Timarcha Latreille: a strange beetle and a living fossil.

Abstract

The genus Timarcha seems unique among Chrysomelidae: Chrysomelinae by having plesiomorphic characters such as genitalia with a ring-like tegmen, covered with a setose parameral cap, together with apomorphic characters, including apterism and fused elytra. The distribution of this genus is also very peculiar: circum Mediterranean and northwestern American. Food selection also seems rather stict, comprising 8 families and 20 genera of plants. Two of the subgenera ( Metallotimarcha and Americanotimarcha ) share one plant family, the Ericaceae. The plant family Rubiaceae is also shared between three subgenera: Timarcha , Timarchostom a and Metallotimarcha . Reflex bleeding among diurnal species, aposematism, thanatosis, stomatic regurgitation are means of defense against predators, but not against parasites and commensals. A very archaic genus, probably originating in early Mesozoic, with around 100 taxa, and 50 subspecies. Mutations remain very common in the group and new species are possibly still emerging.