Geosciurus princeps Thomas

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 : 534

Geosciurus princeps Thomas : Damara (Kaokoveld) ground squirrel

Geosciurus princeps Thomas, 1929, p. 106 . Type locality is “ Otjitundua , Central Kaokoveld, Namibia, Africa.”

A monotypical species.

Etymology. – The name Geosciurus is derived from “geos” (Greek for earth)+ Sciurus (Greek for a squirrel, from “skia” for “shade”+“oura” for “tail” (both Greek), i.e. “a shadetail” “on account of the way a squirrel holds his bushy tail over his back” ( Gotch 1995); Geosciurus is therefore “a ground squirrel” (allusion on its habits). The species name inauris consists of “in” (not, without)+“auris” (ear; both Latin) in allusion “to the very small ear pinnae of the species” ( de Graaff 1981). The name princeps (Latin for “first” or “primary”) “may refer to the larger than average size, brighter coloration and more profusely ringed tail of this species in contrast to the somewhat smaller, drabber inauris .” ( de Graaff 1981).

Diagnosis. – More fossorial than other African bristly ground squirrel. Size is large, fur is bristly; flanks with a stripe ( Figure 2 ); hind foot robust, metatarsal pads absent; the ear extremely reduced to a rounded thickened rim, tragus absent; two pairs of nipples (posterior abdominal and the inguinal). Baculum (length is 8 mm in G. inauris ) consists of long proximal cylindrical portion and elongated distal part; the upper surface of the blade is narrow and strongly constricted; dorsal crest is long ( Pocock 1923). Skull is broad and deep, with a short rostrum and elongate braincase ( Figure 6 ); jugal bone is bluntly truncated against the lacrimal. Cheek-teeth are relatively hypsodont; the 3rd upper premolar is absent ( Figure 8 ).

Distribution. – The genus Geosciurus is endemic to Zambezian savannah ( Denys 1999; Figure 9 ); G. inauris occupy open savannahs in Botswana, Republic of South Africa, and Namibia ( Herzig-Straschil 1979) but possibly disappeared during the last century from Zimbabwe ( Skurski and Waterman 2005). G. princeps is restricted to the western escarpment in Namibia and very marginally occurs in Republic of South Africa and Angola. Although ranges of the two species overlap, they select different habitats and segregate in behavior ( Herzig-Straschil and Herzig 1989).

Remarks. – Both species of Geoscirus are well covered (as Xerus ) in general faunal reviews of the mammals occupying the southern African subregion ( de Graaff 1981, Skinner and Chimimba 2005). For other reviews see Skurski and Waterman (2005), Waterman and Herron (2004) and Waterman (2013d,e).

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.