Derotanypus sibiricus (Kruglova & Chernovskii)

Saether, Ole A., 2004, The chironomids (Diptera, Chironomidae) described by Lundström (1915) from arctic Siberia, with a redescription of Derotanypus sibiricus (Kruglova & Chernovskii), Zootaxa 595, pp. 1-35 : 30-32

Derotanypus sibiricus (Kruglova & Chernovskii)

(Figs. 27–29)

Anatopynia sibirica Kruglova & Chernovskii, 1940: 2 .

Derotanypus sibiricus (Kruglova & Chernovskii) , Fittkau & Roback (1983: 48) Derotanypus Pe 1 Langton (1991: 22).

Type material. Lectotype ɗ of D. sibiricus , here designated: RUSSIA: Tomsk, Universitetsk ozewo (Lake Universitetskoe in the confines of the City of Tomsk), 27 iii 1940, W. M. Kruglova, (Zoological Institute, Russian Academy of Sciences St. Petersburg, Russia). Paralectotypes 2 Ψ of D. sibiricus , as lectotype except 5–15 iii 1940 and 28 iii 1940.

MALE IMAGO (n = 1)

Total length 8.09 mm. Wing length 4.27 mm. Total length/wing length 1.90. Wing length/length of profemur 2.39. Coloration brown with darker vittae and markings. Legs pale brown with femora, basal and apical tibial bands and ta3–ta5 brown. Wing with dark spot over both cross­veins.

Head. Antenna lost. Temporal setae 51, including 13 inner verticals, 16 outer verticals, and 22 postorbitals. Clypeus with 46 setae. Tentorium 244 m long, 83 m wide. Stipes about 225 m long. Palpomere lengths (in m): 98, 169, 225, 281, 330.

Thorax. Antepronotals not countable. Acrostichals about 55, dorsocentrals about 70, prealars 45, median anepisternum II with 13 setae, preepisternum with 24 setae. Scutellum with about 90 setae.

Wing. VR 0.94. Costal extension 131 m long, RM 206 m long, MCu 113 m long, distance between MCu and RM 19 m. Wing membrane with numerous setae in apical half. Cell m with 1 seta, cell r with 46 apical setae, r1 with 9, r2+3 with 23 setae, numerous setae each in cells r4+5, m1+2 and m3+4. Subcosta bare, brachiolum with 12 setae, R with 82, R1 with 100, R2+3 with 35, R2 with 10, R3 with 36, R4+5 with 170, RM with 4, M with 13, M1+2 with about 60, M3+4 with about 60, Cu with 16, Cu1 with about 40, postcubitus with about 12, An with about 35 setae, costal extension with 14–20 non­marginal setae. Squama with about 75 setae.

Legs. Spur of front tibia 124 m long, with 15 lateral teeth; spurs of middle tibia 120 and 98 m long, both with about 20 lateral teeth; spurs of hind tibia 120 and 109 m long, with 16 and 19 lateral teeth, respectively. Width at apex of front tibia 128 m, of middle tibia 124 m, of hind tibia 150 m. Sensilla chaetica apparently absent. Lengths (in m) and proportions of legs:

Hypopygium (Fig. 27). Tergite IX with 2 posterior setae. Phallapodeme in two sclerotized, overlapping parts 120 m and 94 m long. Gonocoxite 469 m long. Gonostylus 285 m long, basal part 101 m wide, but sclerotized for only 60 m; apical part 45 m wide, nearly parallel­sided to apex; megaseta 15 m long. HR 1.67, HV 2.84.

FEMALE IMAGO (n = 1–2)

Total length 6.33–6.57 mm. Wing length 3.94–4.27 mm. Total length/wing length 1.54– 1.61. Wing length/length of profemur 2.53–2.58. Coloration as in male or slightly more pale.

Head. AR 0.22. Flagellomeres 1–13 each 56–68 m long, Fm13 68–75 m, Fm14 165–176 m long. Temporal setae 52–71, consisting of 18–27 outer verticals; 23–28 inner verticals, and 11–16 postorbitals. Clypeus with 49–54 setae. Tentorium 263 m long, 71– 75 m wide; stipes 225 m long. Palpomere lengths (in m): 101–105, 131–169, 225–255, 238–304, 428–499.

Thorax. Antepronotals not countable. Acrostichals about 70–90, dorsocentrals about 90–95, prealars 54–56, median anepisternum II with 18–28 setae, preepisternum with 25– 26 setae. Scutellum with about 90–95 setae.

Wing. VR 0.93. Costal extension 131–154 m long, RM 180–191 m long, MCu 135– 150 m long, distance between MCu and RM 0– 8 m. Wing membrane with numerous setae over whole wing, including anal lobe and costal cell. Cell r with about 55–70 setae, cell m with about 50 setae. Brachiolum with 13 setae, subcosta with 9, R with 95, R1 with 80, R2+3 with 55–65, R2 with 4–6, R3 with 38–53, R4+5 with about 196, M with 15–21, postcubitus with 5–6 setae, costal extension with 30 non­marginal setae, M1+2, M3+4, Cu1 and An each with numerous setae. Squama with about 90–106 setae.

Legs. Spur of front tibia 101–105 m long, with 14–15 lateral teeth; spurs of mid tibia 113–116 m and 94–98 m long, with 23 and 16 teeth, respectively; spurs of hind tibia 124–143 m and 79–94 m long, with 22–23 and 16–20 teeth. Width at apex of front to hind tibiae (in m) as: 105–124, 113–128, 135–146. Hind tibial comb absent. Sensilla chaetica about 70–75 in apical third of ta1 of mid leg, about 60–70 in apical third of ta1 of hind leg. Lengths (in m) and proportions of legs:

Genitalia (Figs. 28, 29). Sternite VIII with about 200 setae. Gonotergite IX apparently with 1 seta on each of moderately developed rudiments of gonocoxite. Segment X with 8 setae, 4 on each side. Cercus 173–188 m long. Seminal capsule 75–94 m long including triangular neck, 64–83 m wide. Notum 255–270 m long.

Remarks

The species at first was thought to be a junior synonym of D. limbatus . However, the wings both of male and female are less setaceous in D. limbatus , with subcosta, vein M and cell m bare in the male. The posterior margin of male tergite IX is bare in D. limbatus while there are 2 setae in D. sibiricus . Also, the shapes of the gonostyli differ significantly, with D. sibiricus having a more parallel­sided apical part. The females of the two species differ in an even more significant way. While D. sibiricus have setae on segment X and possibly on gonotergite IX, these are absent in D. limbatus . In addition, the seminal capsules in D. limbatus are more than twice as large as those in D. sibiricus , one third as long as notum in D. sibiricus , two third as long as notum in D. limbatus . D. sibiricus , however, may be a junior synonym of D. alaskensis (Malloch, 1919) ( Roback 1971: 94) , the only known difference being the presence of two setae on the posterior margin of tergite IX in D. sibiricus . However, too little material has been examined to estimate intraspecific variation in this character.