442.

Black-footed Pygmy Rice Rat

Oligoryzomys nigripes

French: Colilargo a pattes noires / German: SchwarzfulR-Zwergreisratte / Spanish: Rata arrocera pigmea de pies negros

Other common names: Black-footed Colilargo, Delta Pygmy Rice Rat

Taxonomy. Mus nigripes Olfers, 1818, type locality not given. Fixed by neotype selection by P. Myers and M. D. Carleton in 1981 as “Ybycui National Park, Department Paraguari, approximately 85 km SSE Atyra, Paraguay.” This species is monotypic.

Distribution. E Brazil, E Paraguay, Uruguay, and NE Argentina .

Descriptive notes. Head-body 78-116 mm, tail 100-149 mm, ear 14-20 mm, hindfoot 21-28 mm; weight 16-37 g. The Black-footed Pygmy Rice Rat is a moderately large species of Oligoryzomys . Mid-dorsum and rump are tan to pale cream-brown, approaching Dresden Brown on head; older individuals are hazel over rump; all individuals are at least moderately lined with black, most distinct on head; cheeks are often orange; sides of body are paler and less heavily lined; many individuals have narrow but fairly distinct orange-brown lateral line separating dorsum and venter; hairs on chin are white to base but are white-tipped with basal 66-75% of length gray on throat and rest of venter, where hairs occasionally are washed with buff; basal gray is usually visible, giving belly a frosted appearance; and orange pectoral band is often present. Tail is unicolored or weakly bicolored and 126% (112-150%) of head-body length. Feet are relatively small and short (21-5-27-9% of head-body length). Ears long (59-82% of hindfoot length), and hairs on inside are 50% or less black or brown basally and orangish or tan distally. Chromosomal complement is 2n = 62, FN = 78-82.

Habitat. Broadly distributed in primary and secondary vegetation in the Atlantic Forest and Cerrado ecoregions and gallery forests and associated swampy habitats in central Argentina .

Food and Feeding. The Black-footed Pygmy Rice Rat is insectivorous.

Breeding. Pregnant Black-footed Pygmy Rice Rats have been reported in June-November, with an average of four embryos each.

Activity patterns. Black-footed Pygmy Rice Rats are nocturnal and terrestrial, although several reports suggest they climb in understory.

Movements, Home range and Social organization. The Black-footed Pygmy Rice Rat tends to move relatively short distances each day, with males moving almost twice the daily distance of females. Activity does not appear to be influenced by moon phases, but it is negatively influenced by rain. Long-term studies showed that the Black-footed Pygmy Rice Rat has an annual pattern of population cycling, with peaks during dry season.

Status and Conservation. Classified as Least Concern on The IUCN Red List. The Blackfooted Pygmy Rice Rat is considered a generalist with a stable and large overall population and broad distribution. It is not included in the official list of threatened species of Brazil.

Bibliography. Antunes et al. (2009), Bonecker et al. (2009), Bonvicino & Weksler (1998), Bonvicino et al. (2016), Bovendorp et al. (2013), Cademartori, Fabia & Menegheti (2004), Cademartori, Marques & Pacheco (2008), Cademartori, Saraiva et al. (2008), de Camargo et al. (2016), Carbajo & Teta (2009), Cardoso et al. (2016), Coghetto et al. (2014), Contreras et al. (2003), D'Andrea, Gentile, Crequeira et al. (1999), D'Andrea, Gentile, Maroja et al. (2007), Dalmagro & Vieira (2005), Feliciano et al. (2002), Fernandes, FR. et al. (2012), Galetti et al. (2015), Galiano, Kubiak, Estevan et al. (2014), Galiano, Kubiak, Marinho & Freitas (2013), Gentile et al. (2000), Gémez et al. (2012), Gonzalez-Ittig, SalazarBravo et al. (2010), Graipel et al. (2006), Granzinolli & Motta-Junior (2006), Grazzini, Mochi-Junior, de Oliveira, Pontes, de Almeida & Tiepolo (2015), Jorge et al. (2001), Langguth (1963), Leiner & Silva (2012), de Lima et al. (2010), Magrini & Facure (2008), Massoia (1973), Massoia & Fornes (1964c), Melo et al. (2013), Moreira et al. (2009), Myers & Carleton (1981), de Oliveira et al. (2013), Ped¢ et al. (2010), Pinotti et al. (2011), Pires et al. (2002), Puttker, MeyerLucht & Sommer (2006, 2008a), Puttker, Pardini et al. (2008), Quintela et al. (2012), Scheibler & Christoff (2007), Talamoni & Dias (1999), Teixeira et al. (2014), Teta & Pardifas (2010), Vadell, Bellomo et al. (2011), Vadell, Garcia & Gomez (2017), Weksler & Bonvicino (2005, 2015b).