Revision of flightless New Zealand Picrotini (Coleoptera: Cryptophagidae): phylogeny of Thortus, eye reduction, and rarity

The apterous New Zealand genera Picrotus Sharp, 1886 and Thortus Broun, 1893 are revised to include two species and 13 species, respectively, with 12 new species: Picrotus wairarapa sp. nov., Thortus bullerensis sp. nov., T. crowsoni sp. nov., T. helmorei sp. nov., T. latus sp. nov., T. lobatus sp. nov., T. luscus sp. nov., T. michauxi sp. nov., T. parallelus sp. nov., T. simplex sp. nov., T. sulcatus sp. nov. and T. tioripatea sp. nov. One species previously thought to be a member of Picrotus is transferred to a new genus: Callichrotus gimmeli gen. & sp. nov. The largest species, T. michauxi, is endemic to the subantarctic islands while the rest are mainland. Four species of Thortus have eyes consisting of a single ommatidium. We determined the origin of microphthalmy and attempt to reconstruct the biogeography of Thortus with a morphological cladistic analysis that included Callichrotus and Picrotus as outgroups. Thortus michauxi was sister to remaining species with largely unresolved relationships and included two monophyletic clusters. Thortus amoenus (Broun, 1912), T. lobatus, and T. sulcatus formed a group based on the presence of a complete parasutural striae, and within it, the latter two species have parameres with posterior membranous extensions, which supports them as sister species. In some trees, T. bullerensis, T. parallelus, and T. ovalis are supported by a narrowly constricted frons, a character that is variable within the genus. Microphthalmy evolved multiple times in Thortus. Eye reduction in other New Zealand beetles is reviewed. Based on number of collection events and specimen counts, most species would be considered as rare, with six newly described species known from single locations, three species of which are known from singletons. Despite classed as rare, it is likely that most species may be protected from extinction because they live in reserves or national parks.