C. duplex Walker, 1856

Fourth instar larva:  Large bathophilus-type larva, length about 15.9-21.2 mm (female); 14.7-18.8 mm (males).  Ventral tubules relatively short (from about 0.8-1.1 times width of segment), anterior pair usually shorter (ant: fem, 1.00-2.67; male, 0.96-2.17 mm: post: fem, 1.25-2.76; male 1.12-2.33 mm).  Anal tubules relatively short and rounded (about 380-530 x 250-330 µm), i.e. about 1.5-1.7 times longer than wide.
Head capsule heavily darkened on the gula, frontoclypeus and other regions.
Mentum with pointed teeth, particularly on central trifid tooth, which is type II; fourth laterals reduced, sometimes to about the level of the fifth laterals (type I-II).
Premandible with the inner tooth about 5x the width of the outer tooth.
Ventromentum with about 42-57 teeth.  Pecten epipharyngis with about 14-17 sharp teeth.
Antenna with basal segment 3.0-3.4 times as long as wide; ring organ between a quarter and halfway up the basal segment; AR about 2.4 (2.0-2.8); antennal proportions (µm): 170 : 33 : 8 : 15 : 8.
Distance between S4 setae sometimes greater, sometimes less than that between the antennal bases.
Mandible with a distinct, sharp and fully separated third inner tooth (type IIIC); about 14-16 furrows on outer surface near base.

Cytology:  3 polytene chromosomes with the modified pseudothummi arm combination AEG, BF, CD.
Arm G with medial nucleolus, with adjacent BR and other BRs more proximal.  Other nucleoli in arms A (NOR about region 18), C and F (NOR about region 22).
Polymorphism in arms A, B (often sex linked), D, F, and G.
dupA1:    1a-e, 4c-a, 12a-c, 3i-f, 9 - 8a, 2d - 3e, 1f - 2c, 10a - 11, 4d - 7, 13a -18(NOR)- 19
dupA2:    an overlapping inversion or transposition.
dupB1:    Puff and proximal dark bands (groups 7-8) about middle of arm as in oppositus and australis
dupB2:    Puff separated from dark bands to near tip of arm by an inversion and transposition.
dupC1:    nucleolus about one third from centromere.
dupD1:    1 - 2, 16 - 10d, 3 - 10c, 17 - 24
dupD2:    1 - 2c, 17c - a, 10c - 3, 10d - 16, 2h-d, 17d - 24
dupD3:    1 - 2c, 8 - 10c, 17a-c, 7 - 3, 10d - 16, 2h-d, 17d - 24
dupE1:    approx.  7d - 6; arm G; 4(f-a?), 5?, 7e - 10b, 3e - 2c, 4gh, 3f, 10c - 13
dupF1:    1 - 2a, 10 - 2b, 11 -22(NOR)- 23                                            sequence as oppositus F1

The arm B sequences are clearly sex linked in some, southern, populations such that most females are homozygous B1.1, while most males are heterozygous B1.2.  In more northern populations the majority of individuals are B2.2, with little evidence of sex linkage (Martin, 1971b).

Larva morphologically very similar to those of C. australis and C. occidentalis.  Separable from the former by the difference in chromosome number, and from the latter by eastern distribution.

Pupa:  General coloration is dark.  Various characters are given in the Table below.

Length (mm)
10.3 – 15.3
7.8 – 14.0
Inner margin wing case (mm)
2.3 – 3.1
1.8 – 2.9
Cephalic tubercles (µm)
 215 x 240
 145 x 185
Cephalic bristles (µm)
 not visible
 not visible
Recurved hooks on abd. seg. 2
74 – 98
55 – 80
Swim fin filaments (one side)
64 – 175
96 - 146

Caudolateral spurs of segment VIII with about 10 spines, ranging from 4-16.
The pupa of C. duplex can be readily distinguished from those of C. australis and C. occidentalis by the caudolateral spur in which the spines are spread, rather than closely applied, as in the other two species.  In Tasmania there tend to be more spines, so they are not as widely spread.
There also tend to be fewer recurved hooks on segment 2 than in C. australis, but there is considerable overlap.

The polytene chromosomes were initially described by Martin (1971b) and later, with preliminary physical maps, by Martin et al. (2010).  Nucleoli and location of C-bands were studied by Lentzios & Stocker (1979) and Lentzios et al. (1980).

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Modified: 10 April 2020
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Copyright © 2005-2020, Jon Martin.