Kakadudessus tomweiri, a new genus and species of diving beetle from tropical northern Australia, based on molecular phylogenetic and morphological data (Coleoptera, Dytiscidae, Bidessini)

Abstract

The diving beetle genus and species, Kakadudessus tomweiri gen.n., sp.n. are described from the Northern Territory (Kakadu National Park, headwaters of Mary River) and north-eastern Queensland (Cape York Peninsula) of Australia. The new species has an elongate, almost flat habitus and elytra with pale yellowish markings. The head has a cervical line between the hindmargin of the eyes and the clypeus is anteriorly bordered. Pronotum and elytra have well developed striae, the latter without sutural lines and accessory striae. The posterior part of the basal cavity of epipleura has no transverse carina, the fairly elongate and narrow prosternal process reaches the metaventrite. The latter is provided with rows of punctures at its midline and the metacoxal lines are longer than the distance between them and strongly diverging anteriorly. The parameres are bi-segmented, very thin, slender and elongate, and slightly bifid apically. The combination of all these characters separates the new species and, thus, also the new genus from all other Bidessini. Morphologically, Kakadudessus resembles species of Leiodytes Guignot, 1936, Limbodessus Guignot, 1939 and Uvarus Guignot, 1939, the parameres resemble those of species of Allodessus Guignot, 1953. DNA sequence data from the mitochondrial genes cytochrome oxidase subunit I (cox1) and the large ribosomal subunit (16S rRNA), however, suggest that Kakadudessus does not belong to any of the known Oriental and Australasian Bidessini genera. Most importantly, recognition of Kakadudessus does not create paraphyly. All specimens were collected in small pools of shaded and intermittent streams and rivers with sandy or gravely bottom and without any vegetation.