Diochus umphangensis Huang, Janák & Zhou, 2025

4. Diochus umphangensis Huang, Janák & Zhou , sp. nov.

( Figs 1N View FIGURE 1 ; 5-1; 5-2)

Type locality. Thailand: Mts. n Umphang , Mae sot Umphang.

Type material. Holotype: male, THAILAND: Mts. n Umphang, Mae sot Umphang , 1250 m, 10. 2. 93, Schwendinger ( MHNG) . Holotype with an identification label: “ HOLOTYPUS Diochus umphangensis sp. nov. Huang, Janák & Zhou det. 2024”.

Measurements. BL = 3.93 mm, FL = 1.86 mm, HL = 0.52 mm, HW = 0.44 mm, EyL = 0.12 mm, TL = 0.31 mm, ANL = 0.98 mm, ANT1 = 0.15 mm, ANT2 = 0.09 mm, ANT3 = 0.10 mm, ANT4 = 0.08 mm, ANT 11 = 0.10 mm, PL = 0.64 mm, PW = 0.57 mm, EL = 0.65 mm, EW = 0.78 mm, SL = 0.51 mm.

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

Head (Fig 5-1A). Oval shaped, 1.17 times as long as wide. Tempora distinctly widened backwards, posterior angles rounded. Dorsal surface shiny, bearing distinct 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 small-sized, distinctly protruding laterad, longitudinal diameter distinctly shorter than half the length of tempora (eye: tempora = 0.38). Epistoma not flattened, abruptly oblique, anterior margin slightly emarginate medially. Distance between antennal insertions (0.11 mm) distinctly longer than distance from antenna to eye (0.06 mm). Ventral surface with scattered punctures, interspaces between them large about as 4 puncture diameters. Gular sutures deep, confluent near base.

Antennae (Fig 5-1B). Scape rod-shaped, slightly thickened apically, shorter than two subsequent antennomeres combined; antennomere 2 slightly elongate, antennomere 3 about the length of 2; length of antennomere 4 slightly longer than 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 is about 1/2 the width at the widest point. Mandibles (Fig 5-1D) falciform, left one with three small teeth on inner margin, whereas right one with two.

Neck (Fig 5-1A). Cylindrical, shiny, only bearing shallow microsculpture, width 0.13 mm, shorter than 1/3 of head width. Dorsal surface with distinct groove; ventral surface with gular sutures forming obvious triangular region, with deep transverse median furrow.

Prothorax (Fig 5-1A). Pronotum elongate (PL to PW ratio 1.12), distinctly longer and wider than head. Anterior region near anterior angles strongly 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 5-1A). 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 5-1A). Elytra transverse (EL to EW ratio 0.84), longer and wider 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 5-1C). First four segments of protarsi heart-shaped, dilated, and those of meso- and metatarsi slender. Last segment of protarsi distinctly shorter than 2−4 together, that of meso-, meta- nearly equal to 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 5-1E–I; 5-2A–D). Head with small oval elevation between eyes. Posterior margin of sternite VIII slightly emarginate medially (Figs 5-1E; 5-2B). Posterior margin of tergite VIII arcuate (Figs 5-1G; 5-2C). Sternite IX (Figs 5-1F; 5-2D) symmetrical, widest near basal 1/3 to 1/2; basal margin nearly straight, apical margin slightly emarginate; width of apical margin slightly shorter than basal margin.Aedeagus (Figs 5-1H−I, M; 5-2A) symmetrical, medium-sized, ca. 0.53 mm long, mostly membranous. Parameres long and symmetrical, nearly reaching the apical part of median lobe. Internal structures sclerotized, with paired rectangular sclerites in middle, in brown color and an elongated sclerite in bottom, in brown color. Sperm pump coiled, thinned toward apex.

Female. Unknown.

Distribution. Thailand.

Diagnosis. This new species is small in size and with short antennae, similar to D. antennatus . The main difference is the shape of sternite VIII: the new species has a less elongated sternite VIII in male. Moreover, this new species has a rounded head and distinctly shorter antennomeres (antennomeres 6–10 transverse), which can be also used to distinguish it from other species.

Etymology. The species name refers to the type locality.