Praomys Thomas, 1915

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 : 644

Genus Praomys Thomas, 1915

( Fig. 9; Tables 7 ; 8 )

REMARKS

Two species of Praomys are known to occur in sympatry in West Africa ( Akpatou et al. 2007; Nicolas et al. 2008). In the Guinean Nimba, Heim de Balsac & Lamotte (1958) mentioned P. morio (now restricted by Van der Straeten to Mount Cameroon and Bioko named now P. tullbergi ) and P. jacksoni (correct attribution as P. rostratus according to Van der Straeten & Verheyen (1981)). Coe (1975) recorded 94 specimens attributed to P. tullbergi and Misonne & Verschuren (1976) also recovered more than 100 specimens on the Liberian side of Mount Nimba indicating that they represent a single homogeneous series. Gautun et al. (1986) indicated that they karyotyped Praomys from Mount Nimba that displayed the typical 2N =34 chromosomes that fits with P. tullbergi . But, both P. tullbergi and P. rostratus species share the same karyotype and have been considered as sibling species by Nicolas et al. (2008) and Akpatou et al. (2007). During fieldwork in 2008, we only recorded one formula for all six karyotyped specimens (2N=34, NFa=32). The analyses of the sequenced specimens confirmed the coexistence of P. rostratus and P. tullbergi at Mount Nimba. One specimen molecularly attributed to P. tullbergi (MNHN-ZM-2021-1848) and another to P. rostratus (MNHN-ZM-2021-1846) displayed the same karyotype. Because Van der Straten & Verheyen (1981) and Akpatou et al. (2007) found morphometrical differences between these two species, we performed a discriminant analysis on skins and skulls of all the Praomys from our survey.

The canonical analysis was performed upon 55 individuals of which 38 were molecularly attributed either to P. rostratus or P. tullbergi and using 10 skull measurements. This allowed us to effectively separate both species with 90.6% correct classification, after cross-validation, and to confirm the presence of both species on the Guinean and Liberian sides of Mount Nimba ( Fig. 9). On the canonical analysis, we found axis 1 is a size axis because all variables were positively correlated and specimens organized by size along this axis. Among the indeterminate specimens in the Lamotte collection, one fitted within P. tullbergi (MNHN-ZM-MO-1991-2135) close to the barycenter and another specimen groups without ambiguity within the P. rostratus group (MNHN-ZM-MO 1986-106) ( Fig. 9). The newly collected specimens, that were not examined genetically, were classified within P. rostratus .

During our recent fieldworks we collected 20 Praomys tullbergi and 41 P. rostratus (all studied genetically or morphometrically) both on the Guinean and the Liberian sides of Mount Nimba. The old Nimba specimens or broken skulls of the newly collected specimens that could not be identified to species level were labeled as Praomys sp.

Moreover, one specimen of Praomys daltoni ( Thomas, 1892) is recorded in the MNHN collections. It was collected at the Airfield locality, Liberia and would constitute the third species of Praomys from Mount Nimba. The specimen MNHN-ZM-MO-1992-199, was recorded as “prepared in alcohol, skull prepared” in the MNHN collection catalogue, but we were unable to locate the skin of this rodent and found only a prepared skull without mandible. There were no external measurements available. The skull and dental morphology only allowed us to attribute it to Praomys sp. Because no P. daltoni have yet been mentioned by previous authors from Mount Nimba we maintain that the species is not present on Mount Nimba Mount. However , this taxon is very widespread in Sahelo-Sudanian savannas ( Mikula et al. 2020).