Diochus paradoxus Huang, Janák & Zhou, 2025

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

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

Type locality. Indonesia: Sumatra: Aceh.

Type material. Holotype: male, INDONESIA: Sumatra: Aceh #25b, Mt. Leuser NP , 300–500 m, Ketambe , 23–30. XI. 1989, Löbl, Agosti, Burckhardt ( MHNG) . Paratypes: INDONESIA: Sumatra: 1 male, 1 female, Aceh #25a, Mt. Leuser NP , 300–500 m, Ketambe , 23–30. XI. 1989, Löbl, Agosti, Burckhardt ( MHNG) .

Measurements. BL = 6.75 mm, FL = 2.59 mm, HL = 0.74 mm, HW = 0.54 mm, EyL = 0.19 mm, TL = 0.44 mm, ANL = 1.62 mm, ANT1 = 0.27 mm, ANT2 = 0.13 mm, ANT3 = 0.18 mm, ANT4 = 0.14 mm, ANT 11 = 0.17 mm, PL = 1.00 mm, PW = 0.78 mm, EL = 0.92 mm, EW = 1.04 mm, SL = 0.66 mm.

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

Head (Fig 5-1A). Oblong in shape, 1.38 times as long as wide. Tempora straight and 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 small-sized, distinctly protruding laterad, longitudinal diameter slightly shorter than half the length of tempora (eye: tempora = 0.43). Epistoma not flattened, abruptly oblique, anterior margin slightly emarginate medially. Distance between antennal insertions (0.16 mm) distinctly longer than distance from antenna to eye (0.07 mm). Ventral surface with sparsely scattered punctures, interspaces between them as large as about 5 puncture diameters. Gular sutures deep, confluent near basal 1/4 to 1/3, then extended to base.

Antennae (Fig 5-1B). Scape rod-shaped, slightly thickened apically, slightly shorter than two subsequent antennomeres combined; antennomere 2 elongate; antennomere 3 distinctly 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 (Fig 5-1A). Labrum nearly hexagonal, lateral margins rounded, widest at basal 1/2; anterior margin about half of 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 0.18 mm, about 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 1.27), distinctly longer and wider than head.Anterior region near anterior angles 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 and small, 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 distinctly transverse (EL to EW ratio 0.89), shorter but 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, moderately dilated, and those of meso- and metatarsi slender. Last segment of protarsi slightly shorter than 2−4 together, that of meso-, meta- slightly shorter than 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–J; 5-2A–E). Head with an elongate elevation between eyes. Posterior margin of sternite VIII emarginate medially, emargination deep and rounded, also emarginate on each side, with posterior angles sharpened (Figs 5-1E; 5-2B). Posterior margin of tergite VIII arcuate (Figs 5-1F; 5-2C). Tergite IX (Figs 5-1H; 5- 2D) symmetrical, connected mediobasally, narrowed apically. Sternite IX (Figs 5-1G; 5-2E) symmetrical, widest at basal 1/3; basal margin nearly straight, apical margin slightly emarginate; width of apical margin about 2/3 of basal margin. Tergite X (Figs 5-1H; 5-2D) symmetrical, triangular. Aedeagus (Figs 5-1I−J; 5-2A) symmetrical, medium-sized, ca. 0.67 mm long, normally sclerotized. Parameres symmetrical, reaching top of median lobe. Internal structures sclerotized, an irregular shaped large sclerite and paired rectangular shaped sclerites in middle; an elongated sclerite and a round sclerite at bottom. Sperm pump coiled, thinned toward apex.

Female (Figs 5-2F−I). Head without elevation between eyes. Sternite VIII (Fig 5-2F) with posterior margin rounded. Tergite IX bearing numerous setae, elongate and sharply pointed apically. Sternite IX (Fig 5-2H) symmetrical, with deep concaved margin in middle. Tergite X broad, basal margin curved. Sternite X (Fig 5-2G) slender and rhomboidal, with numerous setae in lower half. Tube of spermatheca sclerotized and wavy in middle part, with three bends (Fig 5-2I).

Distribution. Indonesia (Sumatra).

Diagnosis. According to nearly similar aedeagal structures, we suggest this new species and D. paraparadoxus sp. nov. to be closely allied, but the former can be distinguished from the latter by smaller body size, distinctly deeper emargination on the posterior margin of male sternite VIII and longer parameres of the aedeagus.

Etymology. The species epithet is from the latinized Greek word paradoxus.