## Materials and Methods  
### Sampling, Identification, and Morphology  
We obtained whole adult specimens from surveys of dermateran fauna in Victoria, New South Wales (NSW), South Australia (SA), and Western Australia (WA). Surveys comprised two types: a bi-annual (summer and winter) sample of representative sites across each state to investigate spatial variation in species composition and abundance, and a monthly sample of a reduced set of sites to investigate temporal variation. The collections from which adult Anisolabididae were sourced occurred from July 2016 to October 2018. Field sites covered the breadth of the Australian grain belt, except Queensland (Table S1 and Figure S1). Surveys were conducted using cardboard roll traps (a method developed for _F. auricularia_[57]) and pitfall traps (diameter = 4 cm, depth = 10.8 cm) filled with 50 mL 100% propylene glycol, both left at sites for a period of seven days each time. Specimens were stored in 100% ethanol at \(-20\)\({}^{\circ}\)C. Specimens from pitfall traps were washed thoroughly with 100% ethanol prior to storage. Males were distinguished from females based on forceps morphology, then classified into 10 morphospecies. Three (_F. auricularia_, _L. truncata_, and _N. liviolipes_) were easily identified, particularly as only one of the cryptic sister species of _F. auricularia_[58] occurs in Australia [59]. The remaining earwigs were members of the Anisolabididae family, based on the lack of wings in the adult stage [6; 9]. Generic and specific assignments were based on combinations of shapes of the male forceps and genitalia (Figure 1) following [6]. Some morphospecies could be identified to species, while others only to genus, and they are designated numerically. The Anisolabididae morphospecies were _Anisolabis_ sp. 1, _Anisolabis_ sp. 2, _Gonolabis_ forcipata_ [PERSON] (_=Mongolabis forcipata_[60]), _Gonolabis_ nr. _gilesi_ [PERSON] (_=Mongolabis_ nr. _gilesi_[60]), _Gonolabis_ sp. 1, _Gonolabis_ sp. 2, and _Gonolabis_ sp. 3. A single male _Anisolabis maritima_ ([PERSON]) was found in Western Australia (site #6; Table S1 and Figure S1). As this is a well-known and recognisable species, it was not included in subsequent molecular or morphometric analysis which aimed to clarify the phylogeny and test the ability of available resources to distinguish the unknown Anisolabididae. It should be noted that, thus far, the Anisolabididae have not received a comprehensive phylogenetic, numerical, or cladistic treatment, and so any identification must be deemed provisional. To this end, it is noted that [PERSON]'s [60] revision of Anisolabididae systematics would likely give different generic classifications. Dermaptera is an order rife with nonc plantural problems, and so it is difficult to treat any one text as authoritative. Specimens were pooled across sites and collection dates by morphospecies for subsequent morphometric and molecular analysis. To test if the characters used for distinguishing morphospecies could be linked to other forms of morphometric measures, linear measurements were taken for all males (Figure 1) to assess the length (o) and width (p) of both of the forceps, the distance between the points of articulation of the forceps and the ultimate dorsal tergite (q), and the length (r) and width (s) of the right paramere. An index of the asymmetry of the forceps was calculated as the sum of the absolute differences between the greater of the two forceps lengths (o) and widths (p), divided by (q). The ratio of the right paramere's length to its width was calculated, as well as the ratio of the maximum forceps length to the maximum forceps width. Typically, forceps asymmetry is measured by the absolute difference between the distances from the point of articulation to the tips of the forceps [40; 61] but due to differences in body size between morphospecies and in the dimension of asymmetry (i.e., asymmetry in length, width, or both), a measure incorporating the two was deemed more appropriate.