Hydroporus esseri, Fery, Hans & Hendrich, Lars, 2011

Fery, Hans & Hendrich, Lars, 2011, Hydroporus esseri sp. n., a new diving beetle from southern Turkey (Coleoptera, Dytiscidae, Hydroporinae), Zootaxa 2909, pp. 38-46 : 39-43

Hydroporus esseri sp. n.

Type locality. Southern Turkey, Antalya province, Manavgat district, road Sagirin–Beskonak, Köprülü Canyon; 37.1177816N 31.2111551E, altitude ca. 150 m.

Type material studied. Holotype (male): " 17.3.2002 Turkey Antalya prov., Manvagat distr., road Sagirin– Beskonak", "Köprülü Canyon, Köprülü River, backwater pool, 37.1177816N 31.2111551E, 150 m, J. Esser leg". [white printed labels]. " Holotype, Hydroporus esseri sp. n., Fery & Hendrich des. 2011" [red printed label]. The holotype is stored in the ZSM.

Habitus elongate oval ( Fig. 1 ), maximum width behind middle of total length, in second third of elytral length. Pronotum largely black, head and elytra dark brown, sides of latter—in particular near shoulders—somewhat lighter. Entire surface reticulated, but not matt.

Head dark brown with anterior part of clypeus (in particular above antennal cavity) and a transverse broad marking on vertex reddish brown; these lighter parts only diffusely delimited. Interocular distance about same as half of pronotal width at posterior angles. Clypeus with two longitudinal grooves behind anterior margin; these grooves rather flat and mainly apparent by distinct and dense punctation. Entire surface microreticulate with polygonal meshes, these more transverse near anterior margin of clypeus and on vertex. Punctures behind anterior margin of clypeus rather small and sparse; between clypeal grooves and on frons larger and denser, here their diameter equalling that of meshes; before vertex with some smaller punctures; vertex impunctate; beside inner margin of eyes with impressed puncture lines and meshes of reticulation replaced by small longitudinal wrinkles. Setae on head very indistinct, with only a very few in clypeal grooves and near margin of eyes.

Pronotum black; only laterally in anterior half narrowly and very diffusely brownish; lateral bead black. Bead thin, in lateral view distinctly narrower than half of diameter of antenna. Maximum width of pronotum between posterior angles; sides converging from posterior towards anterior angles, more or less evenly and slightly curved over entire length. Between disc and posterior margin distinctly depressed over about half of pronotal width, thus, disc appearing rather vaulted. Surface rather uniformly microreticulated, meshes more or less of same diameter as on head; only near anterior margin meshes more transverse. Near anterior margin unpunctured, behind without punctured line but with irregularly placed rather large punctures (larger than on clypeus); diameter larger than that of meshes, distance between puncture equalling one or at most two diameters of punctures; before posterior margin punctation similar. On disc and also more laterally with similar punctures, but punctation sparser, distance between punctures three to four times that of their diameter. Sublaterally punctures smaller, denser and near posterior angles somewhat longitudinally deformed. Except on disc most punctures with a transparent yellowish, very distinct and rather long (up to 0.05 mm) seta.

Elytra dark brown, near sides a very little lighter, near shoulders still a little lighter; these areas very diffusely delimited; centrally elytra behind mid length without large blackish spot, here only almost imperceptibly darkened. In dorsal view sides of elytra almost evenly curved, only short before apex stronger curved, here not pointed. In lateral view elytral margin slightly ascending towards humeral angle; epipleuron visible until humeral angle. Elytral bead more or less as thin as pronotal bead, in lateral view both forming an angle at bases of pronotum and elytra. Reticulation on elytra more or less uniform, similar to that on pronotum. Punctures on elytra rather evenly distributed, somewhat larger and denser than on disc of pronotum. Elytral puncture lines absent. Setation in anterior central half less distinct (possibly rubbed off), but on rest of elytral surface very conspicuous, similar to that on pronotum.

Ventral surface with head reddish brown, genae of same colour as gula. Prothoracic epipleuron (subnotum) and proepisternum dark brownish, prosternal process blackish brown; rest of ventral surface black, except dark brownish posterior part of metacoxal processes and last abdominal ventrite. Elytral epipleura brownish, near shoulders somewhat lighter.

Prosternal process with blade lanceolate; in cross-section flatly tectiform, sides not flattened; margin only weakly beaded; apex not distinctly pointed; between procoxae without transverse ridge, but a weak protuberance; before with some extremely fine transverse carinae; anteriorly process not prolonged as narrow convexity onto prosternum; prosternum anteromedially flattened and very rugosely sculptured, here not particularly impressed. Vaulted part of lanceolate blade with several coarse punctures, near sides not flattened, but with coarse punctures and long setae. Posterior margins of metacoxal processes more or less straight and forming one line together; next to end of the midline of processes without distinct pointed prolongation. Midline of metacoxal processes very deeply impressed over its entire length. Lateral lines of metacoxal processes very distinct, carinate, weakly diverging anteriorly, reaching posterior margin of metaventrite; inside metacoxal lines with strongly impressed grooves. Second and third abdominal ventrite rigidly connected, without traces of a suture; however, when adequately illuminated a very flat impression perceptible instead of that suture.

Almost entire ventral surface with reticulation, but not appearing matt; gula without reticulation. Sides of metaventrite, metacoxal plates, and first two abdominal ventrites with very coarse punctures; on centre of metaventrite and third to fifth abdominal ventrites less coarsely punctured; last abdominal ventrite very coarsely and densely punctured, particularly at apex; intralinear space of metacoxal processes only with a few small punctures, but impressed grooves beside metacoxal lines coarsely and densely punctured. Distinct and rather long setae present on metaventrite, metacoxal plates, abdominal ventrites and epipleura.

Palpi, mouthparts and legs (including coxae and trochanters) brownish; pro- and mesotarsomeres slightly darkened; first five antennomeres lighter brownish, rest rather dark brownish. Third to sixth antennomeres rather short, fourth especially short, eleventh almost two times as long as tenth. First three pro- and mesotarsomeres with sucker hairs, but without sucker cups. Protarsal claws small and simple, without apparent secondary sexual modifications.

Measurements. Holotype: total length 2.4 mm, total length without head 2.2 mm, maximum width 1.15 mm, total length/maximum width 2.09.

Male: Median lobe of aedeagus in ventral and lateral view as in Fig. 3 ; left paramere as in Fig. 4 . For comparison those of H. umbrosus are illustrated in Figs 5 and 6 .

Female: Unknown.

Differential diagnosis. As stated in the Taxonomy section, H. esseri sp. n. belongs to the puberulus -group of the genus. It is distinctly smaller than H. glabriusculus (2.8–3.2 mm), H. puberulus (2.7–3.1 mm) and H. rufinasus (2.9–3.2 mm) (cf. Nilsson & Holmen 1995 and Larson et al. 2000), and also other characters separate the new species from these three. H. umbrosus is the only species of the group which comes closer to the new one. Size and colouration are the most obvious differences between them: total length: 2.4 mm in H. esseri sp. n., and 2.5–2.8 mm in H. umbrosus ( Nilsson & Holmen 1995) ; upper side generally darker and more uniform in the new species, in H. umbrosus large parts of head, sides of pronotum and elytra reddish brown, and elytra usually with a poorly delimited, but distinct blackish spot in posterior two thirds and a dark stripe along suture (cf. Figs 1 and 2 ).

However, usually size and colour are not accepted as "good" characters, and because we could study only a single specimen, we do not know to which extent the new species varies with respect to these characters. Additionally, H. umbrosus is known sometimes to lack the blackish spot on the elytra and is then much more similar to the new species. That's why someone might argue that the description of the new species cannot be justified with the necessary certainty, and that the specimen from southern Turkey might be nothing else than a variety of H. umbrosus .

We wish to address these concerns, and point to the following facts: During the last years we have seen about 1,200 specimens of H. umbrosus , coming chiefly from Central Europe, but also many from Scandinavia, and some from Buryatia and Kamchatka. We have not been able to recognise a considerable variability in the specimens studied. In particular we noted that among all H. umbrosus studied there was none with a total length of 2.5 mm, and only a few of 2.6 mm, and that the species lacks that blackish spot on elytra only extremely rarely.

In addition, we have observed differences in several other characters, the combination of which leaves no doubt about the existence of two well separated species:

- prosternal process before indistinct transverse protuberance with only very fine transverse carinae in H. esseri sp. n.; in H. umbrosus transverse protuberance often more distinct and transverse carina before less weak;

- lanceolate part of prosternal process (blade) less vaulted and covered with several coarse punctures in H. esseri sp.n., sides of blade roughly punctured, but rest without such punctures in almost all H. umbrosus studied; sides of blade not flattened in H. esseri sp. n., but narrowly flattened in H. umbrosus ;

- midline of metacoxal processes very deeply impressed over its entire length in H. esseri sp. n.; distinct, but less impressed in H. umbrosus ; punctured grooves inside and next to metacoxal line also deeper impressed in the new species;

- hind margin of each metacoxal process next to end of midline without distinct pointed prolongations in H. esseri sp. n.; at posterior end of midline each process with a very small but distinct pointed prolongation in almost all H. umbrosus studied;

- punctation on metaventrite, metacoxal plates and first and second abdominal ventrites coarser and denser in the new species;

- second and third abdominal ventrites without traces of a suture between them in H. esseri sp. n., only a flat impression perceptible if illuminated adequately; among all H. umbrosus studied only a few with complete suture and several ones with incomplete suture, but not a single one without any traces of such;

- median lobe in the new species in ventral view narrower and more converging to tip, in lateral view more curved near basal part and dorsal side more straight between base and apex (cf. Figs 3 and 5 ).

Finally we want to point to the big gap between the geographical distribution area of H. umbrosus and that of the new species. According to Nilsson & Holmen (1995: 63), the distribution of H. umbrosus covers most of Northern, Central and Eastern Europe, plus Asian Russia (from Western Siberia to Far East). The Ukraine and the Southern Territories of Russia are additionally given in Nilsson (2011); these are the most southern areas so far known, and both more than 1,000 km apart from the type locality of H. esseri sp. n. ( Fig. 7 ).

Habitat. The single specimen was collected in very shallow water among gravel and pebbles of a backwater pool near the banks of the Köprülü River. The water was clear and without any submerged vegetation ( Figs 8 and 9 ). Together with the holotype few specimens of Agabus dilatatus (Brullé, 1832) and Agabus nebulosus (Forster, 1771) were collected.

The closely related H. umbrosus occurs all over its range in shallow and well vegetated standing water bodies e.g. exposed fens, bogs, shallow pools, marshland and well vegetated lake shores ( Horion 1941, Nilsson & Holmen 1995, Hess et al. 1999, Hendrich 2003). If it is assumed that H. esseri sp. n. prefers similar habitats, then we might conclude that the single specimen found was flushed away by heavy rain from its original habitat further upstream or from a much smaller tributary of the Köprülü River, and that the collecting site does not represent its preferred habitat. This would also explain why only one and not more specimens have been collected.

Derivatio nominis. This species is dedicated to the coleopterist Jens Esser (Berlin, Germany), specialist in Cryptophagidae , who collected the holotype; the specific epithet is a noun in the genitive case.

Distribution. Only known from the type locality, but probably more widespread in southern Turkey ( Fig. 7 ).

Study area. The Köprülü Canyon National Park is located in the western part of the Taurus Mountains in southern Turkey between Antalya and Manavgat at elevations of 110 m to 2,500 m (summit of the Bozburun mountain range) on very heterogeneous geomorphologic structure. It encompasses 37,000 ha, lying at a distance of 90 km northeast from the province of Antalya. The reserve is separated by the Köprülü River canyon in a western and eastern part. The eastern part is dominated by hills up to 850 m above sea level with several deep canyons joining to the Köprülü Canyon. The western portion consists of higher altitudes often above 1,000 m, with Bozburun range raising over 2,000 m, being the western part boundary. The park has a rich flora with 900 to 1,000 species including stands of cypress forest and many endemics. The area comprises the whole range of vegetation zones from Mediterranean to alpine environments. The area has a Mediterranean climate with high precipitation (1,700 mm) throughout the winter months. Nevertheless, owing to the karst, water availability during summer months is restricted. Average annual temperature is 18.2 C°. The environment of the park still faces many threats. Overgrazing and illegal cutting of trees and shrubs have caused degradation of many parts of the natural vegetation ( Cetinkaya 2002).

Figures

FIGURE 7. Distribution of Hydroporus esseri sp. n. (black star) and western part of that of Hydroporus umbrosus (dark greyish area).

FIGURES 1 – 2. Habitus of: (1) Hydroporus esseri sp. n., (2) Hydroporus umbrosus (specimen from Berlin, Germany).

FIGURES 3 – 6. Median lobe of aedeagus in ventral and lateral view and left paramere of: (3) and (4) Hydroporus esseri sp. n.; (5) and (6) Hydroporus umbrosus (specimen from Berlin, Germany).

FIGURES 8 – 9. The Köprülü River in southern Turkey; arrow: small backwater pool, locus typicus of Hydroporus esseri sp. n.