Otomys simiensis Taylor & Lavrenchenko & Carleton & Verheyen & Bennett & Oosthuizen & Maree 2011, new species
Creators: name: Taylor, Peter J.
name: Lavrenchenko, Leonid A.
name: Carleton, Michael D.
name: Verheyen, Erik
name: Bennett, Nigel C.
name: Oosthuizen, Carel J.
name: Maree, Sarita
Publisher: name: Zenodo
Year: 2011
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Mammalia
Rodentia
Muridae
Otomys
Otomys simiensis

description: Otomys simiensis new species   
Figs. 2c, 5, 6, 17; Table 9  
Simien Vlei Rat  
 Holotype. ZMMU 178757; adult male, dry skin and skull, collector’s number 1338; collected by L.A. Lavrenchenko, 4 May 2005.   
 Type locality. Ethiopia, Simien Mountains National Park, vicinity of Sankaber campsite, 3250 m; 13°14'N, 38°03'E (GPS reading by collector).   
 Diagnosis. A small-sized representative of the O. typus species complex (referred to “Sp. D” above; see Figs. 5, 6, 17 and Tables 7, 9). Similar to O. yaldeni but considerably larger externally (HB mean 155 mm in simiensis, cf. 143 in yaldeni; tail means 83 mm and 72 mm respectively); skull having a narrower interorbital region, less pronounced supraorbital ridges, relatively longer nasal bones, and braincase with flatter dorsal profile (Fig. 17); karyotype distinctive (2N=54, NF=56).   
 Paratypes. ZMMU 178756 (adult female, dry skin and skull, collector’s number 1336); ZMMU 178758 (adult male, dry skin and skull, collector’s number 1352); ZMMU 178759 (adult male, dry skin and skull, collector’s number 1353); ZMMU 178762 (adult female, dry skin and skull, collector’s number 1429); all four specimens from the type locality, collected by L.A. Lavrenchenko between 4 and 20 May 2005.   
 Description. The dorsal pelage is dark brown, with individual hairs having a blackish base, rufous subterminal band, and relatively narrow black tip. Among the guard hairs (17 mm), there are longer bristles (26 mm) that produce the effect of the double-layered fur. Ventral pelage is pale grey, the individual hairs grey at the base and tipped with pale whitish. The ears are blackish, their inner surface covered with short rufous hairs. Dorsal surfaces of the forefeet and hindfeet are dark grey, and the claws are grey. The tail is moderately long (53.4% of HB) and appears distinctly bicoloured, the dorsal caudal hairs relatively long and blackish in contrast to the white ventral hairs.   
 The skull resembles most other members of the O. typus complex, having a relatively narrow interorbital region, reduced supraorbital ridges, shallow braincase, and short anterior palatal foramen (Table 9). Anterior face of the lower incisor has two well defined and equally deep grooves. The upper third molar possesses 7 complete laminae; the lower first molar possesses 4 complete laminae.   
 The chromosomal complement of O. simiensis consists of 2N=54, NF=56; 2m + 52a (Fig. 2c).   
 Otomys simiensis differs from other Ethiopian Otomys (excluding yaldeni) by the lower number of laminae in the upper third molar (7 versus 8–9) and the double-layered dorsal fur. Amongst other members of typus s.l., simiensis is most like jacksoni which is similar in skull size and shape (Table 9) and also has 7 laminae in the third upper molar and a similar dark brown colour (Bohmann 1952); however, jacksoni is much smaller in external dimensions (HB mean 141 mm in jacksoni cf. 155 mm in simiensis) and has a proportionately shorter tail (45.4% in jacksoni cf. 53.4% in simiensis). Furthermore molecular data (Fig. 3) clearly demonstrate the genetic separation of these taxa.   
 Distribution. Known only from the type locality in the Simien Mountains, northern Ethiopia (see above).   
 Ecology. The holotype and paratypes of O. simiensis were captured in tree-heather forest (trees: Erica arborea, Hypericum revolutum; shrub: Rosa abyssinica) with open grassy patches. At higher altitudes, this species is replaced by O. typus s.s., a common inhabitant of the afroalpine zone in the Simien Mountains National Park (e.g., Chennek area, 13°15’N, 38°13’E, 3800 m).   
 Etymology. The rugged Simien Mountains, to which the new species is apparently endemic, dominate the northern plateau of Ethiopia and contain its highest peaks. The name combines the stem Simien with the Latin suffix “ensis,” meaning “native of” or “characteristic of” the place indicated by the stem.
description: Published as part of Taylor, Peter J., Lavrenchenko, Leonid A., Carleton, Michael D., Verheyen, Erik, Bennett, Nigel C., Oosthuizen, Carel J. & Maree, Sarita, 2011, Specific limits and emerging diversity patterns in East African populations of laminate-toothed rats, genus Otomys (Muridae: Murinae: Otomyini): Revision of the Otomys typus complex 3024, pp. 1-66 in Zootaxa 3024 (1) on page 47, DOI: 10.11646/zootaxa.3024.1.1, http://zenodo.org/record/5280584