Hybomys eisentrauti Van der Straeten & Hutterer, 1986

Denys, Christiane, Missoup, Alain Didier, Nicolas, Violaine, Fülling, Olaf, Delapré, Arnaud, Bilong, Charles Felix Bilong, Taylor, Peter John J. & Hutterer, Rainer, 2014, African highlands as mammal diversity hotspots: new records of Lamottemys okuensis Petter, 1986 (Rodentia: Muridae) and other endemic rodents from Mt Oku, Cameroon, Zoosystema 36 (3), pp. 647-690 : 660-661

Hybomys eisentrauti Van der Straeten & Hutterer, 1986

Hybomys eisentrauti Van der Straeten & Hutterer, 1986:36 .

Hybomys badius – Musser & Carleton 2005: 1330, 1331.

TYPE LOCALITY. — Cameroon, Mt Lefo.

MATERIAL EXAMINED. — MNHN: 2011-927, 2011-929 to 2011-941, 2013-42, 2013-43.

ZFMK: Holotype Mt Lefo 74.377, paratype Mt lefo 74.374, Mt Lefo 74.376, Mt Oku 69.175, 91.226, 91.225.

ZFMK: Owl pellets from Lake Oku Cave: 91.92.

Morphological characters

This rodent has a similar size to Lamottemys but can be distinguished easily from its skull and molars. It is characterized by a dark pelage with a dorsal black stripe that is poorly visible compared to H. badius . Specimens of Mt Oku have a more woolly, dense pelage than those from Mt Lefo. Compared to H. badius , H. eisentrauti specimens share very similar size. Only H. basilii is noticeably larger, as indicated previously by Van der Straeten (1985) ( Table 2).

The skulls of the new Oku specimens are smaller and have a more rounded braincase, and a poorly marked interorbital constriction with no crests developing, compared to the Mt Lefo holotype ( Fig. 6 ). The H. eisentrauti molars display well-aligned cusps and small stephanodont crests on the cusps t3 and t1 of M1/, and on the prelobe of M/1 ( Fig. 7 ). They have similar size to the Lefo type serie, and are slightly smaller compared to other CVL Hybomys species. We did not find distinct characters in cusp disposition and shape between all CVL specimens and H. univittatus representatives from Gabon.

The new Mt Oku specimens have similar skull size and general shape compared to the type serie of H. eisentrauti from Mt Lefo. Some slight morphological differences are however apparent, such as the presence of lightly marked fronto-parietal crests and a more constricted interorbital region in Mt Oku specimens. The skull of H. eisentrauti is smaller for nearly all its dimensions ( Table 5). The total length of the skull of H. basilii is greater than that of H. eisentrauti , but no significant differences can be observed in other measurements ( Missoup 2010)

Many species may be found in sympatry on mountains of the CVL. However, these morphological and size differences observed in CVL Hybomys specimens could just be the result of an adaptation to high altitude of the typical H. univittatus species ( Missoup 2010). Pending molecular analyses, we considered here H. eisentrauti as a valid species endemic to Bamenda Highlands (Mt Lefo and Mt Oku), following Van der Straeten & Hutterer (1986).

Figures

FIG. 6. — Hybomys eisentrauti Van der Straeten & Hutterer, 1986 skull (MNHN 2011-935): A, dorsal view; B, ventral view; C, lateral view; D, mandible view. Scale bar: 1 cm.

FIG. 7. — Upper and lower molars of Hybomys spp.:A, G, MNHN 2011-941 newly collected,H. eisentrauti Van der Straeten & Hutterer, 1986,Oku; B, H, ZFMK 69.175,H. eisentrauti, Oku;C, I, ZFMK 74.374,holotype,H. eisentrauti, Mt Lefo; D, J, ZFMK 63.670,holotype, H. basilii Eisentraut,1965,Bioko;E, K, MSP103 H. badius Osgood,1936 new collects Mt Cameroon;F, L, GA144 H. univittatus (Peters, 1876), Gabon. Scale bar: 1 mm.