The epigean Australasian species of Neobidessodes gen.n. diving beetles—a revision integrating morphology, cybertaxonomy, DNA taxonomy and phylogeny (Coleoptera: Dytiscidae, Bidessini)

Abstract

We use mitochondrial DNA sequence data and morphology to the reassess taxonomy and phylogeny of Australasian diving beetles previously assigned to Bidessodes Régimbart, 1900 (Coleoptera: Dytiscidae, Bidessini). Bidessodes was described for a South American species. A molecular phylogenetic analysis of a set of the morphologically rather homoplastic Bidessini shows that Australasian Bidessodes form a clade distant from the Neotropical species and are thus assigned the new generic name Neobidessodes Hendrich & Balke gen.n. The seven Australian Bidessodes species known to date are transferred: Neobidessodes bilita (Watts, 1978), comb.n.; N. denticulatus (Sharp, 1882), comb.n.; N. flavosignatus (Zimmermann, 1922), comb.n.; N. grossus (Zimmermann, 1922), comb.n.; N. gutteridgei (Watts & Humphreys, 2003) (stygobitic species), comb.n.; N. limestonensis (Watts & Humphreys, 2003) (stygobitic species) comb.n. and N. mjobergi (Zimmermann, 1922), comb.n. The epigean species are re-described. Lectotypes for Bidessus flavosignatus Zimmermann, 1922; Bidessus grossus Zimmermann, 1922 and Bidessus mjobergi Zimmermann, 1922 are designated, and two new species, Neobidessodes samkrisi Hendrich & Balke sp.n. from southern New Guinea (Merauke, West Papua) as well as Neobidessodes thoracicus Hendrich & Balke sp.n. from the Kimberley region, the Northern Territory and northern Queensland, are described. We delineate the species using traditionally employed morphological structures such as male genital structure and beetle size, shape and colour pattern. Illustrations based on digital images are provided here and as online resources. Cox1 data for 42 individuals were used too as characters for DNA taxonomy (or barcoding). The signal is mixed. Of the nine species, all retrieved as monophyletic groups or clusters. N. samkrisi sp.n. and N. flavosignatus are morphologically strongly divergent, yet cox1 distance only amounts to 0.85– 1.14%, while intraspecific distances for N. denticulatus are 0.0–1.28%. The epigean species of the genus are distributed from southern New Guinea, tropical and subtropical north of Australia, and along the east coast south to Victoria. All species occur in small streams, creeks, and pools of intermittent rivers or billabongs with sandy or gravelly bottom. The morphologically highly derived, blind and wingless stygobitic species are endemic to the Three Rivers calcrete in the Yilgarn, Western Australia. Important species characters (median lobes, parameres (in part) and colour patterns) are illustrated. A key to all seven epigean species is provided. The known distribution and habitat preferences of each species are outlined briefly.