Odontolabis pareoxa subsp. vietnamensis Yamamoto & Pham 2025, new subspecies

Odontolabis pareoxa vietnamensis Yamamoto & Pham, new subspecies (Figs 1–6; 7C) Odontolabis pareoxa: Bartolozzi & Bambi 2019: 266. Odontolabis sp.: Maruyama 2024: 31, 91. Type locality. Vietnam, Yên Bái. Type material. (11♂♂). Holotype: ♂ (telodont form), “N. Vietnam: / Yen Bai, / July 2023 ” (IEBR). Paratypes (n=10): 1 ♂ (priodont form), Mù Cang Chải, Yên Bái, Vietnam, June 2020 (IEBR); 1 ♂ (telodont form), same data, but August 2021 (IEBR); 1 ♂ (telodont form), same data, September 2022 (IEBR); 1 ♂ (amphidont form), same data, but June 2023 (IEBR); 1 ♂ (amphidont form), Yên Bái, North Vietnam, June 2020 (IEBR); 1 ♂ (telodont form), same data, but July 2020 (IEBR); 2 ♂♂ (mesodont form), same data, but May 2021 (IEBR); 1 ♂ (telodont form), same data, but June 2021 (IEBR); 1 ♂ (telodont form, damaged), same data, but August 2021 (IEBR). Diagnosis. The new subspecies is closely allied to the nominotypical subspecies in general appearance but can be differentiated by the following combination of characters in the males: 1) Post-ocular margin less developed, only weakly to moderately produced laterally (Fig. 7C), rather than strongly projecting laterally (Fig. 7A, B); 2) Pronotal anterolateral margins, particularly in the telodont form, usually smooth and rounded (sometimes only weakly emarginate) (Fig. 7C), instead of apparently roundly emarginate (Fig. 7A, B); 3) Pronotal anterior angles more or less rounded (Figs 4A; 7C), whereas those being angulate in O. pareoxa pareoxa (Fig. 7A, B); 4) Pronotal posterolateral angles, especially in the telodont form, only weakly emarginate (Fig. 7C), rather than deeply and strongly emarginate (Fig. 7A, B). Description of holotype, telodont male. Size small for the genus, BLM: 45.3 mm. Measurements of different body parts in millimetre (mm): BL, 33.5; BW, 16.4; ML, 12.2; HL, 6.1; HW, 13.1; PL, 8.5; PW, 16.4; EL, 19.1; EW, 15.7. Body (Fig. 1A–C) rather narrowly elongate, about 2.8 times (with mandibles) longer than wide. Surface (Fig. 1A–C) generally glabrous; dorsal surface matte in forebody, but strongly glossy in elytra (Figs 1A; 3A). Color uniformly blackish-brown to black; tarsi ventrally with yellowish-reddish brown fine and dense setae. Head (Figs 1A–C; 3A; 4A, C, D) comparatively small, rectangular, moderately transverse, about twice as wide as long, widest across post-ocular projection, maximum width narrower than that of pronotum or elytra; surface matte textured; anterior margin broadly emarginate, somewhat vertically, shield-like in frontal view (Fig. 4D); pre-ocular margin with canthus well developed, flattened, with broadly arcuate lateral margin (Fig. 4A); post-ocular margin or temple (Figs 1A; 4A) somewhat projecting laterally, very slightly beyond level of ocular canthus; frons and vertex with large and shallow depression forming inverted triangle. Eyes (Figs 1A–C; 3A; 4A, C) moderately large, each completely margined with developed canthus. Mandibles (Figs 1A–C; 3A; 4A, C) long, slender, L-shaped, strongly curved near basal 1/3, about 2.0 times as long as head, shorter than head capsule and pronotum combined; first (basal) inner teeth short, inconspicuous, weakly directed inwards; median inner teeth absent; subapical longest (2 nd) inner teeth short, simply pointed inward, with serration consisted of two small teeth between 2 nd inner teeth and apex of mandibles (Fig. 4A). Clypeus small, narrow, weakly produced anteriorly, not visible dorsally. Antennae (Fig. 4A, C) with three-segmented club. Mentum (Fig. 4C) strongly transverse, trapezoidal, about 2.7 times wider than long, with weakly bilobate anterior margin, lacking keel in middle. Pronotum (Figs 1A; 3A; 4A) short and wide, about 1.9 times wider than long; anterior margin with median area only weakly produced apically; pronotal anterolateral margins smooth, arcuate (not roundly emarginate); pronotal anterior angles rounded, rather than angulate; lateral margins in apical 3/4 almost parallel (except apical narrrowing), only very weakly narrowed apically; basolateral margins rather weakly emarginate, forming obtusely acute posterolateral angles; posterior margin moderately sinuate; disc leathery, uniformly finely granulate. Prosternal process between procoxae (Figs 1C; 4C, D) strongly produced, subparallel-sided, with rounded apex. Scutellum (Fig. 4A) subtriangular, slightly wider than long, uniformly black; surface leathery, finely granulate. Elytra (Figs 1A; 3A) long, elongate-oval, about 1.2 times longer than wide, broadest in basal 1/4; shoulders obtusely angulate; lateral margins broadly curved; surface smooth, very strongly glossy, coarsely very finely punctate, without metallic sheen. Legs (Figs 1A–C; 3A; 4A, C) short; protibiae somewhat thick, straight, gradually widened apically, with three noticeable and one inconspicuous teeth and apical bifurcate paired teeth along outer margins in apical half (Fig. 4A, C); protibial teeth short, moderately developed, somewhat wide but acutely projecting; mesotibiae straight, with row of yellowish dense microsetae along inner edges, outer margins without external spines, apices with large apical spines; metatibiae similar structure and size with mesotibiae (but with shorter apical outer spines), as long as metatarsi. Abdomen (Fig. 1B) short, broad, strongly tapering posteriorly; ventrite V about 1.3 times as long as ventrite IV, with feebly medially emarginate apex. Tergite VIII (Fig. 5A) crescent shape, with membranous band along basal (anterior) margin, with incised longitudinal membranous area along midline of basal half. Sternite VIII (Fig. 5B) very strongly transverse, with small emargination along basal margin medially. Pleurite IX (Fig. 5C) not conterminous dorsally, well separated by membranous area. Sternite IX (Fig. 5D) with posterior margin weakly sclerotized. Aedeagus (Fig. 6A–D) elongate, about 2.9 times longer than wide; basal piece (Fig. 6B–D) slightly longer than parameres, moderately constricted in basal part, constriction somewhat narrowed in dorsal and ventral views (Fig. 6B, C) or nearly straight in lateral view (Fig. 6D); flagellum thick and very long, weakly expanded at apex; parameres simple, with apex curved outward, acutely pointed in lateral view (Fig. 6D). Variation. Male paratypes (n=10). Large sized (i. e., telodont form) males much more easily and frequently found than those of nominotypical subspecies (cf. BLM: 28.0– 45.2 mm in O. pareoxa pareoxa; Maruyama 2024). Telodont form (Figs 1D–F): body shape and size (BLM: 42.4–46.3 mm (average 44.68± 1.79 mm, n=5)) generally similar to the holotype without evident morphological variations, but one specimen (Fig. 1E) with protibial teeth seemingly more developed. Mesodont and amphidont forms (Figs 2A, B; 3B, C; 4B): body size (BLM: 35.1–38.6 mm) smaller, with mandibles similar to those of mesodote and amphidont forms in O. pareoxa pareoxa and O. platynota; head with anterior margin not shield-like in frontal view (Fig. 4E; protibiae and other features generally matched with the holotype). Priodont form (Figs 2D–F; 3D; 4E): body size (BLM: 30.8 mm) much smaller, with short and entirely serrate mandibles; head with anterior margin not shield-like in frontal view (Fig. 4E), post-ocular projection slightly but more produced (Fig. 2D); protibiae and other features generally matched with the holotype. Measurements of the paratypes (n=10) in millimetres: BLM, 30.8–46.3; BL, 26.2–34.5; BW, 12.9–16.4; ML, 4.6– 13.1; HL, 4.1–6.9; HW, 9.2–13.4; PL, 6.8–8.7; PW, 12.9–16.4; EL, 16.1–20.2; EW, 12.4–16.1. Female. Unknown. Etymology. This new subspecies is named after the country of origin, Vietnam. Distribution. Vietnam (Yên Bái, but also in Lào Cai based on Bartolozzi & Bambi 2019). Bionomics. The detailed lifestyle has not been known yet, although the specimens were collected from early to late summer (May–September).