Form described by Langton, 1991
Diagnosis
Exuviae 3.5-4.4mm long (n=3).
Cephalothorax: Cephalic tubercles weak, rounded mounds. Frontal setae 100µm long (n=2). Thoracic horn 8-branched, branches much shorter than half the length of the abdomen. Longer precorneal seta 38µm long (n=1). Thorax with conspicuously large granules near suture (112b.jpg).
Abdomen: Length hook row II 0.58x width tergite; hooks 55 (n=1). Tergites II-VI with obvious anterior transverse bands of points stronger than those of the median patch with which they may be confluent for the tergite width. Armament of tergites IV-V discontinuous: at least the anterior transverse point band separate from the postero-median patch, which is narrowed anteriorly to a median point. Median point patches well-developed, on tergites II and III contacting the anterior transverse band medially (125i.jpg); tergite VII without trace of a median point patch. Tergites III and IV armed with a distinct apical band of large points or hooks. Sternite I without two antero-lateral armed humps. 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 composed of more widely separated teeth spreading laterally forwards from the apico-lateral corner (125g.jpg , 125l.jpg , 125n.jpg). Lateral taeniae of segments IV-VIII: 0,3,3,4,4, taeniae well-developed.
Anal segment: Anal lobes with a dorsal seta set towards the inner edge of the lobe; each lobe with 21-28 fringe taeniae (n=3).
Note: Very similar to Polypedilum pullum, Polypedilum scalaenum and Polypedilum quadriguttatum: the short precorneal seta indicates pullum, but the habitat and the fused median and posterior point bands on tergites III and IV is very extreme for that species.
Form keys out at Page 329: Chironomini 226 Polypedilum of the Text Key.
Distribution
(For more information see module IdentifyIt – file: Chironominae).
Ecological notes
A small stream, Surrey, England; a slow flowing stream in Tunisia.