Male terminalia of C. bifurcatus.
A typical C. decorus-type hypopygium, with superior volsella similar to that of C. maturus.
Adult male: The adult male is a typical member of the C. decorus-group. Rather similar to those of C. maturus Johannsen in coloration and in the darkened superior volsella of the male genitalia.
Male terminalia of C. bifurcatus.
A typical C. decorus-type hypopygium, with superior volsella similar to that of C. maturus.
The pupa is typical of most of the species in the C. decorus-group, in lacking the secondary tubercle on the cephalic tubercles found in C. decorus itself. Caudolateral spur normally with about 2 - 3 apical spines, but varying from 1 to 6. It differs from C. maturus in the usually higher number of spines.
Larva essentially of the bathophilus-type but sometimes some development of lateral tubules in Canadian samples, while those of mid-west larvae are of 'fluviatilis' type. Anterior ventral tubules usually longer (ant. 0.9 - 1.7 mm, post. 0.8 - 1.4 mm). Medium size, length about 11.7 - 13.7 mm female (7), 11.3 - 13.4 mm male (4). Gular region dark, frontoclypeus only slightly darkened. Mentum with pointed teeth, c2 teeth only partly separated from the c1 tooth (type I); 4th laterals reduced about to level of 5th laterals (type II). Ventromentum with about 30-37 striae. Pecten epipharyngis with about 11-15 generally sharp, even teeth. Premandible with two teeth typical of the genus, inner tooth about twice the width of the outer. Mandible with the third inner tooth pale and not separated (type I), about 15-20 striae near base. Antenna relatively short, about half to two thirds ventral head length; basal segment about 2.8-3.4 times as long as wide; segment proportions (microns) 110 : 27 : 7 : 12 : 6 ; AR 1.6 - 2; A4/A3 about 1.5-2. Anal tubules with median constriction.
Cytology
: 4 pairs of chromosomes with thummi arm combination AB, CD, EF, G.
Arm G usually at least partially unpaired with a terminal nucleolus and Balbiani ring near the other
end. The nucleolar end is always unpaired, giving the forked appearance referred to in the proposed name. The whole arm may be unpaired, and this may be due to the presence of inversion polymorphism. No nucleoli in the long chromosomes. Polymorphic in arms A, B, C, D, F and G (band polymorphism).
bifA1: 1a-e, 14 - 15, 7b - 4c, 13a-f, 8d - 9, 2d - 3e, 17h-a, 3f-i, 12 - 10, 2c - 1f, 8c - 7c, 4ab, 16a-d, 18 - 19
bifA2: 1a-e, 14 - 15, 7b - 4c, 13a-f, 8d - 9, 2d - 3e, 16d-a, 4ba, 7c - 8c, 1f - 2c, 10 - 12, 3i-f, 17 - 19
bifA3: 1a-e, 14a-g, 3e - 2d, 9 - 8d, 13f-a, 4c - 7b, 15e-a, 14ih, 17h-a 3f-i, 12 - 10, 2c - 1f, 8c - 7c, 4ab, 16a-d, 18 - 19
bifA4: 1a-e, 14a-g, 3e - 2d, 9 - 8d, 13f-a, 4c - 7b, 15e-a, 14ih 4ba, 7c - 8c, 1f - 2c, 10 - 12, 3i-f, 17a-h 16a-d, 18 - 19
bifB1: Large puff (group 7) near the middle of the arm.
bifB2: Puff in more distal position
bifC1: 1 - 6b, 12b - 15, 8 - 11c, 12a - 11d, 6gh, 17a - 16, 7d-a, 6f-c, 17b - 22 as C1 of blaylocki
bifC2: 1 - 4h, 15 - 12c, 6b-4i, 8 - 11c, 12a - 11d, 6gh, 17a - 16, 7d-a, 6f-c, 17b - 22
bifD1: 1 - 3e, 18d - 13d, 7e - 10, 4a-c, 13c - 11, 3gf 18e-g, 7d - 5, 19 - 24
bifD2: 1 - 3e, 10 - 7e, 13d - 18d, 4a-c, 13c - 11, 3gf 18e-g, 7d - 5, 19 - 24
bifE1: 1 - 3e, 5 - 10b, 4 - 3f, 10c - 13; ie. as aberratus, sp. 3p.
bifF1: 1, 9 - 7, 14 - 17, 11e - 13, 11d - 10, 2 - 6, 18 - 23;
bifF2: approx. 1, 14 - 17, 19 - 18, 6 - 2, 10 - 11d, 13b - 11e, 17 - 14, 20 - 23
Click here for the polytene chromosomes
Found: Ontario – Algonquin Provincial Park, Nipissing Co.; Bear Creek, nr. Carlsbad Springs, Russell
Co.; and Copanspin Farm, Dunrobin; and 0.5 ml. Dunrobin; Arboretum, Ottawa;
Lac Deschêne, Ottawa (Type locality); South March (all Carleton Co.)
Quebec – Brewery Creek Hull.
Michigan – Lake Michigan, Epoufette.
Minnesota – Anderson Lake, Clearwater Co.; Turtle Lake, Becker Co.; Bad Axe Lake, Hubbard Co. (M.G. Butler)
Wisconsin – Arboretum, Madison, Dane Co.
Creeks, pools or the shallows of lakes.
All life stages and the salivary gland chromosomes described by Wuelker et al. (2009). Some information on arm F given in Fig. 3 of Martin (1979) and a photograph of the chromosomes in Butler et al. (1995) as C. decorus-gr. species 1.