5.

Arabian Spiny Mouse

Acomys dimidiatus

French: Acomys dArabie / German: Sinai-Stachelmaus / Spanish: Ratén espinoso de Arabia

Other common names: Eastern Spiny Mouse

Taxonomy. Mus dimidiatus Cretzschmar, 1826,

Sinai, Egypt.

It is nearly indistinguishable from A. cahurinus with regard to external morphology, which resulted in great confusion relative to its classification. It was generally synonymized with A. cahirinus until assessment of its morphology, cytogenetics, and molecular affinities. Cytogenetic analyses agreed with molecular studies and dental morphology, leading to recognition of A. dimidiatus as a valid species,distinct from A. cahirinus . Different species have been described, all now synonymized ( A. hispidus; A. megalotis from Saudi Arabia, and A. whiter from Oman). J. R. Ellerman in 1941 created five subspecies; two are now recognized as valid species ( nesiotes and minous) and the other three are still recognized as subspecies ( dimidiatus, flavidus, and homericus). The most recent molecular analysis by D. Frynta and colleagues in 2010 recognized an Afro-Mediterranean clade ( A. cahirinus, A. dimidiatus, A. cilicicus, and A. minous) and an Asian clade (Yemen, Iran + Emirates, and Sinai—Jordan). Y. Hadid and colleagues in 2014 showed phylogenetically that A. dimidiatus is found in sympatry with A. russatus in Israel. Fifteen specimens of A. dimidiatus were trapped on Farasan Kebir in Red Sea Farasan Islands (Saudi Arabia), as reported by M. Masseti in 2010. Five subspecies recognized.

Subspecies and Distribution.

A.d.dimidiatusCretzschmar,1826—Egypt(Sinai),Israel,Jordan,andSaudiArabia.

A.d.flavidusThomas,1917—SWPakistan.

A.d.homericusThomas,1923—SaudiArabiaandSWYemen.

A.d.megalodusSetzer,1959—knownonlyfronthetypelocalityinEgypt,60kmSofSuez.

A. d. megalotis Lichtenstein, 1830 — Arabia.

Also present in S Iran, but subspecies involved not known.

Descriptive notes. Head-body 85-129 mm, tail 88-117 mm, ear 18-22 mm, hindfoot 19-22 mm; weight 30-45 g. Dorsum of the Arabian Spiny Mouse is pale sandy fawn, slightly darker on head and with spines on back and flanks; underparts are pure white. White patchesare visible at posterior ear bases and below each eye. Its skull is larger than in the Northeast African Spiny Mouse ( A. cahirinus). There are three pairs of mammae. Chromosomal complement has 2n = 36-38 and FN = 70 in Saudi Arabia and Sinai.

Habitat. Rocky habitats in dry, arid environments up to elevations of ¢.1900 m. In Israel and Sinai, the Arabian Spiny Mouse lives in xeric and mesic environments with Mediterranean, steppe, and desert climatic regimes;it is relatively stenotopic in Israel.

Food and Feeding. Diets of coexisting omnivorous Arabian Spiny Mice and Golden Spiny Mice ( A. russatus) in southern Israel were studied experimentally (cafeteria test) and in the wild (stomach content analysis). No significant dietary differences were found. They both eat crickets (50-58%), barley seeds (23-27%), green alfalfa (12-17%), and snails (6-7%), with slight differences in stomach contents between nocturnal Arabian Spiny Mice and diurnal Golden Spiny Mice.

Breeding. Cooperative (or communal) breeding occurs among female Arabian Spiny Mice. Lactating females nursed offspring of other females and also helped protect them. Kinship and familiarity had no effect on alloparental care. Less experienced females nursed their own young more than alien young. Near Taif, Saudi Arabia, breeding is seasonal, related to rainfall and temperature. Elsewhere, reproduction can occuryearround, often decreasing in winter. In winter and autumn, males had significantly lower testes mass and volume and plasma testosterone levels, and females had reduced ovarian mass and volume and concentrations of plasma progesterone. Gonad mass and volume and hormone levels increased significantly with increases in rainfall or temperature.

Activity patterns. The Arabian Spiny Mouse is nocturnal.

Movements, Home range and Social organization. No information.

Status and Conservation. Classified as Least Concern on The IUCN Red List. The Arabian Spiny Mouse is common and has a wide distribution.

Bibliography. Bajer et al. (2006), Behnke et al. (2004), Denys et al. (1994), Ellerman (1941), Frynta et al. (2010), Giagia-Athanasopoulou et al. (2011), Hadid et al. (2014), Harrison & Bates (1991), Kronfeld-Schor & Dayan (1999), Kunze et al. (1999), Masseti (2010), Sarli et al. (2016), Setzer (1959), Tutkova et al. (2016), Voloboueyv, Gautun &Tranier (1996), Volobouey, Tranier & Dutrillaux (1991).