Lundbeck's original description provides little information that would enable identification of his species, other than that it is like C. hyperboreus but the beard of the foretarsus is shorter. Townes examined a male and a female of the type series and noted that both were very dark, and the superior volsella of the male was shorter than in North American specimens.
This species is a member of the staegeri group erected by Wülker et al. (1971).
In BOLD Bin no. BOLD3004.
i.e. the same as C. frommeri and C. 'tigris'
Female (measurements from lecto-allotype of C. fasciventris):
Coloration generally as in male, but with posterior pollenose bands on abdominal segments; genital lamellae reddish brown, rather small.
Wing length 4. 88 mm. Antennal proportions 22 : 15 : 15 : 15 : 30, AR - 0.45; A5/A1 - 1.36. Frontal tubercles 82 micron. Palpal proportions (segs. 2-5) 7 : 26 : 34 : 30 (somewhat shrivelled).
Mesoscutum with a slight tubercle. About 10 prealar setae.
Leg ratios: ant 1.51, mid 0.52, hind 0.65.
Pupal exuviae: Cephalothorax blackish-brown, abdomen pale yellowish brown with darker markings. Frontal tubercles short and conical, subterminal seta about 70 µm long. Length 9.13-13.0 mm (Female: about 9.5-13.0 mm, Male: about 9.3-13.0 mm). Base of respiratory organ about 250 x 90 micron. About 62-100 recurved spines at apex of tergite of segment II; caudolateral spur of segment VIII with 7-13 spines (female), 6-11 spines (male), closely appressed. Swim fin with about 118-125 taeniae.
Fourth instar larva a large plumosus-type larva, length 20 mm (Female 13.5-28.0 mm; Male 15.6-24.2 mm), anterior pair of ventral tubules usually shorter (Female: ant. 3.12 mm (1.60-4.44), post. 3.37 mm (1.60-4.52); Male: ant. 2.51 mm (1.60-3.52), post. 2.78 mm (1.48-3.68)). Lateral tubules about 340 (230-580) µm. Anal tubules relatively long, abt, 843 (785-960) µm, at least 3x longer than wide, ventral pair may be shorter and narrower.
Ventral head length about 418 micron (355-475); width of head capsule greater than 0.85mm (Hilsenhoff & Narf 1968). Gular region dark to very dark on posterior 1/2-2/3 with center of margin slightly lower and widest just above the posterior border, frontoclypeus pale or slightly darkened.
Identification: The larva of this species can be recognized by the combination of characters: large plumosus-type; dark gula but pale frontoclypeus; greater than 80 striae on ventromentum, which has a crenullated anterior margin. This does not separate it from C. crassicaudatus or C. frommeri, but does distinguish it from the larvae of C. staegeri in Greenland which is a melanotus-type larva and lacks crenulations on the ventromentum.
Cytology: 3 polytene chromosomes with a modified thummi arm combination AB, CD, GEF.
Arm G region generally unpaired with a large nucleolus; bands distal to nucleolus often not clear but may contain a BR. Arm B with a nucleolus just distal to the 4 characteristic bands. Inversion polymorphism in all arms except G.
staA1: 1-2c, 10-12, 3-2d, 9-4, 13-19; i.e. as holomelas A1
staA2: 1 - 2c 10, 5e - 9, 2d - 3, 12 - 11, 5d - 4, 13 - 19
staB1: Puff with distal dark bands (groups 8 - 7) about middle of arm.
staB2: Puff with proximal dark bands (group 7 - 8) near distal end of arm.
staB3: Puff approximately as sta B2.
staB4: Puff with proximal dark bands (group 7 - 8) about 1/3 from distal end of arm.
staC1: 1 - 6c, 11 - 8, 15 - 11, 6gh, 17a - 16, 7d-a, 6f-c, 17b - 22 i.e. as aberratus, pilicornis, tenuistylus, etc.
staC2: 1 - 5, 16 - 17a, 6hg, 14d - 15, 8 - 11c, 6b - 5f, 7d-a, 6f-c, 17b - 22
staD1: 1a-c, 16 - 11, 3 - 1d, 17 - 18d, 4 - 6d, 18e - 20, 7 - 10, 21 - 24 i.e. derived
staD2: 1 - 3, 11 - 18d, 4 - 6d, 18e - 20, 7 - 10, 21 - 24
staE1: 1 - 3e, 5 - 10b, 4 - 3f, 10c - 13; i.e. as cingulatus, plumosus, etc.
staE2: 4g-h, 10b - 5, 3e - 1, 4f - 3f, 10c - 13
staF1: 1 - 6a, 11 - 17, 6c-b, 9 - 6d, 10, 18 - 23 Inv6d-11 from froF1
staF2: 1a-c 9b-f, 6b-c, 17 - 11, 6a - 1d, 9a - 6d, 10, 18 - 23
staF3: 1a-c, 9b-f, 6b-c,17-14f, 6d-9a, 1d-6a, 11 - 14e, 10 18 - 23 i.e. from staF2
staF4: 1a-c, 9b-f, 6b-c, 17 - 14f, 1d - 6a, 11 - 14e, 9a - 6d, 10, 18 - 23 i.e. from staF2
staG1: Nucleolus in two parts mid arm.
There are sequences for COI (GenBank accession numbers KF278254-KF278268, KF278356) and ITS-2 (GenBank accession number HQ656599).
Found: Numerous localities in North America.:
British Columbia - Royal Oak & Victoria (Townes 1945)
Labrador - Hopedale (Townes 1945)
Northwest Territories - Cameron Bay on Great Slave Lake (Townes 1945)
Manitoba - Southern Indian Lake (Rosenberg et al., 1984); Aweme (Townes 1945); 4 km off Grand Rapids, Lake Winnipeg (Sæther
Ontario - Copanspin Farm, Dunrobin; Lac Deschenes, Central Experimental Farm and
Hogs Back,Ottawa; South March (all Carleton Co.); Lake Potier, w. Sudbury (47.534°N, 82.065°W);
Clarke Lake (45.533°N, 78.271°W), Algonquin Prov. Park, Nipissing Co..
Quebec - Lake D'Alembert (42.38°N, 79.02°W, Lake Duprat (48.33°N, 79.12°W), Lake Kinojévis (48.13°N, 78.90°W), Lake Opasatica
(48.17°N, 79.33°W), all Rowyn-Noranda; Lake St. Joseph (46.88°N, 71.63°W), Quebec City (Proulx et al. 2015).
Saskatchewan - Oungre Memorial Park.
Alabama - Auburn Univerity pond.
California - Lake Davis, Plumas Co.; Prosser Reservoir, Nevada Co.
District of Columbia - Washington (Townes 1945)
Idaho - Moscow (Townes 1945)
Illinois - Dubois (Type locality of C. fasciventris), 3.5 ml n.e. Mahomet, Champaign Co.; Burlington (Townes 1945)
Indiana - Myers Lake; Crooked Lake, Noble Co.
Iowa - Davenport & Mt. Pleasant (Townes 1945)
Kansas - Lawrence, Douglas Co. (Townes 1945)
Louisiana - Many, Sabine Pa; Mound (Townes 1945).
Massachusetts - Lake Pleasant (43.555°N, 72.509°W), , Franklin Co.; Amherst & Cambridge (Townes 1945)
Michigan - Detroit (Townes 1945)
Minnesota - Anderson Lake, Clearwater Co.; Bad Axe Lake, Hubbard Co.; Eagle Creek, Eagle Bend, Todd Co.;
St. Paul, Ramsey Co. (Townes 1945)
Missouri - Atherton, Charleston & St. Louis (all Townes 1945)
New Hampshire - Berlin (Townes 1945)
New Jersy - Riverton (Townes 1945)
New Mexico - Eagle Nest Lake (36.55°N, 105.25°W), Colfax Co.; Hondo Valley, and Rio Bonito (33.45°N, 105.67°W), 2 ml. e. Bonito
Lake, Lincoln Co. (33.45°N, 105.67°W)
New York - Barge canal, nr Knowlesville, Orleans Co.; McLean, Sea Cliff & Syricuse (last 3
North Carolina - Raleigh (Townes 1945)
North Dakota - McVille Dam, Nelson Co.
Pennsylvania - Pottstown (Townes 1945)
South Dakota - Yankton; Lake Francis Case; Gavins Point National Fish Hatchery; Ardmore (Townes 1945).
Tennessee 10-Mile Creek, Knox Co.; Beaver Creek and Clinch River (Mile 20.8), Oak Ridge.
Washington - Port Townsend & Seattle (Townes 1945)
Wisconsin - Reeder Farm, Madison (43.08°N, 89,42°W), Dane Co.; Freibauer Lake, Bayfield Co.; East Horsehead Lake, Oneida Co.;
Grand Portage Lake, Iron Co.
(All of the above would be sites for C. fasciventris)
Greenland - Egedesminde (now Aasiaat)(68.71°N, 52.87°W) (Type specimens) (Townes 1945).
Morphology and cytology have been described by Wülker et al. (1971) and the patterns of arm C and D in Kiknadze et al. 2004, 2010), the latter reference also having an updated photographic map. The mtCOI sequences do not indicate the presence of more than one species, but sequence from a nuclear gene is needed to confirm this.