C. 'tyleri' Martin

Chironomus oppositus f. tyleri - Martin and Lee 1984

The adults are very similar to those of C. oppositus, but tend to be somewhat larger, wing length over 4 mm;  anterior tarsi without a strong beard.

The basis for considering this to be a distinct species is that the basic pattern of the polytene chromosomes is different on some chromosome arms from that of other members of the oppositus-group.  It is obvious that some hybridization occurs on the mainland, but in Tasmania there are some unique sequences which show a general cline from low frequencies in the north-east down to the south and then up to higher frequencies in the north west.  As well the effective male determining gene is on arm G, which is otherwise only found in some populations of f. whitei, and might be the result of introgreesion from C. ŌtyleriÕ.  The case is also supported by a phylogenetic analysis based on allozyme and inversion frequencies.

See description of C. tyleri holotype male

Males:
Head, antennae and mouth parts brown.  Frontal tubercles present, length about 14 - 28 micron.  AR about 2.9 - 3.2.  Frontal tubercles present, about 40 - 48 µm.
Palp segments 2 - 5 (micron):  63 :  230 :  238 :  370.
Thorax generally greenish with brown stripes; thorax pruinose, postnotum and sternopleuron yellowish brown.
Setae: clypeal - 23-33;  achrosticals - 18;  dorsocentrals - 13-16;  prealar - 6;  scutellar - 10 in anterior row, 13-15 in posterior row.
Wings with anterior veins hardly darker than posterior, crossvein slightly darkened.
Wing length 4.3-4.4 mm; width 0.9-1.0 mm.  VR: 0.99-1.04.  Sensilla campaniforma on branchiolum 3,  19 - 26 setae on squamal fringe.
Legs yellowish green, unbanded.
Leg lengths (microns) and proportions as follows:

 

Fe

Ti

Ta1

Ta2

Ta3

PI

1545

1405

2215

1110

920

PII

1660

1565

940

495

380

PIII

1895

1975

1405

775

615

 

Ta4

Ta5

LR

F/T

BR

PI

760

335

1.53-1.66

1.08-1.19

1.78-1.91

PII

250

185

0.59-0.61

1.04-1.08

 

PIII

375

225

0.71

0.95-0.97

 

Male abdomen generally greenish with narrow to broader saddle markings on the anterior segments, gradually extending in length from about tergum V to occupy most of the tergum by segment VIII.


Male terminalia of C. 'tyleri' (above); superior volsella (below left); setae of inferior volsella (below right).

Hypopygium similar to other members of C. oppositus-group;  6 setae medially on tergum IX;  superior volsella of D-type, about as e of Strenzke (1959);  setae of inferior volsella simple

Female:
Antennal segments (micron):  215 :  135 :  146 :  128 :  215.
Frontal tubercles present, about 20 - 50 µm.
Palp segments 2 - 5 (micron):  63 :  215 :  265 :  434.
Setae: clypeal - 25-35; acrostichals - 13-15+; dorsocentrals - 22-34; prealar - 6; scutellar - 6-10 in anterior row, 14-16 in posterior row.
Wing length 4.0 - 4.6 mm;  width 1.1 - 1.6 mm;  VR: 1.02 - 1.09.  3-5 setae on stem vein,  18 - 25 setae on squamal fringe.
Leg lengths (microns) and proportions as follows:

 

Fe

Ti

Ta1

Ta2

Ta3

PI

1643

1393

2258

1062

897

PII

1737

1617

953

503

363

PIII

1902

2003

1410

757

598

 

Ta4

Ta5

LR

F/T

BR

PI

803

347

1.56-1.69

1.19-1.22

1.13-1.75

PII

243

183

0.57-0.61

1.07-1.08

 

PIII

362

217

0.69-0.71

0.93-0.96

 

    93 - 104 Sensilla chaetica on hind tibia


Female terminalia of C. 'tyleri' - dorsal view (above); ventral view (below).

    Genitalia: 6 setae on Gonopophysis VIII.

Molecular data:
Mt COI - see Barcoding of Life Database (BOLD BIN: AAF3284) and Martin (2011a).  These sequences are shared with the forms of C. oppositus, presumably due to ongoing low levels of hybridization.
ITS-2 - see Martin (2011a).

Types:  Holotype male:  Not yet designated.
Allotype female:  Not yet designated.
Paratypes:  Larva and associated polytene chromosomes (on separate slides), 1 km n. Arthur River, Tasmania (43.05°S, 144.65°E) AT.41.1, from egg mass #2, sl. 2.01F.
Type material currently in collection of Jon Martin, but will eventually be distributed to the ANIC and other institutions.

Found: New South Wales – Lake Eucumbene; Kiandra; Thredbo Village.
            South Australia – Lake Edward (37.633°S, 140.600°E) & Lake Leake (37.617°S, 140.583°E),
            Tasmania – Arthur River (43.05°S, 144.65°E); Bellerive; Blackmans Lagoon; Cambridge; Campbelltown; Lake Dulverton; Little
            Swanport; Longford; 15 Km Queenstown; Strahan; Whites Lagoon, Tunbridge.  Flinders Island – Babel Farm, Lackrana; Kronstadt
            Farm, Emita; Ranga.  King Island – Mt. Stanley area; 3-tree Lagoon; Pearshape Lagoon.
            Victoria – Anglesea; Ballarat (37.33°, 143.88°),SBotanical Gardens, Melbourne; Exhibition Gardens, Carlton; Footscray Park; Horden Vale; Manns Beach;
            Mitcham; Moggs Creek; Monteith Flat; Wallington nr Ocean Grove; Squeaky Beach and Derby River, Wilsons Promontory.

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Modified: 7 May 2020
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