Chironomus crassiforceps Kieffer 1916

    Synonyms
        Chironomus esakai Tokunaga 1940
        Chironomujs insolens Johannsen 1946 - synonymised with C. esakai by Hardy (1960).
        Yaesecundus iriobeceus Sasa & Suzuki, 2000
        Chironomus daitoabeus Sasa & Suzuki 2001
        Daitoyusurika daitofegea Sasa & Suzuki, 2001
        Possible synonym - C. nudipes Kieffer 1911 - i.e. this could be the senior synonym for this species.

In BOLD Bin: BOLD:ACC5271
The nearest neighbor is BOLD:AAJ4269 which contains C. magnivalva

Kieffer description - Annales Musei Nationalis Hungaricis 14: 111-112 (1916)
10. T. crassiforceps n. sp.

Male:  Fawn colour.  Frons with two small white lobes.  Palps of a dark brown.
Antennae of 12 segments, brownish, with fawn variegation, transverse segments 3-11 twice as wide as long, the 12th twice as long as previous ten together.
Mesonotum frosted white, with 3 reddish bands, short, dull, whitish; scutellum, metanotum and pleura reddish or fawn.
Halteres white, extremity of club brown.  Wings subhyaline, crossvein black, second longitudinal vein close to radius, cubitus more than half as long as the radius, posterior fork a little distal to the crossvein.
Legs yellowish, the last two tarsal segments and the extremity of the third darker, anterior tarsus not bearded, long anterior tibia, hardly shorter than the unmarked femur, metatarsus at least longer by half than the tibia, sements 2-4 gradually and slightly shortened, the fourth not distinctly shorter than the third one, more than twice as large as the 5th, large pulvilla, shorter than empodium.
Abdomen linear, of a brownish white, lateral edges black, the last two tergites and claspers a little duller than the other tergites.  Large claspers, very large terminal segments, longer and larger than the basal segments, straight, slightly thinner and rounder at the edge, except the distal quarter which possesses, as well as the extremity, short hairs, erect and quite dense, the setae of the lateral part are relatively shorter than usual, shorter than the width of the segment; coxite appendages in a short point; superior appendages extend out a little past the basal segments, flat, linear, curved; inferior appendages very long, nearly reaching the extremity of the terminal segments, more than twice as large as the superior appendages, but not half as big as the terminal segments, slightly swollen before the extremity which is thinner, pubescent, dorsal surface armed, on the distal third, with long hairs, rigid and strongly curved. - L. 4.5 mm.
    (i.e. AR about 1.5, LR at least 1.5)

Adult

Male
Wing length 2.43 (2.28-2.72) mm.; width about 0.64 (0.60-0.68); VR 0.91 (0.88-0.97).
Head: AR 1.90 (1.48-1.98; Palp proportions segs. 2-5 (microns): 41 : 158 : 159 : 205 ; (P5/P4 1.07-1.50; P5/P3 1.11-1.50). Clypeal setae 23-28.
Thoracic setae: acrostichal abt. 12-19; dorsolateral 11-18; prealar 5-7; supra alar 1; scutellar in approx. 2 rows ant. 5-8. post. 9-12 (total 16-20).
Leg proportions and ratios (microns)

 
Fe
Ti
Ta1
Ta2
Ta3
Ta4
Ta5
LR
F/T
BR
PI
1305
1070
1795
880
755
741
349
1.56-1.81
1.18-1.27
1.73-1.92
PII
1318
1279
633
360
290
209
168
0.45-0.59
1.00-1.18
 
PIII
1520
1473
909
498
451
262
189
0.49-0.626
1.00-1.07
 

        Hypopygium: Anal point stout, style large and oval in lateral aspect,
        dorsal volsella long and slender; inferior volsella slightly curved and almost as long as the style.
        No setae centrally on 9th tergite.

Female
        Wing length 2.08-2.77.
        Head: Antennal proportions 40 ; 78 : 64 : 66 : 56 : 122. Palpal proportions 28 : 30 : 78 : 95 : 144.

Leg proportions and ratios

 
Fe
Ti
Ta1
Ta2
Ta3
Ta4
Ta5
LR
F/T
Ta4/Ti
PI
968
808
1500
730
640
630
310
1.15-1.22
1.15-1.22
0.67-0.71
PII
972
956
540
307
233
167
153
0.53-0.68
1.10-1.12
 
PIII
1140
1144
770
430
350
-
-
0.63-0.67
0.96-1.03
 

        Abdomen largely yellow or yellowish-brown, darker at posterior.  Cercus and segment X (below) very similar to that of C. magnivalva, i.e. a generally rounded outline with some indication of a bulge at the base of the ventral margin, while segment X has an enlarged, relatively rounded base.


Variation of the cercus in specimens from Japan. (Drawing by T. Kobayashi)


Pupa (from Tokunaga 1964) Body length 5.9 (5-6) mm.  Frontal tubercles triangular (Fig. a), as long as the basal length, with small apical seta.  Abdominal tergite II with a caudal ridge of 77 hooklets; caudolateral spur of segment VIII (Fig. b) usually with 3 or 4 spines but may be only one.

Fourth instar larva a medium sized plumosus-type larva.  Length (females) about 7-12.3 mm.  Anterior ventral tubules (1.68 mm) generally slightly shorter than the posterior pair (1.72 mm).  Anal tubules 320-480 µm long and about 2.7-3.4 times longer than wide, without a constriction.
Gular region slightly darkened to dark on posterior third to half, slightly wider than the width of the mentum, widest at posterior border; frontal apotome also darkened, and slight darkening elsewhere on dorsal surface.  Oesophageal opening (Fig. d, below) 75.1 (58-96) µm wide and 4.7 (4.0-5.2) times wider than deep.
Mentum with 4th laterals only slightly reduced (essentially type I), and c2 teeth partly separated from c1 (mostly type IB but rarely type III); width about 50-60% of the VHL.
Ventromental plates separated by 43-61 µm (about 0.30-0.35 of mentum width), with about 36 (32-47) striae; VMR 0.26 (0.21-0.30).  Pecten epipharyngis with about 15.8 (14-19) teeth, mostly type B when not worn.
Premandible with inner tooth about 3.5-4.5 times wider than outer tooth, both reducing to a point, sometimes to a sharp point, others to a broad point as in figure.
Antenna with relatively long basal segment, about a third of the VHL and 3.3 (3.1-3.7) times longer than wide; RO about 0.31 (0.25-0.37) up from the base; AR about 1.91 (1.55- 2.24), segment lengths (micron) 103 : 26 : 9 : 11.5 : 7.
Distance between antennal bases (132.4 (119-159)) generally greater than that between the S4 setae (121.3 (109-147)), which are separated by 76-85% of the FA width.  S5 setae about level with the nearby RO.
Mandible about 218.6 (195-237) µm long, with 3rd inner teeth only slightly separated and showing some colour (type I-IIA); about 18.9 (17-20) furrows near the base; 12.5 (12-14) taeniae in Pecten mandibularis; Mdt-Mat 29.5 (25-35) µm, MTR 0.4 (0.36-0.45).

Cytology:  Four polytene chromosomes with the pseudothummi-cytocomplex combination BF, CD, AE, G.
Nucleolus in arm F at about group 19, and a small nucleolus sometimes developed subterminally in arm G.  No known inversion polymorphism.
Differs from C. magnivalva by fixed inversions in arms C, E and G.

craA1:    1-2c, 3-2d, 10-12, 14-13, 4-9, 15-19&                                                                              as magnivalva A1
craB1:    Large puff with distal dark bands (groups 7-8) near distal end of arm                    as magnivalva
craC1:    the distinctive groups 3-4 are about one quarter of the arm length from the centromere
craD1:    as arm D of magnivalva
craE1    1-3a, 10g-c, 3f-4, 10b-5, 3e-b, 4-3f, 11-13           from cingulatus/magnivalva by Inv10g-3b
craF1:    1-2a, 10d-a, 2b-9, 11-23                                                                                                as magnivalva F1
craG1:    Nucleolus sometimes subterminal, with BR immediately next to it, and two other BRs spread along the arm


Arm G of C. crassiforceps.

Found: Type locality - Tainan, Taiwan, (Republic of China).  Types were in the Natural History Museum in Budapest, and so are lost.
        Type localities of the synonyms are not in Asia.
        Japan - Miyako Island, Minamidaito Island, Yonakuni Island & Ryukyu, all Okinawa Prefecture; Yonakuni Island; Iriomote Island; Fukuoka Prefecture, Kyushu.
        Philippines - Sozan, Taihoku.
        Micronesia: S. Mariana Island, Palau, Yap, Caroline Atolls, Ponape, Kusaie, Marshall Is., Gilbert Is.
        ?Micronesia: S. Mariana Island, Palau, Yap, Caroline Atolls, Ponape, Kusaie, Marshall Is., Gilbert Is.
        ?Hawaii - Oahu; Molokai.         Some specimens were obtained from a hot spring at temperature 38°C.
        Thailand - Ban Bu, Amphoe Muang, Nakhon Ratchasima Province; Ban Kud Khaee Khon Kaen Province; San Pa Tong Rice
        Experimental Station; Amphoe San Pa Tong, and Doi Inthanon, Amphoe Hang Dong, both Chiang Mai Province; (all Hashimoto et al.
        1981); Ban Nong Sim, Chaturaphak Phiman Dist., Roi Et Province (Pramual et al. 2016).
        ? - the identity of these specimens is uncertain in the absence of cytological or DNA data.

All life stages were redescribed by Tokunaga (1939, 1964).  C. nudipes was redescribed by Chaudhuri et al. (1992).

This species is very closely related to Chironomus magnivalva Kieffer which occurs in northern Australia and the Pacific Islands, and to the Indian species C. nudipes Kieffer
C. nudipes differs from C. crassiforceps in the presence of dark spots on the abdomen, and the unusually short posterior femur (that of C. crassiforceps being longer than the tibia), as noted above, if synonymy were confirmed, C. nudipes would become the senior synonym.
The information provided by Pal and Hazra (2017) is completely inadequate to confirm that the specimens that they examined were C. crassiforceps, C. nudipes or some other species entirely.  It is unfortunate that they chose to publish in a journal lacking rigorous review.
The major difference in the morphology of the males between C. crassiforceps and C. magnivalva is that, while the gonostyle of C. magnivalva narrows evenly to the distal end, that of C. crassiforceps appears to remain the same width for most of its length and then rounds-off (see figure above). In this latter character, C. crassiforceps seems to be similar to C. nudipes but differs in lacking the dark spots on tergites VI-VIII (although these are only mentioned in the Chaudhuri et al. redescription).  C. crassiforceps and C. nudipes have both been recorded from the same area in West Bengal.

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Revised: 17 September 2021
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