Diamesa leoniella Hansen, 1976

Makarchenko, Eugenyi A., Semenchenko, Alexander A. & Palatov, Dmitry M., 2022, Taxonomy of Diamesa steinboecki group (Diptera: Chironomidae: Diamesinae) with description and DNA barcoding of known species. II. Subgroups davisi, leona and loeffleri, Zootaxa 5190 (3), pp. 361-392 : 374-375

Diamesa leoniella Hansen

( Fig. 28 )

Diamesa leoniella Hansen in Hansen & Cook 1976: 111; Makarchenko 2021: 439.

Diamesa japonica Tokunaga ; Makarchenko 1981: 110, misidentification.

Material examined. U.S.A.: 1 adult male, 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.

Description

Adult male (n = 2). Total length 4.7 mm (n = 1). Wing length 3.44 mm (n = 1). Total length/wing length 1.37.

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

Head. Eyes hairy. Frontal tubercles 16–44 μm long, covered with microtrichia. Temporal setae including about 8–12 frontals, 13–15 verticals, 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/MCu 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 front 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 9 .

Hypopygium ( Fig. 28 ). 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 in form of collar, 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.

Pupa and larva unknown.

Remarks. Male of D. leoniella is very closely related to D. japonica and many years ago senior author misidentified this species as D. japonica ( Makarchenko 1981) . After obtaining comparative material from North America, it turned out that these two species can be well distinguished by the structure of the hypopygium and some other features ( Makarchenko 2021). So, the male of D. leoniella has a finger-shaped inferior volsella and a superior volsella in the form of a collar, while D. japonica without inferior volsella and superior volsella in form of 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 23–28.Adult males of Diamesa japonica Tokunaga from Honshu, Japan (23, 27), Hokkaido, Japan (24) and Kunashir Island (25–26), Diamesa leoniella Hansen from Alaska (28). 23, flagellum of antenna; 24, tergite IX (bent out on slide); 25, anal point in lateral view; 26–28, hypopygium in dorsal view.