Rattus steini Rummler 1935

714.

Stein’s New Guinea Rat

Rattus steini

French: Rat de Stein / German: Stein-Neuguinea-Ratte / Spanish: Rata de Nueva Guinea de Stein

Other common names: Small Spiny Rat, Stein's Rat

Taxonomy. Rattus leucopus steini Rimmler, 1935,

Mount Kunupi, Weyland Range, Province of Papua, West Papua (= Irian Jaya), New Guinea.

Rattus steini is part of a cladeincluding the Recent New Guinea species of Rattus, and it has been recovered as the sister species to R. novaeguineae, with R. praetor sister to this clade. Rattus steini was found to be highly paraphyletic with R. praetor in re-cent genetic studies, which might indicate that there are multiple species within what is currently recognized as R. steini. More research is needed to fully understand placement of R. stein: in Rattus and to determine number of taxa it represents. Four subspecies recognized.

Subspecies and Distribution.

R.s.steiniRimmler,1935—WeylandandNassauranges,SWNewGuinea.

R.s.baliemensisJ.M.Taylor&Calaby,1982—SnowMts,WNewGuinea.

R.s.foersteriRimmler,1935—HuonPeninsula,NENewGuinea.

R. s. hageni Troughton, 1937 — C & E New Guinea, including the Central Cordillera from Star Mts E to Bowutu Mts and the Adelbert Range.

Descriptive notes. Head—body 140-193 mm, tail 140-193 mm, ear 16-21 mm, hindfoot 33-37 mm; weight 110-220 g. Stein’s New Guinea Rat is medium-sized and smaller than the Large New Guinea Spiny Rat (R. praetor), with narrower and lighter feet. Pelage is soft, although larger specimens have sparsely distributed, thin, and flexible spines. Dorsum is grizzled dark brown, with rufous-tipped hairs, gray underfur, and fine guard hairs distributed throughout, being more conspicuous on rump.Juveniles have less developed spines and guard hairs and more subdued rufous-tipped hairs (subspecies steini and baliemensis), more somber with no spines (foersteri), and softer and darker with lighter hair tips and occasionally with pectoral spotting (hageni). Venteris gray, with yellowish bufftipped fur, often with white pectoral spot, and sharply demarcated from dorsum. Feet are covered in cream or light buffy hairs. Ears are fairly short and dark brown; vibrissae are relatively short. Tail is less than 100% of head-body length, shorter than in the Papua New Guinea Rat (R. novaeguineae), and dark brown, with small hairs sparsely distributed. Skull has slightly or moderately bowed incisive foramina, relatively heavy molars, and average sized bulla. Specimens from lower elevations tend to be larger, contain more fine spines, have longer tails, longer rostrums, and more bowed incisive foramina compared with individuals from higher elevations (known from hageni). There are 3—4 pairs of mammae; 1-2 pectoral and two inguinal. Nominate subspecies and baliemensis have six mammae, and foersteri and hageni have eight mammae. Karyotype is 2n = 32, FN = 60.

Habitat. Primary tropical moist forest in low densities and abundant in forest edge, rural gardens, and open and grassy areas at elevations of 450-2800 m.

Food and Feeding. Stein’s New Guinea Rat eats root crops (e.g. sweet potatoes) and various vegetables.

Breeding. Stein’s New Guinea Rats apparently reproduce year-round. Mean litter size was 3-4 young;litters of subspecies hageni had 2-5 young (mean 2-7).

Activity patterns. Stein’s New Guinea Rat is probably mostly terrestrial and mildly arboreal because it usually inhabits burrows. U-shaped burrows with two entrance holes probably belong it, and it has been caught in tree hollows.

Movements, Home range and Social organization. No information.

Status and Conservation. Classified as Least Concern on The IUCN Red List. Stein’s New Guinea Rat has a wide distribution,is reportedly common, and probably occurs in protected areas. Its only possible threat would be competition with the Roof Rat (R. rattus). Itis regarded as an agricultural pest to subsistence farmers growing root crops and vegetables.

Bibliography. Aplin (20161), Aplin, Brown et al. (2003), Aplin, Chesser & ten Have (2003), Dwyer (1984), Flannery (1995a, 1995b),Musser & Carleton (2005), Robins et al. (2014), Taylor et al. (1982).