Thienemanniella cavata Fu, Hestenes & Saether, 2010, sp. n.

Abstract

Thienemanniella cavata sp. n. (Figs 2 A–G) Type material. Holotype 3, GHANA: Brong Ahafo Region, Kintampo Falls, 13. ii. 1993, NUFU-project (J. Kjaerandsen) (ZMBN type nr. 354). Diagnostic characters. The adult male is separated from all other members of the genus by having a large cavity in the gonocoxite. It has a strongly curved phallapodeme, 10 flagellomeres and only small setae on tergite IX. Etymology: From Latin cavata, meaning cavity, referring to the cavity in the gonocoxite. Adult male(n = 1) Total length 0.95 mm. Wing length 0.61 mm. Wing width/wing length 0.34. Total length/wing length 1.51. Wing length/profemur length 3.26. Coloration. Head light brown, thorax brown, tergite I–IV pale, remaining tergites brown, sternites pale. Tergite VI and VII with median pale field. Head (Fig. 2 A–C). Eyes pubescent, hair length equals height of ommatid; height of eye/height of head 0.71. Antenna (Fig. 2 B) with 10 flagellomeres. Ultimate flagellomere broader than other segments, apex rounded or notched; flagellum with apical sensilla chaetica, and 2 setae basally. AR 0.26. Tentorium, stipes and cibarial pump as in Fig. 2 C; tentorium 120 µm long, stipes 81 µm long. Palpomere lengths (in µm): 17, 20, 32, 43, 75. Palpomere 5 / 3 ratio 2.4. Palpomere 2 with 1 sensillum clavatum. Clypeus with 8 setae. Thorax (Fig. 2 D). Anapleural suture 84 µm long, s/a 0.75. Antepronotals 4; dorsocentrals 11, uniserial; prealars 3; scutellars 4. Wing (Fig. 2 E). VR 1.31. One anal vein present, An 1 /wing length 0.37, PCu/wing length 0.58, Cu/wing length 0.46, C/wing length 0.35. Costa with 10 uniserial, marginal setae. Setation on remaining wing margin as for T. trivittata. Legs. Fore trochanter with small dorsal keel. Spur of fore tibia 21 µm long, spurs of mid tibia 11 µm and 8 µm. Hind tibia (Fig. 2 F), spurs serrated, 25 µm and 12 µm long. Width at apex of fore tibia 20 µm, of mid tibia 20 µm, of hind tibia (a) 25 µm. Width of hind tibia 1 / 3 from apex (d) 18 µm, elongation (b) 7 µm long, length of maximum thickening (c 1) 25 µm, total length of thickening (c 2) 37 µm, a/d 1.39, b/d 0.39, c 1 /d 1.00, c 2 /d 1.48. Hind tibia comb with 11 setae. Sensilla chaetica lacking on legs. Ta 1 of p 3 with 1 ventral row of 14 strong, short setae, and ventrolateral row of 16 similar, but shorter setae. Ta 1 of p 2 with ventral row of 5 short, strong setae. Ta 2–4 of p 3, and ta 2–3 of p 2 with weakly mesally curved, strong seta on ventral side of apex. Lengths (in µm) and proportions of legs as in Table 3. Abdomen. Tergite I with 3 lateral setae and 1 mediolateral seta. Number of setae on tergites II–VII: 6, 6, 6, 6, 4, 4. Sternites at least with 1 seta medially on segment II–V, remaining segments damaged. fe ti ta 1 ta 2 ta 3 ta 4 ta 5 LR BV SV BR p 1 193 237 157 58 40 15 24 0.66 3.51 2.74 1.3 p 2 237 226 134 64 38 13 25 0.59 4.03 3.46 1.6 p 3 207 244 164 92 42 15 27 0.67 3.49 2.75 2.1 Distribution. The species is known from the type locality only, Kintampo Falls in Ghana. Kintampo Falls is situated just north of the dry Semi-Deciduous Fire Zone forest subtype (Hall & Swaine, 1981) and the rainfall does not exceed 1.000 mm per annum. The specimens were captured below the cascade. Here the river flows fast over rocks and stones (Kyerematen & Saether, 2000). Remarks. The large cavity on the gonocoxite is not seen in other Thienemanniella species known to us. This type of cavity on the gonocoxite is seen also in the orthoclad genera Orthocladius and Cricotopus. The morphology otherwise is clearly similar to other Thienemanniella species, the clavus, the superior volsella and genital apodemes conform to Thienemanniella. It is interesting to note that the ta 4 of all legs is not cordiform like in most of the other species in the genus, but of a more regular, square-type like in T. fuga (Lehmann 1979: Fig. 141).Published as part of Fu, Yue, Hestenes, Tor Christian & Saether, Ole, 2010, Review of Afrotropical Thienemanniella Kieffer (Diptera: Chironomidae: Orthocladiinae), pp. 1-22 in Zootaxa 2338 on pages 6-8, DOI: 10.5281/zenodo.19323