Xerus rutilus (Cretzschmar)

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 : 532-533

Xerus rutilus (Cretzschmar) : Unstriped ground squirrel

Sciurus rutilus Cretzschmar, 1828, p. 59 , plate 24. Type locality is “eastern slope of Abysinnia”; probably Massawa (cf. Thorington and Hoffmann 2005), today in Eritrea.

Amtmann (1975) recognized eight subspecies but also noted that subspecific classification is uncertain.

Etymology. – Xerus is Greek for “dry”; “called from the character of the fur, which is harsh and often spiny” ( Palmer 1904). Species name rutilus is Latin for “red” or “golden red” in allusion to the colouration of the pelage.

Diagnosis. – Xerus rutilus is a medium-sized member of the subtribe Xerina and the only one with a plain, unstriped pelage ( Figure 2 ). The ears are moderately large, with the tragus present. Metatarsal pads are absent ( Pocock 1922). Females have posterior abdominal and the inguinal pairs of nipples (four nipples totally). The baculum (length= 6 mm) is typified by a wide and spearhead-shaped upper surface of the blade and a low dorsal median crest ( Pocock 1923). Skull is moderately wide ( Figure 6 ) and the 3 rd upper premolar is absent ( Figure 8 ); the jugal bone is bluntly truncated against the lacrimal.

Distribution. – Endemic to a Somali-Masai savannah ( Denys 1999), occupying dry bushland and savannah in Somalia, Ethiopia, Eritrea, Kenya, Tanzania and eastern Uganda ( O’Shea 1991) ( Figure 9 ). A century ago reported for Sinkat ( Anderson 1902) in what is today Sudan, but current presence in Sudan questioned by O’Shea (1991).

Remark. – Xerus rutilus is reviewed in O’Shea (1991) and Waterman (2013c).

Figures

Figure 2: Representatives of genera in African bristly ground squirrels Xerina: 1 – AtlantoxerUS getUlUS (Fuerteventura, Canary Islands; photo courtesy Alenka KryŠtufek); 2 – GeoSciUrUS inaUriS (Etosha National Park, Namibia; photo courtesy Emmanuel Do Linh San); 3 – XerUS rUtilUS (Samburu National Park, Kenya; photo by Jan Matějů); 4 – EUxerUS erythroPUS (captive; photo courtesy Klaus Rudloff).

Figure 6: Bivariate plot of six Xerini species onto the first two principal components (PC) derived from ordination of nine cranial measurements (transformed to log10). Percentage of variance explained by individual PC is in parentheses. 95% confidence ellipses show the dispersion of all specimens within each species and letters indicate group centroids. Skulls (in dorsal view) are depicted to scale: A – AtlantoxerUS getUlUS (PMS 19301); E – EUxerUS erythroPUS (ZFMK 47.972); Gi – GeoSciUrUS inaUriS (NMW 32092); GP – GeoSciUrUS PrincePS (NMW 32097); S – SPermoPhiloPSiS lePtodactylUS (NMW 25782); X – XerUS rUtilUS (ZFMK 81.234).

Figure 8: Left maxillary (above) and right mandibular (below) toothrows in Xerini: 1 – EUxerUS erythroPUS (NHML 69.10.24.18/ZFMK 97.467), 2 – XerUS rUtilUS (ZFMK 81.234/ZFMK 96.251); 3 – GeoSciUrUS inaUriS (ZFMK 55.147); 4 – AtlantoxerUS getUlUS (PMS 19301 / ZFMK 88.195); 5 – SPermoPhiloPSiS lePtodactylUS (ZFMK 92.497/ ZFMK 92.496). Abbreviations for cheek-teeth: P/p – upper/lower premolar, M/m – upper/lower molar; numbers refer to a position in the tooth-row. Scale bar=2 mm.

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.