Two new species of Ancyronyx Erichson, 1847 (Coleoptera: Elmidae) are described from Borneo: A. pulcherrimus (Brunei) and A. reticulatus (Sabah). Habitus views, illustrations of important characters as well as plastron structures of Ancyronyx reticulatus are presented and discussed.
Three species have been recognized in the genus Geoparnus Besuchet, 1978, all collected by sifting ground debris from tropical rainforests of Malaysia. The new species Geoparnus loebli sp. nov. is described; morphological similarities to known species G setifer Besuchet, 1978 and G rhinoceros Kodada, Jach, Ciampor Jr & (Camporova-Zat'ovicova, 2007 are discussed. Habitus of adult, male and female genitalia as well as other diagnostic characters are illustrated.
A new species of riffle beetle, Vietelmis jablonskii, from Laos and Thailand is described and illustrated. Differences to other Vietelmis species are discussed and an identification key for the Vietelmis is presented. New faunistic records are provided for V. kovaci Kodada & Čiampor, 2000; the genus Vietelmis is newly recorded for Thailand.
Ancyronyx lianlabangorumsp. nov. (Coleoptera, Elmidae), a new spider riffle beetle from the Kelabit Highlands (Sarawak, northern Borneo), is described. Illustrations of the habitus and diagnostic characters of the new species and the similar, polymorphic A. pulcherrimus Kodada et al. are presented. Differences to closely related species, based on COI nucleotide sequences and morphological characters, are discussed. Ancyronyx pulcherrimus is here recorded from Sarawak for the first time, based on DNA barcoding.
Ancyronyx clisterisp. nov. (Coleoptera, Elmidae) a new spider riffle beetle discovered from northern Borneo (Brunei; Sabah and Sarawak, Malaysia) and the larva of Ancyronyx sarawacensis Jäch are described. Illustrations of the habitus and diagnostic characters of the new species and the similar and highly variable A. sarawacensis are presented. Differences to closely related species, based on DNA barcodes and morphological characters, are discussed. Association of the larva and the imago of A. sarawacensis, and the occurrence of Ancyronyx procerus Jäch in Peninsular Malaysia and Sabah are confirmed by using COI mtDNA sequences.