Morphology-based phylogeny of seed beetle Ctenocolum Kingsolver and Whitehead (Coleoptera: Chysomelidae: Bruchinae), a specialist on the host Lonchocarpus Kunth (Fabaceae: Papilionoideae: Millettieae)

Ctenocolum is unusual in the Bruchinae because its species are the only ones feeding on seeds of Lonchocarpus. This genus comprises eight species in two groups, podagricus and tuberculatum. We examined the monophyly of Ctenocolum and their groupings under equal weights in an adult morphology-based parsimony analysis. Seven known species of Ctenocolum and five new species were included; one member of Caryedes and one of Meibomeus were used as outgroups for a total of 14 terminal taxa and 26 characters. Monophyly of Ctenocolum is supported by eight synapomorphies: head, median line enlarged; elytron, stria 4 toothed at base; hind femur, external ventral margin with toothed carina; male pygidium truncate apically; median lobe up to 6.5 times longer than width; internal sac entire, not fractured near apex and has sclerites; lateral lobes deeply emarginate. Ctenocolum is divided into two clades: (C. acapulsensis+C. janzeni+C. salvini)+(C. tuberculatum+(C. sp. nov. D (C. sp. nov. B+C. sp. nov. A+(C. podagricus+C. colburni+(C. sp. nov. E (C. sp. nov. C+C. martiale)))))). The three species of the first clade are grouped by two homoplasic characters. The second clade shares a single synapomorphy and includes eight species in the well-supported lineage ‘podagricus’ which is concordant with the group podagricus as proposed in the literature. However, the group tuberculatum not form a monophyletic clade, because of C. tuberculatum, which is a sister species to the ‘podagricus’ lineage and part of the second clade. Due to the polyphyly of the group tuberculatum, the groups of literature are not recognized in this study.