130.

Balochistan Gerbil

Gerbillus nanus

French: Gerbille du Baloutchistan / German: Belutschistan-Rennmaus / Spanish: Gerbillo de Baluchistan

Other common names: Dwarf Gerbil

Taxonomy. Gerbillus nanus Blanford, 1875,

Gedrosia, Pakistan.

Morphology, morphometrics and cytogenetics of G. nanus have been studied in different parts of its range, and its relationships were discussed by D. L. Harrison and P. J. J. Bates in 1991. D. M. Lay in 1983 found some morphological and chromosomal similarities to G. amoenus, while V. T. Volobouev and colleagues in 1995 stressed the polymorphism and possible existence of some cryptic taxa within G. nanus . Some authors included G. garamantis within G. nanus, but this arrangement was refuted by G. G.Musser and M. D. Carleton in 2005. A molecular phylogeny by A. Ndiaye and colleagues in 2013 showed monophyly of G. nanus and a sister relationship with G. henley . Latter authors, however, highlighted existence of two distant allopatric clades, one containing specimens from Israel and Pakistan, the other including Mali, Mauritania and Libya individuals; despite relative similarity in karyotypes of these two clades (but with very high variability), they concluded that north-eastern African and Asian individuals correspond to G. nanus and western African ones to G. amoenus, as suggested by S. Aulagnier and colleagues in 2008 and 2009. A. Ndiaye and colleagues also suggested in 2014 that G. garamantis could be a senior synonym of G. amoenus despite slight difference in diploid number, but no study has yet provided arguments for definitive conclusion on latter hypothesis. Four subspecies recognized.

Subspecies and Distribution.

G.n.nanusBlanford,1875—Egypt(Sinai),Israel,Jordan,Iraq,Iran,Afghanistan, Pakistan,andNWIndia.

G.n.arabiumThomas,1918—Arabia.

G.n.mimulusThomas,1902—N&CYemen.

G. n. setonbrownei Harrison, 1968 — Batinah coast of Oman.

Descriptive notes. Head—body 72-110 mm, tail 80-145 mm, ear 7-14 mm, hindfoot 19-30 mm; weight 14-29 g. The Balochistan Gerbil is a medium-sized gerbil with long hairy tail (120% head-body length) terminating in well-developed tuft of long gray hairs. Soles of hindfeet are naked. Hairs are long and soft and dorsal pelage is brownish gray with some white hairs mixed in. Venter is white, and white spots are visible above eyes, behind ears. Chromosomal complement has 2n = 52, FN = 60 (Jordan).

Habitat. The Balochistan Gerbil preferssaline flats and semi-desertto true sand desert. It has been captured in wadis with some perennial vegetation, and prefers sandy or silty soils to rocky areas. In Israel it was found in bushes of Nitraria retusa (Zygophyllaceae) and shrubby vegetation on salt flats. In Balochistan it prefers rocky or stony regions with hard soil, rather than sandy ones. It occurs also on uncultivated clay flats and in patches ofrelict tropical thorn scrub in Indus plain. The species occurs from sea level to 1000 m altitude.

Food and Feeding. The Balochistan Gerbil is herbivorous;it feeds on seeds and buds of gramineous plants, and seeds of Medicago (Fabaceae) . It does not require water. Breeding. Two pregnant females in Oman bore respectively two and five embryos. In Rajasthan, breeding may occur December—June. Gestation period is ¢.20 days. Young are born naked and blind, open eyes after ten days, and are weaned after 20 days. In Rajasthan litter size was 2-3. Activity patterns. The Balochistan Gerbil is crepuscular and nocturnal. Peaks of activity occur at the beginning and at the end of the night. It digs complex burrows 1-5 m long, 0-75 m undersurface, beneath bush. During nocturnal foraging activities, it was seen to hide in any small shelter. It is a terrestrial species. Movements, Home range and Social organization. The Balochistan Gerbil is known to wanderfar from its burrow at night. It is not a colonial species.

Status and Conservation. Classified as Least Concern on The [UCN Red List in its previous distribution range. A re-evaluation is required, but this species appears quite common in Arabian Peninsula. In eastern part of its range, the Balochistan Gerbil may be threatened by developmentof irrigated cultivations in Indus plain.

Bibliography. Aulagnier et al. (2008, 2009), Harrison (1972), Harrison & Bates (1991), Lay (1967, 1983), Musser & Carleton (2005), Ndiaye, Hima et al. (2014), Ndiaye, Shanas et al. (2013), Prakash & Jain (1971), Qumsiyeh et al. (1986), Roberts (1997), Siahsarvie & Darvish (2007), Volobouev et al. (1995), Zahavi & Wahrman (1957).