Phylogenetic placement of Australian carrion beetles (Coleoptera: Silphidae)

Abstract

AbstractAustralia hosts two endemic species of silphid beetles, Ptomaphila lacrymosa and Ptomaphila perlata, and a third species, Diamesus osculans, that also occurs throughout south‐east Asia. While field studies have shown that Silphidae can provide useful information for determining the post‐mortem interval, the inability to identify larvae in locations with multiple species excludes this application. Before molecular diagnostic tools can be developed for larvae of the three Australian species, an analysis of their phylogenetic relationship is required. However, this has previously not been attempted by using molecular markers. Including DNA sequences of non‐endemic silphid species, we determined the phylogenetic placement of all three Australian species based on mitochondrial and nuclear DNA markers from morphologically identified adult specimens. In our study, Ptomaphila spp. grouped with South American Oxelytrum at the base of the Silphinae and thus represent ancient lineages from the southern hemisphere. Our findings support previous theories that the truncate elytra only found within Necrodini (i.e. Diamesus and Necrodes of the subfamily Silphinae) and the subfamily of Nicrophorinae result from convergent evolution. In an attempt to identify larvae of the three Australian silphid species collected within two locations in the Hawkesbury region near Sydney, we developed a preliminary PCR‐based tool for their molecular identification using the mitochondrial and nuclear DNA sequences obtained from the morphologically identified adult specimens. Sequence analysis and species characteristic PCR amplicon sizes provided a reliable method for identification of silphid larvae from this location to species level in the absence of any comparative morphological keys and descriptions for these life stages, although it is recommended that this method be tested for individuals from throughout the species' distribution in the future.