Oriental Chironomus: C. acutus

Chironomus acutus Das, Majumdar, Mazumdar, & Hazra, 2016

(Junior homonym of C. acutus Goetghebuer 1928 - New name required.)
Since the name refers to the shape of the Superior volsella, Chironomus aguzza is suggested.

Adult

Male:
Total length 4.52-4.70 mm.  Wing length 2.08-2.50; width 0.64-0.76.  AR 2.95-3.02.
Head and thorax light brown, wing light yellow, veins brown; postnotum dark brown.  Legs and abdomen pale yellow; tergites II-IV with faint spots.
Frontal tubercles 82-90 µm long and 34-40 µm wide; clypeus 170-180 µm long and 136-140 µm wide, with 18-20 setae.  Ratio of papal segments (µm): 68-85 : 34-51 : 170-187 : 255-272; P5/P4 abt 1.45-1.5: P5/P3 abt 1.33-1.36.
Thoracic setae: 10-12 acrostichals; 12-14 dorsocentrals; 6-8 prealars; 16-18 biserial scutellars.
2 Scf on brachiolum, 16-18 setae in squamal fringe; VR 1.12-1.14.

Leg lengths (micron) and proportions:

	Fe	Ti	Ta1	Ta2	Ta3	Ta4	Ta5	LR	F/T	BR
PI	1120-1160	960-1000	1560-1640	840-920	760-800	640-680	320-360	1.59-1.62	1.16-1.17	2.62-2.65
PII	1080-1120	960-1000	640-720	320-360	200-280	160-220	120-160	0.64-0.67	0.96-1.12
PIII	1000-1040	1200-1260	880-920	480-520	320-360	240-320	120-160	0.69-0.73	0.83

Lacks a beard

Abdomen pale yellow, Tergites II-IV faint spots; Tergite IX with 15-17 setae, some possily in clear pale spaces.
Anal point 82-87 µm long with an expanded end; Superior volsella somewhat sickle shaped, of D(e)-type of Strenzke (1959); Inferior volsella reaching about to end of anal point and(1/3 of length of gonostylus), with 10-12 incurved setae near apex; gonostylus only moderately swollen and narrowing markedly from about midpoint.

Female: not described.

Pupa: Length 5.56-6.92 mm.; wing sheath 1.36-1.44 mm long.  Yellowish, exuviae grey.  Frontal apotome triangular with subapical frontal setae 30-38 µm long.  Cephalic tubercles cone-shaped 86-92 µm long and 64-69 µm wide.  Basal ring of thoracic horn bean shaped.
Abdomen yellowish brown, tergites II-VI with median shagreen, VII with a single semicircular patch of basomedian shagreen, VIII with little shagreen. &nsp;Hook row comprising 52-56 hooklets.  Segment II with caudolateral PSB (69-72 x 52-56 µm), with a PSA on segment IV (77-82 x 65-69 µm).
Caudolateral spur with two spines.  160-166 taeniae in multiple rows on anal lobe.

Fourth instar larva: Deep red in color, 5.68-8.60 mm long, VT 880-1120 µm long, anal tubules 560-880 µm long. &nsp;There is no mention of lateral projections or indication of whether the ventral tubules are coiled or straight.
Mentum 163-184 µm wide, possibly of type I with the central trifid tooth of type IA.
Ventromentum 52-66 µm wide with a serrated margin, distance between them 73-84 µm.
Premandible illustrated with inner tooth narrower than the outer tooth. Pecten epipharyngis with 12-14 teeth, two apical ones dark brown.
Mandible 220-238 µm long, with pale apical tooth and the inner teeth dark (type IIIC); MTR perhaps 0.29.

Noted as close to C. incertipenis and C. ramosus in structure, but thoracic chaetotaxy is quite different.

Found: India - Type locality Itanagar (27.03°N. 93.63°E, 440 m a.s.l.) Arunachal Pradesh.

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