Acomys dimidiatus (Cretzschmar, 1826)

Amr, Zuhair S., Abu, Mohammad A., Qumsiyeh, Mazin & Eid, Ehab, 2018, Systematics, distribution and ecological analysis of rodents in Jordan, Zootaxa 4397 (1), pp. 1-94 : 26-28

Acomys dimidiatus (Cretzschmar, 1826)

Common name: Eastern spiny mouse.

Diagnosis: Dorsum gray to light brown, ventral white with a very sharp line of demarcation. White patches present on the posterior side of the ear base ( Figure 25 ). Sharp spines mostly on the back, not reaching back of head. Ears without hair. Soles of hind feet yellow brown in color. Tail with large and easy visible scales. Three pairs of mammae. Skull with a broad braincase. Median keel on palate present. Crown area of first upper molar very large ( Figure 26 ).

Localities: Previous records. ‘Aqaba, Aṭ Ṭafīla, Petra, Wādī Al Karak ( Allen, 1915); Moab and Ghawr es Safi ( Aharoni, 1932); AUB collection: Wādī Zarqā Ma’in (Atallah, 1977); ‘Aqaba, Gharandal, Ghawr as Safi ( Amr & Disi, 1988); Wādī Zarqā, S Jarash (Bates & Harrison, 1989); Wādī Al Hidan, Wādī Zarqā Ma'in (Benda & Sádlová, 1999); 20 km N El Quweira, Wādī Ramm (Abu Baker & Amr, 2004); Ḑānā Biosphere Reserve (Yousef & Amr, 2005); Jarash, Petra, Wādī Mūsá, Wādī Ramm (Sözen et al., 2008). Materials extracted from owl pellets. Ex. Bubo bubo, Marj Al Hammam (Obuch per. com.); Ex. Bubo bubo , Tyto alba and Strix butleri, Ḑānā Biosphere Reserve (Obuch per. com.); Ex. Strix aluco , Iraq al Wahaj (Obuch per. com.); Ex. Strix butleri, Wādī Ibn Hammad (Obuch per. com.); Ex. Strix butleri, Ar Rājif, Wādī Suweid (Obuch per. com.); Ex. Strix butleri, Wādī Ramm (Obuch per. com.); Ex. Strix butleri, Petra (Obuch per. com.); Ex. Tyto alba, Wādī Zarqā Ma’in (Pokines per. com.). New records. Al Hemmah, Dhahel, Fifa, Ḩumrat Mā‘īn, Jabal Masuda, Jarash, Malka, Qatar Nature Reserve, Raḩmah, Suwaymah, Wādī Al-Mujib, Wādī Tlah ( Figure 27 ).

Habitat: The eastern spiny mouse is a rock dwelling species inhabiting mesic and xeric biotopes. It is found across the entire mountain ranges extending from ‘ Aqaba to Al Hemmah in the extreme northern part of Jordan. It also invaded Mediterranean forest habitats in northern Jordan such Jarash and Malka forests with dense vegetation of pine and deciduous oak respectively. In southern Jordan, it is associated with dry mountains with minimal vegetation. It is found in rocky fringes in Wādī ‘Araba and along the Dead Sea eastern shores. In Wādī Ramm, Petra and Jabal Masuda, it is associated with sand stone rocky areas and in relatively high density. This species was never recorded in rocky areas in the eastern desert of Jordan.

A study of seasonal population fluctuations was conducted in the rocky slopes habitats of Wādī Fidān during 1987. Higher abundance of Acomys dimidiatus over its associated species, Sekeetamys calarus and Gerbillus dasyurus was observed, except in December and January, when A.dimidiatus population declined and Gerbillus dasyurus populations became co-dominant along with A. dimidiatus (Abu Dhayeh, 1988) . In En Gedi, A. dimidiatus and A. russatus were found to co-occure. The activity pattern of these two species suggests a competitive exclusion of A. russatus (to daytime) by A. dimidiatus (Kronfeld et al., 1994) .

Biology: In arid regions, the eastern spiny mouse feeds on land snails.The entrance of its burrow is usually piled with crushed land snails of several genera. Also, the entrance may be plugged by thorny plants, perhaps to prevent intruders (e.g. snakes) from entering. This was observed in dense populations of this species near the Suwaymah and around Zarqā Ma'in. This is social animal living in large colonies. Gestation lasts for 36–40 days, and the young (2 or 3, at most 5) are born mainly in the spring and summer months. It was found that the spiny mouse bred and produced young throughout the warm season of the year (late April to October). In early April, all the captured females were not pregnant, whereas by late April, 5 out of 7 captured females were pregnant. Neither pregnancies nor young were recorded during the period of December to March (Abu Dhayeh, 1988). In June, all the young captured were 25–40 days old (estimation of age was based upon the color and the size of the animal in comparison with the captive animals). In August, 5 young ranging between 40–60 days old were captured, while in October, 2 one month old specimens were captured from the study area. This may indicate that late pregnancies may take place in August.

Remarks: The distinction between A. cahirinus and Acomys dimidiatus is still debatable and not settled yet. Harrison & Bates (1991) considered cahirinus as a subspecies of A. dimidiatus . Several authors doubted placing mice of the genus Acomys within family Muridae . Agulnik & Silver (1996) presented molecular evidences that A. dimidiatus is more closely related to the Mongolian Gerbil, Meriones unguiculatus , than it is to Mus musculus. Karyotype for this species in Jordan was found to be 2n: 38, NFa: 68 and NF: 70. The autosomes consist of 16 metacentric pairs and two pairs of acrocentric chromosomes (Qumsiyeh et al., 1986; Sözen et al., 2008).

Figures

FIGURE 25.The eastern spiny mouse, Acomys dimidiatus from Wādī Ramm (photo by Mohammad Abu Baker).

FIGURE 26. A. Dorsal,B. Ventral,C. Lateral views of the skull, and D. Upper maxillary teeth for Acomys dimidiatus.

FIGURE 27. Distribution of the eastern spiny mouse, Acomys dimidiatus.