Rheocricotopus reduncus

Author: Saether and Schnell, 1988

Diagnosis (Material in coll. ZMBN; in part after Saether and Schnell, 1988b - in italics)
Exuviae 3.4-3.9mm long (n=5).
Cephalothorax: Frontal setae on frontal apotome. Thoracic horn small-toothed; horn 270-325µm long (n=4); ThR 5.7 (n=1).
Abdomen: Shagreen absent on tergite I, weak anterior on II, stronger and extensive on tergites III-VI, reduced laterally on VII-VIII. Point patches more or less circular, present on tergites IV-VI; points of point patches small, the longest less than 30µm long, usually shorter than the longest tooth of the posterior transverse rows. Sternite I bare, shagreen anterior on II; sternites III-IV with anterior and lateral V-VII with extensive, VIII with anterior shagreen. Pedes spurii A on sternite III-VI(VII); pedes spurii B on segment II, well developed. Lateral setae on segments I-VIII: 2,3,3,3,3,3,3,4-5, all taeniate on segments VII and VIII. The lateral setae of segments III-VI evenly distributed. Three lateral taeniae on segment VII (rarely 2), four on VIII (usually the fifth seta is displaced inwards making four posterior setae on tergite VIII, but occasionally it is expanded as a short taenia and situated next to taenia 4).
Anal segment: Tergite IX with anterior shagreen, sternite IX bare. Anal lobe ratio 1.9-2.2 (n=5). Anal lobes not drawn out posteriorly into a tooth or spur. Fringe of anal lobe with 17-19 taeniae (n=5). The three anal macrosetae situated apically on the anal lobes.

Species keys out at Page 671: Orthocladiinae 83 Rheocricotopus of the Text Key.

(For more information see module IdentifyIt – file: Orthocladiinae).

Ecological notes
A glacial river, Norway.