Polypedilum tritum

Author: (Walker, 1856)

Exuviae 4.6mm long (n=1).
Cephalothorax: Frontal setae present. Thoracic horn of a few (about 10) branches, branches much shorter than half the length of the abdomen. Thorax with conspicuously large granules near suture (112b.jpg).
Abdomen: Length hook row II 0.35, 0.40x width tergite (n=2); hooks 33, 47 (n=2). At its greatest development the median point patches of tergites II-VI are broadly attached on each side of the mid-line to the anterior transverse band, narrowing to a little past mid-segment and thereafter widening rapidly to its fusion with the posterior transverse band; a large elongate-oval bare patch separates the median point patch into two lateral longitudinal bands from about the level of seta D1 to the posterior margin of the posterior transverse band, which may be broken or narrowly joined medially. Reduction of this pattern is common and in extreme cases tergite II possesses no more armament than the anterior transverse band, and on the following segments the median patch is highly reduced. Tergites III and IV armed with an apical band of points or hooks. Tergite VII without trace of a median point patch. Sternite I without two antero-lateral armed humps. Shagreen of sternite II anteriorly of small, sturdy points in distinct transverse rows. Pedes spurii B II well-developed. Conjunctives with points no larger than those of the anterior transverse bands of the tergites. Vortex present. Comb of segment VIII usually in the form of a single outer strong tooth with a number of smaller teeth within, projecting from the posterior edge of the segment. Lateral taeniae of segments IV-VIII: 0,3,3,4,4, taeniae well-developed.
Anal segment: Fringe of anal lobe with 32-37 taeniae (n=2).
(Linked adult male: Langton and Pinder, 2003a)

Species keys out at Page 317: Chironomini 214 Polypedilum of the Text Key.

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

Ecological notes
Ditches and ponds.