Procladius choreus

Author: (Meigen, 1804)

Exuviae 5.5-7.2mm long (m=6.1mm, n=25).
Cephalothorax: Thoracic horn 385-590µm long (m=465µm, n=51), cylindrical, with a transversely oval to circular plastron plate filling the horn apex, which is joined to the broad brown respiratory atrium by a broad but short neck; ThR 2.65-5.06 (m=3.4, n=54). Breadth atrium : breadth horn = 0.81-0.99:1 (m=0.91:1, n=54). Width plastron plate : width horn = 0.37-0.92:1 (m=0.6:1, n=46). (007e.jpg)
Note: A variety from Inverness in Scotland has on average wider plastron plates and narrower atria: Breadth atrium : breadth horn = 0.51-0.83:1 (m=0.76:1, n=35). Width plastron plate : width horn = 0.58-0.85:1 (m=0.75, n=33).
Abdomen: Tergite IV with points arranged in obvious short transverse rows, which posteriorly in the segment are curved, producing a 'fish-scale' effect (007e.jpg). Anterior lateral taenia of segment VII at 0.51-0.83 of length segment VII (m=0.60, n=29). Segment VIII extended posteriorly on each side for over one fifth its median length.
Anal segment: Anal lobes Procladius-type. Anal lobe ratio 1.64-2.2 (m=1.9, n=31).
(Pupa also described by Sergeeva, 1995a: p. 106.)
(Linked adult male: Langton and Pinder, 2003a)

Species keys out at Page 23: Tanypodinae 9 Procladius of the Text Key.
Note: Procladius islandicus runs here. It is endemic to Iceland. The fish-scale effect of the armament of tergites and paratergites is more extensive than on choreus. On choreus the paratergites and posterior tergites rarely show well developed ‘scales’.

Afrotropical and Palaearctic species: widespread in Europe and circum-Mediterranean.
(For more information see module IdentifyIt – file: Other subfamilies).

Ecological notes
Ponds and lakes to swift-flowing rivers.