Neotrombidiidae (Acari, Trombidiformes) from Nullarbor caves, southern Australia including the apparently troglomorphic Cruralonga gen. nov.

Nullarbor caves were sampled during the Yalata Bush Blitz 2021. Collecting methods commonly used above ground were employed. A large diversity of cave mites and other arthropods were uncovered, including two genera of Neotrombidiidae showing remarkable extremes in larval body form.

The first of these genera, Cruralonga gen. nov. (Gracile Velvet mites) has unique features, such as elongate appendages and unusually large numbers of leg sensory setae. Morphotype adults matching these larvae were found widespread in the Nullarbor karst and these also possess putative troglomorphic traits, with longer appendages than previously recorded for the family, and loss of the posterior pair of eyes.

Two other species from eastern Australian caves, formerly Neotrombidium, are also transferred to this genus. The second cave-dwelling taxon, has a compact larval body form and a separate set of unique characters such as an expanded anterior region of the scutum and setae on coxa II modified as spurs. It was collected from the folded wings of a trogophilic beetle.

Integrative systematics of Australian cave-dwelling Neotrombidiidae could offer a previously unexplored insight into troglomorphic adaptation.