Diamesa kownackii Makarchenko & Semenchenko & Palatov 2022, sp. nov.

Diamesa kownackii Makarchenko, sp. nov.

http://zoobank.org/NomenclaturalActs/ 4601893D-170C-427C-8F19-AEED2CA46FB2

(Figs. 9–14, 31, 69–70)

Diamesa steinboecki Goetghebuer; Makarchenko et al, 1980: 6; 1981: 96; 1985: 71; 2006: 261, 472, 614, misidentification.

Type material. Holotype, adult male, RUSSIA: Chukotka Autonomous Region, Wrangel Island, unnamed stream in upper part of Somnitelnaya River, altitude 205–210 m above sea level, 22.VII.1978, N 70.995783, W 179.539117, leg. E. Makarchenko. Paratypes: 52 adult males, 23 pupae, 28 larvae, the same data as holotype, except 22.VII– 15.VIII.1978; 9 adult males, 14 pupae, 33 larvae, the same data as holotype, except 7–10.VIII. 1979; 5 adult males, the same data as holotype, except Khishnikov River, 17.VIII.1978, leg. E. Makarchenko; 2 adult males, Chukotka Autonomous Region, Anadyr District, northeastern spurs of the Koryak Highlands, unnamed stream of Gytgylveirgytgyn Lake basin (Velikaya River basin), 29.VII.1980, altitude ca 300 m above sea level, N 62.962222, E 171.805833, leg. E. Makarchenko.

Derivatio nominis. The species is named in honor of the Polish chironomid taxonomist and hydrobiologist Dr. Andrzej Kownacki, a leading specialist on Caucasian Diamesinae, namely of Diamesa steinboecki group.

Description

Adult male (n = 10, except when otherwise stated). Total length 4.2–5.2 mm. Total length/wing length 1.27– 1.75.

Coloration. Dark brown to black. Head brown. Thorax black. Legs brown. Abdomen dark brown to black. Wings grey.

Head (Fig. 9). Eyes hairy, reniform. Temporal setae including 0 frontals, 4–9 orbitals, 6–9 verticals and 5–6 postorbitals; frontals absent. Clypeus with 2–5 setae. Antenna with 8 flagellomeres and reduced plume of setae; number and length of these setae on 1–7 flagellomeres respectively: 2–3 (26–28 μm), 1–2 (18–32 μm), 3–5 (40–68 μm), 3 (32–44 μm); terminal flagellomere with 2 setae, 20–24 μm long in subapical and apical area. Length of 1–8 flagellomeres (μm): 105–118, 42–53, 42–46, 29–38, 29–38, 25–34, 29–38, 130–160; AR 0.38–0.50. Palpomere length (μm): 330–348, 64–84, 105–126, 78–92, 109–134. Palpomere 3 in distal part with sensilla capitata with diameter 16–20 μm. Head width/palpal length 1.20–1.25. Antennal length/palpal length 1.12–1.40.

Thorax. Antepronotum with 11–18 ventrolateral setae, 48–68 μm long. Dorsocentrals 7–12, 68–84 μm long; prealars 5–10, 60–76 μm long. Scutellum with 32–42 setae. AAII without setae.

Wing (Fig. 31). Length 2.86–3.54 mm, width 0.93–1.10 mm. Costal extension 90–98 µm long. Anal lobe slightly reduced, rounded. Squama with 4–16 setae, 36–44 μm long. R and R 1 with 10–16 setae, R 4+5 with 8–17. RM/MCu 1.33–2.27.

Legs. Spur of front tibia 50–59 µm long. Spurs of mid tibia 46–59 µm and 42–63 µm long. Spurs of hind tibia 88–118 µm and 55–71 µm long. Hind tibial comb with 18–25 setae. Length (μm) and proportions of leg segments are as in Table 2.

Hypopygium (Figs. 10–14). Tergite IX with 15–18 setae, 32–40 µm long and with narrow (6–8 µm), pale, and naked anal point, 76–116 µm long (Fig. 10) which in lateral view apically slightly curved down (Fig. 14); posterior edge of tergite IX slightly concave, anal-lateral angles protrude noticeably beyond edge (Fig. 10); anal tergal bands Y-type; median tergal band 76–104 µm long. Laterosternite IX with 6–10 setae, 32–48 µm long. Transverse sternopodeme (TSA) triangular, peaked (Figs. 11–12) and sometimes with spire-shaped apex (Fig. 11), 160–184 µm high, 216–268 µm wide at the base; TSA height/TSA width 0.71–0.86. Aedeagal lobe as in Figs. 11–12, weakly chitinized, leaf-shaped; phallapodeme sclerotized, 208–336 µm long. Gonocoxite 574–640 µm long, in middle part of dorso-internal position with small flattened transverse lobe, 112 µm long, 32–36 µm wide, directed backwards and with longitudinal lobe in middle, anterior outer margin of which is slightly rounded and not projecting (Fig. 13). Gonostylus 246–264 µm long, curved, megaseta in form of wide terminal spine 10–12 μm long, next to it there is tooth and two setae approximately of the same long. HR 2.0–2.53.

Pupa and larva were described as D. steinboecki Goetghebuer by Makarchenko (1981).

Diagnosis. The male of D. kownackii sp. nov. is most closely related in the subgroup to the D. steinboecki, since both have anal tergal bands Y-type, but the male of first species is larger (4.2–5.2 mm), it lacks the frontal setae of the head, posterior edge of tergite IX slightly concave and anal-lateral angles protrude noticeably beyond edge, median tergal band 76–104 µm long. The male of D. steinboecki 2.0– 3.5 mm long, with some frontal setae of the head, posterior edge of tergite IX almost straight and anal-lateral angles not protrude beyond edge, median tergal band 108–116 µm long.

Ecology. Adults, pupae and larvae were collected from stones and boulders in high arctic river, located at an altitude of 200–400 m, at a flow rate of 0.5–0.8 m /s, with water temperatures 7.4–9.0°C. The density of larvae in the Somnitelnaya River was 8.3–16.7 ind./m 2 (July 1979) (Makarchenko & Makarchenko 1981).

Distribution. Known only from the type locality—Somnitelnaya River basin of Wrangel Island and northeastern spurs of the Koryak Highlands (Figs. 69–70).