A new subgenus for “Acalathus” advena (LeConte, 1846) and the challenge of defining Calathina based on morphological characters (Coleoptera, Carabidae, Sphodrini)

Abstract

The taxonomic position of Pristodactyla advena LeConte, 1848 (= “Acalathus” advena in the sense of previous authors) is discussed in light of a novel review of the morphological characters of Calathina and closely related taxa. All Acalathus Semenov, 1889 species and all other Dolichina share the distinct character state of having the sensory pits of the apical gonocoxites reduced or absent, while these pits are well-developed in P. advena. Therefore, P. advena is moved into the genus Calathus Bonelli, 1810 (Calathina), where it is placed in the molecular phylogeny of Ruiz et al. (2010). This move necessitates the description of Certocalathus subgen. n. for this species. Diagnostic characters of the new subgenus with respect to other Calathina and Dolichina beetles are presented. Given the lack of any clear synapomorphies, the subtribe Calathina is not obviously defined by morphology alone. However, recent molecular phylogenies indicate its monophyly is highly likely and therefore diagnostic morphological characters are polythetic. The states of selected morphological characters in Calathina and Dolichina taxa are provided as a summary for this and future studies.