The larva of the genus Tolmerinus Bernhauer described: does it help to reveal a sister-group for the rove beetle subtribe Anisolinina (Coleoptera: Staphylinidae: Staphylininae)?

We provide a taxonomic description of the larva of the rove beetle Tolmerinus fratrumelliotorum Rougemont, 2017, identified through DNA barcoding. This is the first larval description for Anisolinina, the only subtribe whose sister group within the tribe Staphylinini remains unclear. While most phylogenetic hypotheses, especially molecular-based, suggest sister group relationships between Anisolinina and Staphylinina, conflicts remain, particularly when adult morphology is used for phylogeny reconstruction. Our attempt to use larval morphology for phylogeny reconstruction neither revealed a sister group for Anisolinina, nor unique synapomorphies for this subtribe. However, by mapping larval characters on the reference tree of Staphylinini, i.e., a phylogeny firmly established by phylogenomics in agreement with the adult morphology, we found unique larval synapomorphies to support the tribe Staphylinini and informal clade Staphylinini propria. We review all phylogenetic hypotheses ever proposed for a sister group of Anisolinina and discuss potential reasons for the poor phylogenetic signal in the larval characters alone. We stress some opportunities and challenges of using larval characters in phylogeny reconstructions.