Female: No available information.
Pupa: (from Langton & Visser 2003): Length 7.6-9.4 mm (9.0-11.0 mm in Finland). Contrast in color between thorax and abdomen not so marked; outer margin of anal lobes colored except at base.
Cephalic tubercles 70x44-160x130 µm; frontal setae 34-72 µm long. Basal ring of thoracic horn 125x50-160x60 µm, i.e. HR 2.5-2.7. Thorax extensively granulate.
Hook row of segment II with 70 hooks, extending 0.46 of width of segment. Armament of tergites II-VI not so strongly waisted and with posterior transverse band not successevely increasing in extent to tergite VI; usually reduced on VI. Spur of segment VII with 1-5 stout teeth which may be long, on the end of of an elongated cuticular mound. Anal lobe with 75-130 taeniae.
Fourth instar larva of melanotus-type (Lindeberg calls larva a plumosus-type, although his illustration (above) shows ventral tubules do not show the 'plumosus-type' bending and coiling). Head with dark gular region and dark head stripe on the frontoclypeus. Mentum with 4th laterals reduced almost to level of 5th laterals (type II), C1 tooth of mentum moderately wide with c2 teeth moderately separated (type IB).
Premandible with teeth about equal in length, inner tooth about twice as wide as the outer tooth.
Mandible possibly type IIB or C, about 17 furrows on outer surface near the base.
Cytology: 4 polytene chromosomes with the thummi-cytocomplex arm combination (AB, CD, EF, G). Centromeres heterochromatic.
Arm G often unpaired, with a subterminal nucleolus after a heterochromatic terminal band, and an apparently heterochromatic interstitial band. At least one BR, but not clear enough to be sure if others are developed.
Polymorphism in arms A, D and F in the Palearctic, but presently only arm F known to be polymorphic in North American populations. However, arm A seems to be the sequence A3, which is less common in the Palearctic.
The karyotype is based on identifications by Kiknadze et al. (1996 & 2004).
Found: North West Territories – tundra pond FBV, Horton river area (M.G.Butler)
Also: Finland (type locality); Russia - Altai, Yakutia; Sweden; Iceland.
C. jonmartini was proposed by Lindeberg & Wiederholm as a new name for C. neglectus Lindeberg. It is not certain that the present material is identical to that of Lindeberg & Wiederholm, which was partly cytologically described by Wülker (1973, 1991b) as arm G may differ. However, studies from other parts of the Palearctic indicate that the larval morphology and chromosomal banding patterns are variable (Kiknadze et al. 1996b & 2016, Rakisheva et al. 2001). The North American material seems to be identical to that described by Kiknadze et al. (1996b) and most of the larval description above is based on their description.