Hydraena (Hydraenopsis) quadricollis Wollaston, 1864

Ribera, Ignacio, Hernando, Carles & Cieslak, Alexandra, 2019, Aquatic Coleoptera of North Oman, with description of new species of Hydraenidae and Hydrophilidae, Acta Entomologica Musei Nationalis Pragae 59 (1), pp. 253-272 : 259

Hydraena (Hydraenopsis) quadricollis Wollaston, 1864

Material examined. Loc. 1: 6 spec.; Loc. 2: 3 spec.; Loc. 3: 65 spec. (1 ♁ used for DNA extraction, voucher No. IBE-RA98, sequences published in TRIZZINO et al. 2013); Loc. 6: 4 spec.; Loc. 7: 1 ♀.

Notes. New record for the Arabian Peninsula. The species was described from Tenerife ( WOLLASTON 1864), and subsequently recorded from Cape Verde ( WOLLASTON 1867), Algeria, Tunisia, Sudan, Ethiopia, Kenya ( D’ ORCHYMONT 1940, BERTHÉLEMY et al. 1991) and Djibouti ( JÄCH & DELGADO 2017). In Tenerife it was collected in several occasions on the same spot the same year, but not on subsequent years ( WOLLASTON 1864). D’ORCHYMONT (1940) noted that the habitat in the type locality seemed to be unaltered but the species absent, concluding that it may have been an accidental temporary colonisation. D’ORCHYMONT (1940) established the synonymy of H. nilotica , described from the banks of the Nile in Egypt (lectotype and paralectotype designed in BERTHÉLEMY et al. 1991). In TRIZZINO et al. (2013) two specimens of H. quadricollis were included, one from Tunisia (voucher No. MNCN-AI1312, 24.x.2001, road between Ouessalatia and Kairouan, pond 5 km NW Rouissat, I. Ribera & A. Cieslak leg.) and one of the specimens reported here from Oman (voucher number IBE-RA98, Loc. 3). Differences between the two specimens in the gene COI-3 were close to 5%, which is well within the range of differences between well-established species of Hydraena ( TRIZZINO et al. 2013) . The examination of these specimens, as well as further specimens from Egypt and Cape Verde, demonstrated some differences in the morphology of the aedeagus, but additional material from other areas should be examined to clarify the taxonomy of the complex.