365.

Arnhem Land Rock Rat

Zyzomys maini

French: Zyzomys de Main / German: Arnhemland-Dickschwanzratte / Spanish: Rata de roca de Tierra de Arnhem

Other common names: Arnhem Rock Rat

Taxonomy. Zyzomys main i Kitchener, 1989,

“Djawamba Massif, 1-5 km east of Ja Ja Billabong, Northern Territory, 12°31’S, 132°54°E; altitude c.150 m,” Australia .

Zyzomys main: was previously considered conspecific with Z. woodwardi, but wassplit from latter on basis of smaller size and a range of minor morphological characters. Monotypic.

Distribution. Restricted to the sandstone plateau and escarpment of W Arnhem Land, in monsoonal N Australia.

Descriptive notes. Head-body 115-170 mm, tail 110-150 mm, ear 17-20 mm, hindfoot 24-29 mm; weight 65-180 g. The Arnhem Land Rock Rat is a thickset rat, its most distinctive features being large prominent eyes, long vibrissae, and a tail that is often markedly thickened (with stored fat) at base and has longer hairs around tail tip. Part or all of the tail is often missing (caudal autotomy, presumably as a response to attempted predation). Body fur is gray brown above, and pale on belly and feet.

Habitat. Rugged rocky areas, especially those with large boulders and crevices. Preferred habitat is rainforest, butit is found also in heathlands, hummock grasslands, and eucalypt woodlands.

Food and Feeding. Diet includes a range of seeds, fruits, and other vegetable matter. The Arnhem Land Rock Rat consumes larger fruits and seeds than does the co-occurring Common Australian Rock Rat ( Z. argurus), and is reported as gathering seeds and fruits for consumption at secure “cache” sites. Some preferred plant species are detrimentally affected by frequent fire.

Breeding. Breeds throughout year, with peak in early dry season (March-May), but may reproduce several times per year. Litter size usually two. Sexual maturity attained at 5-6 months.

Activity patterns. The Arnhem Land Rock Rat is terrestrial and nocturnal.

Movements, Home range and Social organization. Arnhem Land Rock Rats are generally sedentary, although males move more than females during breeding times. They may be locally abundant at some sites.

Status and Conservation. Classified as Vulnerable on The IUCN Red List, based on rate of ongoing population decline, small area of occupancy,and restriction to few locations. Listed as vulnerable under Australian legislation. Its area of occupancy is estimated to be ¢.2000 km?. Populations generally declining, possibly as a result of habitat degradation caused by frequent and extensive fires, and possibly also to predation by feral cats.

Bibliography. Begg (1981), Begg & Dunlop (1980, 1985), Begg et al. (1981), Cole & Woinarski (2002), Ibbett et al. (2017), Kitchener (1989), Russell-Smith et al. (1998), Van Dyck & Strahan (2008), Watts & Aslin (1981), Woinarski, Armstrong et al. (2010), Woinarski, Burbidge & Harrison (2014), Woinarski, Pavey et al. (2007).