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

Abstract

Lamottemys okuensis Petter, 1986, is restricted to the Mount Oku montane forest in the central-northern part of the Cameroon Volcanic Line (CVL; Central West Africa). It is endangered and has a decreasing population trend. The genus is monotypic and little is known about its phylogeny and evolutionary history. Using both molecular and morphological evidence, we tested two competing systematic hypotheses involving Lamottemys: whether it is more closely related to Desmomys or to Oenomys. We also discuss Lamottemys' biogeographical origin. Molecular phylogenies indicated a sister-group relationship with the Ethiopian montane forest endemic genus Desmomys. This reinforces the hypothesis of recurrent connections over time between West and East African mountains, probably facilitated by climate changes that led to expansions and contractions of montane environments. Our molecular dating, consistent with a period of intense volcanic activity in Central East Africa and the CVL, suggests that the geological history of East and Central Africa also contributed to promoting the isolation of Lamottemys in the CVL. Moreover, this study provides the most comprehensive phylogenetic analysis for the whole tribe Arvicanthini, sampling 17 of the 18 member genera. In this rodent group, stephanodonty probably appeared independently with grasses expansion. These habitat changes probably promoted the evolution of specialist rodents able to feed on abrasive vegetal matter by a dental adaptation.

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

“…Our results refute a close relationship between Aethomys and members of the Hybomys division, as recently reported by Missoup et al. ().…”

“…Our data validate the existence of a Hybomys division within the tribe Arvicanthini (Lecompte et al., ; Missoup et al., ; Musser & Carleton, ), made up of the genera Hybomys , Dephomys and Stochomys , confirming earlier findings based on dental and cranial characters (Misonne, ; Van der Straeten, ). Our results refute a close relationship between Aethomys and members of the Hybomys division, as recently reported by Missoup et al.…”

“…This study includes all the members of the Arvicanthini tribe (sensu Ducroz et al., ; Lecompte et al., ; or Missoup et al., ). Compared to the most comprehensive work on the tribe (Missoup et al., ), we have added here for the first time representatives of the two species complexes of the traditional genus Hybomys . Our results show that both species complexes belong to the Arvicanthini tribe.…”

“…The tribe Arvicanthini currently includes 18 genera, most of them African, except Golunda , which is the only Asian representative (Lecompte et al., ). The taxonomic composition of the tribe has varied enormously since its creation by Misonne (), but a recent morphological and molecular genetic study allowed to clarify its composition at the genus level (Missoup, Nicolas, Eiseb, Keming Chung, & Denys, ). However, the monophyly of several of these genera and the number of species within them is still a matter of controversy (e.g.…”

“…To date, the monophyly of the genus Hybomys has not been tested thoroughly with either DNA sequence or morphological data. In published molecular and morphological phylogenies, only H. univittatus has been included (Ducroz, Volobouev, & Granjon, ; Lecompte et al., ; Missoup et al., ; Schenk, Rowe, & Steppan, ). A phylogeny of the tribe Arvicanthini, including representatives of all Hybomys species, is necessary to test the monophyly of the genus Hybomys and to assess specific status of several taxa.…”