250.

Lesser Ryukyu White-toothed Shrew

Crocidura wataser

French: Crocidure de Watase / German: Kleine Ryukyu-WeiRzahnspitzmaus / Spanish: Musarana de Ryukyu menor

Other common names: Lesser Ryukyu Shrew, Watase's Shrew

Taxonomy. Crocidura watasei Kuroda, 1924,

Komi, Amami Oshima [Island], Ryukyu Archipelago, Japan.

Like the other former subspecies of C. horsfieldii from East and South-east Asia, it has been raised to a full species. Although sympatrically distributed with C. ori in Ryukyu

Islands, these two are of different origins. A recent molecular study conducted by S. Dubey and his co-workers in 2008 indicated that C. watasei is a relict species with a close relationship to the South-east Asian Crocidura species complex. Monotypic.

Distribution. Endemic to the Ryukyu Is, including 15 small islands of both the Amami and Okinawa Is; it may be distributed to the other small islands as well.

Descriptive notes. Head—body 54-74 mm,

tail 47-60 mm, hindfoot 10-5-12-5 mm. No specific data are available for body weight. Condylo-incisive length 17-2-18-8 mm, tooth row 7-4-8-3 mm. The Lesser Ryukyu White-toothed Shrew is a small shrew. External morphology is somehow similar to the Lesser White-toothed Shrew (C. suaveolens) but with a longer tail. Summer and winter pelages are slightly different in color: in winter, dorsal pelage is dark brown and ventrum is mouse gray; in summer, dorsal pelage is light brown and ventrum is lighter. No significant morphological sexual dimorphism but age variation was recognized in many external, cranial, and mandibular characters. Tail is greater than 70% of head-body in length and bristle hair is distributed on the proximal half of the tail; tail is indistinctly bicolored. Skull is small and palatal area is broad. It has five upper unicuspids, the first being the largest, and the second slightly smaller than the third. Paracone on the upper premolar is undeveloped. Chromosomal complement has 2n = 26 and FNa = 48.

Habitat. Occurs from near sea level to ¢.400 m. In some islands, co-occurs with the Greater Ryukyu White-toothed Shrew (C. oriz). The Lesser Ryukyu White-toothed Shrew occurs in bushes, grassland, and cultivated fields, as well as shrubs in low elevational zones of mountains.

Food and Feeding. The Lesser Ryukyu White-toothed Shrew is insectivorous. Its diet is primarily composed of small insects (Coleoptera, Hymenoptera, Diptera, Plecoptera, Neuroptera, Orthoptera, Lepidoptera, Hemiptera), spiders, centipedes, and crustaceans. Also reported to feed on small vertebrates, such as geckos and other lizards.

Breeding. Reproduction reportedly occurs throughout the year, and might not be seasonal. Litter size is 1-4 (average 2-5). Mating system is monogamous.

Activity patterns. Terrestrial. Known predators include pit vipers (Viperidae), oddtoothed snakes (Colubridae), introduced Small Indian Mongooses (Herpestes auropunctatus), introduced Japanese weasels (Mustela itatsi), and feral cats.

Movements, Home range and Social organization. No information.

Status and Conservation. Classified as Least Concern on The IUCN Red List. There is no serious threat to this species. Although habitat has been reduced during urban expansion since the 1970s, the population appears to be large and stable.

Bibliography. Dubey, Salamin et al. (2008), Hattori et al. (1990), Motokawa et al. (1996), Ohdachi et al. (2009).