African highlands as mammal diversity hotspots: new records ofLamottemys okuensisPetter, 1986 (Rodentia: Muridae) and other endemic rodents from Mt Oku, Cameroon

Abstract

The Cameroon volcanic line (CVL), which represents a major topographical feature of Central Africa, is poorly known concerning its small-mammal biodiversity. Situated in the Bamenda-Banso highland plateau, Mt Oku is the second highest peak (3011 m) of the CVL after Mt Cameroon. Despite intensive cultivation and cattle grazing, especially in the Kilum-Idjim zone, Mt Oku has retained some relict mountain forests, which yielded many endemic small mammals. We conducted new taxonomic inventories for small mammals and present the results for rodents focussing on morphology and morphometry. We also present the skull characters and morphological variability of the Oku endemic genus Lamottemys Petter, 1986 and provide characters for the identification of other endemic species such as

Molecular phylogenetic analyses indicate paraphyly of the genusHybomys(Rodentia: Muridae): Taxonomic implications

“…According to Musser and Carleton (), “the analyses of Van der Straeten and Hutterer provide no clearcut basis for recognition of the populations of badius as specifically distinct from those of eisentrauti .” More recently, Denys et al. () provided additional characters to compare H. eisentrauti specimens from Mount Oku with those of H. badius collected in Mount Cameroon, H. basilii from Bioko, and H. univittatus from Gabon. They proposed to consider H. eisentrauti as valid and endemic to Bamenda Highlands, pending molecular genetic analyses.…”

Phylogenetic position of the endemic Mount Oku rat,Lamottemys okuensis(Rodentia: Muridae), based on molecular and morphological data

“…Mount Oku is located in the north‐central part of the CVL, within the Bamenda‐Banso Highlands, which was probably uplifted during the Cenozoic (Oligocene to Miocene). The CVL supports exceptional endemism of montane vertebrate taxa (Herrmann et al ., 2004, 2005a,b, 2007; Graham, Smith & Languy, ; Gonwouo et al ., ; Blackburn, 2008a,b; Zimkus, ; Missoup et al ., ; Zimkus & Gvoždík, ; Denys et al ., ). It is considered as a distinct ecoregion within the Guineo‐Congolian biome and one of the most important biodiversity hotspots in Africa (Burgess et al ., ).…”

“…This montane forest‐dwelling species, the single member of the genus, is known from a restricted geographical area, being found only on Mount Oku at elevations of 2100 to 2900 m a.s.l. The Mount Oku montane forest, about 100 km 2 in area (Oates, Bergl & Linder, ), is one of the most important hotspots for African small mammal diversity (Denys et al ., ) and represents the largest remaining montane forest in West and Central Africa. It is threatened by grazing, wood harvesting, burning, debarking of Prunus africana and over‐exploitation of small mammals as bushmeat (Smith et al ., ).…”

“…More recently, Denys et al . (), based on 53 recently trapped specimens of L. okuensis , provided the third description of the genus, describing skull and dental characters and their morphological variability, but without any discussion of its phylogenetic relationships. Based on external morphology and cranial and dental patterns, the genus was suggested to belong to the murine tribe Arvicanthini (Ducroz, Volobouev & Granjon, ; Michaux, Libois & Filippucci, ; Lecompte et al ., ), but its closest relatives are doubtful: (1) based on eco‐ethological and morphological characters, Petter () underlined its affinity with Desmomys , an Ethiopian endemic, whereas, (2) based on dental characters, Dieterlen & Van der Straeten () underlined its affinity with Oenomys , which is widespread in sub‐Saharan Africa.…”

Molecular and morphological evidence for a Pleistocene radiation of laminate-toothed rats (Otomys: Rodentia) across a volcanic archipelago in equatorial Africa

“…They include rich small mammal assemblages for which new species continue to be discovered (e.g. Petter, ; Dieterlen & van der Straeten, , ; Van der Straeten & Hutterer, ; Hutterer, Dieterlen & Nikolaus, ; Dieterlen & Van der Straeten, ; Verheyen et al ., ; Fahr et al ., ; Lecompte, Granjon & Denys, ; Missoup et al ., ; Monadjem et al ., , b; Denys et al ., ). The closest relatives of many of these West African endemics are confined to the mountains of the eastern African Great Rift Valley and the Eastern Arc Mountains, suggesting either ancient forest (Miocene) connections (as suggested for the shrew genus Congosorex ; Stanley, Rogers & Hutterer, ), or possibly more recent dispersal events along historical temperate corridors (e.g.…”