hershkovitz 1999). Recently, Saavedra and Simonetti (2001) extended the distributional range of Dromiciops to the north, in the central coast of Chile, by trapping a specimen at Reserva Nacional Los Queules (LQNR 351590S–721410W). From a biogeographic perspective the latter has been an outstanding finding because coastal areas in Chile have been considered a refuge zone for the biota during the last glacial cycles of the Pleistocene (Armesto et al. 1995; Villagran and Hinojosa 1997). Here, we report an additional finding for the northern range of D. gliroides in the forests of central Chile, thus supporting its occurrence in the deciduous Maulean forests of that area. During a small mammal survey in the winter of June 2003 in Reserva Nacional Los Ruiles (LRNR, 351500–721300W, 224m), we trapped a female sub-adult specimen of D. gliroides (Fig. 2). The standard measurements (in mm) ARTICLE IN PRESS