358.

Western Chestnut Mouse

Pseudomys nanus

French: Petit Pseudomys / German: Kleine Australienmaus / Spanish: Ratén de castano occidental

Other common names: Western Chestnut Pseudomys

Taxonomy. Mus nanus Gould, 1858,

Victoria Plains, West Australia, Australia.

Pseudomys nanus was placed in subgenus Thetomys by G. H. H.Tate in 1951, and according to studies by P. R. Baverstock and coworkers in 1977 and 1981 is genetically close to P. gracilicaudatus . It is similar to most other Pseudomys in its sperm-head morphology. According to F. Ford in 2006 and B. Breed and Ford in 2007, it belongs to a molecular clade composed of P. gracilicaudatus and Mastacomysfuscus. Further taxonomic studies are required in order to clarify this, but a molecular phylogeny by P. Smissen and K. C. Rowe in H. J. McLennan andcolleagues’ 2017 study found that P. nanusis sister taxon of P. gracilicaudatus . Two subspecies recognized.

Subspecies and Distribution.

P.n.nanusGould,1858—NAustralia,includingMelvilleandBathurstIsandSirEdwardPellewGroup.

P. n. ferculinus Thomas, 1902 — Barrow, Sholl, and Potter Is, Western Australia.

Descriptive notes. Head—body 71-130 mm, tail 75-121 mm, ear 14-15 mm, hindfoot 23-26 mm; weight 17-56 g. The Western Chestnut Mouse has a light orange-fawn dorsal pelage with long dark hairs, resulting in a grizzled appearance; ventral pelage is cream or white. It has a light, pale orange, eye-ring. Tail is black above and white below, and is similar to, or slightly longer than, head-body length.

Habitat. Dense grass in low eucalyptus woodlands, or on sandy or lateritic soils.

Food and Feeding. The Western Chestnut Mouse is a grass-eater.

Breeding. Reproduction probably occurs throughout much of the year except in very dry periods. The Western Chestnut Mouse has an unusually fast reproductive rate for a Pseudomys species; thus, populations can increase rapidly during wetseason. Gestation is 22-24 days;litter size is 1-5 (average 3), and young are well furred at day 7, open eyes at around day 12, and weaning can occur at day 21.

Activity patterns. Western Chestnut Mice are terrestrial and nocturnal, and build grass nests.

Movements, Home range and Social organization. No information.

Status and Conservation. Classified as Least Concern on The IUCN Red List. No major threats are known for this species, which occurs in a few protected areas.

Bibliography. Baverstock, Watts, Adams & Cole (1981), Baverstock, Watts & Hogarth (1977), Breed, B. & Ford (2007), Breed, W.G. (1983), Ford (2006), Jackson & Groves (2015), Robinson & Cooper (2008), McLennan et al. (2017), Strahan (1983), Tate (1951), Watts & Aslin (1981).