Psallus (Hylopsallus) ramae n. sp.

(Figs. 13 D−F; 14D−E; 15C−D; 16; 30G−K; 31K−N; 32H−K)

Material examined. Holotype (♂). JAPAN: Honshu, Okayama Pref., Hiruzen Plateau, Kawakami Village, Kamiyubune [current Maniwa City, Hiruzen], 35.31, 133.62, Quercus mongolica, 8 Jun 2003, T. Yasunaga (AMNH) (AMNH _ PBI 00380709) . Paratypes: JAPAN: Honshu, same data as for holotype, 11♂ 4♀ (TYCN); Honshu, Hiroshima Pref., Geihoku Town, Chojabaru [current Kita-Hiroshima, Yawata Plateau], 34.71, 132.17, UV lighting, 10–11 Jul 1993, K. Yoshizawa, 2♂ 2♀ (TYCN) (1♂ with USIs, 00380710); Shikoku, Tengu Plateau, 33.48 133.00, Quercus mongolica, 6 Jun 1999, M. Takai, 1♂ 1♀ (TYCN) (1♂ with USIs, 00380711) . Additional material examined. JAPAN: Kyushu, Nagasaki Pref., Isahaya City, Oriyama, 32.956650, 130.08650, 750 m alt., Quercus mongolica, 22 May 2021, T. Yasunaga, 2♀ (TYCN) (00380712) .

Diagnosis. Recognized by its generally dark castaneous, oval body (Fig. 13D–E); small size; densely distributed silvery setae on dorsum (Figs. 13E, 30G); enlarged or sometimes fused dark spots on metatibia (Fig. 13D–E); male genital segment (pygophore) with moderately clustered stiff setae at left-lateral base (Fig. 30J–K); broad, triangular apical part of phallotheca (Fig. 31L); vesica with thick median projection (Fig. 31M), lacking apical spinulate lobe (cf. Fig. 14B) that is possibly modified to cup-shaped rim (Fig. 14D); relatively small, nearly symmetrical sclerotized rings (Fig. 15A); and relatively clear comb-like scaly microstructures on interramal sclerite (Fig. 32J). Most closely related to P. castaneae, this new species can be distinguished by above diagnostic characters.

Description. Body dark castaneous or fuscous, oval, not sexually dimorphic; dorsum with densely distributed, simple, semierect setae recumbent, silvery, lanceolate setae (Fig. 13D–E, 30G). Head dark brown, relatively slanting, with both simple and silvery setae; buccula tinged with red. Antenna yellowish brown; extreme base (basal 1/8–1/7) of segment I infuscate; segment IV grayish yellow. Labium shiny chocolate brown, its apex reaching apex of mesocoxa; apical parts of segments II and III, and basal half of IV yellowish brown. Pronotum, mesoscutum and scutellum fuscous, weakly shining; thoracic pleura dark brown, with silvery setae; ventral margins of propleuron and mesepimeron creamy white; evaporative area of metathoracic scent efferent system relatively narrow (Fig. 30H). Hemelytra fuscous, weakly shining because of dense vestiture (Fig. 13E); anterior margin of cuneus sometimes narrowly pale or reddish; membrane smoky brown. All coxae and femora uniformly dark brown; apex of profemur yellowish brown; ventral surface of metafemur without spotted pattern; tibiae pale brown, with distinct spots or annulations at bases of brown spines; metatibial dark spots sometimes fused together and enlarged (Fig. 13D– E); tarsi pale brown; pretarsal structure as in Fig. 30M; pulvilli relatively narrow. Abdomen shiny fuscous. Male genitalia (Figs. 14 D−E, 30J–K, 31K−N): male genital segment (pygophore) with moderately clustered stiff setae at left-lateral base (Fig. 30J–K); apical part of phallotheca broad, triangular (Fig. 31L); vesica lacking apical spinulate lobe with cup-shaped rim (Fig. 14D); median projection of vesica thickened (Fig. 31M). Female genitalia (Figs. 15 C−D; 32H−K): sclerotized rings relatively small, nearly symmetrical and mesally separated from each other (Fig. 15A); rings reduced, indistinct (Fig. 12F); posterior wall with relatively wide interramal lobe and interramal sclerite (Fig. 27 K−L); posterior margin sclerite weak (Fig. 32N–O); comb-like scaly microstructures on interramal sclerite relatively clear (Fig. 32J); apex of ovipositor (gonapophysis I) somewhat widened (Fig. 15D; 32K).

Measurements: See Table 4.

Etymology. Named in honor of Ram Keshari Duwal who greatly contributed to clarification of the Asian fauna of the Phylinae .

Distribution. Japan (SW Honshu, Shikoku, Kyushu).

Biology. The newly emerged adults were found in early summer (late May in Kyushu and early June in Honshu) and a univoltine life cycle is assumed for this new species. Almost of all available specimens (including teneral ones) were collected from a deciduous oak, Quercus mongolica Fisch. ex Ledeb. (Fagaceae), growing mainly in a cold temperate climatic zone, but the immature forms are yet to be confirmed.

Remarks. Although this new species and P. castaneae Josifov are closely related and at first sight seem very similar to each other, the latter is widespread over the lowlands and urbanized zones from central Honshu to western Kyushu (Ishikawa et al., 2014, 2015; Komatsu, 2018; Miyazaki et al., 2020). Records of P. edoensis (cf. Figs. 13G, 29J–O) from Tokyo Metropolis by Ishikawa et al. (2014, 2015) were recently verified to be based on misidentification of P. castaneae . Host association of P. castaneae ranges across a variety of Fagaceae oaks (mostly inflorescences), such as Castanea spp., Castanopsis spp., Lithocarpus edulis (Makino) Nakai, Quercus accutissima Carruth., and Q. serrata Murray; the adults were frequently found to aggregate on inflorescence of Cinnamomum camphora (L.) J.Pres, Machilus thunbergii Siebold et Zucc. (Lauraceae) and Melia azedarach L. ( Meliaceae). On the other hand, the distribution and plant association of P. ramae n. sp. appear to be restricted to Quercus mongolica in cool mountainous zones (over 600 m alt.) in southwestern Japan (Fig. 16). At three localities (Hiroshima, Okayama, and Kochi Prefectures), P. ramae n. sp. was found to co-occur with P. tonnaichanus; the latter is known to be associated with Quercus dentata Thunberg and Q. mongolica (Yasunaga, 2001d) .