Non-types (5 ♂♂ 4 ♀♀, VNMN): Vietnam • Thừa Thiên Huế Province, Phú Lộc District, Bạch Mã National Park, Lộc Trì, Đường mòn Đỗ Quyên; 16°11'34"N, 107°50'52"E; 6.vi.2024; leg. J. Souma.

Bannacorishyalinus comb. nov. can be distinguished from the only other congener, B.arboreus, by the following characters: head, pronotum, and scutellum mostly yellowish brown (Figs 1A, B, 2A) (mostly reddish to dark brown in B.arboreus); corium of forewing mostly hyaline (Fig. 2D) (reddish to dark brown in middle part in B.arboreus), not punctate in an area enclosed by Sc (subcostal) vein and medial furrow (entirely punctate in B.arboreus); dorsolateral process of genital capsule undeveloped (Figs 2E, 3A) (protruding posteriad in B.arboreus); and ventromedian process concave in posterior margin (gently curved outward in B.arboreus).

Most parts of head, antennomeres I–IV, pronotum except for anterior and lateral margins, ventral surface of thoracic parts, most parts of scutellum, legs except for claws, and abdomen yellowish brown; antennomere V, compound eye, ocellus, anterior margin of scutellum, Sc (subcostal) vein of forewing, claws, and punctures on body dark brown; anterior and lateral margins of pronotum, and outer part of semi-elliptical ridge in anteromedial part of scutellum whitish brown; forewing except for Sc vein and punctures hyaline; setae on body yellowish (Figs 1A, B, 2A–F, 4A, B).

Body (Fig. 1A, B) ovate, 1.5–1.6 times as long as maximum width across abdomen. Head (Fig. 2A–C) declivent, mostly punctate, longer than maximum width across compound eyes in cranial view, with a median sulcus on vertex, sparsely bearing minute setae. Antenniferous tubercle annulate, placed anterior to compound eye. Clypeus distinctly surpassing mandibular plate at both apices. Compound eye round, separated from anterior margin of pronotum. A pair of ocelli placed along midline of vertex, closer together than a diameter of ocellus. Antenna smooth on surface; antennomere I longest among antennomeres, more than 1.5 times as long as antennomere II, bearing minute setae throughout its length; antennomere II longer than antennomere IV, bearing minute setae throughout its length; antennomere III shortest among antennomeres, bearing minute setae throughout its length; antennomere IV as long as antennomere V, bearing minute and long setae throughout its length; antennomere V bearing minute and long setae throughout its length. Labium reaching anterior part of abdominal sternite III. Buccula semi-elliptical in lateral view, highest in middle part.

Thorax (Figs 1A, B, 2A, C) mostly punctate. Pronotum trapezoidal in dorsal view, shorter than its maximum width, punctate except for callus; lateral margin serrate in anterior part, without distinct spine, bearing minute setae throughout its length; humeral angle rounded. Scutellum triangular, shorter than its maximum width, semi-elliptically raised in anteromedial part, punctate except for midline and semi-elliptical ridge. Forewing (Fig. 2D) oblong; anterior margin gently curved outward; clavus shorter than membrane, with 2 rows of punctures throughout its length; corium punctate except in an area enclosed by Sc vein and medial furrow, bearing minute setae in anterior part; membrane provided with several indistinct longitudinal veins; Sc vein, basal part of Cu (cubital) vein, and claval and medial furrows distinct. Epimera and episterna punctate except metepimeron. Sterna smooth on surface. Legs smooth on surface; femora and tibiae cylindrical, bearing setae throughout their length.

Abdomen (Figs 1A, B, 2D–F) longer than combined length of head and pronotum; posterior margin of sternite VI concave in male, undulate in female; sternite VII concave in posterior margin of male, with a longitudinal cleft in female. Genital capsule (Fig. 3A) elliptical in dorsal and ventral views, smooth on surface, bearing setae in posterior part; lateral margin gently curved outward; dorsolateral process undeveloped; ventromedian process widened apically, concave in posterior margin. Paramere (Fig. 3B, C) elongate; crown widened apically, bearing three setae from cuticular sockets along outer margin of dorsum; neck constricted; stem widened apically. Phallus (Fig. 2G) oblong; basal plate and phallotheca coriaceous; conjunctiva with two pairs of sclerites. Female terminalia (Fig. 3D) semicircular in ventral view, protruding posteriad in middle part; laterotergite VIII reduced; valvifer VIII reduced; laterotergite IX rounded in outer margin.

Measurements (male: n = 5; female: n = 4). Body length with forewing 3.5–3.8 mm in male and 3.9–4.0 mm in female, maximum width across forewings 2.3–2.4 mm in male and 2.5 mm in female; head length in cranial view 0.9 mm in both sexes, maximum width across compound eyes 0.8 mm in both sexes; length of antennomeres I–V in both sexes 1.5 mm, 0.8 mm, 0.2 mm, 0.6 mm, and 0.6 mm, respectively; length of labial segments I–IV in both sexes 0.3 mm, 0.3 mm, 0.3 mm, and 0.4 mm, respectively; pronotum length 0.7 mm in both sexes, maximum width 1.8 mm in male and 1.9–2.0 mm in female; scutellum length 0.8 mm in male and 0.9 mm in female, maximum width 1.0 mm in male and 1.1 mm in female; forewing length 2.8–2.9 mm in male and 3.0–3.1 mm in female, maximum width 1.2 mm in male and 1.3 mm in female.

The nine specimens recorded above (Fig. 1A, B) matched well with the original description and illustrations of Bannacorishyalinus comb. nov. (Schaefer and Ashlock 1970) in terms of morphological characteristics, especially the structure of the head (Fig. 2B) and the shape of the genital capsule (Figs 2E, 3A) and paramere (Fig. 3B, C). Therefore, we identified the specimens studied as B.hyalinus comb. nov. and redescribed this species in the above section.

In the original description (Schaefer and Ashlock 1970), B.hyalinus comb. nov. was not compared with the only other congener, B.arboreus, making the identification of the two species difficult. However, based on the comparison among the nine specimens of B.hyalinus comb. nov. and the illustrations (Hsiao 1964; Hsiao and Ching 1977), photographs (Hsiao and Ching 1977; Rider et al. 2018; https://spain.inaturalist.org/taxa/1360964-Bannacoris-arboreus), and original description (Hsiao 1964) of B.arboreus, the five characters described in the Diagnosis section above were recognized to easily differentiate B.hyalinus comb. nov. from B.arboreus.

Vietnam (Thừa Thiên Huế Province, Lâm Đồng Province) (Fig. 5) (Schaefer and Ashlock 1970; present study).

Adults and nymphs of Bannacorishyalinus comb. nov. were observed to congregate in groups of several on the abaxial side of leaves of Litsea sp. (Lauraceae) (Fig. 4C) in Bạch Mã National Park, Thừa Thiên Huế Province, Vietnam (Fig. 4D), by the first author. In addition, nymphs were observed sucking sap from the abaxial side of the leaves of this lauraceous tree in captivity. Thus, Litsea sp. is considered the host plant of B.hyalinus comb. nov., the biological information of which was unknown in the original description (Schaefer and Ashlock 1970).

The adaxial side of the leaves apparently damaged by this saileriolid species was irregularly yellowed in the field and in captivity, suggesting the possibility that B.hyalinus comb. nov. feeds on leaf chlorophyll.

Bannacorishyalinus comb. nov. inhabits evergreen broad-leaved forests in the mountainous areas of Vietnam with a subtropical climate.

Adults were collected in May 1960 and June 2024 (Schaefer and Ashlock 1970; present study), and nymphs were observed in June 2024 (present study).