Derotanypus sibiricus

Author: (Kruglova and Chernovskij, 1940)

Diagnosis (n=4 unless stated otherwise, material in coll. ZSM)
Exuviae 9.8-10.5mm long (n=4) (012-1.jpg).
Note: Very similar to Psectrotanypus varius (Fabricius); this species is however larger, the horn brown as against golden in Ps. varius, and generally more narrowed to the plastron plate, and the mark of tergite I usually longitudinally elongate, whereas in varius it is circular.
Cephalothorax: Thoracic horn 760-870µm long; ThR 2.6-3.25. Plastron plate length 0.14-0.23 of horn length. Plastron plate without rim. Width plastron plate 0.52-0.86x horn width. Struts across the horn atrium broad and obvious even when the horn is flat (012b.jpg). Thorax with well-spaced, regular, transverse grooves from suture. No thorax comb.
Abdomen: Mark on segment I brown or blackish. The minute spinules of tergites and sternites tending to be arranged in groups of two or three, and in places in transverse rows. Conjunctives not shagreened. Length lateral setae VII 0.47-0.60 of length segment VII; anterior lateral taenia at 0.5-0.54 of length segment VII.
Anal segment: Length of the anal lobe 1.85-2.06x length segment VIII; width of anal segment 0.88-0.90x width segment VIII (012c.jpg). Anal lobe ratio 1.8-1.9. Anal lobes fringed with hair-like teeth, externally and internally. Insertion of anterior anal taenia at 0.14-0.17x lobe length. Length of the anal lobe 0.12-0.14x exuvial length. Length male genital sheath 0.43x lobe length (n=1).

Species keys out at Page 39: Tanypodinae 25 Derotanypus/Psectrotanypus of the Text Key.

Palaearctic species: reaching as far west as C Europe.
(For more information see module IdentifyIt – file: Other subfamilies).

Ecological notes
Bavaria, larvae in soft silts of cool springs or in deep, groundwater fed, lentic ditches (Janecek, 1999a).