Orthocladius (Orthocladius) dentifer

Saether, Ole A., 2005, A new subgenus and new species of Orthocladius van der Wulp, with a phylogenetic evaluation of the validity of the subgenera of the genus (Diptera: Chironomidae), Zootaxa 974, pp. 1-56 : 52-54

Orthocladius (Orthocladius) dentifer

( Figs. 70–74 )

Material examined

NORWAY: Hordaland, Vaksdal, Ekse, 1 ɗ reared from larva, 2 Ψ reared from larva, 9 xi 1978, T. Andersen; same locality, 1 ɗ reared from larvae, 4 mature ɗ pupae, 5 vii 1979, E. Willassen ( ZMBN). USA: Georgia, Rabun Co. West Fork Chattooga River, 1ɗ, 10 v 1980. P. L. Hudson ( ZMBN).

Description

Male imago

As mentioned by Soponis (1977), the North American material mostly agrees with the European except for the smaller size and the distinct scutal stripes. In addition, at least the specimen from Georgia has only about 3 sensilla chaetica at 0.13–0.18 of ta1 of mid leg and a 26 m long virga, while the specimens from Ekse have 10–14 sensilla chaetica at 0.05–0.07 to 0.13–0.18 and the virga is only 0–15 µm long. In all other counts and measurements the differences are not significant.

Female imago (n = 3 except when otherwise stated)

Total length 3.64–3.97 mm. Wing length 2.36–2.69 mm. Total length/wing length 1.45–1.54. Wing length/length of profemur 3.21–3.36.

Head. AR 0.67–0.75. 0.71 (4). Flagellomere lengths (in µm, n= 4–6): 83–86, 84; 53– 56, 55; 49–56, 47; 49–56, 50, 161–180, 168. Flagellomeres 3 and 4 fused in one specimen. Temporal setae 8–13, 10 (5); consisting of 3–5, 4 inner; 5–7, 6 outer verticals; and 0–3, 1 postorbital. Clypeus with 16–19, 17 (5) setae . Tentorium 150–169 µm long, 26–30 µm wide. Stipes 150–161 µm long, 41–53 µm wide. Palpomere lengths (in µm): 38; 53–64; 105–124; 83–116, 101 (5); 143–199, 165 (5).

Thorax (n = 6). Antepronotum with 8–13, 10 setae . Dorsocentrals 7–13, 10; acrostichals14–16 (3); prealars 3–6, 4; no supraalar. Scutellum with 8–12, 10 setae .

Wing. VR 1.05–1.11. Costal extension 56–75 m long. Brachiolum with 1(6) seta; R with 11–20, 16 (6) setae ; R1 with 6–12, 10 (6), R4+5 with 12–20, 16 (6); costal extension with 1–2, 1 (6) non­marginal seta. Squama with 16–27, 21 (6) setae .

Legs. Spur of front tibia 49 µm long, spurs of middle tibia 30–38 and 26–30 µm long, of hind tibia 60–79 and 26 µm long. Width at apex of front tibia 45–49 µm, of middle tibia 45–51 µm, of hind tibia 49–56 µm. Pseudospurs present on ta1 of mid leg and hind leg and ta2 of mid leg, 23–34 µm long. Sensilla chaetica 17–23 at 0.06–0.08 to 0.20–0.30 on ta1 of mid leg, 7–17 at 0.06–0.07 to 0.17–0.26 on ta1 of hind leg. Lengths (in µm) and proportions of legs:

Abdomen (n = 6). Number of setae on tergites I–VIII as: 61–73, 67; 36–45, 40; 26–38, 33; 25–34, 31; 28–34, 31; 23–33, 27; 17–29, 22: 17–25, 21; on sternites I–VIII: 0; 2–5, 4; 7–11, 9; 10–19, 13; 18–25, 20; 20–28, 23; 28–31, 23; 22–30, 27.

Genitalia ( Figs. 70–74 , n = 5–6). Tergite IX strongly divided with margins clearly delimited, with 20–31, 24 setae . Gonocoxite with 23–34, 28 setae . Cercus 120–180, 160 µm long. Seminal capsule pear­shaped; 60–78, 69 µm long; anterior 34–45, 41 µm darker sclerotised; 45–54, 50 µm wide. Spermathecal ducts slightly meandering with separate openings. Notum 116–150, 142 µm long.

Remarks

It is not unlikely that the Nearctic specimens represent a different species as evidenced by the differences in sensilla chaetica on the legs and the length of the virga. However, more material from a wider range of localities is needed before any conclusion can be drawn.

Figures

FIGURES 70 – 74. Orthocladius (Orthocladius) dentifer Brundin, female imago, genitalia, 70: ventral view, 71: dorsal view, 72: ventrolateral lobe, 73: dorsomesal lobe, 74: apodeme lobe.