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| Ngaliadessus humphreysi Watts & Villastrigo, in Watts, Villastrigo, Langille, Stringer, Bradford, ... et Cooper, 2023. DOI: 10.1111/aen.12649 |
Abstract
The largest diversity in the world of subterranean diving beetles (Dytiscidae) has been discovered in underground waters of the Australian arid zone. The majority of species are from the Dytiscidae genera Limbodessus Guignot, 1939 (Bidessini) and Paroster Sharp, 1882 (Hydroporini) and are distributed within two major regions: calcrete islands of central Western Australia and the Ngalia Basin of the Northern Territory. Here, we use an integrative approach based on morphological and molecular analyses to describe Ngaliadessus humphreysi gen. et sp. nov. Watts & Villastrigo representing a new genus and species of stygobiotic Bidessini collected from a single well in the Ngalia Basin. Phylogenetic analyses using whole mitochondrial genome, Histone 3 and 18S rRNA data, representing a comprehensive coverage of Bidessini genera, support the distinction of the genus and species as a separate evolutionary lineage sister to the Australasian genus Limbodessus and the widely distributed genus Allodessus Guignot, 1953. Our study further confirms that the Ngalia Basin, containing 13 subterranean dytiscid species from four distinct genera, is one of the most speciose areas within the world's most diverse hotspot of subterranean diving beetles.
Keywords: aquifer, Bidessini, calcrete, groundwater, mitochondrial genome, phylogenetic analyses, water beetle
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| A geological representation of the Ngalia Basin with subterranean groundwaters and its main sampling sites for stygobiotic taxa, including Sullivans Well. |
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| Adult Ngaliadessus humphreysi sp. nov., Watts & Villastrigo. (a) Dorsal view of adult; (b) line drawing; (c) line drawing of ventral surface of mesotrochanter and mesofemur; (d) line drawing of ventral surface of metatrochanter and metafemur; (e) portion of spermatheca with internal spine. |
TAXONOMY:
Ngaliadessus gen. nov., Watts & Villastrigo
Type species: Ngaliadessus humphreysi sp. nov., Watts & Villastrigo by current designation (monotypy).
Description: Small (<3 mm long), integument soft, head without eyes or eye remnants, clypeus not bordered, pronotum without basal stria, elytra without basal stria, without sutural stria, punctures sparce, setae sparce restricted to margins. Prosternal process narrow, reaching mesoventrite, suture between first and second ventrites complete, protarsus 5-segmented, mesofemur without basal spines on posterior margin, metatibia weakly curved. Spermatheca with well-developed triangular spine. Male not known.
Etymology: Named after the Ngalia Basin groundwater system, the type locality for the genus.
Ngaliadessus humphreysi sp. nov., Watts & Villastrigo
Christopher H. S. Watts, Adrián Villastrigo, Barbara L. Langille, Danielle N. Stringer, Tessa M. Bradford, William F. Humphreys, Andrew D. Austin, Michael Balke and Steven J. B. Cooper. 2023. Phylogenetic Placement and Description of Ngaliadessus humphreysi gen. et sp. nov., Watts & Villastrigo (Coleoptera: Dytiscidae), A Subterranean Diving Beetle from the Ngalia Basin in central Australia. Austral Entomology. DOI: 10.1111/aen.12649
