Tanytarsus gracilentus

Author: (Holmgren, 1883)

Exuviae 4.0-6.4mm long (m=5.1mm, n=16).
Cephalothorax: Cephalic tubercles elongate conical, 100-110µm high; 38-50µm broad at base (n=3). Frontal setae 55-103µm long (n=9). Antennal sheath base with a large conical swelling. Thoracic horn smooth, 500-760µm long (m=629µm, n=17); ThR 11.5-17.6 (n=14) (141k.jpg). Posterior thoracic mound moderately swollen. Thorax extensively granulate. Wing sheaths rounded apically, pearl row absent.
Note: The thoracic horn is frequently armed with setulae medially (setulae less than 45µm in length). These are never as dense nor as extensive as in the species keying out earlier and always shorter than the maximum breadth of the horn.
Abdomen: Length hook row II 0.42-0.55x width tergite (n=3); hooks 136-182 (n=5). Tergites III-VI with the antero-median point patches arranged in paired longitudinal bands, those of tergite III elongate, narrow, tapering posteriorly and greater than one quarter the length of the segment (141l.jpg). Armament tergite IV strong, 222-301µm long (n=3). ArR III-VI 0.86-1.30 : 1.0 : 0.80-1.22 : 0.40-0.75 (m=1.02 : 1.0 : 0.96 : 0.58, n=8). Comb of segment VIII 55-95µm long (m=62µm, n=9); with 7-14 marginal teeth (m=10.2, n=11). Lateral taeniae of segments V-VIII: 0,0,0(1),4, taeniae elongate, but narrow and sometimes difficult to distinguish.
Anal segment: Anal lobe ratio 1.06-1.58 (n=7). Fringe of anal lobe with 24-40 taeniae (n=12), forming a complete series.
(Linked adult male: Langton and Pinder, 2003a)

Species keys out at Page 468: Tanytarsini 109 Tanytarsus of the Text Key.

Holarctic species: widespread in Europe.
(For more information see module IdentifyIt – file: Chironominae).

Ecological notes
Stagnant water: nutrient-rich habitats (particularly hard and brackish water situations) and flooded grassland.