The Eastern Arc Mountains (EAM) of Tanzania form an island-type archipelago of wet and cool rainforests widely separated by extremely hot and dry savannah. This paper reports novel phylogeographical analyses of the low-dispersing and forest-dependent Typoderus weevils in the Uluguru block of the EAM. One mitochondrial and two nuclear loci were used to infer phylogenetic relationships among 70 Typoderus specimens, 52 of them from 22 geographically diversified Uluguru litter sifting samples. Various analyses consistently detected 11 geographically coherent Typoderus clades, six of them formed by the Uluguru specimens, where five are taxonomically interpreted as species: T. admetus sp.n., T. furcatus, T. peleus sp.n., T. polyphemus sp.n. and T. subfurcatus. The sixth Uluguru clade temporary named Typoderus sp. 1808 and consistently recovered with the different genetic markers comprises specimens morphologically similar to, and likely conspecific with, those of T. admetus sp.n. If so, then within the confined area of Uluguru forest (40 x 6 km) T. admetus sp.n. displays (i) high genetic differentiation without morphological change and (ii) high morphological variation with very little molecular differences- the driving factors of this phenomenon remain unknown. Observed distribution of Typoderus is interpreted as simple vicariance of a widespread ancestor- no evidence suggests a founder-based dispersal. This study rejects two widely assumed hypotheses that low dispersal (= flightless) forest-dependent clades are represented in each EAM block by an endemic species and that each such species within a single EAM block is panmictic.

Eastern Arc Mountains, DNA barcode, ITS2, 28S, sky islands.