546.

Hairy-tailled Akodont

Necromys lasiurus

French: Akodon a queue velue / German: Haarschwanz-Graslandmaus / Spanish: Raton cavador de cola peluda

Other common names: Hairy-tailed Bolo Mouse

Taxonomy. Mus lasiurus Lund, 1840, “Rio das Velhas’s Floddal,” near Lagoa Santa, Minas Gerais, Brazil .

About a dozen of nominal forms are currently subsumed under [ lasiurus, which reflects morphological variation displayed by this taxon across its huge distribution. Nevertheless, N. lasiurus exhibits little phylogeographic structure according to studies of cytochrome-b sequences. A morphological comprehensive revision of this taxon is pending, and until it is done, it is premature to use trinomial classification. Here, Akodon lenguarum is treated as junior synonym of N. lasiurus . Necromys populations from the Humid Chaco of Paraguay morphologically and molecularly belong to N. lasiurus, and Waikthlatingwaialwa, the type locality of lenguarum, is located in this region ¢.80 km west of Concepcion. In this context, the Chacoan Bolivian clade recovered by G. D’Elia and colleagues in 2008 and incorrectly equated to lenguarum probably belongs to an unnamed species of Necromys . Monotypic.

Distribution. NE, C & S Brazil, extreme SE Peru, Bolivia, Paraguay, N & C Argentina; probably extreme NW Uruguay, limits unresolved.

Descriptive notes. Head-body 114-138 mm, tail 59-96 mm, ear 13-17 mm, hindfoot 22-25 mm; weight 20-67-5 g. The Hairy-tailed Akodont is a moderately large species of Necromys, with important metric and color variation; e.g. mean values from a sample of 40 individuals obtained in central Argentina (traditionally referred to N. benefactus) are head-body 99 mm, tail 66 mm, ear 13 mm, hindfoot 22 mm; weight 27 g. See general characters of the genus under the Ecuadorean Akodont (N. punctulatus) account. Dorsum is olivaceous gray to dark brown, usually with well-defined agouti pattern; rump and sides are generally paler and more ocherous tawny; and venter is whitish to gray, sometimes washed with buff, with individual hairs dark gray at their bases. There is not a defined line between dorsum and venter. Eye-ring absent or poorly defined by buffy or cinnamon hairs. Ears are small, rounded, and sparsely haired; tail is bicolored and covered by moderately dense short hair. Manus and pes are brownish, with well-developed nails and whitish ungual tufts. Chromsomal complement is 2n = 33-34, FN = 34.

Habitat. Grasslands, along borders of cultivate fields, abandoned croplands, and secondary and gallery forests.

Food and Feeding. Diets of the Hairy-tailed Akodons vary geographically and seasonally and include seeds (one of the main items in several analyses), fruits, green vegetation, and arthropods.

Breeding. Reproduction of the Hairy-tailed Akodon occurs year-round but mainly in April-June. In east-central Argentina, it breeds in spring and summer (October-February). Gestation lasts 19-21 days. Numbers of embryos average 4-6.

Activity patterns. Activity of the Hairy-tailed Akodon varies accordingly to season; it is mainly diurnal but more crepuscular and nocturnal in dry season. It is terrestrial, but individuals from north-eastern Brazil have fossorial competence according to field and laboratory data.

Movements, Home range and Social organization. Home ranges of females (1317-5480 m?) are smaller than those of males (4138-21,880 m?*). Female home ranges tend to be exclusive, while males tend to overlap with females’ home ranges. The Hairy-tailed Akodont is seasonally rare, becoming most common during the rainy season. In grassland areas, it is a moderately abundant species, reaching densities up to 19 ind/ha in central Brazil and 33-8 ind/ha in east-central Argentina . It can dig and live in burrows underground with multiple openings and tunnels and builds nests from grass, leaves, and other debris. The Hairy-tailed Akodont (mentioned as benefactus) was reported as experiencing a demographic outbreak in central Argentina .

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

Bibliography. de Almeida et al. (1982), Becker et al. (2007), Bonvicino, Oliveira & D'Andrea (2008), Contreras (1982a), Couto &Talamoni (2005), D'Elia, Pardinas, Jayat & Salazar-Bravo (2008), Dietz (1983), Eisenberg & Redford (1999), Ellis, Mills, Childs et al. (1997), Ellis, Mills, Glass et al. (1998), Feliciano et al. (2002), Francisco etal. (1995), Galliari & Pardinas (2000), Libardi (2013), Macédo & Mares (1987), Magnusson et al. (1995), Marinho-Filho et al. (2016), Mills, Ellis, McKee, Maiztegui & Childs (1992), Oliveira et al. (1998), Pacheco et al. (2009), Pardinas, Teta, Ortiz et al. (2015), Parreira & Cardoso (1993), Pereira, L.A. (1982), Pereira, L.G. & Geise (2007), Pereira, Y.L.M. (2013), Pires et al. (2010), Razuri et al. (2014), Talamoni et al. (2008), Teta, Gonzalez-Fischer et al. (2010), Vieira et al. (2010), de Villafane etal. (1973).