366.

Naked-soled Conyrat

Reithrodon typicus

French: Reithrodon de I'Uruguay / German: Nacktsohlige Kaninchenratte / Spanish: Rata conejo de plantas desnudas

Taxonomy. Reithrodon typicus Waterhouse, 1837, Maldonado, Maldonado, Uruguay.

Reithrodon typicusis the type species of the genus. Two subspecies recognized.

Subspecies and Distribution.

R.t.typicusWaterhouse,1837—extremeSBrazil(RioGrandedoSulState)andUruguay.

R. t. currentium Thomas, 1920 — NE Argentina (Corrientes and Entre Rios provinces); range probably extends into extreme NE Buenos Aires Province.

Descriptive notes. Head-body 140-150 mm, tail 90-120 mm, ear 22-27 mm, hindfoot 27-35 mm; weight 60-105 g. See general characters of the genus under the North-western Conyrat ( R. caurinus) account. Dorsum of the Naked-soled Conyrat is mixed buffy gray, sides and venter are strongly washed with buff; manus and pes are white; tail is almost white; and soles of forefeet and hindfeet are naked or tending to be less haired than those of the Hairysoled Conyrat ( R. auritus). Chromosomal complementis 2n = 28, FN = 40.

Habitat. Natural or modified grasslands. In Uruguay, the Naked-soled Conyrat is usually found in overgrazed pasture, among rocky outcrops, and on well-drained slopes with scant vegetation. According to Darwin’s notes, who secured the holotype of the species in 1832, was frequent in small thickets in the open grassy fields near Maldonado.

Food and Feeding. The Naked-soled Conyrat is herbivorous; preferred plants in Uruguay include corms of Oxalis sp. (Oxalidaceae) and rhizomes and roots of Digitaria sp (Poaceae) . Naked-soled Conyrats took food into the main burrow of feed in specific shelters, but no food stores were found in burrows.

Breeding. Naked-soled Conyrats with reproductive signals have been trapped in spring and summer (October-May). Recorded numbers of embryos were 3-4; a lactating female had four nestling young.

Activity patterns. The Naked-soled Conyrat is nocturnal and terrestrial.

Movements, Home range and Social organization. Naked-soled Conyrats dig burrows in sandy to hard-baked clay soils, or use with or without modification abandoned burrows or natural crevices and holes among rocks. Nearness of burrows to each other suggests that they can be variously gregarious or solitary. Burrow entrances averaged 5 cm in diameter. A passageway descended vertically an average of 25 cm, where tunnels became level and followed a course parallel to the surface. Active systems were marked by fresh cuttings and droppings near entrances. An excavation showed that all burrows were less than 2 m in length and had two entrances; they were occasionally branched and tortuous; burrow entrances were 3-5 cm in diameter; tunnels were 5-7 cm in diameter and were 10-25 cm beneath the surface; some burrows contained central, oval chambers up to 30 cm in diameter; in one such chamber had a nest platform of fine dry grass; defecation sites were just outside entrances of burrows or within a 9m radius from them; no distinct runways led to any of these burrows.

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

Bibliography. Barlow (1969), D'Elia (2016b), Freitas, Mattevi & Oliveira (1983), Gonzalez & Martinez (2010), Ortells et al. (1988), Pardinas & Galliari (2001), Pardinas, Galliari & Teta (2015), Thomas (1920b), Waterhouse (1839).