Form described by Langton, 1991
Diagnosis
Exuviae 3.8-4.8mm long (n=5). Material from a lake in Finland.
Cephalothorax: Cephalic tubercles weak, broad conical. Frontal setae robust, 90-130µm long (n=5). Antennal sheath base with a strong conical tubercle. Thoracic horn 585-790µm long, horn without spinules; ThR 19.5-33.5 (n=3). Posterior thoracic mound weak. Dorsocentral seta 4, though conspicuously thicker than 3, is seta-like, 2.5µm or less in breadth at base usually more or less parallel-sided for the basal half (140c.jpg). Wing sheaths rounded apically, pearl row absent.
Abdomen: Hook row II 0.33-0.34 (n=3); hooks 68-89 (n=4). Small rounded point patches present on tergite II anteriorly; point patches of tergites III-VI elongate oval, on IV more than three times as long as broad, patches 5 or 6 points wide (140a.jpg). Armament tergite IV strong, 75-85µm long (n=5). ArR II-VI 0.41-0.53 : 0.71-1.13 : 1.0 : 0.88-1.13 : 0.82-0.93 (n=5). Postero-lateral comb of segment VIII 35-45µm wide (n=4), set on a flat extension of the corner of the segment; with 5-7 marginal teeth (n=5). Lateral taeniae of segments IV-VIII: 0,1,3,4,4, taeniae well-developed.
Anal segment: Anal lobe ratio 1.17-1.38. (n=5). Fringe of anal lobe with 25-31 taeniae, forming a complete series.
Exuviae 3.6-4.3mm long (n=5). Material from a lake near Partenkirchen, Germany.
Cephalothorax: Cephalic tubercles shallow conical. Frontal setae 130, 133µm long (n=2). Antennal sheath base with a conical projection. Thoracic horn 650-850µm long (n=4); ThR 20-28.3 (n=3). Posterior thoracic mound weak.
Abdomen: Hooks of hook row II 90 (n=1). Armament tergite IV strong, 75-100µm long (n=4). ArR II-VI 0.5-1.0 : 0.73-1.0 : 1.0 : 0.94-1.16 : 0.53-0.79 (n=4). Comb of segment VIII 25, 28µm wide (n=2); with 5-7 marginal teeth (n=3). Lateral taeniae of segments IV-VIII: 0,1,3,4,4.
Anal segment: Anal lobe ratio 1.20-1.48 (n=3). Fringe of anal lobe with 25-29 taeniae (n=4).
Note: "These could be innarensis. A situation where males were collected, and exuviae from the surface." (Lindeberg, pers. comm.) These exuviae are exceedingly similar to those of Tanytarsus debilis and although it seems unlikely that the distinction given in the key will hold good when more material becomes available; six exuviae in the Thienemann collection labelled "Tanytarsus virens-Gruppe" all have 'broad' point patches 5 or 6 points wide (140a.jpg). Positively associated exuviae of Tanytarsus innarensis are necessary before any further separation of these two forms is attempted.
Form keys out at Page 459: Tanytarsini 100 Tanytarsus of the Text Key.
Distribution
(For more information see module IdentifyIt – file: Chironominae).
Ecological notes
Lakes.