Thailand: Khon-Kaen [city and province in the region of Isan, NE Thailand].

8 exs. (1 male, 7 females). Holotype, male: “Nordost-Thailand Khon-Kaen ad lucem / Dr. Sastri Saowakontha leg. 28.4.1980” (HNHM). - Paratypes: Same data as holotype (1 ex. FMNH); same data as holotype but “25.IV.1980” (1 ex. HNHM, 1 ex. NHRS); same data as holotype but “22.IV.1980” (2 exs. HNHM, 1 ex. FMNH); same data as holotype but “20.5.1980” (1 ex. HNHM).

The new species is undoubtedly closest to H. subrotundatus Motschulsky. These two species share the characteristics of having the lateral elytral margin clearly visible from above (Fig. 1a–b, compare with Fig. 1c–d). The two species are distinguished by clear difference in body size and shape; H. diversipunctatus is larger and less rounded-globular than H. subrotundatus. Moreover, H. diversipunctatus deviates by having much coarser pronotal punctures in comparison with general punctation of elytra (diameter of pronotal punctures about 4× larger than general punctures of elytra). Additionally, head between eyes has complete frontal margin in H. subrotundatus, while frontal margin in H. diversipunctatus fades away close to eyes. Shape of male genitalia is quite similar in the two species. Penis is, however, slightly broader in H. diversipunctatus, while parameres seem to be a little more slender, compared with corresponding structures in male genitalia of H. subrotundatus.

Figure 1. 

Dorsal habitus of H. diversipunctatus sp. n. (a), H. subrotundatus (b), H. globosus sp. n. (c) and H. r. rufoniger (d). Scale bar 3 mm.

Body: Almost entirely blackish ferrugineous, with no distinct color pattern. Body-shape not globular but slightly elongated. Broadest posterior to humeral region and from there posteriorly slightly narrowed until abruptly curved towards apex of elytra. Lateral margin between epipleura and elytra pronounced and clearly discernible from above (Fig. 1a). Length of body 3.1–3.3 mm, width 2.0–2.1 mm.

Head: Blackish ferrugineous; near frontal margin head slightly paler, dark ferrugineous. Very finely and sparsely punctate. At eyes and in rather shallow, frontal depressions with some fine punctures. Rather shiny, although finely microsculptured. Reticulation clearly discernible except on minor tubercles frontally close to eyes where reticulation is obliterated. Frontal outline of head rounded, medially slightly straightened. Frontal margin fades away on minor tubercles close to eyes. Antenna pale ferrugineous, slender and with no modifications.

Pronotum: Blackish ferrugineous, laterally with vague dark ferrugineous areas. Densely and distinctly punctate; laterally punctures become sparse and slightly finer. Rather shiny, although distinctly microsculptured; meshes clearly discernible. Sides of pronotum slightly rounded to almost straight; anteriorly distinctly curved inwards.

Elytra: Finely and sparsely punctate. Rows of punctures indistinct and weakly developed except from discal row, which basally is quite distinct. Rather shiny, although very finely microsculptured; reticulation weak but extensively still discernible. Narrowly, close to epipleura reticulation in part obliterated. Epipleura dark ferrugineous; finely punctate frontally at inner margin.

Ventral aspect: Dark ferrugineous, except abdomen, apically slightly paler, ferrugineous. Almost impunctate, except for metacoxal plates and metathorax, which in part are covered with fine to rather fine punctures. Rather shiny with fragments of microsculpture, except abdomen which is entirely microsculptured. Prosternal process laterally with fine margin; medial surface almost flat and punctured. No stridulatory apparatus on metacoxal plates.

Legs: Pale ferrugineous to ferrugineous. Pro- and mesotarsus slightly enlarged. Claws simple.

Male genitalia as in Fig. 2a–c.

Figure 2. 

Male genitalia of H. diversipunctatus sp. n. (a–c) and H. globosus sp. n. (d–g). a, d penis, dorsal aspect b, f penis, lateral aspect c, g paramere e penis, frontal part from above. Scale bar in upper right corner 0.5 mm for a–d, f–g. Scale bar next to (e) 0.5 mm, applies to only e.

Female: Externally similar to male.

Thailand.

Type material collected at light.

The species name diversipunctatus refers to the large difference in size between general punctures of pronotum in comparison to those of elytra.

Thailand: Khon-Kaen [city and province in the region of Isan, NE Thailand].

25 exs. (10 males, 15 females). Holotype, male: “Nordost-Thailand Khon Kaen, ad lucem 22.4. 1980 leg. S. Saowakontha” (HNHM). – Paratypes: Same data as holotype (11 exs. HNHM, 3 exs. FMNH, 3 exs. NHRS); same data as holotype but “20.5. 1980” (2 exs. HNHM, 1 ex. FMNH); same data as holotype but “29.4. 1980 Dr. Saati Saowakontha leg.” (1 ex. HNHM); same data as holotype but “2.9. 1980 Dr. Saati Saowakontha leg.” (1 ex. HNHM); same data as holotype but “19.2. 1981 Dr. Saati Saowakontha leg.” (2 exs. HNHM).

The new species belongs to a complicated group of Hydrovatus, out of which H. rufoniger (Clark) (Fig. 1d) seems to be closest. The new species is distinguished from this species but also other close species from the Oriental region, by its globular shaped body with a very weak extension of the elytral apex (Fig. 1c). Deviating structures in the shape of the penis apex are also characteristic for H. globosus (Fig. 2d–f).

Body: Almost unicolored ferrugineous to dark ferrugineous; no distinct color-pattern exhibited. Body-shape almost globular with apex of elytra moderately extended (Fig. 1c). Length 3.8–4.0 mm, width 2.4–2.6 mm.

Head: Anteriorly between eyes finely margined; outline slightly undulate (frontal edge medially, weakly curved inwards). At each eye with a quite distinct, triangular depression with irregular punctures in it. Close to eye with a row of fine punctures and from frontal depression a row of punctures continues sparsely (disappears gradually) towards middle of head. Other parts of head surface impunctate with scattered, fine and hardly discernible punctures anteriorly. Head slightly matte to rather shiny; extensively finely reticulated. Antenna filiform, with no distinct modifications.

Pronotum: With dense and fine punctures, which laterally fade away gradually. Surface between punctures shiny, almost without reticulation. Laterally, fine, in part indistinct reticulation discernible.

Elytra: Finely and densely punctate. Laterally, punctures fade away and become indistinct/disappear in part. Discal, dorsolateral and lateral row of punctures rather indistinct and in part hardly discernible. Between punctures, surface rather shiny; reticulation very fine and sporadically discernible; extensively reticulation almost absent.

Ventral aspect: Finely to fairly finely and somewhat sparsely punctate. Abdomen almost impunctate. Shiny, reticulation almost absent; hardly visible, rudimentary meshes of microsculpture discernible on metacoxal plates. Abdomen slightly matte; with very fine, elongated meshes of microsculpture. Stridulation apparatus rather narrow, provided with numerous minute striae. Apex of prosternal process laterally finely margined; medial surface flattened with sparse and vague punctures. Apical ventrite medially with a distinct depression; extreme apex of ventrite with a fine bulb (a minor enlargement).

Legs: Ferrugineous. Pro- and mesotarsus slightly enlarged. Protarsal claws asymmetric; internal claw distinctly angled and thickened.

Male genitalia as in Fig. 2d–g.

Female: Elytra posteriorly rather distinctly microsculptured, matte. Protarsal claws not modified. No stridulation apparatus on metacoxal plates.

Thailand.

Entire type material collected at light.

The species name globosus refers to the spherical body-shape of the new species.