Chaetocladius suecicus (Kieffer) sensu Edwards (1929)

Stur, Elisabeth & Spies, Martin, 2011, Description of Chaetocladius longivirgatus sp. n., with a review of C. suecicus (Kieffer) (Diptera: Chironomidae), Zootaxa 2762, pp. 37-48 : 38-41

Chaetocladius suecicus (Kieffer) sensu Edwards (1929)

( Figs. 1 , 3 , 6 , 8, 9 )

? Dactylocladius suecicus Kieffer, 1916: 517 — Thienemann & Kieffer (1916), adult male and female. Taxonomic identity unclear; see Discussion section below.

Spaniotoma (Orthocladius) suecica (Kieffer) — Edwards (1929: 337, in part), adult male and female. Chaetocladius suecicus (Kieffer) – Brundin (1947: 24), adult male; Lehmann (1971, in part), distribution, phenology; Langton & Visser (2003), pupa, distribution; Saether & Spies (2004, in part), distribution; Langton & Pinder (2007, vol. 1: 86, 87; vol. 2: fig. 143B), adult male.

TABLE 1. Pairwise Kimura-2-parameter distances between COI sequences of specimens in the “ Chaetocladius suecicus species group”. Chaetocladius longivirgatus Chaetocladius suecicus sp. AT208 AT408 AT220 AT453 AT452 AT451 AT194 AT14 AT427 AT193 AT200 AT228 AT428 ES265 longivirgatus AT AT AT 2 408 220 0 8 - 0.000 0.000 - 0.000 -

AT453 0.000 0.000 0.000 -

Chaetocladius AT AT AT 452 194 451 0.000 0.002 0.000 0.000 0.000 0.002 0.000 0.002 0.000 0.000 0.002 0.000 - 0.002 0.000 - 0.002 -

suecicus AT AT 427 14 0.128 0.127 0.127 0.128 0.128 0.127 0.127 0.128 0.126 0.129 0.127 0.127 0.128 0.128 - 0.008 -

Chaetocladius AT AT AT AT 428 228 200 193 0.129 0.129 0.129 0.134 0.134 0.129 0.129 0.129 0.134 0.129 0.129 0.129 0.129 0.129 0.134 0.129 0.131 0.136 0.128 0.131 0.128 0.134 0.129 0.128 0.129 0.129 0.129 0.127 0.007 0.012 0.006 0.006 0.002 0.005 0.005 0.006 - 0.008 0.008 0.004 - 0.003 0.007 - 0.003 -

. sp ES265 0.117 0.117 0.117 0.117 0.117 0.120 0.114 0.113 0.112 0.113 0.111 0.117 0.112 -

Material examined (listed alphabetically by country). GERMANY: 1 adult male ( ZSM), Bavaria, Allgäu, Rappensee, 2000 m a.s.l., 25.vii.–08.viii.1977, leg. H. Mendl. — NORWAY, Oppland, Dovre, Rondane Nationalpark (all at VM): 1 adult male (genetic voucher AT14; Genbank accession number HQ712186 ), near Dørålseter, N 61.987°, E 0 9.789 °, 1050 m, 30.v.2008, hand net, leg. E. Stur & T. Ekrem; 2 adult males (vouchers AT427, AT428; Genbank accession numbers HM421520 and HM421521 respectively) øvre Vidjedalsbekken, N 61.97168° E 09.83606°, 1280 m, Malaise trap, 30.vi.–07.vii.2008, leg. T. Hoffstad; 2 adult males (vouchers AT193, AT200; Genbank accession numbers HM421307 and HM421314 respectively), Vidjedalsbekken at Skranglehaugen, N 61.98186°, E 0 9.80454 °, 1117 m, Malaise trap M1, 23.–30.vi.2008, leg. T. Hoffstad; 1 adult male (voucher AT228 Genbank accession number HM421340 ), further data as in preceding entry, except 07.–14.vii.2008. — SPAIN: 2 adult males ( ZSM & VM), Prov. Castilla y León, Puerto de Leitariegos NW of Villablino, N 42.99°, W 0 6.41 °, c. 1500 m, 04.vii.1988, leg. W. Schacht. — SWEDEN: 1 adult male ( ZSM), Norbotten, Abisko, 13.x.1955, leg. E. J. Fittkau; 1 adult male ( NHRS), northern Jämtland, Jormsjön, 8.x.1945, leg. A. Määr (Brundin coll. code "B.7"); 1 adult male, as preceding, except Stora Blåsjön, 23.–25.ix.1945 ("B1:6"); 1 adult male, as preceding, except 4.x.1945 ("B.12"). — UNITED KINGDOM: 1 pupal exuviae with pharate male inside (PHL), Scotland, Perthshire, “burn 14” (a small stream in montane heathland), 8.vii.1985, leg. J. Foster & S. Hogg; 1 adult male, as preceding, except Loch Lannoch, 5.iv.1991, leg. P.H. Langton; 2 adult males (NHM), Shropshire (=Salop), Snailbeach, 22.–28.vii.1920, leg. F.W. Edwards.

Diagnostic characters. The male imago is separable from other known species in the genus Chaetocladius by the following combination of characters: wing length 2.10–2.54 mm; AR higher than 1.25; eyes weakly pubescent; anteriormost acrostichals close to antepronotum; humeral pit ovoid, dark with several patches in one larger spot; LR1 0.63–0.69; wing with setae on squama and on veins R, R1+2 and R4+5; halters light-colored; median setae on tergite IX comparatively robust; virga shorter than half of anal point length, with 5–6 subequal spines arranged in a bundle; anal point not hyaline at base, parallel-sided, apically rounded, reaching about as far posterior as inferior volsella; inferior volsella double, ventrally covered with microtrichia; gonostylus without projections or significant expansions, with one distal macroseta; HR 2.27–2.56.

Male imago (n=6 unless otherwise stated). Wing length 2.43 (2.40–2.54) mm. Gonocoxite length/wing length 90 (81–95) (n=11). Coloration brownish black. Halters brown at base and light distally ( Fig. 1 ).

Head. AR 1.45 (1.3–1.5) (n = 5). Terminal flagellomere 630 (600–680) µm long (n = 5). Temporal setae 9–12, including 2–4 inner verticals, 5–8 outer verticals and 1 postorbital. Clypeus 70–80 µm long, with 5–9 setae. Palpomere lengths (in µm): 30–40, 50–60, 155–165, 115–145, 200–230.

Thorax. Antepronotum with 5–7 setae. Acrostichals 17–20 (n=5), dorsocentrals 12–16 in one row, prealars 4– 7. Scutellum with 10–11 setae in one transverse row.

Wing ( Fig. 3 ). Costa barely extended. VR 0.99–1.03. Anal lobe well developed, projecting, rightangled. Brachiolum with 1 seta; veins bare, except R with 15–18, R1 with 0–3, R4+5 with 1–5 setae. Squama with 9–17 setae. Legs. Spur of front tibia 74–85 µm long, spurs of middle tibia 25–33 µm (n=5) and 30–40 µm long, of hind tibia 23–30 µm (n=5) and 70–80 µm long. Lengths and proportions of leg segments as in Table 2.

fe ti ta1 ta2 ta3 p1 900 (870–950) 1040 (840–1150)* 670 (580–740)* 390 (380–420) 280 (260–300) p2 940 (920–980) 980 (950–1020) 440 (420–460) 270 (260–290) 200 (190–210) p3 1070 (1040–1120) 1180 (1150–1240) 700 (660–730) 390 (380–400) 300 (280–330) continued.

ta4 ta5 LR BV SV BR p1 170 (160–190) 110 (105–115) 0.65 (0.63–0.69)* 2.8 (2.72–2.84) 2.86 (2.80–2.96) 2.45 (1.77–2.67) p2 133 (130–140) 100 0.45 (0.43–0.47) 3.36 (3.31–3.40) 4.35 (4.20–4.51) 2.35 (2.00–2.70) p3 175 (160–190) 115 (110–120) 0.59 (0.57–0.62) 3.03 (2.97–3.13) 3.22 (3.01–3.36) 2.78 (2.27–3.20) Hypopygium ( Figs. 6 , 8, 9 ). Tergite IX with 13–20 setae, laterosternite IX with 8–10 setae (n=5). Anal point 70 (65–75) µm long. Length ratio anal point/wing> 0.25. Phallapodeme 115 (108–125) µm long; transverse sternapodeme 113 (100–120) µm long. Virga 28 (25–30) µm long, with 5–6 subequal spines arranged in a bundle. Gonocoxite 223 (210–230) µm long. Gonostylus ( Figs. 6 , 9 ) 94 (90–97) µm long, simple, without projections or significant expansions; megaseta 14–17 µm long. HR 2.38 (2.30–2.56). Inferior volsella bilobed, ventrally covered with microtrichia.

Pupa (n = 1). The single specimen available to us that is reliably identifiable on account of direct association with the adult stage is an exuviae containing a pharate male on which the features considered as diagnostic above could be evaluated, except for those of the wing. It keys to C. suecicus and agrees with all data in the corresponding description by Langton & Visser (2003), except that on abdominal segment IV the lateral seta 2 is c. 0.38 of segment IV length as described, but is 160 µm long, i.e. substantially longer than both, the maximum length of 135 µm given in the description and than setae ls 1 and ls 3. Thoracic horn length is 215 µm, wing sheath length c. 1.34 mm; the length of the dissected exuviae cannot be estimated, as the abdomen is strongly hyperextended in the mount.

Distribution. See Material examined. Earlier records (e.g., see Saether & Spies 2004) should be revised with regard to the new species described below.

Figures

FIGURES 1 – 2. Halter. 1: Chaetocladius suecicus. 2: Chaetocladius longivirgatus.

FIGURES 3 – 5. Wing. 3: Chaetocladius suecicus. 4: Chaetocladius longivirgatus. 5: Chaetocladius sp. prope suecicus.

FIGURES 6 – 7. Hypopygium. 6: Chaetocladius suecicus. 7: Chaetocladius longivirgatus.

FIGURES 8 – 11. Hypopygium. 8, 9: Chaetocladius suecicus. 10: Chaetocladius longivirgatus. 11: Chaetocladius sp. prope suecicus.