Hydroporus novacula, Fery, 2020

Fery, Hans, 2020, Hydroporus novacula sp. n. from Georgia (Caucasus) (Coleoptera, Dytiscidae Hydroporini) - the first terrestrial species of the genus?, Zootaxa 4861 (2), pp. 290-296 : 291-295

Hydroporus novacula sp. n.

Type locality: Georgia (Caucasus), Adjara Province, ca. 15 km SE Khulo (also Chulo), ca. 41.55N 42.45E .

Type material: Holotype: ♂, „ Georgia [20]—Adjara, SE Khulo, 41°33ʹ07ʺN 42°27ʹ16ʺE, 1070 m, beech for- est, sifted, 12.VII.2019, V. Assing“ [printed], „ Holotype, Hydroporus novacula sp. n., Fery det. 2020“ [red label, printed]. The holotype will be stored in the Museum für Naturkunde Berlin, Germany (MNB).

Description

Habitus elongate, weakly oval ( Fig. 1 ); body outline with slight but perceptible discontinuity between pronotum and elytra; maximum width situated near middle of elytral length. Dorsoventrally rather flat. Dorsal and ventral surfaces blackish in large part; largely with weakly impressed reticulation, thus only little shiny, but not matt; appendages dark brown.

Head broad, width about 75% that of pronotum and about 65% that of maximum width of body; interocular distance large, about 75% width of head and about 55% that of pronotum. Head largely dark reddish brown, near anterior clypeal border and a large dot on frons darker; before and behind eyes, in impressed puncture lines and in grooves as well as on vertex blackish; narrow and short, oblique stripe on clypeus above insertion of each antennae shining through brownish. Reticulation covering entire surface, meshes polygonal, more or less uniform, somewhat more impressed and more transverse only behind eyes. Punctation very sparse, distance between punctures ca. that of four meshes, diameter equal to that of one mesh, before vertex some punctures slightly bigger. Alongside inner margin of eyes with impressed puncture line, each puncture with a short seta. Clypeus with two flat interocular grooves behind anterior margin.

Pronotum relatively broad, maximum width about 90% that of maximum width of body; maximum width before base, more or less at midlength of pronotum; sides almost evenly curved over total length, somewhat converging behind midlength; surface somewhat impressed in posterior third; lateral rim distinct, width more or less same over entire length; at anterior angles very shortly but distinctly broadened. Surface black, but lateral rim brownish translucent, particularly in posterior two-thirds; anterior margin and near mid of posterior margin also brownish translucent. Reticulation similar to that of head. Punctation generally less sparse and punctures larger, however; behind anterior margin and on disc smaller and sparser. Centre of disc without single very coarse puncture or scratch. Without distinct puncture line behind anterior margin, but a few larger punctures might be interpreted as rest of such line. Near anterior and posterior margin as well close to sides several punctures with long backwardly oriented seta, but barely perceptible because clinging to surface.

Elytra rather elongate, but not distinctly parallel, maximum width near midlength. Elytra to large extent blackish, apex brownish, lateral rim brownish in posterior half. Reticulation similar to that of head and pronotum; however, meshes smaller and more impressed at apex, there surface matt. Punctation on disc rather distinct, more or less uniformly distributed, similar to that on lateral parts of pronotum; punctures smaller near sides, next to suture and at apex. Puncture lines almost imperceptible, only indicated by a very few slightly larger punctures. Most punctures bearing a transparent yellowish seta with length about that of distance between two punctures; however, setae usually very close to surface and almost imperceptible. In lateral view margin of elytra ascending slightly towards humeral angle. Epipleuron in lateral view visible to humeral angle. Lateral rim distinct, narrower than that of pronotum. Notes: Lifting of the elytra showed that the metathoracic wings are largely developed and by no means strongly reduced. Thus, it seems to be probable that the species is capable of flight.

Venter predominantly black ( Fig. 2 ); mouthparts, prosternum apart of vaulted medial part, prosternal process and legs including trochanters dark brownish; metafemora in part diffusely delimited darker; gula also dark brownish, genae black. Posterior part of metacoxal processes and posterior margins of last four abdominal ventrites brownish translucent. Antennae and palpi uniformly brownish, segments not darkened apically.

Most parts of venter weakly reticulated; metacoxal processes, small areas at centre of metaventrite smooth; gula with a very few mesh-lines. Reticulation on last abdominal ventrite stronger impressed and meshes smaller. Punctation on metacoxal plates, on metaventrite apart of centre and on first two abdominal ventrites rather coarse and not dense; on rest of abdominal ventrites punctation less coarse and slightly sparser, on epipleura, centre of metaventrite and metacoxal processes very sparse and much finer. Punctures on gula coarse; very sparse centrally, but denser laterally. Genae with very fine and indistinct punctures in intersections of meshes. Anterior angles of hypomeron (subnotum) with rather large, flat, roughly sculptured, posteriorly very sharply delimited, more or less triangular area.

Prosternum in front of procoxae strongly vaulted and very strongly sculptured. Prosternal column (between procoxae) with very distinct protuberance and brush of long setae above this structure; sub-basally before this protuberance with some transverse ridges. Prosternal process elongate lanceolate, apex rounded; near apex more or less tectiform in cross-section, anteriorly surface more rounded; sides beaded and here provided with some long setae.

Anteromedial process of metaventrite separating mesocoxae; anteriorly deeply excavated for reception of apex of prosternal process. Metacoxal lines diverging anteriad, not reaching posterior margin of metaventrite. Posterior margins of metacoxal processes not conjointly truncate ( Fig. 3 ); laterally sinuate, medially interlaminary bridge broadly protruded posteriad, sloping backwards but continued without step into wing-like structure and laterally reaching under metatrochanter of hind-legs. Structure not appressed to anterior margin of second abdominal ventrite and ventrite here distinctly vaulted (see Fig. 3 ). Hind margin of last abdominal ventrite evenly rounded, with rather distinct bead. Punctation on metaventrite and metacoxal plates coarse, sparser left and right midline of metaventrite and postero-medially on metacoxal plates ( Fig. 2 ). On first and second abdominal ventrites punctation less coarse and denser, on other ventrites still less so. On metaventrite only a few punctures with yellowish transparent seta; however, on metacoxal plates and abdominal ventrites each of them with such setae; almost all of these punctures with a very fine more or less backwards directed impressed line serving reception of respective seta. Antennae with fourth segment shorter than third or fifth, second antennomere longer than third, first one yet longer; fourth to tenth antennomeres more or less of equal length, about 1.5 times as long as wide; eleventh yet longer again and somewhat pointed.

Protibiae distinctly curved, broadened distally, somewhat club-like ( Figs 2 , 4 ); protarsomeres I to II broadened, with sucking setae, first tarsomere with eight stalked sucker cups (similar to those in other species of the longulus - group; compare figs. 10–12 in Fery & Erman 2009); claws simple, equal, evenly curved. Mesotibiae also distinctly curved, but less than protibiae ( Figs 2 , 6 ); mesotarsomeres similar to protarsomeres, but less broadened; both claws also simple and similar. Natatorial setae (swimming hairs) on mid- and hind-legs absent ( Figs 6, 7 ) (note that the setae on the metatibia in Fig. 7 are stiff bristles and not swimming hairs).

Median lobe of aedeagus with unique shape among all Hydroporus : distal part in ventral view ( Fig. 8 ) extremely thin, like a knife or a „razor“. Lobe only weakly asymmetrical, distal half not twisted, but basally lobe more developed on right side (see Fig. 8 ). In lateral view ( Fig. 9 ) distally distinctly curved ventrally. Left paramere as in Fig. 10 , with only very few and short setae on tip.

Females: unknown.

Measurements: Total length: 3.4 mm, total length without head: 3.0 mm, length of pronotum: 0.6 mm, maximum width: 1.6 mm, width of head: 1.05 mm, maximum width of pronotum 1.4 mm, interocular distance: 0.77 mm.

Diagnostic remarks: Hydroporus novacula sp. n. differs chiefly by the following features from other male members of the longulus -group (new species first):

- anterior protarsal claw evenly curved and not thickened (recognisable in Figs 4 and 6 ) / distinctly curved near base, almost straight in distal two thirds and somewhat thickened;

- pro- and mesotibiae curved, thickened distally, club-like ( Figs 2 , 4, 6 ) / pro- and mesotibiae not curved, not club-like, more or less triangular, evenly broadened from base to distal end ( Fig. 5 );

- legs without natatorial setae / at least on first metatarsomere natatorial setae perceptible, in some species also few setae on metatibiae. Notes: I have checked males of seven species; whilst I have found some swimming hairs on metatibia and first tarsomere e.g. in H. longulus Mulsant & Rey, 1861 (Obernberg, Gries am Brenner, Tirol, Austria), males of H. cuprescens K.W. Miller & Fery, 1995 (Ayia, Stavros, Cyprus) lack natatorial setae on metatibiae and have only one or two on first metatarsomere.

Finally, the uniquely strange shape of the median lobe of aedeagus separates the new species unambiguously not only from all other members of the species group, but also from all other members of the genus Hydroporus .

Distribution: So far the new species is only known from the type locality in the southwest of Georgia (Caucasus).

Etymology: The specific name of the new species is Latin, meaning „razor“. The name relates to the extremely thin distal part of the median lobe in ventral view—sharp like a razor! It is a noun in the nominative singular stand- ing in apposition.

Ecology: The holotype was found on a steep slope in a beech forest when collecting Staphylinidae species by sifting almost dry or slightly moisty material from the ground. The collectors do not remember a closely situated brook or any other water or wet ground. Possibly, the specimen was crawling over the ground searching for a new locality. The collector reported that it is rare but not unusual that Hydradephaga are found in sifted material (see also Balke & Hendrich 1996).

Figures

FIGURES 1–3: Hydroporus novacula sp. n.: (1) habitus, dorsal view; (2) habitus, ventral view; (3) metacoxal processes and second abdominal ventrite; see the distinctly vaulted anteromedial part of the ventrite.

FIGURES 4–7: (4, 6–7): Hydroporus novacula sp. n.: (4) right fore-leg; (6) right fore- and mid-leg; (7) left hind-leg; (5) Hydroporus longulus, right fore-leg. All photos taken with transmitting light.

FIGURES 8–10: Hydroporus novacula sp. n.: (8–9) median lobe of aedeagus: (8) ventral view; (9) lateral view; (10) right paramere.