Sky islands of the Cameroon Volcanic Line support the westernmost clade of five new Typoderus weevils (Coleoptera: Curculionidae: Molytinae)

The weevil genus Typoderus is for the first time reported west of the Congo basin. Analysis of 2,136 aligned positions from one mitochondrial and two nuclear fragments revealed a moderately supported clade of five new Cameroonian species: T. amphion sp. nov. (Mt. Oku), T. canthus sp. nov. (Mt. Oku), T. clytius sp. nov. (Mt. Cameroon), T. iphitus sp. nov. (Mt. Kupe) and T. telamon sp. nov. (Mt. Kupe). Molecular clock analysis of 20 DNA barcode fragments using a fixed substitution rate estimated divergences within this clade to be during the Middle to Late Miocene (10.5–5.4 million years ago, MYA), which pre-dates the onset of the Pliocene-Pleistocene global climatic fluctuations and corresponding cycles of African forest size fluctuation. Such relatively old dates are unexpected and might reflect four unavoidable shortcomings of the temporal analysis: 1. undersampled ingroup, 2. scarcity of comparative temporal data for other animal clades from the Cameroon Volcanic Line, 3. oversimplification of a fixed-rate molecular clock approach using a single maternally-inherited protein-coding marker and 4. possible overestimation of comparatively old ages when using largely saturated mitochondrial sequences. Two obscure weevil species from the Republic of the Congo are hypothesized to belong to the genus Typoderus: T. distinctus (Hoffmann, 1968) comb. nov. (from Anchonidium subgenus Neoanchonidium) and T. baloghi (Hoffmann, 1968) comb. nov. (from Anchonidium subgenus Subanchonidium). Three genus-group names are newly synonymized under Typoderus: Entypoderus Voss, 1965 syn. nov. (the only non-nominative subgenus of Typoderus), Neoanchonidium Hoffmann, 1968 syn. nov. (subgenus of Anchonidium) and Subanchonidium Hoffmann, 1968 syn. nov. (subgenus of Anchonidium). Habitus images and other supplementary information of all sequenced specimens are available online at dx.doi.org/10.5883/DS-VGDS005 and dx.doi.org/10.5883/DS-VGDS006.