Euxerus erythropus (É. Geoffroy Saint-Hilaire)

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 : 533

Euxerus erythropus (É. Geoffroy Saint-Hilaire) : Striped ground squirrel

Sciurus eyrthoupus (sic) É. Geoffroy Saint-Hilaire, 1803, p. 178. Type locality: “Inconnue” (=unknown). A specimen from Senegal, acquired by Florent Prévost in November 1820 and deposited in Muséum National d’Histoire Naturelle, Paris (MNHN-ZM-MO-2000-601), was designated as neotype ( Rode 1943). Type locality is therefore (“probably”) Senegal ( Allen 1954). The ICZN (1971: 224) ruled erythoupus by Geoffroy Saint-Hilaire to be an incorrect original spelling for erythropus , placed erythoupus on the Official Index of Rejected and Invalid Specific Names in Zoology, and validated the emendation of the specific name erythoupus to erythroupus. Wilson and Reeder (1993) regarded Geoffroy Saint-Hilaire (1803) (“a very rare book”; Jentink 1882) as not validly published, what was rebuffed in Corbet and Hill (1994); with reference to Hill 1980).

Six subspecies were recognized by Amtmann (1975) and tentatively mapped in Herron and Waterman (2004).

Etymology. – “Eu” is Greek for “typical”+ Xerus ; i.e. “a typical bristly ground squirrel”. The species name erythropus is from “eruthros” (red) and “pous” (a foot, both Greek), i.e. “a red-footed”, although “there is nothing to indicate why Geoffroy should have chosen the name... as it is [red-footed] in fact not one which has any particular application to any known form [of E. erythropus ]” ( Rosevear 1969: 132); note the above claim by Hollister (1919) who stated that feet and other parts of body are often stained with the soil what changes the color.

Diagnosis. – Euxerus erythropus is a large member of the subtribe Xerina , recognizable by a combination of flank stripe ( Figure 2 ), narrow skull ( Figure 6 ), and a high incidence of the 3 rd upper premolar (present in ~80% of individuals; Figure 8 ). The ears are moderately large, with tragus present. Metatarsal pads are absent and plantar pads are more reduced in size than in any other African species ( Pocock 1922). Females have two ( Figure 5 ) or three pairs of nipples (mean=2.71±0.469, n=14). The baculum (length= 8–9 mm) consists of a cylindrical proximal part and distal compressed blade; the dorsal crest ossifies only partly ( Pocock 1923). The Y chromosome is acrocentric (biarmed in the remaining Xerini ). The jugal bone is bluntly truncated against the lacrimal (i.e. without a short wedge-like extension between the lacrimal and maxillary; Figure 10 ).

Distribution. – Endemic to the Sudano-Guinean savannah ( Denys 1999). E. erythropus is a habitat generalist ( Rosevear 1969) occupying a wide subtropical and tropical belt between the equator and the transition of the Sahelian zone and Sahara ( Granjon and Duplantier 2009, Monadjem et al. 2015). Range extends from the Atlantic coast in the west to Eritrea, western Ethiopia and north-western Kenya in the east ( Figure 10 ). There is an isolate in the Souss region in western Morocco ( Blanc and Petter 1959). Remnants of the Neolithic age from Bir Kiseiba in southern Egypt ( Osborn and Osbnornová 1998) are another evidence of a wider occurrence in Palaearctic Africa during the Holocene. The 19 th century records for Egypt (Jansen 1882) and “Nubia” (Supplemental Appendix 2) however most probably refer to what is now Sudan (cf. Anderson 1902).

Remarks. – Euxerus erythropus is reviewed in Rosevear (1969), and (as Xerus erythropus ) in Herron and Waterman (2004) and Waterman (2013b).

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 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 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 10: Anterior zygomatic arch in three genera of Xerini to show differences in a suture between the lacrimal (lac), the maxillary (max) and the jugal (ju) bones. 1 – SPermoPhiloPSiS lePtodactylUS (NMW 32092); 2 – AtlantoxerUS getUlUS (NMW 43000); 3 – EUxerUS erythroPUS (ZFMK 97.472). Arrow points on a wedge-like extension of the jugal between the lacrimal and maxillary in SPermoPhiloPSiS and AtlantoxerUS. A bluntly truncated top of jugal bone at the lacrimal bone which is distinctive of sub-Saharan Xerina, is shown by triangle. Not to scale.