Holotype. ♀; HNL2018-073; Vietnam, Gia Lai Province, Kon Chu Rang Nature Reserve; 08.v.2018; X. L. Truong leg.; NSMT. Paratypes. 1♀; HNL2018-036; Vietnam, Dak Lak Province, Chu Yang Sin National Park; 09.v.2018; X. L. Truong leg.; IEBR. 2♀; HNL2018-072; HNL2018-076; Vietnam, Gia Lai Province, Kon Chu Rang Nature Reserve; 08.v.2018; X. L. Truong leg.; IEBR. 1♀; HNL2018-074; Vietnam, Gia Lai Province, Kon Chu Rang Nature Reserve; 08.v.2018; X. L. Truong leg.; NSMT. 1♀; HNL2018-075; Vietnam, Gia Lai Province, Kon Chu Rang Nature Reserve; 08.v.2018; X. L. Truong leg.; VNMN. 1♂; TXL2016-545; Vietnam, Gia Lai Province, Kon Chu Rang Nature Reserve; 28.iv.2016; X. L. Truong leg.; NSMT.

Body shiny blackish brown; anterior pronotal lobe blackish brown or black with some rows of short bent cream-yellow setae; posterior pronotal lobe blackish brown or dark brown, densely covered with short bent cream-yellow setae, interspersed with long erect setae; scutellum black or blackish brown; abdominal sternites sanguineous; laterotergites II–IV luteous; anterior half of laterotergite V suffused with brown; posterior half of laterotergite V to apex of abdomen sanguineous.

This species is similar to B. confusus Hsiao et al., 1979 in general appearance, especially in body color, pronotum, and thoracic sterna. But the new species can be distinguished from B. confusus by a combination of the following characters: antennal pedicel longer than first flagellomere (in B. confusus pedicel as long as first flagellomere), second flagellomere as long as pedicel (in B. confusus second flagellomere longer than pedicel), proportional average length of first to third labial segments 1.1:1.4:0.3 (in B. confusus 0.9:1.2:0.3), anterior pronotal lobe with some rows of bent setae (in B. confusus without row of bent setae), posterior pronotal lobe ~ 2.3 × as long as anterior pronotal lobe (in B. confusus 2.0 ×), and apical margin of median process of pygophore weakly and continuously concave (in B. confusus weakly and continuously convex).

Furthermore, this species is somewhat similar to B. ventralis Hsiao et al., 1979 in general colors of body, pronotum, and sterna but the new species can be distinguished from B. ventralis by a combination of the following characters: antennal pedicel longer than first flagellomere (in B. ventralis pedicel ~ 1/2 as long as first flagellomere), second flagellomere as long as pedicel (in B. ventralis second flagellomere 2.5 × as long as pedicel), proportional average length of antennal scape, pedicel, first and second flagellomeres 3.1:1.6:1.4:1.6 (in B. ventralis 3.3:1.1:2.0:2.8), and proportional average length of first to third labial segments 1.1:1.4:0.3 (in B. ventralis 1.0:1.3:0.3).

Female description. Coloration. Body shiny blackish brown. Head dorsum shiny black or blackish brown; clypeus blackish brown; antenniferous tubercle, base of neck, maxillary plate, and base of first visible labial segment yellowish brown; central fascia to head venter, gena, tips of first and second visible labial segments pale luteous; labium, except base of first visible labial segment, black; a brown stripe present after postero-upper corner of compound eye; area around lateral ocellus with reddish brown suffusion; a longitudinally elongated yellowish brown spot present between lateral ocelli. Base of scape dark brown; remaining of scape brown; pedicel, first and second flagellomeres brown, darker toward tip. Collar, anterior pronotal lobe, thoracic sterna, and pleura blackish brown or black; posterior pronotal lobe blackish brown; scutellum black or blackish brown; stridulatory sulcus, intersecting area of coxa and trochanter yellowish brown; coxae, trochanters, femora, and tibiae blackish brown. Corium and clavus blackish brown, apically brownish yellow; membrane bronzy brown, semi-hyaline. Hind wings faintly semi-hyaline. Abdominal mediotergites I+II to IV and middle of mediotergite V blackish brown; posterior half of mediotergite V to apex of abdomen and abdominal sternites sanguineous; laterotergites II–IV luteous; anterior half of laterotergite V suffused with brown; posterior half of laterotergite V to apex of abdomen sanguineous. Female external genitalia sanguineous.

Structure. Body medium-sized (BL = 10.38–11.35 mm), elongate, and somewhat robust. Head subelongate and robust (HL/PoW = 2.40–2.59), shorter than pronotum (HL/PnL = 0.80–0.86); postocular area of head sub-globose (PoL/PoW = 0.84–0.96), distinctly wider than anteocular area (PoW/AoW = 1.38–1.43), approximately as long as anteocular area (PoL/AoL = 0.95–1.08), constricted behind compound eyes, with a wide and deep interocular sulcus; neck short. Compound eyes protruding laterally, nearly globose, with posterior margin sub-straight; lateral ocelli produced, elevated behind interocular sulcus, widely separated from each other (OCD/PoW = 0.44–0.49); interspace between lateral ocelli wider than distance between compound eye and lateral ocellus (OCD/COD = 2.03–2.06). First visible labial segment shorter than second segment (R1L/R2L = 0.76–0.84), longer than anteocular area of head (R1L/AoL = 1.42–1.60), extending beyond level of middle of compound eye when labium laid backward; proportional average length of first to third visible labial segments 1.1:1.4:0.3. Scape ~ 1.5 × as long as head; pedicel slightly longer than first flagellomere and nearly equal in length to second flagellomere; proportional average length of scape, pedicel, first and second flagellomeres 3.1:1.6:1.4:1.6. Collar very short in dorsal view, with anterolateral angle weakly and roundly produced; anterior pronotal lobe round and bulged, slightly rough, with middle longitudinal sulcus deep and narrow posteriorly; posterior pronotal lobe with slightly swollen anteromedial elevation; humerus roughly triangular, with round apex; posterior margin of pronotum straight; posterior angles round, not exceeded to posterior margin of pronotum. Scutellum triangular, somewhat triangularly depressed basally, apically produced, and sloping downward; posterior apex round; anterior margin slightly convex. Femora thick, apically moderately nodulose; fore femora very slightly incrassated, thicker than mid and hind femora. Hemelytra surpassing apex of abdomen when fully closed, 0.8 × as long as body length; discal cell nearly parallelogram-shaped, twice as long as width; Sc 0.8 × as long as hemelytron length, 1.5 × as long as R + M. Hind wing ~ 3.4 × as long as maximum width. Connexivum slightly dilated and ascending with segmental incisures; abdominal laterotergite VIII (AL8) with thin posterior margin (0.03 mm); abdominal sternite VII (AS7) forming a semi-circular or wide sub-pentagonal median concavity, with posteromedian margin gently U-shaped, with inner posterolateral margin almost straight; gonocoxa VIII (Gc8) ~ 1.3 × wider than length, gently slanting anteromesad along posterior margin, weakly produced mesad and forming an acute apex at apical inner corner, and with inner margin weakly incurved in posterior 2/3; gonapophysis (Gp8) small and subtriangular, 3.2 × longer than width; gonoplac (Gpl) V-shaped, thin, with maximum thick ~ 0.025 mm.

Vestiture. Body clothed with cream-yellow setation. Head, except interocular sulcus and area along anterior margin of compound eye, covered with short bent cream-yellow pubescence, and sparsely with long erect setae; labium with a few bent setae; scape without setae and pubescence; pedicel, first and second flagellomeres with short vertical setae; neck glabrous. Collar, anterior margin, lateral area of anterior pronotal lobe, posterior pronotal lobe, scutellum, pleura, thoracic sterna, and coxae densely covered with short bent cream-yellow pubescence; posterior pronotal lobe, pleura, thoracic sterna, and coxae interspersed with long erect setae; scutellum with long bent slender setae, especially in lateral slopes and in posterior apex; trochanters, femora, and tibiae with short erect setae; corium with short bent setae. Abdomen (including connexivum), except segment VII, with short slender vertical setae; gonocoxa VIII (Gc8) with long slender bent setae.

Male description. General external morphology similar to that of the female.

Coloration. Almost similar to female but slightly brighter than female. Clypeus dark brown; anteclypeus, base of first visible labial segment pale yellowish brown; first and third visible labial segments brown; second visible labial segment dark brown; area around ocellus with pale brown suffusion. Prosternum and propleuron blackish brown; posterior pronotal lobe dark brown; scutellum blackish brown; meso- and metapleura brown or yellowish brown; meso- and metasterna yellowish brown; fore coxa pale yellowish brown; coxae and trochanters of mid and hind legs yellowish brown; femora and tibiae dark brown or blackish brown. Pygophore ventrally orangish sanguineous; paramere semi-hyaline, pale orange.

Structure. Almost same as female except for the following characters. Scape 1.7 × as long as head; pedicel, first and second flagellomeres missing. Hemelytra surpassing apex of abdomen when fully closed, nearly 0.9 × as long as body length. Pygophore elliptic; median process of pygophore (mpp) broad and low, 0.3 × as long as wide, with apical margin weakly and continuously concave, with apicolateral corner distinctly produced posterolaterad and pointed; paramere long, slender, clavate, somewhat incurved in apical part, with round apex (Figs 6A, 15B–E). Aedeagus in dorsal view ovoid, dorsally sclerotized (Figs 6B, 15F, I) and in lateral view long and narrow (Figs 6C, 15G, K); articulatory apparatus (aa) in ventral view with basal plate arms relatively slender and jointly forming a U-shape, and in lateral view arched very strongly (Figs 6C, D, 15G, H); dorsal phallothecal sclerite (dps) in lateral view with posteromedian part weakly produced posterodorsad (Figs 6C, 15G, K); spoon-like sclerites (sps) hyaline and glabrous; both membranous sac-like lobes posterolaterally produced; distal dorsal lobe of endosoma (ddl) round, with membranous surface roughly lumpy (Fig. 15L).

Vestiture. Almost same as female except for the following characters. Head covered with short bent cream-yellow pubescence, and sparsely with long bent setae; pedicel with short vertical setae; first and second flagellomeres missing; neck without setae. Scutellum densely covered with short bent cream-yellow pubescence interspersed with long erect setae; trochanters, femora, and tibiae with long erect setae; connexivum with long vertical thick setae; abdominal venter with vertical setae; pygophore with oblique setae; paramere with long erect setae.

All dimensions are given in mm. Holotype (♀): BL 11.35; HL 2.12; AoL 0.76; AoW 0.58; PoL 0.76; PoW 0.82; OE 1.11; IE 0.57; ED 0.65; OD 0.17; OCD 0.41; COD 0.19; R1L 1.22; R2L 1.45; R3L 0.33; A1L 3.13; A2L 1.67; A3L 1.55; A4L n/a; PnL 2.52; PnW 3.01; APL 0.72; PPL 1.80; HeL 8.61; HeW 2.97; Sc 6.59; R+M 4.43; HWL 6.06; HWW 1.84; AFL 3.32; ATL 4.02; MFL 2.76; MTL 3.41; PFL 4.02; PTL 5.53. Paratype (♂): BL 9.86; HL 1.98; AoL 0.68; AoW 0.56; PoL 0.78; PoW 0.79; OE 1.03; IE 0.54; ED 0.61; OD 0.14; OCD 0.38; COD 0.21; R1L 1.11; R2L 1.39; R3L 0.31; A1L 3.28; A2L n/a; A3L n/a; A4L n/a; PnL 2.31; PnW 2.60; APL 0.70; PPL 1.60; HeL 8.48; HeW 2.72; Sc 6.56; R+M 4.34; HWL 5.60; HWW 1.70; AFL 3.30; ATL 3.91; MFL 2.73; MTL 3.29; PFL 4.00; PTL 5.45. Paratypes (♀). BL 10.38–10.81; HL 2.00–2.06; AoL 0.72–0.75; AoW 0.58–0.60; PoL 0.70–0.78; PoW 0.82–0.86; OE 1.06–1.09; IE 0.54–0.58; ED 0.62–0.63; OD 0.15–0.17; OCD 0.37–0.41; COD 0.17–0.19; R1L 1.07–1.13; R2L 1.37–1.42; R3L 0.31–0.32; A1L 2.99–3.13; A2L 1.52–1.60; A3L 1.25–1.52; A4L 1.44–1.74; PnL 2.36–2.51; PnW 2.73–2.87; APL 0.66–0.81; PPL 1.64–1.82; HeL 8.63–8.98; HeW 2.78–3.04; Sc 6.59–6.71; R+M 4.51–4.62; HWL 6.03–6.18; HWW 1.77–1.87; AFL 3.11–3.41; ATL 3.79–3.93; MFL 2.64–2.77; MTL 3.30–3.42; PFL 3.73–4.00; PTL 5.35–5.50.

Vietnam, Central Highlands (Gia Lai, Dak Lak).

Vietnam, Central Highlands, Gia Lai Province, Kon Chu Rang Nature Reserve.

This new species is named after the Tay Nguyen region, the local name of Central Highlands.

Holotype. 1♀; HNL2018-038; Vietnam, Dak Lak Province, Chu Yang Sin National Park; 09.v.2018; X. L. Truong leg.; NSMT. Paratypes. 1♀; HNL2018-007; Vietnam, Gia Lai Province, Kon Chu Rang Nature Reserve; 05.v.2018; X. L. Truong leg.; IEBR. 1♀; HNL2018-037; Vietnam, Dak Lak Province, Chu Yang Sin National Park; 09.v.2018; X. L. Truong leg.; VNMN. 1♂; TXL2016-546; Vietnam, Gia Lai Province, Kon Chu Rang Nature Reserve; 28.iv.2016; X. L. Truong leg.; NSMT.

Body shiny blackish brown; anterior pronotal lobe black or blackish brown with some rows of long bent griseous setae; posterior pronotal lobe blackish brown or brown and densely covered with short bent griseous setae somewhat interspersed with long griseous setae; scutellum black in basal half and dark brown or brown in lateral margin and apical half; abdominal sternites shiny sanguineous; laterotergites II–VI luteous, segmentally suffused with dark brown spots or blackish brown spots; laterotergite VII sanguineous.

In general appearance, Biasticus griseocapillus sp. nov. resembles B. confusus Hsiao et al., 1979, especially in general colors of body, pronotum, and sterna. But the new species can be distinguished from B. confusus by a combination of the following characters: antennal pedicel longer than first flagellomere (in B. confusus pedicel as long as first flagellomere), second flagellomere of antenna as long as pedicel (in B. confusus second flagellomere longer than pedicel), proportional average length of first to third visible labial segments 1.1:1.4:0.3 (in B. confusus 0.9:1.2:0.3), anterior pronotal lobe with some rows of bent setae (in B. confusus without row of bent setae), posterior pronotal lobe 2.6 × as long as anterior pronotal lobe (in B. confusus 2.0 ×), and apical margin of median process of pygophore weakly convex and emarginate at middle (in B. confusus weakly convex without such emargination).

Furthermore, this species is similar to B. ventralis Hsiao et al., 1979 in general colors of body, pronotum, and sterna but the new species can be distinguished from B. ventralis by a combination of the following characters: antennal pedicel longer than first flagellomere (in B. ventralis pedicel ~ 1/2 as long as first flagellomere), second flagellomere as long as pedicel (in B. ventralis second flagellomere 2.5 × as long as pedicel), proportional average length of antennal scape, pedicel, first and second flagellomeres 3.0:1.6:1.4:1.6 (in B. ventralis 3.3:1.1:2.0:2.8), and proportional average length of first to third visible labial segments 1.1:1.4:0.3 (in B. ventralis 1.0:1.3:0.3).

Also, Biasticus griseocapillus sp. nov. is similar to B. taynguyenensis sp. nov. in the body color pattern, the proportion average length of the antenna segments, and the proportion average length of the visible labial segments. However, B. griseocapillus can be distinguished from the latter by a combination of the following characters: collar, anterior pronotal lobe, and posterior pronotal lobe covered with long bent griseous setae (in B. taynguyenensis short bent cream-yellow setae), and median process of pygophore (mpp) 0.2 × as long as wide, with apical margin weakly convex and emarginate medially, and with apicolateral corner slightly produced laterad and pointed (in B. taynguyenensis, 0.3 × as long as wide, with apical margin weakly and continuously concave, and with apicolateral corner distinctly produced posterolaterad and pointed).

Female description. Coloration. Body shiny blackish brown. Head dorsum (except anteclypeus, maxillary plate, and gena) black; anteclypeus, labrum, maxillary plate, and anterior region of gena brown; central fascia to head venter, and posterior region of gena pale luteous; first visible labial segment brown; second and third visible labial segments blackish brown; tips of first and second visible labial segments yellowish brown; area around lateral ocellus with reddish brown suffusion; a longitudinally elongated yellowish brown spot present between lateral ocelli. Base of scape brownish black; remaining of scape and pedicel, first and second flagellomeres blackish brown. Collar, anterolateral angles, anterior pronotal lobe, and anterior acetabulum black; posterior pronotal lobe, pleura, and thoracic sterna blackish brown; scutellum black in basal half and dark brown in lateral margin and apical half; stridulatory sulcus luteous; coxae and trochanters yellowish brown; intersecting area of fore coxae and fore trochanters luteous; femora, tibiae, and tarsi blackish brown. Corium and clavus darkish brown, apically brownish yellow; membrane bronzy brown, semi-hyaline. Hind wings faintly semi-hyaline. Abdominal mediotergites I+II to V reddish brown or sanguineous, somewhat suffused with blackish brown; mediotergite VI suffused with reddish brown and irregularly suffused with sanguineous; mediotergite VII and laterotergite VII to apex of abdomen sanguineous; abdominal sternite shiny sanguineous; laterotergites II–VI luteous, segmentally suffused with dark brown spots; laterotergite VII sanguineous. External genitalia sanguineous.

Structure. Body medium-sized (BL = 10.61–10.84 mm), elongate, and somewhat robust. Head subelongate and robust (HL/PoW = 2.37–2.45), shorter than pronotum (HL/PnL = 0.81–0.82); postocular area of head sub-globose (PoL/PoW = 0.85–1.03), distinctly wider than anteocular area (PoW/AoW = 1.44–1.47), slightly longer than anteocular area (PoL/AoL = 1.05–1.27), constricted behind compound eyes, with a wide and deep interocular sulcus; neck short. Compound eyes protruding laterally, nearly globose, with posterior margin sub-straight; lateral ocelli produced, elevated behind interocular sulcus, widely separated from each other (OCD/PoW = 0.43–0.46); interspace between lateral ocelli wider than distance between compound eye and lateral ocellus (OCD/COD = 1.93–2.17). First visible labial segment shorter than second segment (R1L/R2L = 0.80–0.84), longer than anteocular area of head (R1L/AoL = 1.58–1.63), extending beyond level of middle of compound eye when labium laid backward; proportional average length of first to third visible labial segments 1.1:1.3:0.3. Scape ~ 1.5 × as long as head; pedicel slightly longer than first flagellomere and nearly equal in length to second flagellomere; proportional average length of scape, pedicel, first and second flagellomeres 3.0:1.6:1.4:1.6. Collar very short in dorsal view, with anterolateral angle weakly and roundly produced; anterior pronotal lobe round and bulged, slightly rough, with middle longitudinal sulcus deep and narrow posteriorly; posterior pronotal lobe with slightly swollen anteromedial elevation; humerus roughly triangular, with round apex; posterior margin of pronotum straight; posterior angles round, not exceeded to posterior margin of pronotum. Scutellum triangular, somewhat triangularly depressed basally, apically produced and sloping downward; posterior apex round; anterior margin slightly convex. Femora thick, apically moderately nodulose; fore femora very slightly incrassated, thicker than mid and hind femora. Hemelytra surpassing apex of abdomen when fully closed, 0.8 × as long as body length; discal cell nearly parallelogram-shaped, twice as long as width; Sc 0.7 × as long as hemelytron length, 1.4 × as long as R + M. Hind wing ~ 3.2 × as long as maximum width. Connexivum slightly dilated and ascending with segmental incisures; abdominal laterotergite VIII (AL8) with thin posterior margin (0.01 mm); abdominal sternite VII (AS7) forming a wide subpentagonal posteromedian concavity, with inner posterolateral margin almost straight; gonocoxa VIII (Gc8) broad, ~ 1.4 × wider than length, slightly opened inward for gonapophyses VIII (Gp8), with posterior margin gently slanting anteromesad, and with apical inner corner not produced; Gp8 small and subtriangular, 3.9 × longer than width; gonoplac (Gpl) V-shaped, thin, with maximum thick ~ 0.025 mm.

Vestiture. Body clothed with griseous setation. Head, except interocular sulcus and posterior margin of clypeus, covered with long erect setae; posterior margin of clypeus, head venter, anterolateral area of neck with short bent setae and sparsely with long erect setae; anteclypeus, labium, scape with a few short setae; pedicel, first and second flagellomeres covered with short erect to recumbent setae; dorsum of neck without setae. Collar, anterior margin of anterior pronotal lobe with dense bent pubescence; anterior pronotal lobe with some rows of long bent griseous setae; lateral area of anterior pronotal lobe with long erect setae; posterior pronotal lobe densely covered with short bent griseous setae somewhat interspersed with long griseous setae; lateral slope area and posterior apex of scutellum with dense short to long setae; posterior area of posterior pronotal lobe with long erect setae; pleura, thoracic sterna, and coxae with short bent setae; trochanters, femora, and tibiae with long erect setae; corium with bent griseous pubescence. Anterior margin of abdominal mediotergite I+II with some long slender erect yellowish brown setae; mediotergites and dorsal laterotergites sparsely covered with a few short vertical setae; abdominal sternites interspersed with long vertical setae; posterior margin of abdominal laterotergite VIII (AL8) with long erect slender setae; gonocoxa VIII (Gc8) with long slender bent setae; apex of external genitalia with long thick erect setae.

Male description. General external morphology similar to that of the female.

Coloration. Almost similar to female but brighter than female. Gena brown in anterior half and luteous in posterior half; labium blackish brown; tips of first and second visible labial segments luteous. Collar, anterolateral angles, anterior pronotal lobe, and anterior acetabulum blackish brown; posterior pronotal lobe, pleura, and thoracic sterna brown; scutellum black in basal half and brown in lateral margin and apical half; stridulatory sulcus pale gray. Laterotergites II–VI pale luteous, segmentally suffused with blackish brown spots; laterotergite VII sanguineous. Pygophore ventrally orpiment-orange; paramere semi-hyaline, pale orange.

Structure. Almost similar to female except for the following characters. Scape 1.8 × as long as head and more than twice as long as pedicel; pedicel slightly longer than first flagellomere; second flagellomere missing; proportional length of scape, pedicel, and first flagellomere 3.5:1.6:1.4. Hemelytra surpassing apex of abdomen when fully closed, 0.9 × as long as body; Sc 0.8 × as long as hemelytron, and 1.5 × as long as R + M. Pygophore ovoid; median process of pygophore (mpp) broad and low, 0.2 × as long as wide, with apical margin weakly convex and emarginate medially, with apicolateral corner slightly produced laterad and pointed; paramere long, slender, clavate, somewhat curved medially, and apically subnodulose and round (Figs 6E, 18B–F). Aedeagus in dorsal view ovoid, dorsally sclerotized (Figs 6F, 18G, J) and in lateral view long and narrow (Figs 6G, 18H, L); articulatory apparatus (aa) in ventral view with basal plate arms relatively slender and jointly forming a U-shape, and in lateral view arched strongly (Figs 6G, I, 18H, I); dorsal phallothecal sclerite (dps) in lateral view with posteromedian part weakly produced posterodorsad (Figs 6G, 18L); spoon-like sclerites (sps) hyaline and glabrous; both membranous sac-like lobes posterolaterally produced; distal dorsal lobe of endosoma (ddl) round, with membranous surface covered with large hyaline prickles (Figs 6H, 18M).

Vestiture. Almost similar to female except for the following characters. Posterior margin of clypeus with short bent pubescence; anteclypeus and scape without setae. Collar and anterior margin of anterior pronotal lobe with short bent setae and some long bent setae; anterior pronotal lobe with some rows of long bent griseous setae; posterior pronotal lobe with bent griseous setae; scutellum with long slender erect setae abundantly, especially in lateral slopes; posterior apex of scutellum with a pinch of long slender erect and bent setae; pleura, thoracic sterna, and coxae with short bent setae, with a few long slender setae; trochanters sparsely with short bent pubescence and a few long setae; corium with bent pubescence. Pygophore ventrally covered with a few bent pubescence, more abundant laterally; paramere with a few long erect thick setae.

All dimensions are given in mm. Holotype (♀): BL 10.84; HL 1.99; AoL 0.67; AoW 0.56; PoL 0.85; PoW 0.82; OE 1.05; IE 0.56; ED 0.60; OD 0.17; OCD 0.36; COD 0.18; R1L 1.09; R2L 1.31; R3L 0.32; A1L 3.01; A2L 1.59; A3L 1.52; A4L 1.56; PnL 2.45; PnW 2.74; APL 0.79; PPL 1.67; HeL 8.56; HeW 2.67; Sc 6.69; R+M 4.67; HWL 5.68; HWW 1.68; AFL 3.37; ATL 4.00; MFL 2.77; MTL 3.47; PFL 3.94; PTL 5.44. Paratype (♂): BL 9.77; HL 1.91; AoL 0.64; AoW 0.54; PoL 0.78; PoW 0.79; OE 1.05; IE 0.53; ED 0.63; OD 0.14; OCD 0.38; COD 0.19; R1L 1.05; R2L 1.31; R3L 0.29; A1L 3.48; A2L 1.62; A3L 1.49; A4L n/a; PnL 2.12; PnW 2.57; APL 0.59; PPL 1.52; HeL 8.45; HeW 2.79; Sc 6.78; R+M 4.52; AFL 3.44; ATL 4.06; MFL 2.90; MTL 3.52; PFL 3.99; PTL 5.36. Paratypes (♀). BL 10.61–10.75; HL 1.94–1.95; AoL 0.67; AoW 0.54–0.57; PoL 0.70–0.76; PoW 0.79–0.82; OE 1.05; IE 0.54–0.55; ED 0.58–0.62; OD 0.16; OCD 0.36–0.38; R1L 1.05–1.06; R2L 1.27–1.31; R3L 0.31–0.34; A1L 2.92–2.97; A2L 1.57–1.61; A3L 1.36–1.43; A4L 1.60–1.64; PnL 2.36–2.38; PnW 2.58–2.74; APL 0.72–0.84; PPL 1.52–1.66; HeL 8.65–8.88; HeW 2.75–2.98; Sc 6.30–6.49; R+M 4.40–4.48; HWL 5.78–5.89; HWW 1.79–1.91; AFL 3.31–3.33; ATL 3.78–3.93; MFL 2.70–2.78; MTL 3.42–3.51; PFL 3.69–3.87; PTL 4.91–5.35.

Vietnam, Central Highlands (Gia Lai, Dak Lak).

Vietnam, Central Highlands, Dak Lak Province, Chu Yang Sin National Park.

This new species is named after griseous pubescence on the pronotum.

Holotype. ♂; HNL2018-025; Vietnam, Dak Lak Province, Chu Yang Sin National Park; 09.v.2018; X. L. Truong leg.; NSMT. Paratypes. 1♀; TXL2016-616; Vietnam, Dak Lak Province, Chu Yang Sin National Park; 05.v.2016; X. L. Truong leg.; IEBR. 1♂; TXL2016-617; Vietnam, Dak Lak Province, Chu Yang Sin National Park; 05.v.2016; X. L. Truong leg.; IEBR. 4♀; HNL2018-078; HNL2018-080; HNL2018-081; HNL2018-082; Vietnam, Gia Lai Province, Kon Chu Rang Nature Reserve; 08.v.2018; X. L. Truong leg.; IEBR. 4♂; HNL2018-079; HNL2018-083; HNL2018-084; HNL2018-085; Vietnam, Gia Lai Province, Kon Chu Rang Nature Reserve; 08.v.2018; X. L. Truong leg.; IEBR. 1♂; HNL2018-086; Vietnam, Gia Lai Province, Kon Chu Rang Nature Reserve; 08.v.2018; X. L. Truong leg.; NSMT. 1♀; HNL2018-017; Vietnam, Dak Lak Province, Chu Yang Sin National Park; 09.v.2018; X. L. Truong leg.; VNMN. 3♀; HNL2018-018; HNL2018-019; HNL2018-020; Vietnam, Dak Lak Province, Chu Yang Sin National Park; 09.v.2018; X. L. Truong leg.; IEBR. 3♀; HNL2018-021; HNL2018-023; HNL2018-024; Vietnam, Dak Lak Province, Chu Yang Sin National Park; 09.v.2018; X. L. Truong leg.; NSMT. 1♂; HNL2018-022; Vietnam, Dak Lak Province, Chu Yang Sin National Park; 09.v.2018; X. L. Truong leg.; NSMT.

Body shiny luteous; first visible labial segment and base of second visible labial segment luteous; apical 2/3 of second visible labial segment to third visible labial segment yellowish brown or brown; posterior pronotal lobe luteous; scutellum dark brown in basal half and luteous in apical half, with median pale brownish luteous portion; femora luteous with dark brown or yellowish brown suffusions at apex and sometimes at middle.

This species is most similar to Biasticus flavus (Distant, 1903) in general appearance, especially in coloration and color pattern of the pronotum, scutellum, and abdomen. However, the new species can be easily separated from the latter by a combination of the following characters: femora luteous with some dark brown or yellowish brown suffusions at apex and sometimes at middle (in B. flavus uniformly blackish brown) and abdominal sternites luteous without blackish brown or black suffusion (in B. flavus abdominal sternites luteous with blackish brown or black segmental transverse stripes laterally).

Male description. Coloration. Body shiny luteous. Head dorsum, except antenniferous tubercle and neck, black; clypeus, antenniferous tubercle, and labrum brown; maxillary plate, gena, and head venter (except anterior margin of maxillary plate and anterior margin of gena) pale yellowish brown; anterior margin of maxillary plate and anterior margin of gena yellowish brown; first visible labial segment and base of second visible labial segment luteous; apical two-thirds of second visible labial segment to third visible labial segment yellowish brown or brown; a luteous suffusion present above upper margin of compound eye; a luteous stripe running along dorsal margin of compound eye and between postero-upper corner of compound eye and ocellus; area around lateral ocellus with yellowish brown suffusion; a longitudinally elongated luteous suffusion present between lateral ocelli; neck yellowish brown. Scape, except base, yellowish brown; base of scape blackish brown; pedicel, first and second flagellomeres dark brown. Collar, anterolateral angle, and posterior pronotal lobe pale luteous; anterior pronotal lobe, except lateral margin, shiny dark brown, sometimes with luteous suffusion centrally; lateral margin of anterior pronotal lobe, acetabulum, thoracic sterna, stridulatory sulcus, coxae, and trochanters pale luteous; coxae and trochanters sometimes with dark brown or yellowish brown spots; pleura, except lower half of propleuron, dark brown; lower half of propleuron pale luteous; scutellum dark brown in basal half and luteous in apical half, with median pale brownish luteous portion; femora luteous; fore femora apically dark brown, sometimes with dark brown or yellowish brown suffusion; mid and hind femora apically and medially yellowish brown; tibiae dark brown. Corium and clavus yellow or brownish yellow; membrane bronzy brown, semi-hyaline. Hind wings faintly semi-hyaline. Abdominal mediotergites, except posterior half of mediotergite VII, brownish yellow; posterior half of mediotergite VII luteous; abdominal sternites pale luteous; connexivum pale luteous, with segmentally dark brown suffusions. Pygophore ventrally luteous; paramere semi-hyaline, luteous.

Structure. Body medium-sized (BL = 9.19–10.21 mm), elongate, and somewhat robust. Head subelongate and robust (HL/PoW = 2.35–2.48), as long as or a little shorter than pronotum (HL/PnL = 0.84–1.03); postocular area of head sub-globose (PoL/PoW = 0.77–0.93), distinctly wider than anteocular area (PoW/AoW = 1.36–1.43), nearly as long as anteocular area (PoL/AoL = 0.84–1.03), constricted behind compound eyes, with a wide and deep interocular sulcus; neck short. Compound eyes protruding laterally, nearly globose, with posterior margin sub-straight and sometimes concave; lateral ocelli produced, elevated behind interocular sulcus, widely separated from each other (OCD/PoW = 0.42–0.48); interspace between lateral ocelli wider than distance between compound eye and lateral ocellus (OCD/COD = 1.95–2.36). First visible labial segment shorter than second segment (R1L/R2L = 0.79–0.82), longer than anteocular area of head (R1L/AoL = 1.39–1.51), not extending beyond level of middle of compound eye when labium laid backward; proportional average length of first to third visible labial segments 1.1:1.3:0.4. Scape ~ 1.4 × as long as head; pedicel slightly shorter than first flagellomere and nearly 0.7 × as long as second flagellomere; proportional average length of scape, pedicel, first and second flagellomeres 2.9:1.4:1.5:2.0. Collar very thick in dorsal view, with anterolateral angle roundly produced laterad; anterior pronotal lobe round and bulged, slightly rough, with middle longitudinal sulcus deep and narrow posteriorly; posterior pronotal lobe shallowly depressed on disc, abundantly punctured, with slightly swollen anteromedial elevation (never sulcate or concave); humerus roughly triangular, with round apex; posterior margin of pronotum concave; posterior angles round, slightly exceeded to posterior margin of pronotum. Scutellum triangular, somewhat triangularly depressed basally, apically produced and sloping downward; posterior apex round; anterior margin slightly convex. Femora thick, apically moderately nodulose; fore femora very slightly incrassated, thicker than mid and hind femora. Hemelytra surpassing beyond apex of abdomen when fully closed, 0.8 × as long as body length; discal cell nearly parallelogram-shaped, twice as long as width; Sc 0.8 × as long as hemelytron length, 1.5 × as long as R + M. Hind wing ~ 3.3 × as long as maximum width. Connexivum slightly dilated and ascending with segmental incisures; pygophore ovoid; median process of pygophore (mpp) broad and low, 0.2 × as long as wide, with apical margin weakly and continuously convex, and with apicolateral corner slightly produced laterad and pointed; paramere long, slender, clavate, somewhat curved medially, and apically subnodulose and round (Figs 6J, 21B–E). Aedeagus in dorsal view ovoid, dorsally sclerotized (Figs 6K, 21F) and in lateral view long and narrow (Figs 6L, 21G); articulatory apparatus (aa) in ventral view with relatively broad basal plates jointly forming a V-shape, and in lateral view arched moderately (Figs 6L, N, 21G, I); dorsal phallothecal sclerite (dps) in lateral view with posteromedian part strongly produced posterodorsad (Figs 6L, 21G); spoon-like sclerites (sps) semi-hyaline and covered with tiny blunt prickles; both membranous sac-like lobes laterally produced; distal dorsal lobe of endosoma (ddl) round, with membranous surface covered with small but distinct prickles (Figs 6M, 21J).

Vestiture. Body clothed with cream-yellow setation. Head dorsum (except antenniferous tubercle, posterior base of clypeus, and gena) covered with short thick erect setae; area around antenniferous tubercle, posterior margin of clypeus, head venter, and lateral area of postocular area of head covered with short bent pubescence; head venter somewhat with a few long bent setae; maxillary plate without setae; first visible labial segment basally covered with a few erect setae; second and third visible labial segments without setae; scape with a few tiny erect setae; pedicel, first and second flagellomeres densely covered with short slender oblique setae. Anterior margin of collar densely covered with very short erect setae; dorsum of collar with bent cream-yellow pubescence; anterolateral angle and lateral region of collar with long thick erect setae, one of them placed at tip of anterolateral angle; pronotum and scutellum with long thick erect setae; lateral region of slopes of scutellum covered with long slender bent setae; posterior apex of scutellum with a pinch of long slender bent setae and long thick vertical setae; prosternum, except posterior margin, covered with long thick erect setae; posterior margin of prosternum, meso- and metasterna, pleura, and coxae abundantly covered with short bent pubescence. Corium densely covered with bent setae along anterior margin, centrally covered with short slender oblique setae. Abdomen sometimes with erect setae, slightly denser in posterior margin of abdomen; anterior margin of mediotergite I+II, anterior margin of sternite II, and lateral region of laterotergite II with very long slender erect setae; pygophore posteroventrally with some long erect setae and some bent slender setae; paramere with long thick erect setae.

Female description. General external morphology similar to that of the male.

Coloration. Almost similar to male but slightly darker than male. Abdominal mediotergites, except posterior half of mediotergite VII, dark brown and darker backward; posterior half of mediotergite VII luteous; external genitalia pale luteous.

Structure. Almost similar to male but slightly larger than male. Body medium-sized (BL = 10.11–10.91 mm). Proportional average length of first to third visible labial segments 1.1:1.4:0.4. Scape ~ 1.3 × as long as head; pedicel ~ as long as first flagellomere and ~ 0.8 × as long as second flagellomere; proportional average length of scape, pedicel, first and second flagellomeres 2.7:1.3:1.3:1.7. Sc 0.8 × as long as hemelytron length, and 1.5 × as long as R + M. Hind wing ~ 3.1 × as long as maximum width. Abdominal laterotergite VIII (AL8) with very thick posterior margin (0.09 mm); abdominal sternite VII (AS7) forming a wide subrectangular concavity, with posteromedian margin almost straight, with inner posterolateral margin weakly sinuous; gonocoxa VIII (Gc8) broad, ~ 1.2 × wider than length, slightly opened inward for gonapophyses VIII (Gp8), sinuate along outer lateral margin, almost horizontal or weakly sinuate along posterior margin, weakly produced posteromesad and forming a blunt apex at apical inner corner, and with inner margin strongly incurved in its posterior 2/3; Gp8 small and subtriangular, ~ 3 × longer than width; gonoplac (Gpl) V-shaped, with maximum thick ~ 0.05 mm.

Vestiture. Almost similar to male. Abdominal laterotergite VIII (AL8) and tergite IX (AT9) with some long thick erect setae and with shorter setae; apex of abdomen with some very long thick erect setae.

All dimensions are given in mm. Holotype (♂): BL 9.29; HL 2.01; AoL 0.75; AoW 0.60; PoL 0.62; PoW 0.81; OE 1.12; IE 0.58; ED 0.63; OD 0.16; OCD 0.35; COD 0.18; R1L 1.03; R2L 1.30; R3L 0.32; A1L 2.85; A2L 1.41; A3L 1.55; A4L 2.07; PnL 2.21; PnW 2.64; APL 0.90; PPL 1.31; HeL 7.26; HeW 2.47; Sc 5.66; R+M 3.84; HWL 4.92; HWW 1.54; AFL 3.33; ATL 3.87; MFL 2.46; MTL 3.24; PFL 3.58; PTL 4.84. Paratypes (♂): BL 9.19–10.45; HL 1.94–2.12; AoL 0.70–0.79; AoW 0.57–0.62; PoL 0.64–0.77; PoW 0.80–0.86; OE 1.08–1.17; IE 0.55–0.59; ED 0.60–0.64; OD 0.14–0.19; OCD 0.34–0.41; COD 0.15–0.18; R1L 1.03–1.14; R2L 1.26–1.41; R3L 0.32–0.46; A1L 2.68–3.06; A2L 1.30–1.55; A3L 1.37–1.61; A4L 1.74–2.17; PnL 1.95–3.10; PnW 2.42–2.74; APL 0.74–0.99; PPL 1.22–2.25; HeL 7.26–7.88; HeW 2.23–2.63; Sc 5.32–6.09; R+M 3.44–4.08; HWL 4.92–5.22; HWW 1.46–1.62; AFL 3.15–3.46; ATL 3.78–4.08; MFL 2.33–2.69; MTL 2.73–3.50; PFL 3.56–3.91; PTL 4.80–5.10. Paratypes (♀): BL 10.11–10.91; HL 2.00–2.10; AoL 0.73–0.79; AoW 0.60–0.63; PoL 0.67–0.76; PoW 0.82–0.87; OE 1.06–1.15; IE 0.55–0.60; ED 0.59–0.63; OD 0.15–0.19; OCD 0.36–0.46; COD 0.18–0.20; R1L 1.08–1.15; R2L 1.31–1.41; R3L 0.32–0.37; A1L 2.52–2.83; A2L 1.26–1.35; A3L 1.23–1.41; A4L 1.61–1.87; PnL 2.09–2.47; PnW 2.24–3.65; APL 0.70–0.88; PPL 1.39–1.65; HeL 7.66–8.21; HeW 2.60–2.92; Sc 5.86–6.32; R+M 4.01–4.45; HWL 5.25–6.82; HWW 1.67–2.15; AFL 3.00–3.33; ATL 3.63–4.07; MFL 2.31–3.13; MTL 2.94–3.83; PFL 3.33–3.80; PTL 4.61–5.13.

Vietnam, Central Highlands (Dak Lak, Gia Lai).

Vietnam, Central Highlands, Dak Lak Province, Chu Yang Sin National Park.

The new species is named after its yellow posterior pronotal lobe.

Figure 5. 

Female external genitalia of six morphospecies in ventral view A type fA, Biasticus taynguyenensis Ha, Truong & Ishikawa, sp. nov., holotype, ♀, HNL2018-073 B type fB, B. griseocapillus Ha, Truong & Ishikawa, sp. nov., holotype, ♀, HNL2018-038 C type fC, B. luteicollis Ha, Truong & Ishikawa, sp. nov., paratype, ♀, HNL2018-024 D type fD, B. flavinotus (Matsumura, 1913), ♀, HNL2018-117 E type fE, B. confusus Hsiao et al., 1979, ♀, VN-Hem-1998-012 F type fF, B. flavus (Distant, 1903), ♀, LA-Redu-2004-006.

Figure 6. 

Male genitalia of four morphospecies A–D type mA, Biasticus taynguyenensis Ha, Truong & Ishikawa, sp. nov., paratype, ♂, TXL2016-545 E–I type mB, B. griseocapillus Ha, Truong & Ishikawa, sp. nov., paratype, ♂, TXL2016-546 J–N type mC, B. luteicollis Ha, Truong & Ishikawa, sp. nov., holotype, ♂, HNL2018-025 O–R mF, B. flavus (Distant, 1903), ♂, HEM-TH2004-018. A, E, J, O pygophore with paramere(s) in dorsal view B, F, K, P phallus in dorsal view C, G, L, Q phallus in lateral view D, I, N, R articulatory apparatus H, M distal dorsal lobe of endosoma.

Figure 7. 

Biasticus flavinotus (Matsumura, 1913), ♀, TW-Redu-2014-001 A body in dorsal view B body in lateral view C head in dorsal view D head in lateral view E pronotum in dorsal view F female external genitalia in ventral view.

Figure 8. 

Biasticus confusus Hsiao et al., 1979, ♀, VN-Hem-1998-012 A body in dorsal view B body in lateral view C head in dorsal view D head in lateral view E pronotum in dorsal view F female external genitalia in ventral view.

Figure 9. 

Biasticus flavus (Distant, 1903), ♀, LA-Redu-2004-006 A body in dorsal view B body in lateral view C head in dorsal view D head in lateral view E pronotum in dorsal view.

Figure 10. 

Biasticus flavus (Distant, 1903) A female genitalia in ventral view, ♀, LA-Redu-2004-006 B–L male genitalia, paratype, ♂, HEM-TH2004-018 B–E pygophore with parameres B dorsal view C lateral view D ventral view E apical portion of pygophore showing median process (mpp) and parameres F–L phallus F dorsal view G lateral view H articulatory apparatus (aa) I phallus with endosoma semi-everted, dorsal view J aedeagus with endosoma semi-everted, ventral view K phallus with endosoma semi-everted, lateral view L distal dorsal lobe of endosoma (ddl).

Figure 11. 

2D PCA-plots from morphological dataset of the female adults (A) and male adults (B) of Biasticus collected from Vietnam and its surrounding areas.

Figure 12. 

Bayesian inference phylogenetic tree based on the concatenated 16S + Uni dataset (661 bp) of Biasticus species collected from Vietnam and its surrounding areas. Posterior probability values and bootstrap values (in %) were given beside the basal nodes. The tips are labeled with the specimen IDs. The circles after specimen IDs showed the collecting localities.

Figure 13. 

Biasticus taynguyenensis Ha, Truong & Ishikawa, sp. nov., holotype, ♀, HNL2018-073 A body in dorsal view B body in lateral view C head in dorsal view D head in lateral view.

Figure 14. 

Biasticus taynguyenensis Ha, Truong & Ishikawa, sp. nov., holotype, ♀, HNL2018-073 A pronotum in dorsal view B anterior pronotal lobe in dorsal view C, D setae on posterior pronotum E right hemelytron F right hind wing.

Figure 15. 

Biasticus taynguyenensis Ha, Truong & Ishikawa, sp. nov. A female genitalia in ventral view, holotype, ♀, HNL2018-073 B–L male genitalia, paratype, ♂, TXL2016-545 B–E pygophore with parameres B dorsal view C lateral view D ventral view E apical portion of pygophore, showing median process (mpp) and parameres F–L phallus F dorsal view G lateral view H articulatory apparatus (aa) I aedeagus with endosoma semi-everted dorsal view J aedeagus with endosoma semi-everted, ventral view K aedeagus with endosoma semi-everted, lateral view L distal dorsal lobe of endosoma (ddl).

Figure 16. 

Biasticus griseocapillus Ha, Truong & Ishikawa, sp. nov., holotype, ♀, HNL2018-038 A body in dorsal view B body in lateral view C head in dorsal view D head in lateral view.

Figure 17. 

Biasticus griseocapillus Ha, Truong & Ishikawa, sp. nov., holotype, ♀, HNL2018-038 A pronotum in dorsal view B anterior pronotal lobe in dorsal view C, D setae on posterior pronotum E right hemelytron F right hind wing.

Figure 18. 

Biasticus griseocapillus Ha, Truong & Ishikawa, sp. nov. A female genitalia in ventral view, holotype, ♀, HNL2018-038 B–M male genitalia, paratype, ♂, TXL2016-546 B–F pygophore with paramere B dorsal view C lateral view D ventral view E apical portion of pygophore, showing median process (mpp) and paramere F left paramere G–M phallus G dorsal view H lateral view I articulatory apparatus (aa) J aedeagus with endosoma semi-everted, dorsal view K aedeagus with endosoma semi-everted, ventral view L aedeagus with endosoma semi-everted, lateral view M distal dorsal lobe of endosoma (ddl).

Figure 19. 

Biasticus luteicollis Ha, Truong & Ishikawa, sp. nov., holotype, ♂, HNL2018-025 A body in dorsal view B body in lateral view C head in dorsal view D head in lateral view.

Figure 20. 

Biasticus luteicollis Ha, Truong & Ishikawa, sp. nov., holotype, ♂, HNL2018-025 A pronotum in dorsal view B anterior pronotal lobe in dorsal view C setae on posterior pronotum D right hemelytron E right hind wing.

Figure 21. 

Biasticus luteicollis Ha, Truong & Ishikawa, sp. nov. A female external genitalia in ventral view, paratype, ♀, HNL2018-024 B–J male genitalia, holoype, ♂, HNL2018-025 B–E pygophore with parameres B dorsal view C lateral view D ventral view E apical portion of pygophore, showing median process (mpp) and parameres F–H phallus F phallus with endosoma semi-everted, dorsal view G phallus with endosoma semi-everted, lateral view H phallus with endosoma semi-everted, ventral view I articulatory apparatus (aa) J distal dorsal lobe of endosoma (ddl).