4. Chironomus forsythi Martin, 1998.

Adult

Male:
Wing length: 3.6-5.3 mm;  width 1.1-1.3 mm;  VR 0.98-1.04.
AR: 3.6-4.4
Palpal segments 2 - 5 (micron): 80 : 280 : 260 : 330.  Clypeal setae about 28-38.
At least 12-18 acrostichal setae; 16-24 dorsocentrals; 5-7 prealars; scutellars in two approximate rows - anterior row about 6 - 23, posterior row about 15 - 18 setae.
Fore leg ratio: 1.52-1.56 may be diagnostic.  Legs pale, unbanded, with only a short sparse beard.
Leg proportions (micron):
 
Fe
Ti
Ta1
Ta2
Ta3
PI
1550
1410
1990
940
785
PII
1580
1595
830
470
350
PIII
1860
1940
1300
780
600
 
Ta4
Ta5
LR
F/T
Ta5/Ti
PI
650
270
1.47-1.48
1.08-1.11
0.19-0.25
PII
245
195
0.55-0.57
0.97-1.00
0.12-0.13
PIII
320
220
0.63-0.72
0.96-0.97
0.11

Abdominal tergites 2-5 with dark brown patches across about two thirds of the segment, although sometimes reducing towards the basal margin to a more triangular appearance.

Anal point relatively narrow; 4-11 setae at centre of tergite IX.
Superior volsella curved, D(e)-type of Strenzke 1959); setae on Inferior volsella forked.  Gonostylus reducing significantly on distal third

Female:
Wing length: 3.4-5.9 mm;  wing width: 0.9-1.7 mm;  VR 0.93-0.97
AR: 0 32-0.49;  flagella length (micron): 190 : 140 : 135 : 130 : 210
Palpal segments 2 - 5 (micron): 70 : 230 : 250 : 385.  Clypeal setae about 26-56.
About 15 acrostichal setae; 18-38 dorsocentrals (incl. humerals); 6-8 prealars; scutellars in two approximate rows - anterior row about 5-23, posterior row about 6-30 setae.
LR slightly lower than that of males, about 1.47-1.48 (2).
Leg proportions (micron):
 
Fe
Ti
Ta1
Ta2
Ta3
PI
1550
1410
1990
940
785
PII
1580
1595
830
470
350
PIII
1860
1940
1300
780
600
 
Ta4
Ta5
LR
F/T
Ta5/Ti
PI
650
270
1.47-1.48
1.08-1.11
0.19-0.25
PII
245
195
0.55-0.57
0.97-1.00
0.12-0.13
PIII
320
220
0.63-0.72
0.96-0.97
0.11

Pupa:  Total length 11.3-11.8 mm (female), 6.8-10.8 mm (male); inner margin of wing case about 2.15 mm.  Cephalic tubercle about 110-160 micron, with sub-apical seta about 45 - 65 micron; about 76-112 recurved hooks on abdominal tergite II; muscle scars on tergites pale or slightly pigmented; caudolateral spur of segment VIII ormally with only two or three spines at the type locality (Haast) and in most North Island populations, but about 6-11 spines (see below) are found in some, mostly South Island, specimens tentatively assigned to this species.  About 135-157 (female) and 56-131 (male) multiple ranked taeniae on each side of the anal lobe.

Larva: A salinarius-type larva.  Length about 12.0-20.5 mm (female), 12.2-20.0 (male) (larger specimens may be a further new species).  Anal tubules elongated and rounded, from 2-3 times as long as wide, often with a constriction in the middle.
Head capsule with slight darkening of the frontoclypeus, and posterior third of gula dark.
Mentum (Fig. c) of type II; central trifid tooth with c1 tooth relatively broad and c2 teeth separated (type IIA).
Ventromental plate (Fig. e) with about 35-40 striae; VMR about 0.30.  Pecten epipharyngis (Fig. a) with about 8-16 usually relatively broad even teeth.
Antenna (Fig. b) with a moderately broad basal segment about 2.6-3.4 times longer than wide; AR 1.8-2.5; antennal proportions (microns) 133 : 29 : 8 : 14 : 7.
Mandible (Fig. f) generally type IIB, although 3rd inner tooth somewhat variable in pigmentation and degree of separation; about 13-23 furrows on outer surface near base.

Cytology: 4 polytene chromosomes, pseudothummi-complex arm combination (BF, DC, EA, G).
Two nucleoli, one proximal in arm F, the other subterminal in arm G close to a BR, this latter nucleolus not always apparent.  Arm G closely paired in some populations, but paired only in the middle in others.
Arm A of some individuals with sequence oppA4 of Australian species; forC1 with sequence as thmC1; arm E with one sequence as oppE1 of Australian species.
Polymorphic in arms A - F; some South Island populations polymorphic in all arms, including at least 3 sequences each in arms A, B, D, and F, while others have limited polymorphism in arms A and B.  This may indicate the presence of 2 or more species in these samples.
forA1:    1a-e, 11-10, 2c-1f, 3e-2d, 8-9, 3f-i, 12c-a, 4-7, 13-19                 ie. as A4 oppositus, analis
forA2:    1a-e, 2e - 3, 1f - 2c, 10 - 11, 2d, 8 - 9, 3f-i, 12c-a, 4 - 7, 13 - 19                (int. opp A4 & A5)
forA3:    1a-e, 10d-a, 2c - 1f, 3 - 2e,10e - 11e, 2d, 8 - 9, 3f-i, 12c-a, 4 - 7, 13 - 19                    from forA2
forA4:    large inversion of forA1?
forB1:    Puff (group 7) with proximal dark bands (group 8) about middle of arm
forB2:    Inversion of about centre half of arm, reversed puff and dark bands (groups 7 & 8).
forB3:    From forB2 by inversion which reverses puff (group 7) again and moves it near the distal end.
forC1:    as C1 of oppositus, australis and 'thermarum'
forC2:    10A-10D6, 11B11-10D7, 11B12-11E;                                  ie. as C1 of sp. NZ9
forC3:    10A-10D6, 11B11-11A7, 11D6-11B12, 10D7-11A6, 11D7-11E                                  from C2
forD1:    1 - 2, 16c-a,17e-a, 10c-a, 3e - 9, 3d-a, 10d -15, 18 - 24
forD2:   1 - 2, 16c-a, 17e-a, 10c-a, 3e-g, 18, 15 - 10d, 3a-d, 9 - 4, 19 24                     from forD1
forD3:  approx.  1 - 2, 16c-a, 10c-a,, 3e - 5, 19 - 18, 15 - 10d, 3a-d, 9 - 6, 20 - 24                    from forD1
forE1:    1 - 3e, 10b - 3f, 10c - 13                                      ie. as E1 oppositus
forE2:    1a-e, 3f - 10b, 3e - 2a, 10c - 13
forF1:    1 - 2a, 10 - 2c, 15c - 11a, 2b, 15d - 23            ie. as F3 of oppositus, and F1 of australis, analis, novae-zelandiae and sp. NZ9
forF2: (approx.) 1 - 2a, 10 - 9c, 4 - 9b, 3 - 2c, 15c - 11, 2b, 15d - 23            more common in Sth Is.
forF3: (approx.) 1 - 2a, 10 - 7d, 11 - 15c, 2c - 7c, 2b, 15d - 23                in Sth Is only.
forG1:

Click here to see the chromosomes BF & CD or chromosomes EA & G

Molecular:
Mt COI - see BOLD
COI data for larvae from the same egg mass (NZ.67.1 Emass #6) as the holotype larva, is different to that of other specimens, confirming the presence of multiple species under this name.

Morphology and cytology given by Martin (1998), but some details were incorrect.  Both arms A and F show a different sequence to that stated, and the limits of some inversions in those arms were incorrect.  These have been corrected in the present sequences and figures.
Based on the banding sequence of arm F, there could be three species included under this name, because the three sequences identified usually occur only as homozygotes (see below).  If this proves to be true, the type specimen of C. forsythi is associated with sequence F1.  Larvae with F2 are most common in the South Island, but a single larva from Lake Ngaroto, Sth Auckland, was heterozygous for F1.2.  Larvae with F3 have been found at only three localities in the South Island: Bealey, Ross Creek Dam and Lake Wakitipu, although a single larva from Sullivans Dam was heterozygous F1.3.
In order to help define the true C. forsythi a description is provided for specimens from the same egg mass as the Holotype and Allotype.

Known Localities

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Modified: 7 September 2020
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