Molecular analysis and morphological variability confirm Hydaticus dhofarensis Pederzani, 2003 as the westernmost population of the Indomalayan H. bipunctatus Wehncke, 1876 (Coleoptera: Dytiscidae).

Hydaticus dhofarensis Pederzani, 2003, the only endemic diving beetle known from Dhofar Region is newly recorded from Masirah Island, central Oman. Analysis of 3ʹ region of the mitochondrial cytochrome oxidase I gene (cox1) reveals that specimens from Oman differs only in 1% of the sequence from specimens of the widespread Indomalayan H. bipunctatus Wehncke, 1876. In addition, study of extensive material of H. dhofarensis shows that the elytral colour pattern and body shape, previously considered as diagnostic characters, vary significantly, and especially the specimens from more northern localities agree completely with H. bipunctatus. Therefore, Hydaticus dhofarensis is considered as a junior subjective synonym of H. bipunctatus. The occurrence of this predominantly Indomalayan species in southern Oman is briefly discussed. [ABSTRACT FROM AUTHOR]