Lophuromys dieterleni Verheyen, Hulselmans, Colyn & Hutterer, 1997

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 : 671-672

Lophuromys dieterleni Verheyen, Hulselmans, Colyn & Hutterer, 1997

Lophuromys dieterleni Verheyen, Hulselmans, Colyn & Hutterer, 1997: 173 .

TYPE LOCALITY. — Cameroon, Mt Oku.

MATERIAL EXAMINED. — MNHN: 2012-1010 to 2012- 1014.

ZFMK: Holotype (69.289), 69.286 to 69.288, 69.290.

Morphological characters

The length of the tail of the best-preserved specimens varies between 56 and 75 mm (average: 66 mm) and the hind foot length varies between 20 and 23 mm (average: 21 mm). These values fit with the range of previous collections of L. dieterleni (including the holotype) from Mt Oku, reaching 75 mm (N = 3) and 21 mm (N = 5), respectively. These measurements are smaller than those of L. roseveari for HF (Mean: 22 mm; N = 10) as well as for the tail length (Mean: 61 mm; N = 10). They are larger than those of the L. eisentrauti holotype (TL=53; HF=19).

The new collected specimens of L. dieterleni display a nasal bone that is enlarged in front of the rostrum but less than in L. sikapusi specimens. The mandible is low and long, the posterior margin of the palate is rectilinear and the pterygoid processes (U shaped pterygoid fossa) are large and parallel as in the holotype ( Fig. 9 ). In contrast, in L. roseveari the pterygoid processes are divergent and the posterior margin of the palate is narrow ( V shape of the pterygoid fossa); the palate is very short and ends before the level of the third upper molar. Lamottemys eisentrauti displays an intermediate disposition of the pterygoid region with a curved posterior margin of the palate, with an inflexion in the middle, and the pterygoid process are not parallel.

The skulls of L. dieterleni display a larger interorbital constriction, zygomatic width and parietal width compared to L. sikapusi , L.roseveari and L. eisentrauti representatives ( Table 10). Lophuromys dieterleni is smaller than the other species for the greatest length of the skull, the nasal length, the upper molar row length and the tympanic bulla length.

The molars of the new collected specimens all display stephanodont crests at t3 and t6 of the upper molars M/12 ( Fig. 10 ). On the lower M1 there is trace of an antero median cusp (tma), as seen in some L. sikapusi but not in L. eisentrauti or L. roseveari . Lamottemys roseveari displays much more bunodont cusps and larger molars than L. dieterleni .

Pending further molecular works, all these differences allow us to retain the species as valid.

Figures

FIG. 9. — Lophuromys dieterleni Verheyen, Hulselmans, Colyn & Hutterer, 1997 skull (MNHN 2012-1010) from Oku: A, dorsal view, B, ventral view; C, lateral view; D, mandible view. Scale bar: 1 cm.

FIG. 10. — Dental rows (top row upper molars, bottom lower molars) of Lophuromys dieterleni Verheyen,Hulselmans,Colyn & Hutterer, 1997 from Oku:A, E, MNHN 2012-1014;B, F, MNHN 2012-1013;C, G, holotype L. dieterleni ZFMK 69.289;D, H, holotype L. eisentrauti Dieterlen, 1979 ZFMK 74.436 from Mt Lefo. Scale bar: 1 mm.