Hydroporus golestanensis, Hájek, Jiří, 2016

Hájek, Jiří, 2016, Hydroporus golestanensis, a new species of the H. longulus group from northern Iran (Coleoptera: Dytiscidae: Hydroporinae), Zootaxa 4072 (4), pp. 496-500 : 497-498

Hydroporus golestanensis sp. nov.

( Figs. 1–6 )

Type locality. Iran, Golestan province, Eastern Alborz Mts., ca. 8 km SSE Galikash village, 37.215N, 55.485E, 880 m a.s.l.

Material examined. Holotype ♂, labelled: “ IRAN, Golestan prov., 28.V.2006 / 8 km SE GALIKASH / (forest streamlet) / 37°12,9’N 55°29,1’E; 880 m / Jiří Hájek & Pavel Chvojka leg. [printed]”, “ HOLOTYPE ♂ / HYDROPORUS / golestanensis sp. nov. / Jiří Hájek det. 2015 [red label, printed]” ( NMPC). Paratypes: 10♂ 8♀, same label data as holotype ( BMNH, CHF, NMPC, ZSMG). Each paratype is provided with the respective red printed label.

Description of holotype. In dorsal view elongate oval; body outline with very slight and indistinct discontinuity between pronotum and elytra; maximum width near body midlength. Entire dorsal and ventral surface shiny ( Fig. 1 ). TL: 3.7 mm; TL-h: 3.4 mm; TW: 1.9 mm.

Colouration. Head brown-blackish; anterior and posterior part somewhat paler, medial part and around eyes darker. Pronotum almost black, lateral margin testaceous. Elytra pitchy-brown, laterally somewhat paler than on disc. Ventral part black, except for paler prosternal and metacoxal processes. Legs and head appendages testaceous.

Surface sculpture. Head rather broad, interocular distance equalling about half of pronotal width at posterior angles. Frons with two shallow rounded interocular depressions and with two grooves along eyes inner margin. Head with microreticulation composed of shallowly impressed isodiametric polygonal meshes; meshes somewhat smaller in frontal depressions and on vertex; posterior to eyes meshes becoming transversal. Punctation consisting of fine punctures, irregularly distributed, distance between punctures bigger than their diameter; punctures smaller and sparser on vertex, in depressions and grooves denser. Antennomere IV shorter than antennomeres III and V; III as long as V; antennomeres VI–X slightly longer than V, more than 1.5 times as long as wide, slightly flattened, in cross section more or less elliptical.

Pronotum with maximum width between posterior angles; sides in anterior half weakly curved, in posterior half less so and divergent. Lateral beading distinct. Pronotum postero-laterally with elongate depressed area on each side. Microreticulation similar to that of head, laterally more impressed than on disc. Punctation on disc very fine and sparse; centre of disc with one very coarse longitudinally deformed puncture, punctation becoming progressively coarser and denser laterally, there coarser than on head; along anterior margin with distinct line of setiferous punctures, line shortly interrupted in middle; before posterior margin without puncture line.

Elytra with microreticulation similar to that of head and pronotum, but less impressed. Punctation setiferous, size of punctures mostly similar to that on lateral parts of pronotum; punctures on disc more or less uniformly distributed, somewhat smaller on sides, apex and next to suture. Distance between punctures on disc equal or slightly bigger than their diameter. Discal puncture lines almost imperceptible, marked only by somewhat denser normal punctures; sutural and lateral puncture lines lacking. Margin of elytra slightly ascending towards humeral angle in lateral view. Lateral elytral beading distinct, narrower than pronotal beading. In lateral view epipleuron visible to humeral angle.

Legs. Protibia distinctly broadened distally. Pro- and mesotarsomeres I–III slightly dilated and with sucking setae, tarsomeres I with small oval sucker discs in addition to sucking setae. Protarsal claws short, more or less of same length, thin, slightly and evenly curved; mesotarsal claws of same length and evenly curved, longer than protarsal claws.

Venter with most parts smooth; weakly impressed polygonal microreticulation perceptible on metacoxae and moderately impressed transverse microreticulation present on abdominal ventrites IV–VI. Head posterior to mouthparts with several wrinkles. Gula on sides with a few coarse punctures, genae impunctate. Punctation on sides of metaventrite, on metacoxal plates, and on sides of abdominal ventrites I–II rather coarse; on epipleura, centre of metaventrite, metacoxal processes and rest of abdominal ventrites less coarse. More or less all punctures with a seta.

Prosternal process lanceolate, elongate; longitudinal carina narrow, more or less tectiform in cross-section, but ridge rounded; sides broadened. Process reaching between mesocoxae and onto furrow of anteromedial metaventral process; thus, mesocoxae not contiguous. Base of prosternum strongly impressed; file broad, smooth, transverse ridges very weak; between procoxae with one strong transverse ridge.

Posterior margins of metacoxal processes medially protruded backwards, laterally sinuate; metacoxal lines diverging anteriorly, not reaching posterior margin of metaventrite; intralinear space posteriorly with numerous long golden setae ( Fig. 2 ).

Male external genitalia. Median lobe of aedeagus almost symmetrical, slight asymmetry quite indistinct in ventral view; in ventral view only slightly convergent in basal two thirds, evenly tapering to apex in distal third, apex pointed ( Fig. 3 b); in lateral view distinctly curved near base, sinuate at midlength, then almost straight, distinctly narrowed to shortly rounded apex ( Fig. 3 a). Lateral lobe (paramere) as in Fig. 4 .

Variability. Specimens of the type series agree well with the holotype. Slight variation is in dorsal body colouration—some (teneral) specimens are almost uniformly piceous.

Females without conspicuous external differences from males except slightly narrower pro- and especially mesotarsomeres and lack of sucker discs. Gonocoxae without distinct angularity on inner side ( Fig. 5 ), gonocoxosternum as in Fig. 6 .

Measurements (N = 18): TL: 3.5–3.7 mm; TL-h: 3.2–3.4 mm; TW: 1.8–1.9 mm.

Differential diagnosis. The new species is classified within the H. longulus group based on the combination of the following characters: 1) body more or less subparallel in outline; 2) disc of pronotum and elytra microreticulated; 3) lateral pronotal beading broad, in lateral view broader than lateral elytral beading; 4) epipleuron visible up to humeral angle in lateral view; 5) metacoxal lines clearly diverging anteriorly; 6) posterior margin of the metacoxal processes sinuate; (7) median lobe asymmetric in ventral and often also in frontal view. Hydroporus golestanensis sp. nov. can be easily recognised from all other members of the group by the pitchybrown colouration of the elytra and predominantly by the almost symmetric male median lobe, with distal third evenly tapering to pointed apex in ventral view (see Fig. 3 ).

With its almost symmetric male median lobe, the female gonocoxae without distinct angularity and the metacoxae with suberect setae, the new species resembles also members of the H. melanarius subgroup of the H. memnonius group, namely the widely distributed western Palaearctic Hydroporus longicornis Sharp, 1871 which however lacks the sinuate posterior margin of the metacoxal processes—the characteristic of species of the H. longulus group. In addition, H. longicornis can be easily separated from the new species also by its black surface and the shape of the male median lobe (cf. Erman & Fery 2006: 43, fig. 5).

Etymology. The new species is named after the area of its occurrence—the Golestan province; the specific epithet is an adjective.

Collecting circumstances. All specimens were collected in a shaded, drying-up streamlet flowing in a broadleaved forest. The streamlet was ca. 20 cm wide, with a gravelly or clayey bottom, partly covered with decaying leaves; the water column was very thin, in some places the streamlet formed seepages ( Figs. 7–8 ). The new species was found in association with Agabus bipustulatus (Linnaeus, 1767) , A. glacialis Hochhuth, 1846 , and Hydroporus planus (Fabricius, 1781) .

Distribution. So far known only from the type locality in the eastern Alborz Mountains, northern Iran.

Figures

FIGURES 1 – 6. Hydroporus golestanensis sp. nov.: 1. habitus of holotype; 2. metacoxal processes; 3. median lobe in lateral (a), and ventral (b) view; 4. lateral lobe (paramere); gonocoxae; 6. gonocoxosternum. Scale bar = 0.5 mm (Figs. 2 – 6).

FIGURES 7 – 8. Type locality of Hydroporus golestanensis sp. nov.: 7. forested valley in eastern Alborz Mts., Golestan province; 8. forest streamlet near Galikash, habitat of new species. Photos by P. Chvojka.