Hydrovatus globosus, Bistroem, Olof & Bergsten, Johannes, 2016

Bistroem, Olof & Bergsten, Johannes, 2016, Two new species of the megadiverse lentic diving-beetle genus Hydrovatus (Coleoptera, Dytiscidae) described from NE Thailand, ZooKeys 632, pp. 57-66 : 61-62

Taxon classification Animalia Coleoptera Dytiscidae

Hydrovatus globosus sp. n.

Type locality.

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

Type material

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).

Diagnosis.

The new species belongs to a complicated group of Hydrovatus , out of which Hydrovatus 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 Hydrovatus globosus (Fig. 2 d–f).

Description.

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. 2 d–g.

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

Distribution.

Thailand.

Collecting circumstances.

Entire type material collected at light.

Etymology.

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