Chironomus c.f. transvaalensis (not Kieffer 1923)

In BOLD Bin: BOLD:AAW3995. - members of the C. transvaalensis complex but few if any C. transvaalensis

The original description of Kieffer along with the basics of Freeman (1957), plus the McLachlan (1969) description of the immatures are available at SEAtransdesc.htm

The present species, described below, is a member of this complex, currently known from Israel and Pakistan.

A single male from Tivon, Israel was available for examination:

Wing length 3.65 mm long, 850 µm wide, VR 1.03; 4-5 Scf on brachiolum, about 41-42 setate in squamal fringe.
AR about 3.4.  Frontal tubercles about 56-66 µm long and 3.7-4 times longer than wide.  Palpal proportion (µm) 50 ; 47 : 240 ; 235 ; 260+ (shrivelled).
Clypeus about 0.69 of the width of the antennal pedicel with 28 setae.
Thorax very damaged, so numbers of most setae not clear: acrostichal not seen; at least 16 dorsolaterals; 5 prealar; 2 supa-alar; scutellars in 2 rows, at least 6 in the anterior row and 3 in the posterior row, but total would be much higher.
Lengths (microns) and proportions as follows:
 
Fe
Ti
Ta1
Ta2
Ta3
Ta4
Ta5
LR
F/T
PI
1370
1220
1842
895
763
710
360
1.51
1.13
PII
1524
1425
762
420
320
195
160
0.53
1.07
PIII
1665
1675
1207
685
540
305
200
0.72
0.99
BR 2.8


Male hypopygium of an Israeli specimen of C. transvaalensis

Superior volsella closest to D-type of Strenzke (1959); Inferior volsella reaching part way up the anal point and to basal third of the gonostylus, which is moderately swollen and narrows markedly over the distal half with 4+1-5 setae at the tip.  Anal point twisted but appears to be narrower at the base and expanded at the end as noted by Freeman.

Adult female and Pupa: Not known

Fourth instar larva:  Two female larvae were available for study.  The larvae were plumosus-type although no metrics were recorded.  The anal tubules are not enlarged as in C. transvaalensis, but the ventral pair of one larva were 304 µm long and about 2.5 times longer than wide.  Ventral head length (VHL) about 280-320 µm.
The head capsule has a darkened gula region, covering the posterior 2/3 and at its widest about half-way down from the anterior edge; the frontoclypeus is also darkened.  The salivary reservoir is 58-71 µm long and 3.8-4 times wider than deep.  Mentum width 165-173 µm, 0.54 of the ventral head length; central tooth type type III; 4th laterals only slightly reduced in height; IPD about 61-65 µm.
Ventromentum length about 174-230 µm, length/depth 3.81-4.05, and 1.05-1.23 times the mentum width; with 41-46 striae; VMR 0.26-0.30.
Antenna with basal segment about a third of the VHL and 2.7-3 times longer than wide, with RO about a third to a fifth up from the base; segment proportions (µm) about 95 : 25 : 6 : 11 ; 6.  AR 1.84-2.1.
Pecten epipharyngis comprised of 13-14 sharp pointed teeth (i.e. Type A of Proulx et al 2013).  Premandible with inner tooth about 3.3-4 times wider than the outer tooth, teeth coming to a relatively sharp point (type B1).
Width between antennal bases greater than width between S4 setae.
Mandible about 211-230 µm in length, 4th inner tooth darkened but only partly separated (ty. IIC); with perhaps 12-18 furrows on the outer surface at the base; 11-12 taeniae in the Pecten mandibularis; Mdt-Mat 25-28, MTR 0.3-0.43.

Cytology:


Whole complement of polytene chromosomes of C. c/f transvaalensis from Israel.

Four polytene chromosomes with the pseudothummi-arm combination AE, BF, CD, G.  The sequences show considerable similarity to those of the African C. transvaalensis: nucleolus sub-terminal in arm C, puff in arm B subterminal with dark bands on distal side, chromosome AE may have a similar banding pattern in the two species, arm A perhaps close to that of C. dorsalis; arm E perhaps similar to C. holomelas.  BF may also have similar sequences and CD also appears similar, although there is an inversion around the region of the nucleolus that has not been observed in the African population.
However the sequences of arm G are different - no nucleolus but 2 obvious BRs in the Israeli species, while the African species has a nucleolus about a third from one end and three BRs.

The African and the Israel/Pakistan species are obviously closely related but have been isolated for long enough for differentiation of COI sequence and cytology (at least of arm G) to occur.

Found:
            Pakistan - BUITEMS, Quetta, Baluchistan (30.1909°N, 66.9612°E)
            Israel - Tivon Sewage Ponds, Kiryat Tiv'on, Haifa Dist.(31.20°N, 35.75°E)

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Revised: 5 September 2024
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Copyright © 2024, Jon Martin.