Diamesa leoniella Hansen, 1976

Makarchenko Usgs, Eugenyi A., 2021, Confirmation of a species status of Diamesa leoniella Hansen, 1976, stat. resurr (Diptera, Chironomidae) from North America, Zootaxa 4985 (3), pp. 439-442 : 439-440

Diamesa leoniella Hansen, 1976 , stat. resurr.

( Figs. 1–2 )

Diamesa leoniella Hansen in Hansen & Cook 1976: 111.

Material examined. 1 adult male, U.S.A.: Alaska, Juneau City, Mendenhall Lake , N 58.4217 E 134.5388, 26.III.2013, leg. K. Frangos and P. Hudson ; 1 adult male, the same data except Nugget Falls , N 58.4270 E 134.5373, 17.VII.2013, leg. P. Hudson.

Adult male (n = 2). Total length 4.7 mm. Wing length 2.56–3.44 mm. Total length/wing length 1.37.

Colouration. Head, thorax, legs and hypopygium dark brown; antenna brown; palpomeres light brown; abdomen light brown to brown; wing greyish, veins brownish.

Head. Eyes hairy, i.e., length of eye microtrichia about 1.5 or more times the height of ommatidial lenses and visible along lateral eye margin when head is viewed from front ( Hansen & Cook 1976). Frontal tubercles 16–44 μm long, covered with microtrichia. Temporal setae including about 13–15 verticals, 8–12 preoculars, 5 postorbitals. Clypeus with 5–6 setae. Antenna with 8 flagellomeres and reduced plume of setae; flagellomeres 1–7 with 2–3 setae, 24–40 μm long; terminal flagellomere in basal part with 4–5 setae, 60–72 μm long and with 2 subapical setae, 16–20 μm long. Flagellomeres 1–8 length (μm): 88–104, 36–40, 40, 32, 32, 26–32, 32–44, 164–248; AR 0.41–0.78. Antennal length/palp length 1.09–1.21. Palpomeres lengths (in μm): 32–40; 56–64; 108; 84–100; 136–156. Palpomere 3 in distal part with sensilla capitata with diameter 20 μm. Palpomeres 1–5 length/head width 0.92.

Thorax. Antepronotum with 9–11 ventrolateral setae. Dorsocentrals 5–7, prealars 7, scutellars 9–11.

Wing. R and R 1 with 25–34 setae; R 4+5 with 18–19 setae. Costa extension 52–60 μm long. RM length/MCu length 2.8–3.5. Anal lobe slightly reduced, angularly. Squama with 14–17 setae, 52–68 μm long. VR 0.96–1.0.

Legs. Spur of fore tibia 40–44 μm long; spurs of mid tibia 44 μm long; of hind tibia 74–80 μm and 44–48 μm long. Hind tibial comb with 15–16 setae. Lengths and proportions of leg segments as in Table 1 .

Hypopygium ( Figs. 1–2 ). Tergite IX with 11–13 setae (from one side), 16–24 μm long and wedge-shaped anal point 100–140 μm long, covered in basal half with numerous microtrichia forward and laterally directed. Laterosternite IX with 10–11 short setae. Transverse sternapodeme triangular 128 μm long. Gonocoxite 400–496 μm long. Inferior volsella finger-like, 40–48 μm long and 24 μm width, covered with short setae and microtrichia. Superior volsella collar-like, covered with microtrichia and short setae. Gonostylus slightly curved, 212–246 μm long, with numerous, proximally directed strong setae 48–64 μm long; megaseta 6–8 μm long. HR 1.65–1.93.

Diagnostic characters. Male of D. leoniella is very closely related to D. japonica and distinguished from later by the following main features: 1—antennal flagellomeres 1–7 with 2–3 short setae, 2—inferior volsella finger-like, covered with short setae and microtrichia, 3—superior volsella collar-like, covered with microtrichia and short setae. Male of D. japonica : 1–without setae on flagellomeres 4–7, 2—inferior volsella absent, 3—superior volsella in form of an angular tubercle.

Distribution. Nearctic species. Known from U.S.A. — California, Montana, Utah, Washington, Wyoming ( Hansen & Cook 1976) and Alaska (recorded for the first time).

Figures

FIGURES 1–4. Males of Diamesa leoniella Hansen (1–2) and D. japonica Tokunaga (3–4). 1, 4, central part of hypopygium without tergite IX; 2–3, hypopygium in dorsal view.

Tables

TABLE 1. Lengths (in µm) and proportions of leg segments of Diamesa leoniella Hansen, male (n=2)

	fe	ti	ta 1	ta 2	ta 3	ta 4	ta 5
P 1	1607–2280	1591–2120	1082–1400	541–720	295–440	107–140	148–180
P2	1706–2160	1394–1760	763–960	377–440	230–360	98–140	148–180
P3	1738–2400	1624–2160	1033–1440	607–800	312–400	98–160	148–200

Continued.