Adephagous water beetles (Coleoptera: Gyrinidae, Haliplidae, Noteridae, Dytiscidae) of Yemen and Dhofar region (Oman) with description of a new Hyphydrus from Socotra Island

Hyphydrus dioscoridis sp. nov. from Socotra Island is described and illustrated. The new species belongs to the H. signatus species group, and is similar to Hyphydrus pictus Klug, 1834 from the Arabian Peninsula, from which it differs in the significantly coarser, deeper and denser punctation, broadly bordered clypeus, head between punctures microreticulated, tubercle on the apex of apical ventrite in male rounded, and microreticulate dorsal surface of the female. Adephagous water beetles of Yemen (including Socotra Island) and Dhofar region, southernmost Oman, are reviewed. Altogether eight species of Gyrinidae (of which one is not identified to species level), one species of Haliplidae, one species of Noteridae, and 52 species of Dytiscidae are documented. New records of 48 species are presented, while two previously described species, Dineutus arabicus Regimbart, 1907 and Hydaticus arabicus Guignot, 1951, are diagnosed and illustrated. Four species of Dytiscidae are recorded from Oman for the first time; twelve species (one Gyrinidae, 11 Dytiscidae) are recorded from Yemen for the first time eight from continental Yemen and four from Socotra; in addition two other Dytiscidae species are recorded from Socotra for the first time, and the occurrence of another Gyrinidae species previously known from a doubtful record is confirmed. Habitat information is provided for recently collected species. The zoogeographical patterns of the region are briefly summarized.