Marsh beetles (Scirtidae) are a worldwide family that are particularly diverse in Australia with over 300 species described. Here, we produce a robust phylogeny of the sub-family Scirtinae using ultraconserved elements (UCEs) and investigate the systematics and evolutionary origins of Australian taxa. Our analyses revealed six major groupings of Australian Scirtinae, four with Gondwanan history and two with a relatively recent origin from Asia. Our results further highlight the value of UCEs for resolving systematic relationships of ancient arthropod groups.

We assessed the systematics of the poorly known genus Petrichus, a philodromid spider endemic to arid and semi-arid environments of South America. For this, we evaluated phylogenetic relationships among the species and with other Philodromidae genera combining morphological and molecular data. We recognised 13 species for Petrichus, of which four are described here. Our findings extend previous phylogenetic analyses of Philodromidae and provide evidence to support a reclassification within the family.

Cave spiders are meaningful models to uncover evolutionary processes. In this work, we combined morphological, molecular and physiological methods to describe two new species and to discuss their origin. A major role in the speciation of this group was played by the glaciation cycles of the last million years. Remarkably, the newly described species exhibit very low tolerance to thermal variations, which makes them unable to disperse outside caves and retain their genetic variability. The photograph is of Troglohyphantes achillis, sp. nov. (credit: Emanuele Biggi).

New Zealand is home to many groups of organisms that are found there and nowhere else in the world; one such group is Aoraki, a genus of tiny leaf litter arachnids. Here, we use morphological and genetic data to identify and describe two new species of Aoraki, and map the distribution of all known collections of the genus. We find surprising contrasts in species range sizes and intraspecies genetic variation that may reflect major events in New Zealand’s geological history.