Hypopygium of C. species 3a.
C. decorus was originally described by Johannsen 1905.
Adult with typical C. decorus hypopygium
Larva a small to medium sized bathophilus-type anterior pair of ventral tubules slightly longer. In his original description (above) Johannsen does not mention lateral tubules or coiling of the ventral tubules, but by 1938 the larva is described as plumosus-type. This may represent another member of the complex. Gular region very dark over at least posterior half, frontoclypeus pale. Mentum with somewhat sharp teeth; centre (c1) tooth relatively broad with parallel sides; side teeth reasonably well but not completely separated (type I); 4th laterals slightly reduced, down to about height of 5th laterals (type (I)-II). Ventromentum with about 30-34 striae. Pectin epipharyngis with about 10-14 teeth. Mandible with the third inner tooth pale or slightly darkened and not separated (type I-(II)), about 12-17 striae near base. Antenna relatively short, less than half ventral head length; basal segment about 2.8-3.6 times as long as wide; A4/A3 about 1.4-2.
Cytology: 4 pairs of chomosomes with the thummi
arm combination AB, CD, EF, G.
Arm G with an essentially terminal nucleolus and three Balbiani
rings; often only paired at end away from nucleolus. No
nucleolus in the long chromsomes. Chromosome AB is
somewhat difficult to recognise from the Keyl pattern, since the
"olive" in arm A is not obvious and the 4 characteristic
bands of arm B are not near the centromere but in variable positions
due to inversion polymorphism. A Balbiani ring is
sometimes developed about one third from the end of arm B.
Polymorphism in arms A (4 sequences), B (at least 4
sequences), C (2 sequences), D (4 sequences), E (2 sequences), F (at
least 6 inversions allowing 14 sequences) and G (2 sequences).
decA1: Pattern difficult to identify as the bands of the
typical "olive" are dispersed.
decA2: Large medial inversion.
decA3: A distal inversion of A2.
decA4: A small medial inversion.
decB1: Characteristic bands 20-23 not near centromere,
puff towards distal end of arm.
decE1: 1 - 3e, 8 - 5, 9 - 10b, 4 - 3f, 10c - 13
i.e. as maturus, stigmaterus
and sp. 3f (Seq. A).
decE2: 1 - 3e, 8i-e, 3f - 4, 10b - 9,
5 - 8d, 10c - 13 i.e.
as sp. 3f (Seq. S)
decF1: 1, 9 - 2, 10 - 23
i.e. as decorusB, utahensis, etc.
decF2: 1, 3d - 9, 3c - 2, 10 - 23
decF3: 1a-d, 9 - 3d, 1i-e, 3c
- 2, 10 - 23(?)
from F2
decF4: 1, 3d-9, 3c-2d, 18 -10,
2a-c, 19 - 23 from
F2
decF5: 1, 3d-9, 17-10, 2 -3c, 18 - 23
from F2
decF6: 1a-d, 9 - 3d, 1i-e, 3c-2, 10 - 18, 23 - 19
from F3?
The combination F3+4 appears to occur in species 3f:
decF3+4: 1a-d, 9 - 3d, 1i-e, 3c - 2d, 18 - 10, 2a-c, 19 - 23
Click here for polytene chromosome arms A-D or arms E-G
Found: Ontario -
Copanspin Farm, Dunrobin and South March, Carleton Co.
New
Mexico - Eagle Nest Lake, Colfax Co.; Taylor Springs, Colfax
Co.; Rio
Grande
River, Dona Ana Co.; Hill Tank,
Eddy Co.; Pecos River, Puerto de Luna,
Guardalupe
Co.; Gila River, nr. Virden, Hidalgo Co.; 2 ml e. Hondo, Lincoln Co.
South
Dakota - James River, Yankton.
Wisconsin
- Murphys Creek and Madison, Dane Co.
Windmill tanks, pools in rivers, shallows of lakes.
Some information on arm F given in Fig. 3 of Martin (1979) and Wülker, Devai & Devai
(1989). The karyotype was described in some detail in a Report
to New Mexico Energy
Institute by Martin, Sublette and
Sublette (1979).
Sublette (pers. comm.) believes
this species best fits Johannsen's original description of C.
decorus. He notes the adult male has a dark band
across the middle of each abdominal segment, and the superior
volsella, while darkened, is paler and longer than that of species
a. The pupa has a definite secondary tubercle on the cephalic
tubercles, and multiple spines on the spur. In his original
description of the larva, Johannsen
(1905) did not mention lateral tubules, it was only in his 1938 revision that he describes the
larva as a plumosus-type. This probably refers to a different member
of the C. decorus-complex.