682.

Valdivian Long-clawed Mouse

Geoxus valdivianus

French: Géoxus de Valdivia / German: Valdivia-Langkrallenmaus / Spanish: Ratén topo de Valdivia

Other common names: Long-clawed Mole Mouse, Valdivian Long-clawed Akodont

Taxonomy. Oxymycterus valdivianus Philippi, 1858, “Valdivia,” Region de los Rios, Chile.

Geoxus valdivianus is the type species of the genus. Several nominal forms from Chilean mainland and islands are uncritically treated as synonyms, including araucanus, bicolor, bullocki, and chiloensis. Taxonomic status and relationships clearly merit further study. Monotypic.

Distribution. Andean SW Argentina and CS Chile, including Mocha and Chiloé Is.

Descriptive notes. Head-body 95-106 mm, tail 30-45 mm, ear 10-12 mm, hindfoot 18-23 mm; weight 25-5-38 g (mean 32 g). The Valdivian Long-clawed Mouse is small, with fur velvety and mole-like; upperparts are blackish brown to olive-brown and slightly paler than dorsum, slaty gray to brown. Ears are small but visible externally; tail is shorter than 50% of head-body length, may be unicolored or indistinctly bicolored, and is very thickly covered with hairs that conceal scales. Pollex and other digits on forefeet have long and strong claws; claws on hindfeet are much shorter, withoutfringes of hairs along lateral margins. Diploid number in Argentinean specimens was 2n = 52; Chilean individuals apparently have 2n = 54.

Habitat. Pure and mixed forests of Nothofagus (Nothofagaceae), occasionally lush meadows or marshes bordering forests, areas with heavy undergrowth of cane and Berberis (Berberidaceae) shrubs, in small clumps of Nothofagus pumilio surrounded by pasture, or at imberline in tussock grass with patches of Araucaria araucana (Araucariaceae) or low bushes of Nothofagus from sea level to elevations of ¢.2000 m. The Valdivian Long-clawed Mouse is also recorded, at low abundance, in exotic plantations of Pinus spp. (Pinaceae) .

Food and Feeding. In Chilean primary forest, arthropods (17%), insects larvae (15%), annelids (24%), fungi (8%), fruits (5%), and plant material (34%) were detected in stomach contents. A 38g captive individual ate all the muscle, liver, heart, and lungs of a dead 46g Andean Long-clawed Mouse ( Paynomys macronyx) in less than 18 hours.

Breeding. In north-western Patagonia, testes of breeding male Valdivian Long-clawed Mice were 11-13 mm long; during non-breeding season, they were 5 mm or less. Autumn specimens were not in breeding condition, but all adults caught late in October, November, and December were breeding. Young males born early in spring can reach breeding competence at c.3 months old. All overwintered females in spring were pregnant, estrous, or recently parturient; some had bred while their habitat was still snow-covered. Breeding probably continues in summer, as suggested by presence ofjuveniles in April-May. Embryo counts averaged 3-5.

Activity patterns. The Valdivian Long-clawed Mouse is active day and night. It is partially subterranean but often is found in denselitter or herbaceous vegetation in runaways alongside logs; it will use tunnels made by other rodents, or it makes its own burrows in soft soil rich.

Movements, Home range and Social organization. Densities in Nothofagus forests of Rio Negro, Argentina, were 0-4-0-5 ind/ha; similar values were obtained in primary forests in Osorno, Chile. Recorded lineal movements were ¢.36 m.

Status and Conservation. Classified as Least Concern on The IUCN Red List.

Bibliography. Canén et al. (2014), Chebez et al. (2014), D'Elia, Pardinas & Patterson (2016b), Iriarte (2008), Kelt (1994, 1996), Mann (1957, 1978), Meserve, Lang, Murua et al. (1991), Meserve, Lang & Patterson (1988), Munoz-Pedreros & Gil (2009), Murua et al. (2005), Osgood (1925, 1943a), Patterson (1992a), Patterson et al. (1989, 1990), Pearson (1983, 1984, 1995), Reig (1987), Reise & Venegas (1987), Teta (2013), Teta, Canon et al. (2017), Teta, Pardinas & D’Elia (2015b), Saavedra & Simonetti (2005a, 2005b), Saavedra et al. (2003), Silva (2005).