The first-instar larva of the genus Arthropterus (Coleoptera:Carabidae: Paussinae): Implications for evolution of myrmecophily and phylogenetic relationships within the subfamily

The first-instar larva of the genus Arthropterus W.S. MacLeay, 1838 is described and illustrated. This is the first description of a newly hatched (first-instar) larva in the myrmecophilous tribe Paussini and the first known larva from a basal paussine lineage. A phylogenetic analysis of the subfamily based on larval characters confirms the placement of the genus Arthropterus as a sister-group of the remaining Paussini and supports the hypothesis that Metriini is the sister-group of Ozaenini+Paussini, with 'Ozaenini' as a paraphyletic group. Within this phylogenetic framework, we reassess which larval characters are diagnostic of the tribes Paussini and Ozaenini. Several larval features of Arthropterus, such as the riddled sensilla S-VIII and the fused terminal disk, are interpreted as adaptations to myrmecophily. This interpretation supports the hypothesis that larvae have played an important role in the evolution of myrmecophily within the subfamily Paussinae.