Thienemanniella antennata Freeman

Fu, Yue, Hestenes, Tor Christian & Saether, Ole, 2010, Review of Afrotropical Thienemanniella Kieffer (Diptera: Chironomidae: Orthocladiinae), Zootaxa 2338, pp. 1-22 : 4-6

Thienemanniella antennata Freeman

( Fig. 1 A–H)

Thienemanniella antennata Freeman, 1953: 212 ; Freeman, 1956: 367. Harrison, 1992: 193 [Key].

Material examined. SOUTH AFRICA: Cape Province, Wellington, Berg River, Piquetberg, paratype 1 3, 30.x.1952, K.M.F. Scott ( BMNH); Cape Province, Berg River, Station 3, 1 3, 14.iv.1953, K.M.F. Scott ( BMNH); Transvaal, Vaal River, Vereigenung, 5 3, 22. x. 1952, K.M.F Scott, ( BMNH); Transvaal, Lydenburg, 1 3, 14.ix.1954, A.D. Harrison ( BMNH). Natal, Tugela River, Colenso, 1 3, 14 –30.ix.1953, A.D. Harrison ( BMNH); Natal, Great Usutu River, Amsterdam, 2 3, 19.ix.1954, A.D. Harrison ( BMNH); Natal, Mooi River, Kambergs Game Reserve, 1 3, 14 –30.ix.1953, A.D. Harrison ( BMNH); GHANA: Volta Region, Lake Volta, Akosombo, Boat Harbour, 3 3, 9. x. 1992, NUFU-project, T. Andersen, ( ZMBN).

Diagnostic characters. The adult male can be separated from all other members of the genus, except T. lobapodema Hestenes et Saether (Hestenes & Saether 2000) by having inferior volsella as a digitiform median projection with a weak apodeme. It is distinguishable from T. lobapodema by having only one anal vein in the wing and no setae on tergite IX. The superior volsella is a broad, flat rim along the gonocoxite narrowly fused anteriorly. The first abdominal tergite carries 1 mediolateral seta to each side.

Adult male (n = 10–12). Total length 1.03–1.57, 1.24 mm. Wing length 0.76–1.08, 0.89 mm. Total length/ wing length 1.24–1.57, 1.37. Wing length/ length of profemur 3.39–4.26, 3.73. Wing width/wing length 0.38– 0.39 (2).

Coloration. Head dark brown to black with yellow brown antenna; thorax black, scutum and vittae evenly colored; abdomen black with pale median area in tergite VI and VII, sternites paler.

Head ( Figs 1 A–C). Eyes hairy; height of eye/height of head 0.56–0.73, 0.66. Antennal ratio varies between localities; Lydenburg 0.88 (1), Vaal River and Tugela River 0.64–0.79, 0.69 (6), Usutu River and Berg River 0.46–0.64, 0.55 (4), Lake Volta 0.65–0.68 (3). Antenna ( Fig. 1 B) with 10 flagellomeres; flagellum apically club-shaped, flat and notched; with apical several sensilla chaetica and 26–45, 33 basal setae; 186– 247, 213 (8) µm long. Tentorium, stipes and cibarial pump as in Fig. 1 C; tentorium 104–129, 116 µm long, stipes 68–95, 79 µm long. Length of palpomeres (in µm): 11–18, 14; 13–18, 15; 22–35, 26; 33–47, 40, 80– 117, 102. Palpomere 5/3 ratio: 3.0–4.3, 3.5; palpomere 3 rounded rectangular to round. Clypeus with 6–11, 8 setae. Palpomere 3 apparently lacking sensilla clavata. No outer verticals, coronals 4.

Thorax ( Fig. 1 D). Anapleural suture 77–143, 108 µm long. Antepronotals absent, dorsocentrals 7–11, 9 uniserial, prealars 1–3, 2, scutellars 1–2, 1.

Wing ( Fig. 1 E). VR 1.68–1.88, 1.77 (6). Only one anal vein present; An1/wing length 0.44–0.48, 0.47 (6); PCu/wing length 0.54–0.69, 0.58 (6); C 278–463, 352 (6) µm long; Cu 384–491, 416 (6) long. Brachiolum with 1 seta; costa with 11–16, 13 uniserial setae, wing setation otherwise as for T. trivittata .

Legs. Fore trochanter with dorsal keel. Spur of fore tibia 18–27, 23 (4) µm long, serrated with additional 2 thin setae 16 (1) µm long apically. Spurs of mid tibia 9–12 (3) µm land 10 (2) µm long, and of hind tibia ( Fig. 1 F) 12–23, 17 µm and 9 (3) µm long, and slightly inwards curved seta 16–20 (3) µm long. Apex of fore tibia 15–27, 23 µm, of mid tibia 18–27, 23 µm, of hind tibia (a) 25–34, 39 µm wide. Width of hind tibia 1/3 from apex (d) 16–24, 20 µm, elongation (b) 11–18, 14 µm long, maximum thickening at (c1) 23–45, 32 µm from apex; total length of thickening (c2) 34–73, 52 µm; a/d 1.08–1.88, 1.46; b/d 0.55–0.94, 0.72; c1/d 1.05–1.22, 1.64; c2/d 1.88–3.84, 2.42. Hind tibial comb with 11–13, 12 setae. Sensilla chaetica on legs apparently lacking. Ta1 of p2 with 5–7 strong setae, ta1 of p3 with two ventral rows of 6–8 and 8–10 strong setae. Tarsomere 4 of all legs weakly cordiform. Lengths (in µm) and proportions of legs as in Table 2.

fe ti ta1 ta2 ta3 ta4

p1 200–320, 214 219–314, 260 175–251, 212 62–109, 76 29–47, 38 16–25, 18 p2 263–408, 332 255–382, 308 164–230, 209 73–117, 92 32–51, 40 11–18, 15 p3 204–346, 293 266–408, 323 193–299, 234 88–142, 111 33–69, 45 18–33, 28

ta5 LR BV SV BR

p 1 22–31, 25 0.67–0.81, 0.77 3.78–5.26, 4.35 2.29–2.92, 2.76 2.4–4.0, 3.0 p 2 18–40, 26 0.61–0.72, 0.68 3.87–5.43, 4.72 2.31–3.30, 2.95 2.7–4.2, 3.3 p 3 18–33, 28 0.65–0.84, 0.72 3.77–4.96, 4.25 2.11–2.90, 2.54 3.1–8.0, 5.3 Abdomen. Tergite I with 1 seta laterally on each side. Tergites II–VIII as 3–4, 3; 3–5, 3; 3–5, 3; 3–4, 3; 2– 3, 3; 3–5, 3; 2–3, 2; sternites bare.

Hypopygium ( Fig. 1 G–H). Sternite VIII bare, tergite IX with 4–6 short setae, laterosternites IX with 1 seta. Superior volsella anteriomedially narrowly fused, posteriorly as a broad pale rim on gonocoxite. Inferior volsella digitiform, bare, with weak internal apodeme. Phallapodeme straight 29–38, 34 µm long. Transverse sternapodeme 23–35, 27 µm, lateral sternapodeme 25–43, 27 µm long. Gonostylus megaseta stout, 6–7 µm long. Thin glandular setae on inner margin of gonocoxite. HR 2.46–3.50, 3.05 (8), HV 3.91–5.33, 4.86 (6)

Distribution. The species is known from Cape Province, Natal and Transvaal in South Africa and from the Lake Volta Area in Ghana.

Remarks. The variation in antennal ratio from different localities, even though the total length of the specimen is quite uniform, suggests that the intraspecific variation is due to ecological differences as seen in other species ( Grimås & Wiederholm 1979).

Figures

FIGURE 1. Thienemanniella antennata Freeman. Adult male. A. Head. B. Antenna. C. Tentorium, stipes and cibarial pump. D. Thorax. E. Wing. F. Hind tibial apex. G. Hypopygium, dorsal view. H. Hypopygium, ventral view. I. Measurements of hind tibia.