Hypoderma sinense: solving a century-old enigma

Among the species of Hypoderma (Diptera: Oestridae) that have been described and named over the last three centuries, Hypoderma sinense Pleske has been the subject of several scientific discussions. Hypoderma sinense was described by T. Pleske in 1926 on the basis of only three females collected by the Russian explorer P. K. Kozlov nearly 25 years earlier during a scientific expedition to China (1900-1901). This species was examined by the foremost oestrid authorities and synonomized with H. lineatum. Recently a unique, unidentified species of Hypoderma was observed to infect cattle and yaks in China. Molecular and morphological observations confirmed the unique nature of the third-stage larvae. This data initiated a debate within the scientific community regarding the proper name of this species, in particular with reference to previous taxonomical discussion on the validity of H. sinense. The present work provides a historical overview of the Russian scientific expeditions that collected the specimens and of the explorers and the entomologists who contributed to the description of H. sinense. The morphological examination of the original type material of H. sinense and the comparison with females of H. lineatum indicated that the H. sinense lectotype, deposited at the Zoological Institute of the Russian Academy of Sciences, St Petersburg, was within the range of variation of H. lineatum. Comparisons of the cox1 (688 bp) sequence obtained from the leg of a paralectotype of H. sinense with those of H. bovis (Linneaus), H. lineatum (De Villers) and of a sixth valid species of Hypoderma identified as "H. sinense" available in GenBank revealed differences of 9.7%, 7.2% and 0.3%, respectively. On the basis of these results, we concluded that the nominal species H. sinense should be treated as valid.