Chironomus ramosus Chaudhuri et al. 1992

Adult:

Male
Wing length 2.33 (2.27-2.40), width 0.72 (0.70-0.76); SCf on brachiolum - 2; VR 1.01 (1.00-1.03).
Head: Antennae brown, AR 3.86 (3.72-3.94).  Frontal tubercles small; ratio of palpomeres (I-V) 14 : 11 : 47 : 48 : 66.  Clypeus with 20 (18-20) setae.
Mesonotum with 4 brown vittae; fore tibial scale with 4 long setae; tarsomeres of foreleg dark brown, tergites I-VI with brown oval spot medially; curved anal point, beak-like superior volsella; setae of inferior volsella finely branched.
Leg proportions and ratios (units):
 
Fe
Ti
Ta1
Ta2
Ta3
PI
30
29
43
21
18
PII
31
29
18
10
7
PIII
38
35
25
14
11
 
Ta4
Ta5
LR
F/T
BR
PI
15
7
1.48
1.03
no beard?
PII
4
3.5
0.62
1.07
-
PIII
6
4
0.72
1.09
-

Abdomen: Greenish yellow, tergites I-VI with brown oval spot medially; curved anal point, beak-like Superior volsella (as in C. samoensis, C flaviplumus, etc.); setae of Inferior volsella finely branched.


Adult male of C. ramosus (Chaudhuri, Das and Sublette 1992)

Female:
Wing length 2.59 (2.49-2.66), wing width 0.88 (0.82-0.95).
Antenna 5 segmented, relative lengths 10 : 7.5 : 7 : 6.5 : 12.  AR 0.38, A5/A1 about 1.2.


Female genitalia and antenna of C. ramosus (Chaudhuri, Das and Sublette 1992)

Pupa:

Length of male 6.67-7.64 mm, of female 6.52-8.86.

Frontal tubercles about 0.09 mm long and 0.06 mm wide, with the subapical seta about 0.05 mm in length.

Wing sheath 1.42-1.72 mm in length, respiratory base elliptical and about 0.15 mm wide.

Pedes spurii A caudolateral on segment IV-VI; Pedes spurii B basolateral on segment I and caudolateral on segment II.

Hook row on segment II comprised of about 46-58 hooklets.

Shagreen pattern as shown in figure.

Caudolateral spurs of segment VIII with 3 spines.


Fourth instar larva:  a small to medium plumosus-type (length 8-13.2 mm).  Anterior pair of ventral tubules shorter than posterior pair;anal tubules 0.31 (0.29-0.33) mm long.  Gula and frontoclypeus apparently not darkened.
Mentum with c2 teeth well separated and c1 broad (type IIA), 4th lateral slightly reduced (type I-II).
Ventromentum about 3.9 times longer than its depth; figure indicates numerous striae.
Pecten epipharyngis with 20 teeth (type B).  Premandible with two equal teeth.
Antenna with basal segment about 2.25 times longer than wide, RO less than 1/3 up from the base; AR 1.69 (1.53-2.10); ratio of antennal segments 23.1 : 6.7 :2.2 : 3.1 : 1.6.
No information on mandible type or number of furrows on outer surface; or of number of tainiae in Pecten mandibularis.

Cytology: Four polytene chromosomes with the pseudothummi-cytocomplex combination BF, CD, AE, G.
Nucleolus in arm B (at 11B)(as in map of Nath and Godbole 1997), but may be developed in arm F (at 10D - abt. groups 22-23), as in other Indian species.  Two BRs, about equally distant from each end, are on arm G.   No reported polymorphism.
Some points can be made by reference to the map of Nath & Godbole (1997):
ramA1:    1 - 2c, 10 - 12, 3- 2d, 9 - 4, 13 - 19                as circumdatus A2, holomelas, etc.
ramB1:    Characteristic bands at 10F.  May be a nucleolus at 11B
ramC1:    Developmentally stage specific puff at 6B.            as C2 of flaviplumus type B
ramD1:   
ramE1:    1a-i, 5 - 10b, 3e - 2, 4 - 3f, 10c - 13            i.e Inv2-5 from aprilinus, as flaviplumus type B
ramF1:    1 - 2a, 10 - 3d, 14c - 11, 2b - 3c, 14d - 23    Nucleolus sometimes about region 22-23.
ramG1:    BRs at 18C and 19C

Found: Type locality - Satgachhia, West Bengal, INDIA.
Other localities:
            India - Hooghly, West Bengal; Pune; Cachar hills, Assam.

Larva, pupa and adult described by Chaudhuri, Das & Sublette (1992).  Chromosomes described by Nath & Godbole (1997).  In their map, chromosome I is comprised of arms D and C, chromosome II of arms F and B; chromosome III of arms A and E, and chromosome IV is arm G.  As noted, the nucleolus in the map is at 11B in arm B, but in other specimens, the nucleolus is in arm F at 10D.  Since the available specimens have all come from an inbred laboratory stock, it is not clear what the situation is in natural populations.
Morphologically close to the C. samoensis group; cytologically close to C. flaviplumus type B.

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Modified: 22 February 2019
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