Tanytarsus pallidicornis

Author: (Stephens, 1856)

Exuviae 3.9-5.5mm long (m=4.9mm, n=12) (139-1.jpg).
Cephalothorax: Frontal setae 94µm long (n=1). Antennal sheath base with a large, conical swelling, as high as broad, but often crumpled inwards apically. Thoracic horn without long setulae (139b.jpg). Thoracic horn 650-1040µm long (m=830µm, n=13); ThR 15.7-28.1 (n=7). Posterior thoracic mound moderately swollen. Wing sheaths rounded apically, pearl row absent.
Abdomen: Length hook row II 0.39x width tergite (n=1); hooks 111, 117 (n=2). Tergite II without anterior point patches. Armament on tergite III anteriorly of strong points and short spines, shortly thereafter of long spines for the remainder of the band; on tergite IV of points only, or rarely with a few spines medially (139c.jpg). Longest spine tergite III 53-78µm long (n=5). Tergites IV and V with the armament arranged in longitudinal bands. Armament tergite IV strong, 145-165µm long (n=9). ArR III-VI 0.9-1.2 : 1.0 : 0.7-0.9 : 0.35-0.6 (n=9). Postero-lateral comb of segment VIII 43-77µm wide (m=60µm, n=9); with 7-13 marginal teeth (m=9.7, n=12). Lateral taeniae of segments V-VIII: 3(2),3,4,4.
Anal segment: Fringe of anal lobe with 31-43 taeniae (m=36.4, n=14), forming a complete series beginning near the anterior edge of the lobes (139d.jpg).
(Linked adult male: Langton and Pinder, 2003a)

Note: Occasionally specimens of Tanytarsus buchonius have five or six large points at the beginning of the spine row of tergite IV and, although most specimens of pallidicornis have the spines starting a fifth of the way or more along the band, some are similar to such specimens of buchonius. In Tanytarsus pallidicornis on each side of the smooth mid-line of tergite II the points gradually decrease in size posteriorly, the anterior points conspicuously larger than the posterior, often bifid at apex and arranged irregularly, whereas in buchonius the anterior points are mostly no larger than the posterior and are arranged in short transverse rows of 2-5 points, most obvious where the anterior points spread out laterally in front of setae D1.

Species keys out at Page 446: Tanytarsini 87 Tanytarsus of the Text Key.

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

Ecological notes
Stagnant and running water.