Phylogeny of Paussus L. (Carabidae: Paussinae): unravelling morphological convergence associated with myrmecophilous life histories

Ant nest beetles (Paussus L.) are ecologically fascinating and phenotypically bizarre. Obligate myrmecophiles, Paussus have undergone extreme adaptations for life with ants and their profound range of phenotypic diversity has been difficult to reconcile in a systematic framework. We conducted a detailed morphological study of Paussus utilizing novel techniques and character systems in order to discover anatomical apomorphies diagnostic of the major clades of Paussus strongly supported by molecular data. Bayesian inference (BI) of molecules alone, morphology alone and varying combinations of the two data types reveal that morphology is informative for placing Paussus species, despite the extreme phenotypic diversity and convergence prevalent in the group. We propose a new classification for Paussus based on this phylogeny. The genus Paussus is revised to include all genera, subgenera and species formerly classified as Paussus by Nagel (2003) in addition to Hylopaussus syn.n., Hylotorus syn.n. and Granulopaussus syn.n. The following species are transferred to Paussus: Paussus sebakuanus (Péringuey) comb.n., Paussus gracilis (Reichensperger) comb.n., Paussus bucephalus Gyllenhal, Paussus caroli (Reichensperger) comb.n., Paussus uelensis (Reichensperger) comb.n., Paussus hottentottus (Westwood) comb.n., Paussus blanchardi (Raffray) comb.n., Paussus basilewskyi (Luna de Carvalho) comb.n., Paussus granulatus Westwood, Paussus sankuruensis Reichensperger, Paussus leleupi (Reichensperger) comb.n., Paussus reichenspergeri (Luna de Carvalho) comb.n. We formally delineate and diagnose the following major subgroups of Paussus: Paussus I series, comprising the subgenera Bohemanipaussus Luna de Carvalho stat. rev. sensu n., Bathypaussus Wasmann stat. rev. sensu n., and Edaphopaussus Kolbe stat. rev. sensu n.; the Paussus II series comprising the subgenera Paussus L. stat. rev. sensu n., Klugipaussus Kolbe stat. rev. sensu n., Scaphipaussus Fowler stat. rev. sensu n., Hylotorus Dalman stat.n. sensu n., and Anapaussus Wasmann stat. rev. sensu n.; and the Paussus III series comprising the subgenera Lineatopaussus Kolbe stat. rev. sensu n. and Shuckardipaussus Kolbe stat. rev. sensu n.