Molecular data extend A ustralian C ricotopus midge ( C hironomidae) species diversity, and provide a phylogenetic hypothesis for biogeography and freshwater monitoring

Resolving species relationships and confirming diagnostic morphological characters for insect clades that are highly plastic, and/or include morphologically cryptic species, is crucial for both academic and applied reasons. Within the true fly ( D iptera) family C hironomidae, a most ubiquitous freshwater insect group, the genera C ricotopus   W ulp, 1874 and P aratrichocladius   S antos‐ A breu, 1918 have long been taxonomically confusing. Indeed, until recently the A ustralian fauna had been examined in just two unpublished theses: most species were known by informal manuscript names only, with no concept of relationships. Understanding species limits, and the associated ecology and evolution, is essential to address taxonomic sufficiency in biomonitoring surveys. Immature stages are collected routinely, but tolerance is generalized at the genus level, despite marked variation among species. Here, we explored this issue using a multilocus molecular phylogenetic approach, including the standard mitochondrial barcode region, and tested explicitly for phylogenetic signal in ecological tolerance of species. Additionally, we addressed biogeographical patterns by conducting Bayesian divergence time estimation. We sampled all but one of the now recognized A ustralian C ricotopus species and tested monophyly using representatives from other austral and A sian locations. C ricotopus is revealed as paraphyletic by the inclusion of a nested monophyletic P aratrichocladius , with in‐group diversification beginning in the E ocene. Previous morphological species concepts are largely corroborated, but some additional cryptic diversity is revealed. No significant relationship was observed between the phylogenetic position of a species and its ecology, implying either that tolerance to deleterious environmental impacts is a convergent trait among many C ricotopus species or that sensitive and restricted taxa have diversified into more narrow niches from a widely tolerant ancestor. © 2015 The Linnean Society of London