Hydrobaenus golovinensis Makarchenko et Makarchenko

Makarchenko, Eugenyi A., Makarchenko, Marina A., Semenchenko, Alexander A. & Veliaev, Oleg A., 2017, Morphological description and DNA barcoding of Hydrobaenus golovinensis sp. nov. (Diptera: Chironomidae: Orthocladiinae) from the Russian Far East, Zootaxa 4286 (2), pp. 277-284 : 278-282

Hydrobaenus golovinensis Makarchenko et Makarchenko , sp. nov.

( Figs. 1–20 )

Material. Holotype: adult male, Russian Far East , Khabarovsk Territory , Khabarovsk district, Bolshekhekhtsirsky Nature Reserve, Ussuri River basin, Golovina Stream , N 48°11' 131" , E 134°41'039", 13.V. 2016, leg. N. Yavorskaya. Paratypes: 4 adult males, 6 mature pupae (males), 1 larva, the same data as holotype; 1 larva, the same data as holotype, except 6.V. 2016 ; 3 adult males, Primorye Territory, Nadezhdinsky District , unnamed stream not far from railway station “32nd kilometer”, N 43°26'29" , E 131°59'10", leg. O. Orel.

Etymology. The specific epithet golovinensis is derived from the name of the Golovin Stream, where the type material was collected.

Adult male (n=5). Total length 2.5–3.1 mm. Wing length 1.8–2.0 mm. Total length/wing length 1.50–1.61.

Head. Eyes slightly pubescent, with short dorsomedian prolongations Temporal setae: 5–6 outer verticals, 2–3 inner verticals and 4–5 postorbitals. Clypeus with 5–8 setae. Antenna with 13 flagellomeres and well developed plume; 13th flagellomere 480–528 µm long, with apex pointed. AR 1.07–1.17. Length of palpomeres 2–5 (in µm): 44–52, 80–96, 72–92, 120–128.

Thorax. Dark brown. Antepronotum with 4–9 lateral setae. Ac 12–16 (short and scalpellate, situated in middle of mesonotum), Dc 5–7, Pa 3–5, Scts 9–10 in one row on yellow background.

Wing. R with 5–8 setae, R1 without setae, R4+5 with 1–2 setae apically. R4+5 ending distally of apex M3+4. Costa extension 32–40 µm long. Cu1 curved in apical part. Anal lobe well developed, rounded. Squama with 6–21 setae.

Legs. BR1 1.7–2.6, BR2 1.7–2.0, BR3 2.0–4.2. Spur of fore tibia 48–52 µm long. Spurs of mid tibia 16–20 µm and 20–22 µm long. Spurs of hind tibia 48–60 µm and 12–20 µm long. Hind tibial comb with 12–14 setae. Basitarsus of hind leg with 6–9 sensilla chaetica in basal part. Lengths and proportions of legs as in Table 1.

Hypopygium ( Figs. 1–6 ). Tergite IX roundish, with 7–12 setae; anal point bare, 20–28 µm long, with rounded apex. Laterosternite IX with 5–7 setae on each side. Transverse sternapodeme 96–108 µm long, with slightly triangular projections ( Fig. 5 ). Virga 32–36 µm long, consisted of 3–4 setae. Phallapodeme dark in distal part, wide and tape-like, slightly serrated apically ( Figs. 5–6 ). Gonocoxite 200–236 µm long; inferior volsella as shown in Figs. 1–4 ; dorsal part of inferior volsella nose-like, without microtrichia but with setae; ventral part of inferior volsella covered with microtrichia and setae. Gonostylus 84–100 µm long, with preapical rounded crista dorsalis ( Figs. 3–4 ); megaseta 8–12 µm long.

Pupa (n=4). Total length 2.90–3.5 mm. Cephalothorax brownish, abdominal tergites light brownish or yellowish. Exuviae transparent, only dorsal part of mesonotum darker. Tergites II–VIII and sternites II–VIII with brown or dark brown apophyses.

Cephalothorax. Frontal apotome with 2 setae 68–80 µm long and with well developed warts. Antepronotum with two median and two lateral antepronotal setae 36–88 µm long; both lateral antepronotals thin and hair-like. Thoracic horn 244–288 µm long, up to 60–84 µm wide, leaf-shaped with strongly pointed apex, covered by spinules ( Figs. 7–9 ). Precorneal setae lengths (in µm): Pc1 52–80, Pc2 92–120, Pc3 32–44. Bases of setae arranged in form of triangle. Surface of mesonotum covered with small spines along suture. Dorsocentrals thin and hair-like; Dc 1– 4 40 –80 µm long. Distance between Dc1 and Dc2 36–52 µm; between Dc2 and Dc3 44–64 µm; between Dc3 and Dc 4 28–40 µm.

Abdomen. Tergite I without shagreen. Tergite II with shagreen of spinules in middle of posterior half; shagreen at posterior edge with relatively large spines, their apex pointed orally ( Fig. 10 ). Shagreenation of tergites III–VI as shown in Figs10–12 , spinules at posterior edge larger than in middle part. Tergites VII–IX almost bare ( Figs. 12–13 ). Sternites I–IV, VII–IX without shagreen. Sternites V–VI with weakly shagreen along posterior edge. Segment II with PSB. Sternites IV–VII with PSA. Segment I with 0–1 pairs of lateral setae. Segment II with 3–4 pairs of hair-like lateral setae. Segments III–VI with 4 pairs of simple lateral seta. Segments VII mostly with 4 pairs of taeniate lateral setae, and one specimen with 3 pairs of taeniate lateral setae ( Fig. 12 ). The number of setae on segment VIII variable: from 3 to 5, exceptionally segment VIII with 3 taeniate lateral setae from one side and 4 taeniate lateral setae from another side (n = 1) or with 5 taeniate lateral setae from one side and 4 taeniate and 1 simple lateral setae from another side (n = 1) or 4 taeniate lateral setae from one side and 4 taeniate and 1 simple lateral setae from another side (n = 2). Anal lobe 240–288 µm long, with fringe of 4–12 setae which 8–76 µm long, occupy middle part of anal lobe edge ( Fig.13 ). Male genital sac overreaching anal lobe, 20–76 µm. Anal macrosetae 180–200 µm long.

Fourth instar larva (n = 2). Total length 4.7–5.7 mm.

Head. Brown, with postoccipital margin, teeth of mentum, mandible and premandible almost black. Labral setae S I plumose, labral lamella abutting sockets of S I triangular ( Fig. 14 ); S II strong, S III weak and hair-like, S IV short, tubercle-like. Pecten epipharyngis consisted of 3 long and narrow scales. Premandible distally with 2 long apical teeth and 1 short tooth nearest ( Fig. 19 ). Antenna with 6 segments; AR 1.22–1.50; apex of segment 2 with stylus and lauterborn organs ending at apex of 3rd segment; antennal blade ending near base of 5th segment; one large and one small ring organs in proximal 1/3 of basal segment ( Figs.15–16 ). Mandible with apical tooth, which shorter of combined width of inner teeth and the same length as 3rd inner tooth; seta interna with 6 bare branches, seta subdentalis long, with beak-shaped apex ( Fig. 18 ). Mentum with 1 median tooth and 6 pairs of dark brown or black lateral teeth; median tooth 1.75–2.3 time wider than first lateral tooth. Setae submenti at level of posterior edge of ventromental plates. Ventromental plates extending beyond last lateral tooth ( Figs. 17, 20 ). Maxilla with pecten galearis.

Abdomen. Procercus length/width ratio 1.4, with 7 anal setae 270–380 µm long and 2 thin lateral setae. Supraanal setae 120 µm long. Anal tubules elongated, egg-shaped, shorter than posterior parapods. Posterior parapods with simple hooks in apex.

Diagnostic characters and taxonomic notes. The new species is closely related to the Far Eastern species Hydrobaenus majus and H. sikhotealinensis . Adult males of these species are weakly separable from the H. golovinensis by morphological features but only the new species has the hypopygium with expanding and dark phallapodemes in distal part, wide and tape-like, slightly serrated apically ( Figs. 5–6 ). The phallapodemes of other species not expanding and straight apically, turned to the middle and without the serrated edge. Data for all other features overlap. In such cases, a comparative study of the morphology of the pupae and larvae, as well as DNA barcoding can provide characters for identification of the species. Pupae and larvae of H. sikhotealinensis , H. majus and H. golovinensis are easily separable by several features. H. sikhotealinensis has a pupa with the thoracic horn 310–320 µm long, tapering towards the tip ( Makarchenko et al 2009: Fig. 48); the abdominal segment VI with 3 pairs of simple lateral setae and the segment VIII with 5 pairs of taeniate lateral setae ( Makarchenko et al. 2009: Fig. 49); the mentum of larva with one light-brown or brown median tooth and six pairs of lateral teeth of the same colour, the median tooth 4.0–4.5 times wider than the first lateral tooth and the head yellow. H. majus has a pupa with the thoracic horn 368–400 µm long, with the extension in distal third ( Makarchenko et al. 2015: Figs. 9–10 ); the abdominal segment VI with 1–2 pairs of short hair-like and 2 pairs long taeniate lateral setae, segment VIII with 4 pairs of taeniate lateral setae ( Makarchenko et al. 2015: Fig. 12 ); the mentum of larva with 2 yellow or yellowish median teeth and 6 pairs of dark brown lateral teeth ( Makarchenko et al. 2015: Figs. 15, 17 ). H. golovinensis has the leaf-shaped, 244–288 µm long thoracic horn, with strongly pointed apex ( Figs. 7–9 ), the abdominal segment VI with 4 pairs of hair-like lateral setae, and the segment VIII with 3–5 pairs of taeniate lateral setae, sometimes with 4 taeniate and 1 hair-like lateral seta; the mentum of larva has 1 median tooth and 6 pairs of dark brown or black lateral teeth; median teeth 1.75–2.3 times wider than the first lateral tooth, and the head brown or brownish ( Figs. 17, 20 ).

A comparative characteristic of adults, pupae and larvae of closely related species is also given in our updated keys based on that by Makarchenko & Makarchenko (2014: 431), as well as the results of DNA barcoding.

Figures

FIGURES 1 – 6. Adult male of Hydrobaenus golovinensis sp. nov. 1, hypopygium in dorsal view; 2, inferior volsellae; 3 – 4, gonocoxite and gonostylus; 5 – 6, TSA and phallapodemes. Scale bars 50 µm.

FIGURES 7 – 13. Pupa of Hydrobaenus golovinensis sp. nov. 7 – 9, thoracic horn; 10, tergites II – III; 11, tergites IV – V; 12, tergites VI – VII; 13, tergite VIII and anal segment. Scale bars: Figs. 7 – 9 – 50 µm; Figs. 10 – 13 – 200 µm.

FIGURES 14 – 20. Larva of fourth instar of Hydrobaenus golovinensis sp. nov. 14, S I and labral lamella; 15, antenna; 16, antennal segments 2 – 6; 17, mentum; 18, distal part of mandible; 19, premandible; 20, middle teeth of mentum. Scale bars 20 µm.