Abiskomyia korbokhon Makarchenko et Makarchenko

Makarchenko, Eugenyi A. & Makarchenko, Marina A., 2015, Review of the genus Abiskomyia Edwards (Diptera: Chironomidae: Orthocladiinae), with description of new taxa from the Russian Far East and bordering territories, Zootaxa 3919 (1), pp. 41-60 : 44-48

Abiskomyia korbokhon Makarchenko et Makarchenko , sp. nov.

( Figs. 1–27 )

Material. Holotype: adult male, extracted from mature pupa. Russian Far East: Khabarovsk Territory, Verkhne- Bureyinsky District, Amur River Basin, Korbokhon Lake (Levaya Bureya River Basin), from stomach of Brachymystax tumensis Mori , 27–28.VI. 2011, leg. P. Mikheev & A. Antonov. Paratypes: 18 males extracted from mature pupae, 98 mature pupae, 1 larva, same data as holotype.

Adult male extracted from mature pupa (n=3)

Total length c. 2.84–3.0 mm.

Head. Eyes without dorso-median extensions. Temporal setae 7–11, including outer verticals and postorbitals, inner verticals absent. Clypeus massive, with 7–12 setae. Antenna with 13 flagellomeres and reduced plume ( Fig. 5 ); 13th flagellomere tapering in apical part, blunt-pointed; AR 0.39–0.43. Palp with 4 or 5 palpomeres. Palpomere length respectively (in µm): 20–24, 32–40, 56–64, 80–88 or 20–22, 24–32, 40–48, 40–44, 56–64.

Thorax. Antepronotum with 7–8 lateral setae. Scutum brown. Acrostichals 2–4 only in lightly coloured oval area, dorsocentrals 9–15, prealars 5–7, scutellars 14–22 in 2 rows.

Wings. Not spread.

Legs. Spur of fore tibia 40–48 µm long. Spurs of mid tibia 44 µm and 48–52 µm long. Spurs of hind tibia 40–48 µm and 56 µm long. Hind tibial comb with 8–9 setae ( Fig. 3 ). Empodium short, pulvilli absent. For length and proportions of leg segments see Table 1 .

Hypopygium ( Figs. 1–2, 4 ). Tergite IX with 34–44 long setae and 40–44 µm long anal point (bare in apical part); anal point width near apex 10–12 µm. Laterosternite IX with 13–18 setae on each side. Transverse sternapodeme 100–120 µm long, without oral projections. Gonocoxite 240–252 µm long; inferior volsella with dorsal naked finger-like part and ventral roundish part covered with setae. Gonostylus 144–152 µm long, covered with numerous setae, nearly parallel-sided and with short preapical crista dorsalis; megaseta absent.

Pupa (n=6). Total length 3.15–3.75 mm. Colouration. Cephalothorax dark brown, abdomen greenish-brown. Exuviae with light brown cephalothorax and brownish abdomen; tergites VI–IX lighter.

Cephalothorax. Frontal apotome with cephalic tubercles 44–52 µm long and with simple or sometimes bifid frontal setae 108–188 µm long; frontal apotome and cephalic tubercles covered with small spines or wart-like granulation (Fig. 6). Thoracic horn 276–300 µm long, tapering to pointed apex and covered with spinules (Figs. 7–8). Nearest of thoracic horn 1–2 precorneals split into 2–7 branches and situated on tubercle. In central part of antepronotum 3 setae on tubercle, one of which apparently belong to precorneals (located 160–180 µm from thoracic horn); other two setae belong to median antepronotals, one of them simple, other branched. Lateral antepronotal setae absent. Three dorsocentrals in group and Dc4 somewhat distant; Dc1 with 2–4 branches, Dc2 simple, Dc3 with 2–5 branches, Dc4 simple.

Abdomen. Tergite I without shagreen. Tergite II with posterior shagreen consisted of small spinules and large spines arranged in 3 rows located in middle part. Tergites III–V with group of spines along posterior edge of its middle part, wider than those on tergite II and consisted of spinules and larger spines arranged in 4–6 rows, located in brown spots at base ( Figs. 21, 24 ). Tergites IV–VI and sometimes tergite VII with anteromedian oval group of brown spines (Figs. 9, 21); group of spines on tergite V surrounded with small spinules reaching spines of posterior edge (Fig. 9). Tergite III without anteromedian oval group of brown spines but sometimes with 2 spines. Sternite I without shagreen. Sternites II–III with shagreen of small spinules in middle part and with lateral longitudinal stripes of spinules. Sternites IV–V with lateral longitudinal stripes of spinules in apical ¼ or apical half (sometimes stripes extending across the entire lateral part). PSA on sternites IV–VII developed, on sternite III vestigial. Segment I without lateral setae. Segments II–V with 3 pairs of lateral setae 20–36 µm long, segments VI–VII with 3 pairs setae 36–60 µm long. Segment VIII with 1 pair of lateral setae. Anal lobe 280–304 µm long and 320–368 µm wide, with slightly chitinized projection 28–48 µm long and rounded or triangular-roundish apex (Figs. 10–14, 23). Male genital sac extending beyond anal lobe.

FIGURES 6–20. Abiskomyia korbokhon sp. nov., pupa (6–14) and fourth instar larva (15–20). 6, frontal apotome seta; 7–8, thoracic horn; 9, anteromedian group of spines on tergite IV; 10, anal segment of male; 11, same of female; 12–14 —project of anal lobe; 15, S I and labral lamella; 16, premandible; 17, mentum; 18, antenna; 19, distal part of mandible; 20, distal part of antenna. Scale bars: Figs. 6–9, 12–14—50 µm; Figs. 15–20—20 µm.

Fourth instar larva (n = 1). Total length 4.3 mm.

Head. Head capsule brownish, postoccipital margin black. S I of labrum large, oval and finely plumose on its edge, S II strong, S III weak and hair-like, S IV short. Labral lamella with rounded anterior edge and small medial notch (Figs. 15, 25). Pecten epipharyngis consisting of 3 narrow, pointed scales. Premandible weakly divided into two apical teeth and with two shorter wide inner teeth (Fig. 16); brush developed and consisted of simple long spines. Antenna with 5 segments, located on pedestal with pointed projection 52–60 µm long; segment 4 very small, shorter than segment 5; two ring organs on proximal 1/4 of basal segment, distal ring organ with long apical seta; lauterborn organs large, one on apex of second segment and one on apex of third segment; blade ending at apex of segment 5; style 6 µm long, placed on distal part of segment 3 (Figs. 18, 20); AR 1.5–1.65. Mandible with 4 teeth, apical tooth lighter and slightly longer than combined width of 3 inner teeth; seta subdentalis straight, tapering to pointed apex (Fig. 19); seta interna with 4 plumose branches. Pecten galearis weakly developed and visible only at high magnification. Apex of mentum apparently shabby; 5 pairs of lateral teeth present; first pair of lateral teeth smallest and located at the base of middle part of mentum; ventromental plate broad, subtriangular; covered with small spines; setae submenti plumose in apical part (Fig. 17). Anal tubules shorter than posterior parapods. Procercus dark, sclerotized, wider than long, bearing 7 apical anal setae, incl. 2 setae longer and thicker than others. Body with plumose and simple setae on thoracic segments I–III; abdominal segments II–VI with 1 bifurcate seta in basal part and 1 seta with many branches; segment VII with 1 bifurcate seta and 1 simple seta.

Diagnostic characters. See the keys.

Etymology. The species is named after the type locality: the Korbokhon Lake; the name is noun in apposition.

Ecology. Pupae and larvae live in the mountain oligotrophic Korbohon Lake, located at an altitude of 1160 m.

Figures

FIGURES 1 – 5. Abiskomyia korbokhon sp. nov., male. 1 – 2, hypopygium in dorsal view; 3, spurs and tibial comb of hind leg; 4, gonocoxite and gonostylus in ventral view; 5, antenna. Scale bars: Figs. 1 – 4 — 50 µm; Fig. 5 — 200 µm.

FIGURES 21 – 27. Abiskomyia korbokhon sp. nov. (21 – 26) and A. levanidovi sp. nov. (27), pupa (21 – 24) and larva of fourth instar (25 – 27). 21, shagreenation of tergites IV – V; 22, anal segment of male; 23, project of anal lobe; 24, spines of shagreen on tergite IV; 25, labral lamella; 26 – 27, mentum.

Tables

TABLE 1. Lengths (in µm) and proportions of leg segments of Abiskomyia korbokhon sp. nov., male (n = 3).

fe	ti	ta1	ta2	ta3	ta4	ta5
P1 480	584–704	352–432	176–208	136–160	128–144	128
P2 512–560	592–688	224–240	144–160	112–128	112	112–128
P3 560–800	624–848	224–352	128–208	192	112	120
continued.