Diochus balangensis Huang, Janák & Zhou, 2025

5. Diochus balangensis Huang, Janák & Zhou , sp. nov.

( Figs 1L View FIGURE 1 ; 6-1; 6-2)

Type locality. Thailand: Balang Nat. Park , Than To Waterfall.

Type material. Holotype: male, THAILAND: Balang Nat. Park, Than To Waterfall, Than To Dist ., 150 m, 1. 2. 1993, P. Schwendinger ( MHNG) . Holotype with an identification label: “ HOLOTYPUS Diochus balangensis sp. nov. Huang, Janák & Zhou det. 2024”.

Measurements. BL = 4.39 mm, FL = 2.12 mm, HL = 0.59 mm, HW = 0.45 mm, EyL = 0.15 mm, TL = 0.33 mm, ANL = 1.28 mm, ANT1 = 0.15 mm, ANT2 = 0.12 mm, ANT3 = 0.13 mm, ANT4 = 0.10 mm, ANT 11 = 0.14 mm, PL = 0.80 mm, PW = 0.61 mm, EL = 0.75 mm, EW = 0.76 mm, SL = 0.56 mm.

Description. Body long, narrowed anteriorly and posteriorly, medium-sized. Body dark brown, abdominal intersegmental membrane lighter. Legs brown, tarsi distinctly lighter. Antennae brown, apex of each antennomere lighter. Maxillary and labial palpi brown.

Head (Fig 6-1A). Oblong in shape, 1.31 times as long as wide. Tempora straight and nearly parallel, posterior angles rounded. Dorsal surface shiny, bearing distinct and transverse microstriae, also with coarse and sparse punctures. Head with 5−7 irregular punctures scattered around each eye and numerous smaller punctures on deflexed portion of temple and near posterior margin. Each side of head with characteristic punctures: one frontal puncture on frontal region, two anterolateral punctures near antennal insertion, three lateral punctures near dorsal margin of eye, with temporal puncture and occipital puncture near basal margin; disc surface bearing two additional paired punctures in middle area. Frontal furrows and anteocular furrows absent. Eye medium-sized, distinctly protruding laterad, longitudinal diameter slightly shorter than half the length of tempora (eye: tempora = 0.45). Epistoma not flattened, abruptly oblique, anterior margin slightly emarginate medially. Distance between antennal insertions (0.12 mm) distinctly longer than distance from antenna to eye (0.08 mm). Ventral surface with scattered punctures, interspaces between them as large as about 4 puncture diameters. Gular sutures deep, confluent at basal 1/4, then extended to base.

Antennae (Fig 6-1B). Scape rod-shaped, slightly thickened apically, distinctly shorter than two subsequent antennomeres combined; antennomere 2 slightly elongate, antennomere 3 slightly longer than 2; length of antennomere 4 about twice of width, antennomere 4 to 10 gradually shortened, antennomere 4 observably longer than 10; antennomere 11 distinctly longer than 10.

Mouthparts. Labrum oval shaped, lateral margin rounded, widest at basal 1/3 to 1/2; width of anterior margin about 1/3 the width at the widest point. Mandibles (Fig 6-1D) falciform, left one with three small teeth on inner margin, whereas right one with two.

Neck (Fig 6-1A). Cylindrical, shiny, only bearing shallow microsculpture, width 0.15 mm, about 1/3 the head width. Dorsal surface with distinct groove; ventral surface with gular sutures forming obvious triangular region, with deep transverse median furrow.

Prothorax (Fig 6-1A). Pronotum elongate (PL to PW ratio 1.29), distinctly longer and wider than head. Anterior region near anterior angles slightly deflexed, lateral margins widened posteriad to basal 1/4 (widest at 1/4), then convergent backwards, anterior and posterior angles broadly rounded. Dorsal surface glossy, extensively with micropunctures, but without any microsculpture. Each side of longitudinal midline with one row of punctures composed of 3 large punctures and 2 additional punctures outside of puncture row, 13–15 punctures scattered near each margin (including anterior, lateral and posterior margins). Prosternum bearing an observable transverse ridge between basisternum and furcasternum, angularly backwards.

Pterothorax (Fig 6-1A). Mesoscutellum triangular, surface shiny, bearing distinct microstriae, but without any punctures. Transverse ridge on mesoventrite wave shaped; paired oblique furrows short but deep; carina limiting mesocoxal cavity slightly arcuate. Discrimen region on metaventrite normally elevated.

Elytra (Fig 6-1A). Elytra slightly transverse (EL to EW ratio 0.98), distinctly wider but shorter than pronotum. Humeri well developed, lateral margins divergent posteriorly, posterior margin not rounded, but obliquely truncate. Dorsal surface shiny, flattened, without microsculpture; each elytron with row of 5 punctures along suture, row of 5 punctures on disc, also with 4−5 rows of punctures on deflexed portion.

Legs (Fig 6-1C). First four segments of protarsi heart-shaped, moderately dilated, and those of meso- and metatarsi slender. Last segment of protarsi about the length of 2−4 together, that of meso-, meta- slightly shorter the length of each 2−3.

Abdomen. Broadest at segment V. Tergites III–VII covered with dense and obvious transverse microstriae; each tergite with dense brown pubescence, also with row of darker and coarser setae at posterior margin of III–VI. Tergites III–VII with a basal impression near anterior margin, respectively, each one only possessing one basal transverse carina; all abdominal tergites with surface shiny, bearing polygonal microsculpture, with dense punctures. Posterior margin of tergite VII with distinct palisade fringe. All abdominal sternites shiny, with microstriae and punctures as those on tergites.

Male (Figs 6-1E−J; 6-2A–E). Head with elongate elevation between eyes. Posterior margin of sternite VIII emarginate medially (Figs 6-1E, H; 6-2B). Posterior margin of tergite VIII arcuate (Figs 6-1F; 6-2C). Tergite IX (Figs 6-1H; 6-2D) symmetrical, connected mediobasally, narrowed apically. Sternite IX (Figs 6-1G; 6-2E) symmetrical, widest near basal 1/2 to 1/3; basal margin straight, apical margin slightly emarginate; width of apical margin distinctly shorter than basal margin. Tergite X (Figs 6-1H; 6-2D) symmetrical, triangular. Aedeagus (Figs 6- 2I−J; 6-2A) symmetrical, medium-sized, ca. 0.54 mm long, normally sclerotized. Parameres symmetrical, reaching about apical quater of median lobe. Internal structures sclerotized with several irregular and black sclerites distally; black, paired strip-shaped and black paired rectangular sclerites in middle; an elongate, brown sclerite basally. Sperm pump coiled, thinned toward apex.

Female. Unknown.

Distribution. Thailand.

Diagnosis. The new species is similar to D. bilobatus sp. nov. and D. bisegmentatus in appearance, and in the medially emarginate posterior margin of male sternite VIII. However, the pronotum is distinctly elongate and longer than the elytra in the new species, the basal furrow of male sternite VIII is not so deeply emarginate, basal margin of male sternite IX is straight, and the aedeagus possesses numerous irregular sclerites distally, which can distinguish it from these two species.

Etymology. The species name refers the type locality.