Paraplatyarthrus Javidkar and King, 2015

Javidkar, Mohammad, King, Rachael A., Cooper, Steven J. B., Humphreys, William F. & Austin, Andrew D., 2017, Taxonomy of Paraplatyarthrus Javidkar and King (Isopoda: Oniscidea: Paraplatyarthridae) with description of five new species from Western Australia, and comments on Australian Trichorhina Budde-Lunde, 1908 (Platyarthridae), Zootaxa 4243 (3), pp. 401-431 : 404-406

Genus Paraplatyarthrus Javidkar and King, 2015

Type species: Paraplatyarthrus subterraneus Javidkar and King, 2015 ; in Javidkar et al. 2015: 566.

Diagnosis. Smooth, fan-like scale setae covering body. Maxilliped endite with 2 small arrow-like setae on distal margin. Pereonal tergite 7 with 2 noduli laterales on each side (4 on whole pereonite), pereonal tergites 1–6 with 1 nodulus lateralis on each side (2 on whole pereonite).

Species level characters. The relative position of the noduli laterales to the lateral margins of the pereonites was found to be useful for distinguishing P. pallidus from other paraplatyarthrid species. In this species, D/C ratios (Appendix 2) are relatively constant in tergites 1–7 (except for the one next to the lateral margin in tergite 7), whilst there is a significant variation in the other paraplatyartrid species described here for this character. For this reason D/C ratios were not used in the key.

The morphology of the posterior corners of tergites 1 to 4 in dorsal view, used in the species’ descriptions, showed some variability within P. pallidus and P. crebesconiscus so this character was not used to diagnose these species. For example, in some individuals of both species the posterior corners of tergite 4 were directed posteriorly. It is possible that the direction of the posterior corner can be influenced by muscle movements when the animal flexes upwards or inwards or alternatively, it may be an artefact caused by fixing specimens in absolute ethanol. This character has been used previously in determination of some Australian Trichorhina species ( Lewis 1998a, 1998b), however, in future, it should be treated with some caution and its variability assessed for a large number of individuals.

Diversity and distribution of species. With the species treated here there are now seven described species of Paraplatyarthrus , however, there are 12 potential species in the phylogenetic analysis using a COI divergence threshold of>11%.

Distributional patterns ( Fig. 3 ) of subterranean Paraplatyarthridae include both restricted and relatively widespread taxa. For instance, P. pallidus sp. nov. (Lake Miranda East/West), P. cunyuensis sp. nov. (Cunyu) and P. occidentoniscus sp. nov. (Sturt Meadows) are only recorded from single calcrete aquifer bodies, are likely to have distributions that match the area of the calcrete (i.e. only a few hundred square kilometres) and, therefore, should be considered as short range endemic taxa ( Harvey 2002). However, P. crebesconiscus sp. nov. has been recorded from multiple distinct calcretes including Nambi, Halfpenny and Laverton Downs. To date, the surface species, P. nahidae sp. nov., has only been recorded from a single site at Mt Morgans, but this general area has not been well collected and the species may well have a broader distribution than this.

Figures

FIGURE 3. A map of the Yilgarn region of Western Australia and the sampled calcrete aquifers (black) with their position in the palaeodrainages (grey shading) including Carey, Nabberu and Raeside. Numbers for calcretes and non-calcrete areas include: 1, Sturt Meadows (SM); 2, Cunyu (CUN); 3, Lake Miranda East (LME); 4, Lake Miranda West (LMW); 5, Halfpenny Well (HAW); 6, Nambi (NAM); 7, Laverton Downs Windarra (LDW); 8, Mt Morgans (MOR); 9, Goosberry Hill, Wooroloo (WOO); 10, Wongalinga Beach, Qld.