Polypedilum scalaenum

Author: (Schrank, 1803)

Exuviae 5.1, 5.2mm long (n=2).
Cephalothorax: Cephalic tubercles projecting, 25-40µm high. Frontal setae 85µm long (n=1). Thoracic horn 8-branched, branches much shorter than half the length of the abdomen. Precorneal setae more robust, the longer 88 and the shorter 30µm long (n=1). Thorax with conspicuously large granules near suture (112b.jpg).
Abdomen: Length hook row II 0.56, 0.60x width tergite (n=2); hooks 61 (n=1). Tergites II-VI with obvious anterior transverse bands of points stronger than those of the median patch. Armament of tergites II-V or III-V discontinuous: at least the anterior transverse point band separate from the postero-median patch, which is narrowed anteriorly to a median point. Tergites with the median patches reduced, highly marmorate. Posterior transverse band of points narrow, on tergites III-VI spreading only a little, if at all, beyond seta D5 anteriorly (125e.jpg). Hooked points of apical bands of tergites III and IV about the same size as the points of the median patches of those tergites. Tergite VII without trace of a median point patch. Sternite I without two antero-lateral armed humps. Pedes spurii B of segment II usually present. 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 29/26, 32 fringe taeniae (n=2).
Note: This form and Polypedilum quadriguttatum are extremely alike as adults and pupae and may not be distinct.
(Linked adult male: Langton and Pinder, 2003a)

Species keys out at Page 332: Chironomini 229 Polypedilum of the Text Key.

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

Ecological notes