North American Chironomus: C. prior

Species 3z. C. prior Butler, 1982.

Adult

Male: Dark species, AR 4.89-5.48 (mean 5.20); frontal tubercles 20-40 µm.
Weak or absent scutal tubercle
Abdominal segments dark, but often pale on posterior margins.
Fore leg with moderate beard, BR 4-7.
LR1 1.10-1.22; LR2 0.58-0.63; LR3 0.65-0.71.
Sensilla chaetica: Leg2 8-21; Leg3 5-15 (lower than C. tardus; and when taken in conjunction with the higher LR, is useful for separating males of the two species)
Anal point relatively narrow; superior appendage of the D-type; Inferior volsella turns slightly outward over distal third; 2-17 setae on segment IX.

Female: Thoracic color slightly lighter than that of the males, base color light to medium brown,
with scutal stripes, postnotum, etc., dark brown.
Abdomen similar color to males.

Larva a salinarius type. Gular region and frontoclypeus completely brown, with darkening of the rest of the head capsule except for a pale area just posterior to the eye spots. ventral head length 309 - 342 (mean 325) µm.; head width 529 - 618 (mean 569) µm.
Head capsule smaller and darker than that of its sibling C. tardus.

Cytology: 4 polytene chromosomes with the thummi arm combination: AB, CD, EF, G.
According to Butler (1982) there are differences in arms F and G compared to C. tardus.
pri A1: 1 - 2c, 10 - 12c, 3 - 2d, 9 - 4, 13 - 19 ie. as tardus A1
pri E1: 1 - 3e, 5 - 10b, 4 - 3f, 10c - 13 ie. as tardus E1

Found: Alaska - Pond J, Barrow; Loon Pond, Prudhoe Bay (Type locality).

Tundra ponds.

Description and a brief comment on the karyotype in Butler (1982).
This species is the sister species to C. tardus.

[ See also C. tardus | Return to Index| Go to References ]