Oriental Chironomus: C. vitellinus Freeman.

Chironomus vitellinus Freeman 1961

Placed as a synonym of C. javanus by Chaudhuri et al. 1992, but this seems to be incorrect as the anal point of the adult males is expanded at the end; there is a patch of setatae on TIX; there is a difference in tooth number of the larval premandible and there are significant differences in the BARCODE sequences.

Adult
Original description of Freeman 1961.

Further description:

Male: (including from a Paratype male from Mafulu, Papua New Guinea):
Wing length 2.81 (2.54-3.08) mm, width about 0.61 mm, VR about 1.05; 18 (11-26) setae in squamal fringe; 2 SCf on brachiolum.
Head: AR 3.04 (2.78-3.46). Frontal tubules about 40 (30-45.5) µm; 16.5 (11-21) clypeal setae
Palpal proportions (µm) 44 : 45.5 : 157 : 196 : 275; P5/P4 1.38-1.45; P5/P3 1.78-1.82
Thoracic setae: 3 (0-5)acrostichal; 8.4 (5-15) dorsocentral; 4.1 (3-7) prealar ; supraalar: 0.67 (0-2) in anterior row, 10.32 (5-16) in posterior row, total 10.7 (10-16) scutellars.
Leg lengths (micron) and proportions:

	Fe	Ti	Ta1	Ta2	Ta3	Ta4	Ta5	LR	F/T	BR
PI	1265	975	1320	930	825	755	355	1.60-1.93	1.16-1.27	2.1-2.5
PII	1210	1060	705	365	270	180	130	0.63-0.68	1.11-1.17
PIII	1325	1330	1065	575	430	265	150	0.77-0.83	0.99-1.00

Tergite IX with 8.5 (7-10) setae in individual patches. Anal point narrow but expanded at distal end, narrow in lateral view (see figure below); Superior Volsella closest to E(g)-type of Strenzke (1959); Inferior Volsella reaching to about 1/3 of the gonostylus length, with simple setae; gonstylus quite swollen (not always as much as in the Tokunaga figure below) and decreasing markedly over posterior third.

Superior and inferior volsellae (left) and lateral view of anal point (right) of paratype male of C. vitellinus

Male hypopygium and Superior volsella of C. vitellinus from Tokunaga, 1964

Female:  Coloration essentially as in male.
Wing length 2.81 (2.08-2.93) mm, width 0.83 (0.66-0.96) mm; VR 1.09 (1.07-1.11); 2 Scf on brachiolum; 15.6 (13-16) setae in squamal fringe.
Head:  Frontal tubercles present 28.1 (7.5-35) micron long and 1.0-2.8 times longer than wide.  Antennal segments (micron) with percentage neck in brackets: 169 (28) : 115 (46) : 124 (49) : 126 (49) : 200; AR 0.37 (0.33-0.43); A5/A1 1.10 (1.07-1.17).
Palpal segments (micron): 54 : 50 : 180 : 220 : 335; P5/P4 1.53; P5/P3 1.86.  Clypeus heart-shaped, about 1.28-1.55 wider than antennal pedicel; abt 23 (16-39) setae.
Thoracic setae: 11.5 (9-16) acrostichals; 3.6 (3-5) humerals, mostly linear but may be grouped (e.g. as a triangle); dorsocentrals - 15.2 (9-260); 18.7 (13-30) including the humerals (lower in Pacific Islands); 5 (4-8) prealars; 2.2 (0-6) anterior row and 10 (8-13) in posterior row (total 8-19) for scutellars.
Leg lengths (microns) and proportions as follows:

	Fe	Ti	Ta1	Ta2	Ta3	Ta4	Ta5	LR	F/T	Ta4/Ti
PI	1345	950	1715	975	825	875	390	1.69-1.92	1.16-1.65	0.80-0.99
PII	1240	1160	690	335	245	180	125	0.58-0.65	1.04-1.13
PIII	1365	1460	980	500	415	270	150	0.63-0.77	0.90-0.99

Anterior Ta4 longer than Ta3.

GcIX with 3.7 (2-6) setae; segment X usually a half-oval 91-177 µm wide and 2.99 (2.1-5.36) times longer than greatest width, with about 11.4 (10-13) setae. Sasa & Hasagawa (1983) note that the cercus is roughly rhombic, 112x152 µm; usually with a ventral basal bulge.

Pupa, Fourth instar larva and cytology: see immatures, etc.

The adult male was described from Thailand by Hashimoto et al. (1981), and all stages for specimens from Japan (Hasagawa and Sasa 1987) and from Micronesia by Tokunaga (1964), all as C. javanus. The expansion at the tip of the male anal point, the setae on TIX and the 7 toothed premandible clearly show that these descriptions refer to the present species (and supported by the BARCODE data which show that C. vitellinus is more common and more widely distributed).

Molecular: Mitochondrial CO1 barcode sequence appears to be in the BOLD database under the name C. javanus and is much more numerous than those of C. javanus.
The BARCODE sequences of the two species differ at about 47 base positions (this does not include some rare polymorphisms where one or two C. vitellinus specimens carry the sequence present in C. javanus) and the majority are in the 5' region (as is common for differences between closely related Chironomus species):

Found: Type locality - Darwin, Northern Territory, Australia;
Japan: – Shizuoka (34.989°N; 138.38°E), Shizuoka Prefecture, Honshu; Tamagusuku, Okinawa; Otsu City (35.00°N, 135.88°E),
Shiga Pref., Honshu
China – Lingshui City (18,50°N, 110.03°E), Hainan; Shanghai (31.22°N, 121.47°E).
Korea – locality not specified.
Bangladesh – Chittagong (22.4685°N, 91.7808°E).
Malaysia – Minden (5.13°N; 100.13°E); and Bukit Merah Agricultural Experimental Station (BMAES) (5.13°N, 100.13°E),
University of Malaysia; Penang; Seberang Prai (Al-Sharmi et al. 2012, as C. javanus).
Singapore – Pandan and Bedok Reservoirs.
Thailand – 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, may not all be C. vitellinus);
Tambon Talad (16.33°N, 103.50°E) Mueang Maha Sarakham District.
Other regions:
Papua New Guinea – Mafulu (1200 m)( Paratype).
Fiji – Nadi (-17.67°S, 177.50°E); Suva (-18.13°S, 178.45°E), both Viti Levu.
Malawi – Blantyre (-15.78°S, 35.00°E).
Micronesia – Caroline Islands and Marshall Islands (Tokunaga 1964).

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