Diplazon varicoxa

Diplazon varicoxa (Thomson, 1890)

(Figs 41–46)

Bassus varicoxa Thomson, 1890: 1468.

Bassus japonicus Ashmead, 1906: 183. Synonymized by Uchida (1957)

Diplazon tibiatorius: Uchida, 1957: 231. Misident.

Diagnosis.­­ Face covered with dense punctures. Antenna with 16–17 flagellomeres in both sexes. Mesopleuron polished and covered with punctures except for on and below speculum (Fig. 43). Propodeal carinae complete Metasoma polished and dorsoventrally depressed. Transverse impressions distinct on T I to T III. T I 1.00–1.25 × as long as maximum width in both sexes. T II 0.55–0.75 × as long as maximum width in both sexes. T II and T III rugulose but also covered with irregular punctures except for behind transverse impression of T III largely smooth (Fig. 44). Face black except for a median spot of face which sometimes disappeared and a pair of longitudinal stripes along inner orbit yellow in females (Fig. 42), similar to females or entirely yellow (Fig. 46) in males. Scutellum largely yellow or whitish-yellow. Mesopleuron entirely black (Figs 41, 43, 45). Coxae black except for apical part of fore and mid coxae yellow in females (Fig. 41), yellow except for basal part of fore and mid coxae and hind coxa black in males (Fig. 45). Hind tibia is banded as “black-white-black” (Figs 41, 45). Metasoma black except for posterior part of T I yellow.

Specimens examined. JAPAN: 5♀, Hokkaido, Horokanai Town, Moshiri, Hokkaido Univ. forest, Bukom- anbetsu-rindo 17. VII. 2012, K. Watanabe leg. (KPMNH); 1♀, Hokkaido, Horokanai Town, Uryu-kenkyurin 17. VI. 2012, M. Ito leg. (KPMNH); 1♀, Hokkaido, Higashikawa Town, Yukomanbetsu 29. VII. 1967, M. Miyazaki leg. (SEHU); 1♀, Hokkaido, Kamikawa Town, Sounkyo 17. VII. 1968, M. Suwa leg. (SEHU); 1♀, Hokkaido, Hidaka Town, Uenzarugawa 10. VII.–1. VIII. 2007, A. Ueda leg. (MT) (KPMNH); 5♀, ditto, 1–28. VIII. 2007 (MT) (KPMNH); 1♀, Hokkaido, Obihiro City, Takusei Town, Tottabetsu-rindo 24. VI. 2017, K. Watanabe leg. (KPMNH); 1♀, Aomori Pref., Sukayu 5–6. VIII. 1958, R. & F. Ishikawa leg. (KPMNH); 1♀, Tochigi Pref., Nikko City, Okukinu 23. VII. 1969, H. Takizawa leg. (SEHU); 1♀, Gunma Pref., Katashina Vil., Mt. Hotakasan 1. VIII. 2007, H. Katahira leg. (KPMNH); 1♀, Gunma Pref., Katashina Vil., Sugenuma 12–13. VII. 2014, K. Watanabe leg. (KPMNH); 1♀, Gunma Pref., Tsumagoi Vil., Kanbara, Takamine-kogen 3. IX. 2015, K. Watanabe leg. (KPMNH); 1♀, Gifu Pref., Kani City, Katabira 29. V.–4. VI. 2004, K. Ito leg. (MT) (MU); 1♀, ditto 17–23. IV. 2004 (MT) (MU); 1♀, Nagano Pref., Outaki Vil., Mt. Ontakesan 7. VIII. 2010, K. Watanabe leg. (KPMNH); 1♀, ditto, 31. VII. 2013 (KPMNH); 1♀, ditto, 4. VIII. 2017 (KPMNH); 1♀, Kumamoto Pref., Gokanosho, Hakuchosan 14. V. 1980, K. Ohara leg. (SEHU); 8♂, Hokkaido, Horokanai Town, Moshiri, Hokkaido Univ. forest, Bukomanbetsu-rindo 17. VII. 2012, K. Watanabe leg. (KPMNH); 1♂, Hokkaido, Horokanai Town, Uryu-kenkyurin 16. VI. 2012, M. Ito leg. (KPMNH); 1♂, Hokkaido, Chitose City 1. VI. 2006, T. Hironaga leg. (SEHU); 1♂, Hokkaido, Sapporo City, Misu- mai, Kannon-sawa 6–27. X. 1993, N. Kuhara leg. (MT) (KPMNH); 2♂, Hokkaido, Obihiro City, Takusei Town, Tottabetsu-rindo 24. VI. 2017, K. Watanabe leg. (KPMNH); 1♂, Hokkaido, Okushiri Is., Mt. Kamui 27. VII. 2000, T. Nambu leg. (KPMNH); 1♂, Yamagata Pref., Nishikawa Town, Shizu, Mt. Gassan 19. VI. 2015, K. Watanabe leg. (KPMNH); 2♂, Gifu Pref., Kani City, Katabira 15–21. V. 2004, K. Ito leg. (MT) (MU); 7♂, ditto, 29. V.–4. VI. 2004 (MT) (MU); 3♂, Nagano Pref., Outaki Vil., Mt. Ontakesan, Mt. Hakkaisan 7. VIII. 2010, K. Watanabe leg. (KPMNH); 1♂, Fukui Pref., Izumi Vil., Hayashidani 22. VII. 1982, H. Kurokawa leg. (KPMNH). IRELAND: 1♀ (det. Klopfstein and Roman), Rathdrum, County Wicklow, 26. VII 1930, A. W. Stelfox leg. (NHRS). RUSSIA: 1♂ (det. Klopfstein), “ Kamtschatka Malaise” (NHRS).

Distribution. Japan (Rebun Is., Rishiri Is., Okushiri Is., Etorofu Is., Hokkaido, and Honshu); widely distributed in Palearctic region and also recorded from India (Oriental region).

Bionomics. Two hoverfly species, Episyrphus balteatus (De Geer, 1776) and Eupeodes frequens Matsumura, 1917, have been recorded as the host in Japan (Uchida, 1930).

Remarks. This is the first record of this species from Rishiri Island and Okushiri Island. The Japanese specimens of D. varicoxa are very similar to the character states of this species proposed by Klopfstein (2014), except for a median yellow spot of face sometimes reduced in some females (not reduced in European specimens) and face sometimes with black areas in some males (yellow areas sometimes restricted as orbital stripes and a median spot) (entirely yellow in European specimens)). In this study, we conclude that these color variations are intraspecific variation of this species.