Genus Cysteochila Stål, 1873

Cysteochila Stål, 1873: 121. Type species by subsequent designation (Distant 1903a: 138): Monanthia? tingoides Motschulsky, 1863.

Bredenbachius Distant, 1903b: 50. Type species by subsequent designation (Distant 1903a: 139): Bredenbachius pictus Distant, 1903. Synonymized by Bergroth (1921: 104).

Diagnosis. Recognized among other tingid genera by a combination of the following characters: body oblong; maximum width across hemelytra narrower than maximum width across paranota; head shorter than its maximum width across compound eyes, with five spines; antennal segments I close to each other at their bases; bucculae contiguous with each other at anterior ends; rostrum not reaching abdominal sternite IV; pronotum convex in anterior part, tricarinate; lateral margin of pronotum emarginate in anterior part; hood roof-shaped, lower than pronotal disc at highest part; pronotal carinae carinate; paranotum reflexed, expanding inward, without longitudinal ridge, not bulged upward in posterior part, not forming a cyst; outer margin of paranotum resting on pronotal disc in its entire length; posterior process well-developed; anterior margins of hemelytra not parallel to each other at rest; costal area distinct; subcostal area subvertical; discoidal area flat; Cu (cubital) and R+M (radiomedial) veins carinate; hypocostal lamina with a single row of areolae in its entire length; ostiolar peritreme well-developed; metasternum wider than mesosternum; metasternal laminae continuous each other at posterior ends; abdominal sternites IV–VIII in male and IV–VII in female each with a transverse furrow throughout their width; pygophore elevated at center of venter; ovipositor with well-developed ovivalvula at base; and paratergite IX in female unilobed.

Remarks. The genus Cysteochila comprises 128 species from the Old World (Drake & Ruhoff 1965a, 1965b; Linnavuori 1977; Duarte Rodrigues 1982a, 1982b, 1982c, 1982d, 1983, 1988, 1990, 1992; Péricart 1982, 1983, 1985b; Péricart & Golub 1996; Guilbert 2001, 2002, 2006, 2008; Deckert & Göllner-Scheiding 2006; Aukema et al. 2013; Guilbert & Heiss 2016). In Japan, four species, namely, C. chiniana, C. consueta, C. monstrosa, and C. vota, have been recorded to date (Scott 1874, 1880; Drake 1942, 1948b; Drake & Ruhoff 1965a; Miyamoto & Yasunaga 1989; Yamada & Tomokuni 2012; Yamada & Ishikawa 2016). Here, we identified two species of Cysteochila from Japan. Although a key to the Japanese species of the genus has been provided by Yamada & Tomokuni (2012), we provide a key to these two species.

Cysteochila and Physatocheila are closely related to each other, and their delimitation has been discussed by Péricart (1979, 1982, 1983, 1992). According to this author, Cysteochila can be distinguished from Physatocheila by the following characteristics: paranotum bulged upward in posterior part, forming a cyst; outer margin of paranotum not resting on pronotal disc in its entire length; metasternum wider than mesosternum; metasternal lamina curved outward; and ovipositor without ovivalvula at base. However, the type species of the genus, C. tingoides (Motschulsky, 1863) (Fig. 3A–D), does not match the definition of Cysteochila provided by Péricart (1979) in the paranotum being not bulged upward in the posterior part, not forming a cyst, and the outer margin resting on the pronotal disc in its entire length. In addition, based on the comparison of C. tingoides and P. costata (Fabricius, 1794) (Fig. 15A–D), Cysteochila and Physatocheila can be easily differentiated based on the following three major characteristics: maximum width across hemelytra narrower than maximum width across paranota; lateral margin of pronotum emarginate in anterior part; and metasternal laminae continuous each other at posterior ends. Therefore, we redefined the morphological characteristics shared by Cysteochila species, as described in the Diagnosis section above.

Cysteochila resembles Baeochila Drake & Poor, 1937 in general appearance but differs in the following characteristics: lateral margin of pronotum emarginate in anterior part; hood roof-shaped, lower than pronotal disc at highest part; anterior margins of hemelytra not parallel to each other at rest; and metasternal laminae continuous each other at posterior ends. In contrast, Baeochila presents the following characteristics: lateral margin of pronotum not emarginate in anterior part; hood semi-globose or semi-ellipsoid, higher than pronotal disc at highest part; anterior margins of hemelytra nearly parallel to each other at rest; and metasternal laminae separated from each other at posterior ends.