Chironomus bicoloris Tokunaga, 1964


Tokunaga's (1964) description of C. bicoloris.

Type data: holotype USNM US66552 adult male, paratype(s) USNM 2 adults male.
Type locality: Dugor, Weloy, Yap Island.

Additional specimens:

Male:
Wing length: 2.96-3.76 mm.; wing width 0.80-0.86 mm.; VR about 1.0.  Brown spot over crossvein; usually 4, or 3, Scf on brachiolum; 22-23 setae on squamal fringe.
AR about 3.10-3.16.
Frontal tubercles longer than in Micronesian specimens - about 50-60 micron and 2.5-2.8 times longer than wide, longer than the width of two eye facets.  Clypeus width about 157-170 µm, about 0.75 of diameter of antennal pedicel; with about 27-33 setae.
Palp proportions (µm): 66 : 64 : 253 : 249 : 436; P5/P4 1.53, P5/P3 1.66.
Thoracic setae - about 19 acrostichal; 26-30 dorsocentral; 1 supraalar; 6-7 prealar; 28-37 scutellar - 12-17 in 1 or 2 anterior rows and 16-20 in posterior row.
Legs with femur and tibia greenish, tarsi yellowish with at least slight darkening of knees and at tips of tarsi.
Lengths (microns) and proportions as follows:

 
Fe
Ti
Ta1
Ta2
Ta3
Ta4
Ta5
LR
F/T
BR
PI
1460
1405
2275
-
-
-
-
1.62
1.04
-
PII
1540
1485
940
530
390
215
150
0.63-0.67
1.06
-
PIII
1675
1825
1355
750
600
350
155
0.73-0.75
0.93-0.94
 

Abdomen greenish proximally, anterior segments with proximal dark band which becomes larger in the more posterior segments until whole segment is darkened.


C. bicoloris: Male hypopygium (left) and superior volsella (right)

Tergite IX with 14.3 (13-16) setae in a large single patch.  Inferior volsella reaching to about the end of the anal point; setae forked.
Superior volsella closest to E(h) type of Strenzke (1959) (see above); gonostylus slender and tapers gently over posterior half, with 4 long and 1 shorter setae at the distal end.

Female: (based on single specimen from near Sarina Beach, Queensland (AQ.66.1).
Colour yellowish, with brown vittae; legs as in males.
Wing length 3.42 mm., width 0.89 mm.; VR 0.91.  3-4 Scf on brachioum; 17-18 setae on squamal fringe.
Relative length of antennal segments (micron) (proportion of neck in brackets): 164 (0.25) : 109 (0.38) : 124 (0.44) : 118 (0.45) : 182.  Frontal tubercles about 22 µm long and 2.5 times longer than wide.  Clypeus about 1.7 times the diameter of the antennal pedicel, with 35 setae.  Palpal proportions (micron) 63 : 48 : 188 : 250 : 385 (P5/P4 1.54; P5/P3 2.05).
Thoracic setae: acrostichal abt 14; humeral 5-6 linear; dorsolateral 22 (humeral+dorsocentral 27-28); prealar 3; supraalar 1; scutellar with 2 rows - 7 in anterior row and 10 in posterior row.
Leg lengths (micron) and proportions
 
Fe
Ti
Ta1
Ta2
Ta3
Ta4
Ta5
LR
F/T
Ta4/Ti
PI
1315
935
1770
860
760
705
340
1.89
1.41
0.73
PII
1265
1140
660
350
250
190
135
0.58
1.11
-
PIII
1355
1380
950
510
410
270
160
0.69
0.98
- 

Segment IX crescent shaped, about 3.9 times longer than its greatest width and with 9 setae.

Cercus and segment X (at left) of C. bicoloris

Cercus shorter on the dorsal margin, posterior margin slighly curved towards ventral end and merging into the longer ventral margin with a basal bulge.

Found: Queensland - Lake Boemingen and Lake Wabby (25.27°S, 153.80°E), Fraser Island (25.15°S, 153.10°E)(H. burton, light trap); 3 km w. Sarina Beach (21.40°S, 149.25°E).
            Also found in Micronesia - Caroline Islands: Pelau Islands and Yap Island.

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Modified: 12 November 2022
Access: Unrestricted
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