C. javanus Kieffer 1924

Synonym: C. vitellinus Freeman (1961).

Yamamoto (2002) has suggested that this species should be in a separate subgenus Austrochironomus, as type of the subgenus. However there is doubt that there is a consistent set of characters for the species he included.

In BOLD Bin: BOLD:AAG6924.

Adult:

Kieffer's original description of C. javanus.

Female.  Yellow.  Eyes separated by not more than their terminal width, gradually thinning at the top.  Palps long, brownish black, 4th segment matching the previous two segments combined, 2nd shorter than 3rd, 1st much longer than wide [these are actually segments 2 - 5].  Antenna 2nd segment narrowed in the middle, the neck a little longer than wide, the rest broken.  Metanotum, three short bands, mesonotum and mesonotum reddish.  Halteres light green.  Wing whitish, not distinctly stippled, veins a whitish yellow, crossvein and base of the cubital black, cubital arched, ending very near the tip of the wing.  Legs light green, fore tarsus long and thin, white, both ends of segments 1-4 deep black, 5th slightly clouded, pulvilli a little wider, with long hairs, not exceeding the middle of the crotchets, hardly shorter than the empodium, probably branched four hind tarsi broken; fore femur much longer than the tibia, the latter and the tarsal segments are 2 : 3 2/3 ; 2 : 1 1/2 : 2 : 3/4 [i.e. LR = 1.80], the 4th segment is longer than 3rd, the four hind tibias have confluent combs which occupy two thirds of the circumference, the two spurs short.  Abdomen a bright green, unmarked.  L. 4 mm.
Male.  Pale yellow, abdomen spotless, four bands on mesonotum, metanotum and mesosternum fawn, red scape, flagellum broken.  Wing as female.  Legs white, distal end of tarsomeres 1-4 and 5th tarsal segment black. Anterior tarsus broken.  Eyes separated by 1.5 times their terminal width.  Terminal articles of the genitalia (‘'pince') arcuate, the distal half suddenly narrowed in a straight beak, glabrous, having only one third of the width of the proximal half and carrying on the distal half of the medial side straight six large rigid bristles.  Superior appendages very thin, glabrous, linear, reaching the end of the basal article (gonocoxite), weakly curved and ending in a point; inferior appendages large, pubescent, exceeding just the gonocoxite and bearing dorsally the usual long and thick curved setae.  Anal point long and thin.  L. 4.5 mm.

Male:
A yellowish-green species with dark bands on the tarsi, and darkening of the cross veins of the wings.
Thorax yolky colour, dull with practically no pruinosity.
Abdomen without dark markings but with strong pruinosity at the incisures and on segments 5 and 7.  Anal point narrow.  Freeman (1961) quotes the AR as about 4.5, but in other populations the AR is quoted as lower (2.9-3.82 (Tokunaga 1964; Chaudhuri et al. 1992)).  LR about 1.6-1.8.
Wing length 2.75 (2.07-3.08) mm; width 0.62 (0.56-0.73) mm; VR 0.92-0.98.
Head  Frontal tubercles about 30µm; about 17-21 clypeal setae; Palpal proportions (segs. 1-5) (µm): 60 : 60 : 185 : 220 : 330.
Thoracic setae: achrostichals abt. 10, but often not evident; 6-14 dorsolaterals; 2-4 prealars; scutellars with only a single row of 12.6 (10-16) setae.
Wing: Hyaline, brachiolum with 2 sensilla campaniformia; squama with 20 (15-26) setae.

Leg proportions (µm) and ratios:


Fe
Ti
Ta1
Ta2
Ta3
PI
1215
1050
1120
955
840
PII
1305
1120
725
375
280
PIII
1445
1445
1120
605
470
Ta4
Ta5
LR
F/T
BR
PI
770
350
1.6-1.8
1.15
2.1-2.5
PII
185
140
0.60-0.64
1.16
-
PIII
300
160
0.70-0.77
1.00
-


Illustration of the hypopygium of C. javanus
From Johannsen (1932)

Tergite IX with 6-9 setae, apparently in individual pale patches.  Hypopygium with long tubular anal point, strongly turned down; Superior volsella well developed and curved, perhaps closest to E(h) of Strenzke (1959); Inferior volsella reaching just beyond the end of the Superior volsella, with 12-14 incurved setae.  Gonostylus quite swollen and conspicuously narrowed over posterior half with 5=1 setae at tip.

Female
Body length 3.69 (3.57-3.89) mm.  Wing length 2.57 (2.08-2.93) mm; width 0.83 (0.66-0.96) mm; VR 0.89-0.90.
Antennal segments (micron) with proportion of neck in brackets: 169 (0.26) : 127 (0.42) : 134 (0.48) : 128 (0.48) : 206; AR 0.34-0.43; A5/A1 1.15-1.45.
Palpal segments (micron): 54 : 45 : 184 : 216 : 338; P5/P4 1.40-1.66.  Clypeus width abt 1.32-1.45 times the diameter of the antennal pedicel, with 25.7 (20-31) setae.
Thoracic setae: acrostichals 12.7 (10-16); humerals 3-5 usually linear but may be in triangle; dorsocentrals 11.2 (10-12) (dorsocentrals plus humerals 13-17; prealar 5 (4-7); supraalar 1; scutellar with main row 9-12, and 0-2 small setae anterior.
Leg lengths (micron) and proportions:

Kieffer gives abdomen as green, unmarked, but Sasa & Hasagawa (1983) imply that the last couple of segments may be darkened. Segment X usually about a half oval, 2.1-3.6 times longer than greatest width, with about 10-13 setae. Sasa & Hasagawa (1983) note that the cercus is roughly rhombic, 112x152 µm; usually with a ventral basal bulge.

Pupa:  The pupa has been described by Chaudhuri et al. (1992) and illustrated by P.S. Cranston in his Electronic Guide to Chironomidae of Australia, as C. vitellinus.  This illustration is reproduced here (with permission).
Length: Male 6.38–6.70 (6.40) mm; female 6.90–7.14 (7.01) mm. (6–7 mm in Lenz 1937).  Exuviae grey.  Frontal tubercles 0.10-0.11 long and 0.06-0.07 in diameter, subapical seta 0.09-0.10 long, i.e. about as long as the tubercles.  Respiratory base about 0.11-0.14 wide.  2 pairs of precorneal setae.
Abdomen with Pedes spurii A caudolateral on segments IV-VI, Pedes spurii B basolateral on segment I and caudolateral on segment II, which also bears a caudal row of about 66-70 hooks.

Fourth instar larva: a medium sized, essentially plumosus-type larva, although lateral tubules (about 380 micron long) are more ventrally placed than in other species.  Chaudhuri et al. (1992) show the ventral tubules arising very close together, but this is not normal in this species from other countries.  Anal tubules variable across distribution from about 220-425 microns long, and 3-3.6 times longer than wide with median constriction.
Gula pale or slightly darkened on posterior third;  frontoclypeus generally pale.
Mentum (Fig. c) with c2 teeth of central trifid tooth markedly separated from c1 tooth (type III) and pointed towards it, 4th laterals at most slightly reduced (type I).
Pecten epipharyngis (Fig. a) with about 12-13 often irregular teeth.  Ventromentum (Fig. d) with about 27-28 striae.
Antenna (Fig. b) with the basal segment about 4 times as long as wide; AR about 2.4; ratio of segments 125 : 29 : 6 : 9 : 5.
Distance between S4 setae slightly larger than with between antennal bases.
Mandible (Fig. e) with third inner tooth darkened and completely separated (type IIIC), with three spines on inner margin, and about 12-13 striae at the base.
The larva is most readily recognised by the unusual premandible, which has 6 (as illustrated by Chaudhuri et al. (1992) for Indian specimens) or 7 teeth (as illustrated here) rather than the usual two.  However, specimens have been described from Malaysia and Singapore (e.g. Kuvangkadilok 1969) where the premandible has a normal premandible with only two teeth.

Cytology:  4 polytene chromosomes, possibly with the thummi arm combination AB, CD, EF, G, but Keyl arms very difficult to recognize.
Nucleolus virtually terminal in arm G, with large Balbiani Ring near middle of the arm; closely paired.  No nucleolus in long chromosomes.
javA1:
javB1:    Puff (gp. 7) about one third from distal end of the arm with dark bands distal.
javC1:
javD1:
javE1:
javF1:
javG1:    Nucleolus subterminal, BR about one third from other end; closely paired.

Molecular:  The mitochondrial CO1 barcode sequence is available in GenBank for specimens from Japan (Accession number DQ648203).

Found:Type locality - Buitenzorg, Java, INDONESIA.
            India - Jammu & Kashmir: University of Jammu Campus.
            Indonesia - ¿Sumatra.
            Japan - Shizuoka, Honshu.
            Malaysia - Minden, Penang; Tregganu.
            Thailand - Don Suan (16.254oN, 103.258oE); Mahasarakham University (15.303°N, 103.371°E); Kantharawichai Dist.;
            Rajabhat Maha Sarakham University (16.191°N, 103.268°E), Tambon Talad (16.333°N, 103. 491°E), Ban Tha Pratai 16.355°N,
            103.542°E), Mueang Maha Sarakham District; all Maha Sarakham Province; ¿Ban Bangkanark, Chachoengsao Province;
            San Pa Tong Rice Experimental Station, Amphoe San Pa Tong, Chiang Mai Province; Ban Mae Kachiang,
            Amphoe Wiang Pa Pao, Chiang Rai Province (Hashimoto et al. 1981)
            South Korea (GenBank & BOLD)
            Fiji - Viti Levu.
            Melanesia - Caroline Islands and Marshall Islands
            Australia - Manning River, Kundibakh, New South Wales; Darwin, Northern Territory (Type locality of C. vitellinus Freeman); Mareeba;
            Sarina; and 3 km w. Sarina Beach, Queensland.
            Papua New Guinea - Mafulu (1200 m); Lae-Goroka Road, Eastern Highlands Province; Sogeri, Central Province.
            Central Africa - Blantyre, Malawi.

Broadly distributed through India, south east Asia,the Pacific regions and Africa, in rice paddies and small temporary water bodies, even sewage works.

Redescription of adults and immatures from Malaysia by Al-Shami et al. (2012).

Dr. Midya has an alternative species from India identified as C. javanus, it is not certain whether this corresponds to the form with a normal premandible, e.g. as described by Karunakaran (1969).
Cytology: Four polytene chromosomes with the pseudothummi-cytocomplex combination BF, CD, AE, G.  Nucleoli in arms C (or D?) and A.  Arm G subacrocentric and closely paired, with a BR near the centre of the chromosome and another near the distal end. No reported polymorphism.
Found - India, Calcutta.

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Modified: 21 February 2020
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