Integrative taxonomy and analysis of species richness patterns of nocturnal Darwin wasps of the genus Enicospilus Stephens (Hymenoptera, Ichneumonidae, Ophioninae) in Japan

The predominantly tropical ophionine genus Enicospilus Stephens, 1835 is one of the largest genera of Darwin wasps (Hymenoptera, Ichneumonidae), with more than 700 extant species worldwide that are usually crepuscular or nocturnal and are parasitoids of Lepidoptera larvae. In the present study, the Japanese species of Enicospilus are revised using an integrative approach (combined morphology and DNA barcoding). On the basis of 3,110 specimens, 47 Enicospilus species are recognised in Japan, eight of which are new species (E. acutus Shimizu, sp. nov., E. kunigamiensis Shimizu, sp. nov., E. limnophilus Shimizu, sp. nov., E. matsumurai Shimizu, sp. nov., E. pseudopuncticulatus Shimizu, sp. nov., E. sharkeyi Shimizu, sp. nov., E. takakuwai Shimizu, sp. nov., and E. unctus Shimizu, sp. nov.), seven are new records from Japan (E. jilinensis Tang, 1990, E. laqueatus (Enderlein, 1921), E. multidens Chiu, 1954, stat. rev., E. puncticulatus Tang, 1990, E. stenophleps Cushman, 1937, E. vestigator (Smith, 1858), and E. zeugos Chiu, 1954, stat. rev.), 32 had already been recorded in Japan; three (E. biharensis Townes, Townes & Gupta, 1961, E. flavicaput (Morley, 1912), and E. merdarius (Gravenhorst, 1829)) have been erroneously recorded from Japan based on misidentifications, and four names that were previously on the Japanese list are deleted through synonymy. The following taxonomic changes are proposed: E. vacuus Gauld & Mitchell, 1981, syn. nov. (= E. formosensis (Uchida, 1928)); E. multidensstat. rev.; E. striatus Cameron, 1899, syn. nov. = E. lineolatus (Roman, 1913), syn. nov. = E. uniformis Chiu, 1954, syn. nov. = E. flatus Chiu, 1954, syn. nov. = E. gussakovskii Viktorov, 1957, syn. nov. = E. striolatus Townes, Townes & Gupta, 1961, syn. nov. = E. unicornis Rao & Nikam, 1969, syn. nov. = E. unicornis Rao & Nikam, 1970, syn. nov. (= E. pungens (Smith, 1874)); E. iracundus Chiu, 1954, syn. nov. (= E. sakaguchii (Matsumura & Uchida, 1926)); E. sigmatoides Chiu, 1954, syn. nov. (= E. shikokuensis (Uchida, 1928)); E. yamanakai (Uchida, 1930), syn. nov. (= E. shinkanus (Uchida, 1928)); E. ranunculus Chiu, 1954, syn. nov. (= E. yezoensis (Uchida, 1928)); and E. zeugosstat. rev. = E. henrytownesi Chao & Tang, 1991, syn. nov. In addition, the following new regional and country records are also provided: E. flavocephalus (Kirby, 1900), E. puncticulatus, and E. vestigator from the Eastern Palaearctic region, E. laqueatus from the Eastern Palaearctic and Oceanic regions, and E. maruyamanus (Uchida, 1928) from the Oriental region; E. abdominalis (Szépligeti, 1906) from Nepal, E. flavocephalus from Laos, E. formosensis from Laos and Malaysia, E. insinuator (Smith, 1860) from Taiwan, E. maruyamanus from India and Philippines, E. nigronotatus Cameron, 1903, E. riukiuensis (Matsumura & Uchida, 1926), and E. sakaguchii from Indonesia, E. pungens from 14 countries (Australia, Bhutan, Brunei, Indonesia, Laos, Malaysia, Nepal, New Caledonia, Papua New Guinea, Philippines, Solomon Islands, Sri Lanka, Tajikistan, and Taiwan), and E. yezoensis from South Korea. An identification key to all Japanese species of Enicospilus is proposed. Although 47 species are recognised in the present study, approximately 55 species could potentially be found in Japan based on ACE and Chao 1 estimators. The latitudinal diversity gradient of Enicospilus species richness is also tested in the Japanese archipelago based on the constructed robust taxonomic framework and extensive samples. Enicospilus species richness significantly increases towards the south, contrary to the ‘anomalous’ pattern of some other ichneumonid subfamilies.