Palearctic Chironomus: C. alpestris

C. alpestris Goetghebuer 1934

Syn: Chironomus dorsalis sensu Strenzke 1959.
Chironomus nippodorsalis Sasa 1979 (Yamamoto and Hashimoto, unpubl.) - incorrect synonymy.

In BOLD Bin: BOLD:AAW4001.
In same Bin as C. nippodorsalis.

Adult:

The adults of C. alpestris were well described by Strenzke (1959) as C. dorsalis and C. nippodorsalis was initially described by Sasa (1979), in Japanese. Re-examination of C. nippodorsalis by Yamamoto and Hashimoto in 1976 convinced them that it was indistinguishable from C. dorsalis (personal communication), and hence from C. alpestris.
Specimens previously called Sp. PK5, from India and Israel are in the same BOLD Bin and differ from C. alpestris only in the presence of a complex inversion of arm E.
Given the low heterozygosity of European populations (heterozygosity only of arm G) this could represent a very closely related species.
By 2018, Yamamoto and Yamamoto had decided that C. nippodorsalis was not a synonym of C. alpestris due to differences in larval morphology.
There also appears to be a difference in the Superior volsella, which is D-type in C. alpestris but S-type in C. nippodorsalis.

Male:  (from Strenzke (1959):
Wing length 3.3 (3.07-3.53) mm.  AR 3.2 (3.02-3.38); LR 1.61 (1.56-1.66); BR 2.4 (2.27-2.53).
Ground color of head and thorax grey-yellow, thoracic vittae black, postnotum uniformly black.  Legs with tarsal segments dark brown.
Thoracic setae: Acrostichals 10.3 (8-13); dorsocentrals 24.4 (21-28); prealar 5.4 (4-6); supra-alar 1.4 (1-2); scutellar 22.9 (19-26).
Relative length of Fore leg segments cf. tibia length: Fe 1.16 ; Ti 1.0 : Ta1 1.61 ; Ta2 0.82 ; Ta3 0.68; Ta4 0.56 : Ta5 0.25.
Abdominal coloration similar to C. nippodorsalis, i.e. ground color whitish-yellow, and each segment has a dark brown band: posterior on tergite I, but anterior on other tergites, produced posteriorly on segments II and III.
Hypopygium with about 8-10 setae in pale patches on tergite IX; anal point narrow at base; Superior volsella of D-type; gonostyle only moderately expanded and narrows over posterior half.

Female:
Wing length 3.5 (3-4) mm. Thoracic setae: Acrostichal 14.0 (11-17); dorsolateral 33.7 (29-39); prealar5.9 (5-7); supraalar 1.7 (1-2); scutellar 32.2 (28-36).
Relative length of Fore leg segments cf. tibia length: Fe 1.24 ; Ti 1.0 : Ta1 1.65 ; Ta2 0.77 ; Ta3 0.70 ; Ta4 0.60 ; Ta5 0.26. Br 1.9 (1.7-2.1).
Abdomen largely grey brown, pale areas at posterior of segments slightly larger than those of C. nippodorsalis.

Pupa: (based on C. dorsalis from Langton & Visser 2003).
Length 7.5-8.1 mm. Exuviae golden brown to dark brown.
Cephalic tubercles 90 µm by 80 µm, setae 50 µm. Thoracic horn much branched, basal ring 107-120 x 45-55 µm, 9-12 tracheoles across. Hook row of abdominal segment II entire occupying 0.51-0.55 of width of segment, with 44-55 hooks. Caudolateral spur of segment VIII with 2-5 somewhat elongated teeth. Anal fringe with 82-116 taeniae.

Cytology: Four polytene chromosomes with the pseodothummi arm combination AE, BF, CD, G.
Nucleolus subterminal in arm G, which is closely paired and has three BRs, the largest about a third from the distal end. No nucleolus in other chromosomes. Chromosomal polymorphism is known only in arm G.

alpA1: 1 - 2c, 4 - 9, 2d -3, 12 -10a, 13 - 19
alpB1: not mapped. Puff (group 7?) about a third from the distal end.
alpC1: 1 - 2f, 11c - 10, 16 - 17a, 6 -2g, 11d - 15, 9 - 7, 17b - 22
alpD1: 1a(b), 17d - 19d, 10d - 1c(b), 17c - 10e, 19e - 24g
alpE1: 1 - 2c, 8b - 2d, 8c - 9b, 12b - 9c, 12c - 13
alpF1: 1 - 10, 15 -11, 16 - 23
alpG1: The three BRs are in the distal part of the arm. BRa is developed only in the special lobe.
alpG2: simple inversion between the nucleolus and the large BRc, including BRb.

All mapping from Kiknadze et al. 2016 (as C. dorsalis sensu Strenzke with C. alpestris as a synonym). Other studies of the cytology have been made by a number of authors.

The synonymy of C. nippodorsalis with C. dorsalis Strenzke was recognized by Yamamoto and Hashimoto in 1976, and this conclusion is supported by the DNA analyses of Kondo et al. (2016). Langton and Visser (2003) list this as a synonym of C. dorsalis, but this is only true of C. dorsalis sensu Strenzke, for which it is the senior synonym.

Found: Type locality - nr. Garmish-Partenkirchen, Bavaria, GERMANY.
The extent to which C. alpestris actually occurs in the Oriental region is uncertain.

Molecular:
MtCOI sequence from Chironomus nippodorsalis, C. dorsalis sensu Strenzke 1959 and C. alpestris is in GenBank and the BOLD databases (where all are in the same BIN, although the distance plot does suggest some specimens have a greater percentage difference).

[ Return to Index | Go to References ]