Hydroporus sejilashan, Jia, Fenglong, Zhao, Shuang & Fery, Hans, 2012

Jia, Fenglong, Zhao, Shuang & Fery, Hans, 2012, Hydroporus sejilashan sp. n., a new diving beetle of the acutangulus - complex from Xizang, China (Qinghai-Tibet Plateau), and notes on other taxa of the genus (Coleoptera, Dytiscidae, Hydroporinae), Zootaxa 3223 (1), pp. 55-67 : 58-60

publication ID	https://doi.org/ 10.11646/zootaxa.3223.1.4
DOI	https://doi.org/10.5281/zenodo.5914731
persistent identifier	https://treatment.plazi.org/id/952587BC-1C7E-FF96-FF32-FC6866EFFD67
treatment provided by	Plazi
scientific name	Hydroporus sejilashan
status	sp. nov.

Treatment

Hydroporus sejilashan View in CoL sp. n.

Type locality: China, Xizang Autonomous Region, ca. 20 km SEE Linzhi [= Nyingchi], Sejilashan mountains; ca. 29.62N 94.60E, altitude ca. 4100–4200 m.

Type material: Holotype: 3, " China, Xizang (Tibet), Linzhi, Sejilashan mountains, ca. 29.62N 94.60E, 4100- 4200 m, 12.– 18.8.2009, leg. Fenglong Jia" [printed], a further label with same text, but with Chinese letters, " Holotype, Hydroporus sejilashan sp. n., Jia, Zhao & Fery det." [red, printed] ( SYSU). Paratypes: 121 exs, same label data, but with the respective red paratype label ( SYSU, CGC, CHF).

Habitus elongate oval ( Fig. 5 View FIGURES 1 – 5 ), appearing slightly parallel-sided; maximum width behind middle of total length, more or less in middle of elytral length. Dorsal and ventral surface almost entirely black, microreticulated and matt. Pronotum at posterior angles slightly broader than elytra at base (but by far not so distinctly broader than in the members of the sibiricus -group), thus, outline in dorsal view here with a slight discontinuity.

Head black, with indistinct transverse dark brownish marking near anterior margin of clypeus and on vertex; above antennal cavity indistinct transparent brownish spot. Interocular distance distinctly smaller than half of pronotal width at posterior angles. Between eyes with two nearly triangular clypeal grooves. Reticulation of head distinct, on large parts with even, polygonal, more or less isodiametric meshes; at anterior margin and on vertex transversely elongate; in clypeal grooves meshes smaller and more strongly impressed. Punctation sparse, absent on vertex, diameter of punctures equalling that of meshes on clypeus; in clypeal grooves punctation coarser and denser; next to inner margin of eye with a distinct line of impressed punctures. Setation absent. First and second antennomeres dark brown; third and fourth proximally dark brown, distally black; rest of antennomeres black. First maxillary and labial palpomeres reddish brown, others largely darkened. Third and fifth antennomeres rather short, fourth still shorter, almost as wide as long; fifth to eighth about one and a half times as long as wide, ninth and tenth somewhat longer, eleventh more than two times longer than wide.

Pronotum entirely black. Maximum width between posterior angles; in dorsal view sides almost straight in posterior two thirds, before curved to anterior angles. Lateral bead broader than half of diameter of antennomeres, more or less of same width over entire length. Between disc and posterior margin pronotum slightly impressed over about half of its width, thus, disc appearing somewhat vaulted; with shallow impression at posterior angles. Surface rather uniformly reticulated, meshes more or less of same diameter as on clypeus; in posterolateral impressions somewhat smaller. Punctation on disc similar to that on clypeus and frons, behind and towards sides coarser and slightly denser; middle of pronotum with a very large puncture; near anterior margin with several finer punctures, behind them a line of irregularly placed rather coarse punctures perceptible. Most punctures provided with a transparent whitish, rather long seta (ca. 0.05 mm).

Elytra entirely black as pronotum; surface appearing slightly more matt than on head and pronotum. Base of elytra slightly narrower than pronotal base. In dorsal view sides of elytra rather weakly curved in anterior two thirds, behind stronger curved to apex. In lateral view elytral margin very slightly ascending towards humeral angle, straight directly before angles, far behind slightly curved; epipleuron visible until humeral angle; elytral bead distinctly thinner than pronotal bead, in lateral view both forming an angle at bases of pronotum and elytra. Reticulation on elytra more or less uniform, meshes larger than those on pronotum. Punctation also rather uniform, punctures sparse, coarser than those on head and disc of pronotum; diameter of punctures same as that of meshes; punctures spaced approximately three to four puncture widths apart. Near sides punctures somewhat smaller and still sparser. Puncture lines almost imperceptible, only visible when adequately illuminated; indicated by slightly enlarged and/or more closely placed punctures; each elytron with two discal lines and one sublateral line; in anterior half elytra alongside first (inner) line additionally slightly impressed. Sutural puncture line absent. Setation distinct, similar to that on pronotum.

Ventral surface almost entirely black, including gula. Mouthparts, pro- and mesocoxae, and apex of metacoxal processes dark brownish; apex of prosternal process, hind margins of fourth to sixth abdominal ventrites narrowly transparently brownish. Genae distinctly reticulate, but shiny; gula smooth, with some coarse punctures. Prosternal process with blade narrowly lanceolate, in cross-section tectiform; sides not flattened, coarsely punctured and with long setae; margin beaded; apex not distinctly pointed, narrowly rounded; between procoxae with a weak protuberance, before protuberance with a few transverse carinae; anteriorly process not prolonged as narrow convexity onto prosternum. Prosternum anteromedially flat and very rugosely sculptured. Posterior margins of metacoxal processes straight and forming more or less one line together. Metacoxal lines subparallel, reaching posterior margin of metaventrite. Large parts of ventral surface reticulated, but appearing not so matt as upper surface; meshes mostly elongate, often weak and incomplete, only on last two abdominal ventrites more impressed; centre of metaventrite smooth. Sides of metaventrite, metacoxal plates, and first two abdominal ventrites with coarse, but not very dense punctation; smooth centre of metaventrite with sparse and fine punctures; elytral epipleura and third and fourth abdominal ventrites also sparsely covered with fine punctures; on last two ventrites punctures again coarser. Middle of third to fifth ventrite with one shallow large puncture, with several very long setae originating in it. Almost all other punctures on ventral surface bearing one rather long transparent seta. Intralinear space of metacoxal processes covered with very dense setae; this setal area prolonged anteriorly onto small posteromedial area on metaventrite (this area much more developed anteriad than illustrated for H. acutangulus in fig. 88 of Nilsson & Holmen 1995: 49).

Legs with all trochanters and pro- and mesotibiae dark reddish brown, metatibae somewhat darker; femora black, proximal and distal ends indistinctly brownish. Tarsomeres more or less of same colour as respective tibiae, proximally indistinctly lighter.

Measurements: Holotype: TL: 3.2 mm, TL-H: 3.0 mm, MW: 1.7 mm, TL/MW: 1.88. Paratypes: TL: 3.1–3.5 mm, TL-H: 3.0– 3.2 mm, MW: 1.65–1.75 mm, TL/MW: 1.88–1.89.

Males: Median lobe of aedeagus in ventral (a) and lateral (b) view as in Fig. 6 View FIGURES 6 – 10 ; left paramere as in Fig. 7 View FIGURES 6 – 10 . For comparison those of H. tibetanus are illustrated in Figs. 8–10 View FIGURES 6 – 10 . First three tarsomeres of male dilated; second one rather short, length only one half of width; third more or less as long as wide, outline almost circular; fifth indistinctly longer than fourth. First and second pro- and mesotarsomeres with sucker hairs and a few additional elongate oval sucker cups. Anterior protarsal claw indistinctly broader than posterior one, both more or less similarly shaped and evenly curved. (anterior one not thickened at base and here not strongly arcuate, and then straight as in H. acutangulus .) Margin of pro- and mesotrochanters with a short line of approximately six coarse punctures, each with a rather long seta. Hind margin of metatrochanter with a conspicuous fringe of light yellowish setae.

Females: Similar to males, but pro- and mesotarsomeres less dilated, without sucker cups, and metatrochanters lacking setal fringe. Reticulation on ventral surface more impressed than in males, almost all meshes complete, smooth area on centre of metaventrite absent or very strongly reduced. Gonocoxosternum and gonocoxae as in Figs. 11–12 View FIGURES 11 – 12 .

Variability: There is little variability in H. sejilashan sp. n. The brownish parts on the ventral surface are sometimes more extended. Third and fourth antennomeres are sometimes almost black, similar to following ones. The puncture lines on elytra are in some specimens more perceptible. The base of the pronotum is in some males only slightly broader than the base of the elytra; this is also the case in about half of the females. The shape of the metacoxal lines also varies a little: in some cases these are slightly diverging shortly before hind margin of the metacoxal plates, in others slightly converging.

Notes: Due to the matt surface, fine punctation and weak puncture lines of the elytra, the new species at first glance resembles a dark Hydroporus nigellus Mannerheim, 1853 (belonging to the species-group of the same name) but not any of the members of the acutangulus -complex nor a single one of the planus -group. An inspection of the dorsal and ventral surfaces of the new species (of males as well as females), however, readily shows that it belongs to the acutangulus -complex—rather broad pronotal lateral bead, subparallel metacoxal lines, strong setation on their intralinear space, and a striking setal fringe on the hind margin of the male metatrochanters.

Distribution: Eastern Qinghai-Tibet Plateau; so far H. sejilashan sp. n. is only known from the type locality.

Etymology: The new species is named after the mountain range Sejila Shan where it has been found. It is a noun in the nominative case in apposition.

Ecology: The collecting area in the Sejilashan Mountains is covered by swamps with dense bushes and grass in altitudes of 4100–4260 m. In addition, several shallow pools can be found which are due to Yak activities. The new species was found in swamps with dense vegetation, and shallow pools of stagnant and very clear water with only sparse vegetation; some specimens were collected under grass roots. It was always found together with Boreonectes emmerichi (Falkenström, 1936) .