Hydrovatus diversipunctatus, 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 : 59-61

Taxon classification Animalia Coleoptera Dytiscidae

Hydrovatus diversipunctatus sp. n.

Type locality.

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

Type material

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).

Diagnosis.

The new species is undoubtedly closest to Hydrovatus subrotundatus Motschulsky. These two species share the characteristics of having the lateral elytral margin clearly visible from above (Fig. 1 a–b, compare with Fig. 1 c–d). The two species are distinguished by clear difference in body size and shape; Hydrovatus diversipunctatus is larger and less rounded-globular than Hydrovatus subrotundatus . Moreover, Hydrovatus 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 Hydrovatus subrotundatus , while frontal margin in Hydrovatus diversipunctatus fades away close to eyes. Shape of male genitalia is quite similar in the two species. Penis is, however, slightly broader in Hydrovatus diversipunctatus , while parameres seem to be a little more slender, compared with corresponding structures in male genitalia of Hydrovatus subrotundatus .

Description.

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. 2 a–c.

Female: Externally similar to male.

Distribution.

Thailand.

Collecting circumstances.

Type material collected at light.

Etymology.

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