Phylogenetic restitution and taxonomic revision of the New Caledonian endemic genus Thasycles Chapuis (Coleoptera: Chrysomelidae, Eumolpinae)

The fauna of Eumolpinae of New Caledonia has been under intense scrutiny in over the last decade and numerous species are being described on a regular basis. In this study, we revise in detail the group of Colaspis laboulbenei Montrouzier, 1861, curently in the genus Dematochroma Baly, 1864, using a combined approach with DNA-based phylogenies and the study of morphology and species distributions. Several relevant systematic conclusions result from this revision: (1) recognition of the monophyletic group around D. laboulbenei; (2) recognition of an important morphological character, namely the presence or absence of a dorsal groove on pygidium, separating two narrowly parapatric lineages in this group; (3) reversal of a long-held synonymy with D. laboulbenei and reinstatement of Thasycles cordiformis Chapuis, 1874 stat. rev.; (4) restitution of Thasycles Chapuis, 1874 stat. rev. based on phylogenetic and taxonomic arguments to delimit this group of species; (5) transfer of D. fusca Jolivet, Verma & Mille, 2007, D. laboulbenei and D. panieensis Jolivet, Verma & Mille, 2007 to Thasycles; and (6) description of seven new species, including T. castaneus Gómez-Zurita n. sp., T. compactus Gómez-Zurita n. sp., T. grandis Gómez-Zurita n. sp., T. magnus Gómez-Zurita n. sp., T. puncticollis Gómez-Zurita n. sp., T. tenuis Gómez-Zurita n. sp., and T. variegatus Gómez-Zurita n. sp. A species identification key and a brief discussion about the systematics and potential factors affecting the diversification and distribution of Thasycles are provided.