Stenocranus takasagonis Matsumura, 1935

Fujinuma, Satoshi & Hayashi, Masami, 2025, Taxonomic revision of Japanese Stenocranus (Hemiptera: Fulgoromorpha: Delphacidae), Zootaxa 5706 (3), pp. 301-336 : 324-325

Stenocranus takasagonis Matsumura, 1935

[Japanese name: Takasago-naga-unka]

( Figs 2 , 3 , 5–7 , 9 , 10 , 13 , 15 )

Stenocranus takasagonis Matsumura, 1935: 72 [ Type locality: Japan ( Honshu: Hyogo: Takasago )].

Stenocranus rufilinearis Kuoh, 1981: 81 [ Type locality: China ( Anhui)]. syn. nov.

Lectotype designation. Three syntypes of Stenocranus takasagonis are preserved, as indicated in the original description. However, one pair of them with a red label can be identified as S. harimensis . Although this species cannot be distinctly separated from S. harimensis in their original descriptions, subsequent studies have clearly realized them as different species based on the male genitalia (e.g., Matsumura & Ishihara 1945, Ishihara 1949, Ichita 1996). Therefore, we follow the recognition of this species in these studies for consistency and designate one of the males as the lectotype.

In the original description of this species, the collection date is noted as July 11. However, the coloration of the scutellum indicates the winter form. Additionally, all the syntypes (including S. harimensis ) are identical to each winter form, and one of them is labeled with the date November 7. Consequently, the collection date on the original description may be erroneously reproduced.

Type material examined. Lectotype ♂ (here designated; SEHU), “11. VII // Stenocranus takasagonis Matsum. ”.

Other material examined. [Honshu] 2♀ ( SF), Kamitakamori, Tsukidate, Kurihara , Miyagi Pref., 29. X. 2022 , S. Fujinuma; 5♂ 5♀ ( SF), same data except 3. VII. 2023 ; 1♂ 4♀ ( MH), Hozoji-numa, Mitakaya, Hanyu , Saitama Pref., 25. XI. 2012 , M. Hayashi et al.; 2♂ 3♀ ( MH), Kurohama, Hasuda , Saitama Pref., 6. VIII. 1999 ( light trap) , S. Ishida; 2♂ ( MH), Heirinji, Iwatsuki, Saitama Pref., 20. IX. 1999 ( light trap) , S. Ishida; 7♂ 2♀ ( MH), same data except 29. X. 1999 ; 13♂ 19♀ ( MH), Murakuni, Iwatsuki , Saitama Pref., 22. XI. 1999 , S. Ishida; 2♂ 1♀, Higashiwada, Sakado, Saitama Pref., 7. XI. 1999 , T. Nakata; 17♂ 14♀ ( MH), Sue, Hatoyama , Saitama Pref., 15. XI. 2010 , S. Shibazaki; 2♀ ( MH), Sadamine ( 390 m), Chichibu , Saitama Pref., 14. VIII. 1992 , M. Hayashi et al.; 8♂ 5♀ ( SF), Yoanji, Oami-shirasato , Chiba Pref., 28. VI. 2014 , S. Fujinuma; 3♂ ( MH), Osoki, Ôme, Tokyo Met. , 9. X. 1986 , M. Hayashi et al.; 1♂ ( MH), Bessho, Hachioji, Tokyo Met. , 15. IX. 2010 , N. Nakayama; 2♂ ( MH), Takayacho-Nakashima, Higashihiroshima , Hiroshima Pref., 13. VII. 1999 , S. Nakamura; 1♀ ( MH), Sugezawa, Nichinan, Tottori Pref., 1. VIII. 2003 ( light trap) , M. Sueyoshi; [ Shikoku ] 4♂ 5♀ ( MH), Enomura, Nakamura , Kochi Pref., 3. IX. 2004 ( light trap) , M. Takai; [ Kyushu ] 2♀ ( SF), Osetocho-Yukinoura, Saikai , Nagasaki Pref., 20. III. 2016 , T. Nozaki; 4♂ 2♀ ( SF), Ikeda, Oniki, Amakusa , Kumamoto Pref., 18. X. 2015 , T. Nozaki; [ Tsushima Is. ] 1♀ ( SF), Sago, Kami-agata , 14. VIII. 2010 ( light trap) , S. Fujinuma; 1♂ ( MH), Tanohama, Kami-agata , 27. X. 2001 , M. Hayashi et al.; 1♂ ( MH), Kuwa, Izuhara , 29. X. 2002 , M. Hayashi et al.; [ Hirado Is. ] 1♀ ( SF), Haifuku, 5. VIII. 2017 ( light trap) , T. Nozaki; [ Amami-Oshima Is. ] 1♀ ( RUMF), Mt. Yuwan-dake , 16. X. 1988 , S. Azuma; 1♀ ( MH), Ôgachi, Tatsugo , 7. VII. 2005 , M. Hayashi et al.; [ Okinawa Is. ] 1♂ ( MH), Ura, Kunigami , 16. VII. 1991 ( light trap) , M. Hiratate; 1♀ ( MH), Fungawa Dam, Kunigami , 28. VI. 1992 , M. Hayashi et al.

Redescription. General coloration as in S. harimensis except forewings of summer form distinctly darker particularly in males. Vertex about 1.6× as long as wide. Frons about 2.7× as long as wide; median carina forked in apical 1/3. Antennal segment II about 2.4× as long as wide. Forewing venation and hind leg spinulation as in S. niisimai . Post-tibial spur with 15–18 fine teeth.

Body length (mean): ♂ 4.7–5.1 mm ( 4.9 mm); ♀ 5.5–6.2 mm ( 5.8 mm).

Male genitalia: Similar to S. sapporensis except phallotheca broad in lateral view, with opening on left side, furnished with two apical processes: left process long, falcate; right process long, downcurved, then recurved to right side, with short process on its base. Female genitalia: Similar to S. sapporensis except gonapophyses IX with 15–19 teeth, weakly diverged; gonoplacs semicircular in ventral view, broad, wider in apical half.

Distribution. Japan (Honshu, Shikoku, Kyushu, Tsushima Is., Hirado Is., Amami-Oshima Is., Okinawa Is.), Korea, China.

Remarks. This species is very similar to S. harimensis Matsumura in habitus but can be distinguished by the phallotheca with two apical processes (one in S. harimensis ) and the wide gonoplacs (narrower in S. harimensis ). Unlike other Japanese congeners, nymphs are mostly dark in the dorsum. The coloration and structures in the original description of Stenocranus rufilinearis Kuoh from Anhui, China are consistent with those of the winter form of this species. Therefore, S. rufilinearis is regarded as a junior synonym of this species.

Biological notes. This species inhabits mountainous to lowland marshes and feeds on Schoenoplectiella juncoides (Roxb.) ( Cyperaceae ). Numerous adults and nymphs were sometimes found with S. harimensis in wetly fallow paddy fields.

Figures

FIGURE 2. Habitus and faces of Stenocranus (all males except H). B, D, F, H, I, winter form; A, C, E, G, J, summer form.—A, S. tateyamanus; B, C, K, S. kisimotoi sp. nov.; D, E, L, S. takasagonis; F–H, M, S. fallax; I, J, N, S. chenzhouensis. Scales: 1.0 mm.

FIGURE 3. Habitus, faces, forewings, and hind legs of Stenocranus and Ceratocranus gen. nov. (all males). A, winter form; B, summer form.—A, B, E, S. tonghuaensis; C, F, L, C. agamopsyche; D, G, M, O, C. aurantius sp. nov.; H, S. niisimai; I, N, S. tamagawanus; J, S. kisimotoi sp. nov.; K, S. takasagonis. Scales: 1.0 mm (A–D, H–M), 0.5 mm (N, O).

FIGURE 5. Habitus and labels of type material of Stenocranus (all males except G, K, M, Q). D, J, under side of locality label is surrounded by dotted line.—A, B, S. tateyamanus (lectotype); C, D, S. sukumonus (lectotype); E, F, S. takasagonis (lectotype); G, H, S. fallax (lectotype); I, J, S. formosanus (lectotype); K, L, S. akashiensis (lectotype); M, N, S. ogasawarensis (lectotype); O, S. hopponis (syntype); P, S. silvicola (holotype); Q, S. agamopsyche (holotype); R, S. pacificus (holotype).

FIGURE 6. Male genitalia of Stenocranus. A–D, suspensorium in anterior view; E–H, phallotheca in ventral view; I–L, gonostyle in widest view.—A, E, I, S. niisimai; B, F, J, S. tamagawanus; C, G, K, S. sapporensis; D, H, L, S. takasagonis.

FIGURE 7. Female genitalia of Stenocranus and Ceratocranus gen. nov. A, B, gonapophysis IX covered with gonapophysis VIII in dorsal view; C–H, apical part of gonapophysis VIII in ventral view.—A, S. takasagonis; B, C. agamopsyche; C, S. niisimai; D, S. tamagawanus; E, S. sapporensis; F, S. kisimotoi sp. nov.; G, S. fallax; H, C. aurantius sp. nov.

FIGURE 9. Male genitalia of Stenocranus and Ceratocranus gen. nov. in lateral view.—A, S. niisimai; B, S. tamagawanus; C, S. sapporensis; D, S. harimensis; E, S. tateyamanus; F, S. kisimotoi sp. nov.; G, S. takasagonis; H, S. fallax; I, S. chenzhouensis; J, S. tonghuaensis; K, C. agamopsyche; L, C. aurantius sp. nov. Scales: 0.2 mm.

FIGURE 10. Male genitalia of Stenocranus and Ceratocranus gen. nov. in ventrocaudal view.—A, S. niisimai; B, S. tamagawanus; C, S. sapporensis; D, S. harimensis; E, S. tateyamanus; F, S. kisimotoi sp. nov.; G, S. takasagonis; H, S. fallax; I, S. chenzhouensis; J, S. tonghuaensis; K, C. agamopsyche; L, C. aurantius sp. nov. Scales: 0.2 mm.

FIGURE 13. Male genitalia (A–I) and female genitalia (J–L) of Stenocranus. A–C, phallotheca in lateral view; D–F, same in ventral view; G–I, gonostyle in widest view; J–L, gonoplac in ventral view.—A, D, G, J, S. takasagonis; B, E, H, K, S. fallax; C, F, I, L, S. chenzhouensis.

FIGURE 15. Oviposition holes and eggs of Stenocranus on plants.A, D, G, L, N, oviposition holes covered with wax; B, E, H, O, the holes removed wax; C, F, I, K, M, P, eggs in the holes.—A–C, S. niisimai on Phalaris arundinacea; D–F, S. tamagawanus on P. arundinacea; G–I, S. sapporensis on Scirpus wichurae; J, K, S. harimensis on Carex dispalata; L, M, S. tateyamanus on Carex scabrifolia; N–P, S. takasagonis on Schoenoplectiella juncoides.