Orthocladius (Orthocladius) pallidicornis Lundström, 1915 : 13

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 : 15-17

Orthocladius (Orthocladius) pallidicornis Lundström, 1915: 13

( Figs. 14–18 )

Type material. Lectotype ɗ, here designated: RUSSIA: Chara­Ullach Mts., 12 vii 1902, M. I. Brussnew. Paralectotypes: 3 Ψ (including 1 misidentified Tokunagaia sp., and 1 misidentified Tanytarsini lacking the abdomen), as lectotype except 12 vii and 16–17 vii 1902.

MALE IMAGO (n = 1)

Total length 3.63 mm. Wing length 2.11 mm. Total length/wing length 1.72. Wing length/length of profemur 2.86. Coloration pale brown with dark brown vittae, postnotum and preepisternum.

Head. AR 0.95. Ultimate flagellomere 420 m long. Temporal setae 15, including 7 inner verticals, 4 outer verticals, and 4 postorbitals. Clypeus with 7 setae. Tentorium 173 m long, 26 m wide. Stipes 150 m long, 41 m wide. Palpomere lengths (in m): 38, 45, 101, 94, 173. Third palpomere with 2 lanceolate sensilla clavata 15 m long.

Thorax. Antepronotum robust, projecting, with 2 setae. Acrostichals apparently 11, dorsocentrals 7, prealars 3. Scutellum with 4 setae.

Wing. VR 1.10. Anal lobe conspicuous, projecting [, as in O. (O.) decoratus (Holmgren) , see Soponis (1977: fig.14 f)]. Costal extension 8 m long. Brachiolum with 1 seta, other veins bare. Squama with 15 setae.

Legs. Spur of front tibia 41 m long, spurs of middle tibia 26 and 23 m long, of hind tibia 60 and 23 m long. Width at apex of front tibia 41 m, of middle tibia 39 m, of hind tibia 45 m. Sensilla chaetica (possibly only curved setae?): 6 spaced along full length of ta1 of mid leg, and 2 apically on hind leg. Lengths (in m) and proportions of legs: Hypopygium ( Fig. 14 ). Tergite IX with 17 setae, including 9 on anal point; laterosternite IX with 5 setae. Anal point sharply pointed, 38 m long. Phallapodeme 60 m long; transverse sternapodeme 68 m long, oral projections indicated. Virga 19 m long, apparently consisting of several longitudinally arranged, shorter spines. Gonocoxite 233 m long, superior volsella prominent, hook­shaped, with conspicuously broad microtrichia; inferior volsella weak. Gonostylus 109 m long, nearly semicircular, megaseta 11 m long. HR 2.14, HV 3.33.

FEMALE IMAGO (n = 1)

Total length 2.93 mm. Wing length 2.49 mm. Total length/wing length1.24. Wing length/length of profemur 3.32. Coloration as in male.

Head. AR 0.58. Lengths of flagellomeres (in m): 98, 45, 45, 45, 139. Temporal setae 12, consisting of 4 outer verticals; 4 inner verticals, and 4 postorbitals. Clypeus with 13 setae. Tentorium 169 m long, 30 m wide; stipes 184 m long, 41 m wide. Palpomere lengths (in m): 38, 53, 124, 94, 180. Coronal suture nearly complete, 158 m long.

Thorax. Antepronotum with 6 lateral setae. Acrostichals 10, dorsocentrals 7, prealars 3. Scutellum with 4 setae.

Wing. VR not measurable. Costal extension 38 m long. Brachiolum with 1 seta, R4+5 with 6 setae, costal extension with 2 non­marginal setae. Squama with 14 setae.

Legs. Spur of front tibia 41 m long, spurs of mid tibia 30 m and 26 m long, spurs of hind tibia 64 m and 23 m long. Width at apex of front to hind tibiae (in m) as: 53, 45, 53. Comb of 9 setae; shortest seta 26 m long. longest seta 45 m long. Pseudospurs present on ta1 of mid and hind legs, 28 m long. Sensilla chaetica not observed. Lengths (in m) and proportions of legs:

Abdomen. Setae on sternites I–VIII as: 0, 2, 8, 9, 7, 15, 14, 18.

Genitalia ( Figs. 15–18 ). Half of tergite IX missing, other half with about 7 setae. Gonocoxite with 10 setae. Cercus 105 m long. Seminal capsule 71 m long, 53 m wide. Spermathecal ducts nearly straight. Gonapophysis VIII divided, with large ventrolateral ( Fig. 18 ) and dorsomesal ( Fig. 17 ) lobes. Apodeme lobe ( Fig. 16 ) strongly sclerotised, conspicuous. Notum 128 m long.

Remarks

The species keys to O. (O.) decoratus (Holmgren) in Soponis (1977) whose redescription included the type material. Rossaro et al. (2003) also redescribed the species including the lectotype. They report their specimens as having a not produced anal lobe of the wing, and 10 scutellars in a single row. Both the lectotype of O. (O.) decoratus , other specimens of O. (O.) decoratus ­ including some at the Museum of Zoology, Bergen ­ examined by Soponis and the present species are characterised by the strongly developed anal lobe. O. (O.) decoratus has 8–15 uni­biserial scutellars, while the present species has 4 uniserial scutellars. O. (O.) decoratus has 5–11 setae on vein R, O. (O.) pallidicornis none. O. (O.) pallidicornis also differs from O. (O) decoratus in a number of other features such as a lower antennal ratio (0.95 compared to 1.4–2.0), the lower front leg ratio (0.58 with a wing length of 2.11 mm compared to 0.69–0.77 with wing lengths of 2.20–2.85 mm), the conspicuous and unique microtrichia on the superior volsella, the even more reduced inferior volsella, and the nearly semicircular gonostylus.

Figures

FIGURES 11 – 14. Male hypopygium, 11: Orthocladius (Pogonocladius) consobrinus (Holmgren) from holotype of O. marginatus Lundström, 12: Orthocladius nitidoscutellatus Lundström, holotype, 13: Chaetocladius binotatus (Lundström) comb. n., holotype, 14: Orthocladius (Orthocladius) pallidicornis Lundström.

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.