Stenocranus fallax Matsumura, 1935

Stenocranus fallax Matsumura, 1935 View in CoL

[Japanese name: Nise-naga-unka]

( Figs 2 View FIGURE 2 , 5 View FIGURE 5 , 7 View FIGURE 7 , 9 View FIGURE 9 , 10 View FIGURE 10 , 13 View FIGURE 13 , 16 View FIGURE 16 )

Stenocranus fallax Matsumura, 1935: 128 View in CoL [ Type locality: Japan ( Hokkaido ( Sapporo), Honshu ( Iwate)), China ( Hong Kong)]. Stenocranus fallax View in CoL : Ishihara, 1949: 26.

Stenocranus fallax View in CoL : Ichita, 1996: 18.

Stenocranus silvicola View in CoL : Kisimoto & Hayashi, 2000: 115 (nec Vilbaste, 1968).

Lectotype designation. Among the syntypes of Stenocranus fallax Matsumura View in CoL , eight females are preserved on the same pin with a determination label as S. fallax View in CoL , collected in Hong Kong, China. Moreover, we were unable to find other syntypes labeled as S. fallax View in CoL , including the specimen figured by Ishihara (1949). Consequently, one of the females is designated as the lectotype. Some specimens labeled as S. fallax View in CoL in the Matsumura collection are misidentified and actually belong to S. niisimai Matsumura. View in CoL

Type material examined. Lectotype ♀ (here designated; SEHU), “20/X Honkon (= Hong Kong) // S. fallax Mats. ” . Paralectotypes: 7♀ ( SEHU), same data as lectotype ; 2♂ 5♀ ( SEHU), “20/X Honkon” .

Other material examined. [ Hokkaido] 2♂ 2♀ ( SF), Nishioka, Toyohira, Sapporo, 21. V. 2016, T. Ban; 1♂ ( MH), Mizuhori, Esashi , 7. X. 2010 , M. Hayashi et al.; [ Honshu ] 5♂ 1♀ ( MH), Miroku-rindou, Takko , Aomori Pref., 13. IX. 1992 , T. Ichita; 3♀ ( MH), same data except 26. VI. 1993 ; 3♂ ( MH), same data except 29. V. 1994 ; 3♂ 1♀ ( MH), same data except 21. IX. 1997 ; 2♂ 2♀ ( MH), Mt. Haruna, Harunako, Takasaki , Gunma Pref., 12. X. 2000 , R. Kisimoto; 1♂ 1♀ ( SF), Yozawa, Akiruno, Tokyo Met. , 2. X. 2016 , S. Fujinuma; 1♂ 3♀ ( SF), Kasuga, Saku , Nagano Pref., 19. VI. 2016 , S. Fujinuma; 3♂ 2♀ ( SF), same data except 2. X. 2016 ; 2♂ 9♀ ( SF), Takasucho- Nishibora, Gujo , Gifu Pref., 11. IX. 2010 , S. Fujinuma.

Redescription. General coloration stramineous, paler in summer form, sometimes distinctly darker after overwintering. Frons with dark stripes except in basal 2/3 feeble to lacking. Genae with dark stripes. Mid-dorsal parts of vertex, pronotum, and mesonotum narrowly whitish, fringed with orange stripes (stripes feeble in summer form). Forewings as in S. kisimotoi . Male pygofer dark brown except caudal margin narrowly pale.

Vertex about 1.5× as long as wide. Frons about 3.0× as long as wide; median carina forked in apical 1/3. Antennal segment II about 2.7× as long as wide. Forewing venation and hind leg spinulation as in S. niisimai . Post-tibial spur with 17–21 fine teeth.

Body length (mean): ♂ 4.7–5.2 mm ( 4.9 mm); ♀ 5.0– 5.7 mm ( 5.3 mm).

Male genitalia: Similar to S. kisimotoi in pygofer, suspensorium and gonostyles. Phallotheca broad in lateral view; opening near caudal side; two apical processes: left process long, falcate; right process short, slightly converged to left process. Anal tube rectangular in lateral view; ventral margin with one pair of small and acute processes produced caudad near midlength. Female genitalia: Similar to S. sapporensis except gonapophyses IX with 17–18 teeth, symmetrically diverged basally. Gonoplacs semicircular in ventral view, broad, wider in apical half.

Distribution. Japan ( Hokkaido, Honshu), China.

Remarks. This species is distinguishable by its frontal dark stripes, which are usually paler in the basal two-thirds, and by the phallotheca with two apical processes, the right being shorter. Ichita (1996) recognized this species from Aomori Prefecture, northern Honshu. Subsequently, Kisimoto & Hayashi (2000) recorded this planthopper as Stenocranus silvicola Vilbaste , a very similar and probably allied to this species originally described from the Russian Far East. Examination of the syntypes of S. fallax , the holotype of S. silvicola photographed in IAES, and other specimens of both species indicates that the specimens recorded by Ichita (1996) are S. fallax based on the following characteristics: two apical processes of the phallotheca converged to the apices (diverged to the apices in S. silvicola ), ventral processes of the anal tube produced caudad (curved anteriad in S. silvicola ).

Biological notes. This species inhabits mountainous to lowland marshes and feeds on Carex dispalata Boott and Carex curvicollis Franch. et Savat ( Cyperaceae ). The oviposition site on the host plant is similar to that of S. harimensis .