672. Losea Rat Rattus losea French: Rat losea / German: Kleine Reisfeldratte / Spanish: Rata de arrozal menor Other common names: Lesser Ricefield Rat Taxonomy. Mus losea Swinhoe, 1871, “Formosa [= Taiwan].” Rattus loseais in the R. rattusspecies groups, is sister to the R. rattus clade (R. rattus, R. tanezumi, R. sakeratensis, R. tiomanicus), and is related to R. osgoodi. R. sakeratensis was originally included as a synonym of R. losea, but following phylogenetic studies, populations in northern Thailand and Laos have been allocated to R. sakeratensis. Specific identity of a population in Peninsular Thailand and Malaysia is uncertain but is included in R.losea until further review. There were three subspecies recently recognized (exiguus, losea, and sakeratensis) in China, but this arrangement is not followed here. Monotypic. Distribution. SC & SE China (including Hainan, Taiwan, and Penghu Is), extreme N Laos, N, C & S Vietham, W & C Cambodia, and provisionally S peninsular Thailand and extreme NW Peninsular Malaysia. Descriptive notes. Head—body 120-185 mm, tail 110-175 mm, ear 15-21 mm, hindfoot 24-32 mm; weight 22-92 g. The Losea Rat is small and very similar to but larger than the Little Indochinese Field Rat (R. sakeratensis) but much smaller than the morphologically similar Ricefield Rat (R. argentiventer). Pelage is short, soft, and dense. Dorsum is dull gray brown, with mix of pale brown and black-tipped hairs, becoming somewhat paler along sides and blending into ventral pelage. Venter is buffy brown, with gray-based hairs. Feet are whitish gray dorsally and white on sides and digits. Ears are small and light brown; vibrissae are long. Tail is 90-100% of head-body length and slightly bicolored, being brown dorsally and paler ventrally. Skull is small and stocky, with short wide rostrum and high braincase. Various ticks (Ixodes granulatus and Borrelia spirochetes), fleas, mites, trematodes (Notocotylus loeiensis), gastrointestinal helminths (at least twelve species), and blood-flukes (Schistosoma japonicum) have been recorded from the Losea Rat. It is also a vector for Bartonella, Lyme disease, and hantavirus. There are five pairs of mammae: two axillary and three inguinal. Chromosomal complement is 2n = 42, FN = 60-62. Habitat. Grass, scrub, mangroves, cultivated fields (rice in particular), gardens, orchards, and other human modified areas from sea level up to elevations of ¢.1000 m. Food and Feeding. The Losea Rat feeds heavily on grain and is probably mostly herbivorous. Breeding. Litters have 3-14 young (mean 7-3). Females probably reach maturity at weights of c.45 g. Reproduction seems synchronized with rice crops in spring and summer. Activity patterns. The Losea Rat is probably nocturnal and mainly terrestrial, usually creating nests in burrows, sometimes in rice fields. Movements, Home range and Social organization. Abundance of Losea Rats fluctuates with availability offield crops in populations reliant on agriculture. Status and Conservation. Classified as Least Concern on The IUCN Red List. The Losea Rat has a wide distribution, is relatively common, is found in many protected areas, and is considered an agricultural and urban pest. It is often poisoned to prevent crop damage; some individuals that have an immunity to the poison Warfarin. Bibliography. Aplin (2016d), Aplin, Brown et al. (2003), Aplin, Chesser & ten Have (2003), Aplin, Suzuki et al. (2011), Aoki & Tanaka (1938), Balakirev & Rozhnov (2012), Baverstock, Adams et al. (1983), Brown et al. (2005), Chaisiri, Chaeychomsri et al. (2012), Chaisiri, Morand et al. (2011), Chao Lilian et al. (2012), Francis (2008), He Yixun et al. (2001), Musser & Carleton (2005), Musser & Newcomb (1985), Smith & Yan Xie (2008), Wang Jianshe et al. (2008), Wang Yingxiang (2003), Yu Hontsen et al. (1996).

Published as part of Don E. Wilson, Russell A. Mittermeier & Thomas E. Lacher, Jr, 2017, Muridae, pp. 536-884 in Handbook of the Mammals of the World – Volume 7 Rodents II, Barcelona :Lynx Edicions on pages 834-835, DOI: 10.5281/zenodo.6887260