Original description of Chironomus duplex from Skuse 1889
Synonyms:
C. imitans Walker 1856
A large species with the anterior tarsi of the male strongly bearded.
Leg ratio about 1.2 - 1.3.
Antennal ratio (AR) about 3.81 - 4.75.
Frontal tubercles present, length about 44 - 73 micron; 29 - 55 clypeal setae.
Scutellum with setae in two rows; anterior with 11 - 23 setae (higher numbers generally in two rough rows), posterior with 15 - 23 setae.
Wing length about 4.8 - 6.3 mm; VR about 1.02 - 1.07.
Abdomen black with a pale posterior margin on the anterior segments.
Leg lengths (microns) and proportions as follows:
|
|
Fe |
Ti |
Ta1 |
Ta2 |
Ta3 |
|
PI |
1720 |
1670 |
2140 |
1230 |
880 |
|
PII |
1920 |
1870 |
1080 |
670 |
520 |
|
PIII |
2370 |
2440 |
1580 |
950 |
740 |
|
|
Ta4 |
Ta5 |
LR |
F/T |
BR |
|
PI |
920 |
400 |
1.22-1.42 |
1.00-1.05 |
4.1-7.8 |
|
PII |
190 |
140 |
0.54-0.62 |
0.98-1.07 |
|
|
PIII |
300 |
188 |
0.77 |
0.94-1.01 |
|
Morphologically very similar to C. occidentalis and C. australis (with which it was incorrectly synonymised by Freeman 1961), but is distributed allopatrically to the former and differs from the latter by the generally longer length of the femur and tibia of the mid and hind legs. ( A complex discriminant function formula that partially separates the two species was used by Martin (Ph.D. Thesis 1966)). The ratio of Mid femur/Ant femur = 1.08 - 1.17; Mid tibia/Ant tibia = 1.04 - 1.18; Hind femur/Ant femur = 1.25 - 1.45; Hind tibia/Ant tibia = 1.38 - 1.53.
It seems likely that a male with a mid femur >1.12 x the anterior femur will be C. duplex. The values for females would be lower, but have not yet been calculated.
Found: New South Wales: Forbes.
South Australia: Barmera; Lake Edward & Lake Leake, Kalangadoo; Brown Lake, & Valley Lake, Mt. Gambier; Victor Harbor.
Tasmania: Cape Wickham Rd., nr. Little Cask Lagoon, King Island; Lake Dulverton, Oatlands.
Victoria: Albert Park; Lake Bullen Merri, Camperdown; Snake Gully, Monash University, Clayton; French Island; Hoddles Creek; Lara; Lake Learmonth, Learmonth; Leslie Manor; Royal Botanical Gardens, Melbourne; Edwardes Lake, Reservoir; Albert Park Lake, South Melbourne; Emu Bottom, Sunbury; 7 Km s. Wangaratta; Melbourne Water Metropolitan Farm, Werribee; Wycheproof.