Hylomyscus simus G. M. Allen & Coolidge, 1930

Denys, Christiane, Missoup, Alain Didier, Nicolas, Violaine, Sylla, Morlaye, Douno, Mory, Kadjo, Blaise, Lalis, Aude & Monadjem, Ara, 2025, Annotated checklist of rodents from a biodiversity hotspot, Mount Nimba (West Africa), Zoosystema 47 (27), pp. 617-689 : 646

Hylomyscus simus G. M. Allen & Coolidge, 1930

Hylomyscus alleni simus G. M. Allen & Coolidge, 1930: 599 .

Hylomyscus simus – Rosevear 1969: 454.

REMARKS

Specimens MNHN-ZM-2021-1833 to 1836 (SER173, 163, 172, 186, 191) were molecularly analysed by Nicolas et al. (2020). Moreover, they were karyotyped in the field and their karyotypes were homogeneously determined as 2N=48, NFa =70 formula ( Appendix 4).

This small rodent has a tail longer than head and body (about 140-165% of HB) and a relatively long hindfoot ( 15- 19 mm). It has generally a brown dense short dorsal pelage and a white-grey belly. Hands and feet are pale yellow-white like the tail ( Table 7 ). The Nimba H. simus displays a small and narrow skull without marked fronto-parietal crests. The rostrum is narrow and short. The braincase width does not exceed the width of the zygomatic arches which lends a rectangular shape to the back of the skull. The incisors are orthodont. In ventral view, the incisive foramina end just before the upper M1 roots, the palate is narrow, the molar rows are parallel, the tympanic bullae are small and flat and the foramen magnum is quite large. The mandibles are short and the region of the apophyses high. Skull measurements are provided in Table 8 . The molar rows are small and preserve the usual Praomyini bunodont cusp pattern with small t3 poorly differentiated from the t2, a small M3/3 and relatively narrow palate at the t4 level. On some upper M1 there is the presence of a longitudinal crest on the t4 and on the M2/ on the t6. On the M2/ the t9 is small or absent. The upper M3 harbours 4 cusps in two laminae with a strong round t1. On the lower molars the prelobe is related to the first lamina by a small median longitudinal crest. Cusps are slightly compressed labio-lingually and do not alternate. There is a posterior cingulum visible on m12 and accessory cusps visible on the m12. The m3 shows three cusps in two laminae.