Chaetocladius perennis (Meigen)

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 : 19-20

Chaetocladius perennis (Meigen)

( Fig. 21 )

Chironomus perennis Meigen, 1830: 249 .

Camptocladius incertus Lundström, 1915: 15 , syn. n.

Type material examined. RUSSIA: New Siberian Islands, west coast, lectotype ɗ, here designated, 12 vi 1903, M. I. Brussnew; paralectotype ɗ, south coast at Holzgebirge”, 9 vii 1903, M. I. Brussnew.

MALE IMAGO (n = 1–2)

Total length 3.47–3.87 mm. Wing length 1.89–2.07 mm. Total length/wing length 1.84–1.87. Wing length/length of profemur 2.38–2.41. Thorax and abdomen brown, legs dark brown.

Head. AR 1.12–1.15. Ultimate flagellomere 435–444 m long. Temporal setae 15–17, consisting of 6–7 inner verticals, 6–7 outer verticals and 3 postorbitals. Clypeus with 7–8 setae. Tentorium 173–176 m long, 38–45 m wide; stipes 158–165 m long, 71–75 m wide, with well sclerotised median plate. Palpomere lengths (in m): 45–49, 60–68, 128– 154, 120–143, 180–203. Third palpomere apparently with 3 very weak sensilla clavata.

Thorax. Antepronotum with 8–10 lateral setae. Acrostichals 18–21, dorsocentrals 18– 19, prealars 6, supraalars 1–2. Scutellum with 10–12 setae.

Wing. VR 1.04. Costal extension 68 m long. Brachiolum with 1 seta, R with 13–15 setae, R1 with 6–7 setae, other veins bare. Squama with 10–11 setae.

Legs. Spur of front tibia 68–75 m long, spurs of mid tibia 38 and 34 m long, spurs of hind tibia 75–86 and 30 m long, lateral denticles well developed. Pseudospurs 2 on ta1 and ta2 of mid leg and ta1 of hind leg, about 30 m long; ta2 of hind leg lost. Sensilla chaetica about 3–5 in apical half of ta1 of mid leg, about 6 in apical half of ta1 of hind leg, spinelike. Width at apex of front to hind tibiae (in m) as: 49–56, 53–54, 68–71. Comb of 15 setae, shortest seta 34–38 m long, longest seta 41–60 m long. Lengths (in m) and proportions of legs:

Hypopygium ( Fig. 21 ). Tergite IX including anal point with 16–20 setae, laterosternite IX with 8–10 setae. Anal point 75–98 m long, bare of microtrichia in distal two thirds. Phallapodeme 113–131 m long, transverse sternapodeme 101–105 m long. Virga absent. Gonocoxite 293–296 m long; inferior volsella double, well developed; gonostylus 135 m long, megaseta 13–15 m long. HR 2.17–2.19, HV 2.572.87.

Remarks

The characteristic hypopygium is illustrated by Brundin (1947, fig 44) and Pinder (1978, fig. 123 c). Although the types of C. perennis not have been re­examined, the present specimens at least are in accordance with the present definition of that species. The leg ratio according to the measurements in Lundström would be 0.73, i. e. quite different from the ones measured on the present specimens (0.54–0.57). However, measurements obtained from pinned, not prepared specimens cannot be regarded as having any significance. The figure in Lundström (1916, fig.18) conform to C. perennis .

Figures

FIGURES 15 – 21. Orthocladius, Paralimnophyes and Chaetocladius, 15 – 18: female genitalia, Orthocladius (Orthocladius) pallidicornis Lundström, 15: ventral view, 16: apodeme lobe, 17: dorsomesal lobe, 18: ventrolateral lobe, 19 – 20: Paralimnophyes trilineatus (Lundström) comb. n., 19: male hypopygium, 20: female genitalia, lateral view, 21: Chaetocladius perennis (Meigen), male hypopygium from lectotype of Camptocladius incertus Lundström.