Rheosmittia spec-a

Author: Cranston and Saether, 1986

Diagnosis (in part after Cranston and Saether, 1986a - in italics)
Exuviae 2.5-2.8mm long (n=6). (2.15-2.45mm (m=2.25mm, n=10), hyaline.)
Cephalothorax: Frontal setae absent; cephalic area smooth, without warts or tubercles. Ocular area with 1 postorbital and 1 vertical seta, orbital and postocular setae about 50µm long. Thoracic horn absent. Thorax with 1 or 2 median and 1 or 2 lateral antepronotal setae; 3 precorneals in a line with second the longest; dorsocentrals arranged in 2 groups of 2 setae. Precorneal and dorsocentral setae none longer than about 50µm long (damaged and/or obscured). Thorax smooth to weakly rugulose; wing sheaths smooth; leg sheath arrangement normal for Orthocladiinae.
Abdomen: Tergite I and sternite(s) I or I-IV and V-VIII or VII-VIII without shagreen. Tergite II-IV or III and IV with caudal, anteriorly directed points. Tergites II-VII (or (VII) with posterior transverse band of posteriorly-directed points and an antero-median area of smaller spinules which may extend posteriorly to contact posterior band. Median spinule area weaker on posterior segments and very reduced on tergites VII and/or VIII. Tergites IV-VI without a distinct circular antero-median point patch. Apophyses absent. Pedes spurii A present on sternites IV-VI; pedes spurii B absent. Segment I with 2(?) weak or 5 stronger dorsal setae, 0-2 ventral setae and 1 lateral seta. Segments II-VII with 4 or 5 dorsal setae, 4 or 5 ventral setae and 3 or 4 lateral setae. Segment VIII with 2 or 4 dorsal setae, 1 ventral seta and 2 lateral setae. On tergites II-IV or VI dorsal seta 5 enlarged, simple, up to 40µm long on tergite III. Lateral setae longer than usual (058l.jpg), the longest between 60 and 90µm long. Lateral seta 2 often more strongly developed than remaining lateral setae.
Anal segment: Tergite IX medially with or without shagreen. Anal lobe very reduced with tergite IX postero-laterally expanded into spinose tails (058l.jpg). Anal lobe, including tails, 180-225µm (m=200µm) long. Three anal macrosetae present and weak, longest 37-54µm (m=42µm) long. Genital sacs of male large, nearly extending to apex of tails.

Species keys out at Page 736: Orthocladiinae 148 Rheosmittia of the Text Key.

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

Ecological notes
Northern and montane flowing water.