South East Asian Chironomus: C. striatipennis type 2

Chironomus striatipennis type 2

Adult:

Male:
Wing length = 1.98-2.84 mm.; width = 0.53-0.70) mm.  VR = 1.04-1.08.
LR = 1.49-1.82;
Face yellowish brown, antennae and palps brown.  AR about 2.47-2.97.  Frontal tubercles about 41 (35-49) µm long and 14 (10-20) µm wide.  Palpal proportions (micron) 45 : 44 : 161 : 164 : 240.  Clypeal setae - abt 16-22.
Thorax pale brown with brown stripes, lateral stripes darker along the medial edge, and ending in a darker spot; postnotum and sternopleuron brown.
Setae: acrostichals - abt 17 (13-23); dorsocentrals - 19 (16-26); prealar - 5 (3-5); scutellar - 2 - 4 in anterior row, 8-14 in posterior row.
Wings with dark spot over the crossvein and with obvious dark clouds and seams, particularly in cell R5;  abt 6-14 setae on stem vein in two clusters, abt 18 setae on squamal fringe.
Haltere pale.
Leg proportions (arbitrary units):

	Fe	Ti	Ta1	Ta2	Ta3	Ta4	Ta5	LR	F/T	BR
PI	1031	938	1390	760	613	413	250	1.32-1.64	1.10-1.11	2.3-3.5
PII	1092	1048	735	366	266	175	136	0.60-0.82	1.01-1.07
PIII	1224	1270	987	557	430	256	170	0.78	0.96

BR less than 4, i.e. apparently lower than in C. striatipennis.

Wings with dark clouds as in C. striatipennis.

Superior volsella of the E(h)-type of Strenzke (1959)

Larva (1 female specimen): a small plumosus-type (length 9.2 mm).  Anterior ventral tubules bent and posterior ventral tubules coiled with posterior longer (ant 0.74 mm, post 0.78.mm). Lateral tubules 220 µm; anal tubules rel. long: dorsal 350 x 120 µm (l/w 2.9); ventral 380 x120 µm (l/w 3.2).
Gula of this Malaysian specimen dark, extending over posterior 2/3; and frontoclypeus also darkened.
Mentum with c2 teeth of central tooth separated and sharp (type III), 4th lateral possibly slightly reduced, but broken on available specimen (type 1?).  Pecten epipharyngis with about 14 teeth.
Ventromental plates 175 µm wide and 3.45 times wider than deep; separated by about 0.28 of the mentum width, about 38-40 striae reaching at least halfway to anterior margin; VMR 0.28; 1.08 times the mentum width.
Premandibles with teeth approximately equal in length, inner coming to a rounded point, outer to a sharp point (type B1); inner tooth about 3.2x wider than the outer tooth.
Antenna with basal segment relatively long, 3.2 times longer than wide; RO from about 0.37-0.42 up from base of segment; AR about 1.8; proportions (µm) 102 : 23 : 9 : 11 : 8.  Distance between antennal bases (121 µm) less than the distance between the S4 setae (126.5), which occupy about 0.81 of width of Frotoclypeus at that point.
Mandible with third inner tooth partially separated, and pale (i.e. type IIA), with 19-20 furrows; 11 taeniae in Pecten mandibularis; Mdt-Mat 28 µm; MTR 0.37.

Cytology: Four polytene chromosomes with the pseudothummi-cytocomplex combination BF, CD, AE, G. Centromeres not obviously heterochromatic.
Nucleolus terminal on arm G, no nucleoli on long arms. No other details clear.

Arm G of C. striatipennis Type 2

Found: Malaysia - Minden, Penang (5.13; 100.13)
Singapore - Bedok Canal (1.367; 103.939)
Thailand - Pattani, Pattani Province (6.87; 101.25)
Japan

Adult and immatures described by Al-Shami et al. (2012) as C. kiiensis probably refer to this species.

Molecular: The mitochondrial COI differs from that of Type 1, and this sequence is found in Japan and SE Asia, but has not been found in India.
BOLD accession numbers: COTW009, COTW010, COTW013

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