Xerini Murray

Kryštufek, Boris, Mahmoudi, Ahmad, Tesakov, Alexey S., Matějů, Jan & Hutterer, Rainer, 2016, A review of bristly ground squirrels Xerini and a generic revision in the African genus Xerus, Mammalia (Warsaw, Poland) 80 (5), pp. 521-540 : 531-532

Tribe Xerini Murray : Bristly ground squirrels

For synonyms see under Xerinae .

Ground squirrels with coarse, bristly or spiny fur during at least one season; hair is usually scanty; the feet is elongate and slender, the 3 rd digit longer than 4 th ( Figure 4 ); the claws are long and comparatively straight (fossorial); pinna minute or reduced to a stiffened skin fold, antitragal thickening set near the middle of the posterior edge of pinnae; membranous cheek-pouches are missing. Xerini have supplementary superciliary vibrissae and the antebrachial vibrissae ( Figure 4 ). The baculum consists of a compressed blade which carries a cartilaginous or partly ossified crest. Number of nipples is two to four pairs ( Figure 5 ).

Skull ( Figure 7 ) is typically with (i) the bony palate considerably prolonged beyond the ends of the tooth-row, (ii) enlarged lacrimal bone, (iii) well developed and anteriorly projected external ridge on the front face of the zygomatic plate, (iv) the squamosal bone extending up to the base of postorbital process of the frontal bone, (v) a powerful masseteric tubercle, (vi) a short and massive pterygoid processes, and (vii) the opisthodont upper incisors ( Flower and Lydekker 1891, Pocock 1922, Ellerman 1940, Ognev 1940, Moore 1959). The karyotype is conservative (2n=38).

Xerini occupy dry open habitats in the Palaearctic region (central Asia and the area of the Atlas Mts.), and of sub-Saharan Africa (the Sudano-Guinean, Somali-Masai, and Zambezian savannas; Denys 1999). Genera occupy exclusive non-overlapping ranges, except for slight overlap between Xerus and Euxerus in Eritrea, Ethiopia, Uganda and Kenya ( Figure 9 ). Four genera of total five are monotypical what induced Moore (1959) to speculate that Xerini are in the contracting phase of their evolution.

Xerini , as typical ground squirrels, dig underground burrows and do not climb trees; Atlantoxerus seeks shelter among rocks and easily climbs on rock slopes. Spermophilopsis is a habitat specialist, mainly dependent on moving sands. All species are diurnal and do not practice torpor.

No common name is in use for the African and the Asiatic Xerini combined. We propose “bristly ground squirrels”, a name capturing an evident character in common to these animals.

The tribe contains two subtribes: Xerina of Africa and Spermophilopsina of Central Asia.

Figures

Figure 4: Right front paw (ventral view) in (1) SPermoPhiloPSiS lePtodactylUS (ZFMK 92.478) and (2) AtlantoxerUS getUlUS (NMW 28084). Roman numerals correspond to digits (No. I is the thumb); a.v. – antebrachial vibrissae. Note that digit III is longer than either digits II and IV. Also note differences in length of claws (decidedly longer in SPermoPhiloPSiS) and in hairiness of the palm (nude in AtlantoxerUS). Not to scale.

Figure 5: Nipples in (1) SPermoPhiloPSiS lePtodactylUS (ZFMK 92.496) and (2) EUxerUS erythroPUS (ZFMK 76.38): p – pectoral; a1 and a2 – 1st and 2nd abdominal; i – inguinal. Not to scale.

Figure 7: Skull of AtlantoxerUS getUlUS (NMW 43000) in dorsal, lateral and ventral views (from top to bottom). Arrows point on traits which are informative for taxonomic ranking of Xerini. 1 – lacrimal bone; 2-postorbital process of the frontal bone; 3 – anterior extension of the squamosal bone; 4 – parietointerparietal suture; 5 – interparietal suture; 6 – anteriorly projected external ridge on the front face of the zygomatic plate; 7 – jugal bone; 8 – opisthodont upper incisor; 9 – masseteric tubercle; 10 – buccinator foramen; 11 – masticatory foramen; 12 – posterior margin of hard palate; 13 – external meatUS acUSticUS.

Figure 9: Distributional ranges of Xerini. Fossil (Late Oligocene to Early Pleistocene) records (top inset) are based on Fortelius (2015) with corrections and additions from Gromov and Erbajeva (1995), Kozhamkulova and Bendukidze (2005), Winkler et al. (2010), Flynn and Wessels (2013), and Maridet et al. (2014). Map of recent ranges (inset below) does not show the isolate of EUxerUS erythroPUS in Morocco, and the population of AtlantoxerUS getUlUS introduced to Fuerteventura, Canary Islands.