Adult:

Male terminalia (left) and superior volsella (centre) and other superior volsella and gonostylus (right) of C. oppositus type specimen.
Superior volsella of this specimen of D-type, between d and e of Strenzke (1959).

Details of the type specimen are given here.

Four forms were recognized by (Martin & Lee 1984), mainly on the basis of larval polytene chromosome banding patterns.    A fifth form, noted by D.H.D. Edward (unpubl.), occurs in Western Australia
No means of reliably distinguishing the adults is known.  However, the type specimen is a large adult and similar large adults were collected near the large central lakes of Tasmania, and these were associated with a single larval type, therefore called form oppositus (o).

The other forms are:
form connori (c)
form tyleri (t) - see C. 'tyleri'.
form whitei (w) - results for this form suggest that it may be a composite of several other more or less differentiated forms - see C. oppositus MD variants.
The forms can be reasonably separated on the basis of allozyme and inversion frequencies.
form 'edwardi' (e) - this should also be recognized as a distinct species.

All these forms are essentially similar in coloration and morphology of hypopygium.  Further study is required to see if characters exist to separate the forms.

Molecular Data:mtCOI - GenBank (AF110155 - f. connori, KJ946667-KJ946677) and BOLD.  These sequences are shared between the forms of C. oppositus and with C. 'tyleri', presumably due to ongoing hybridization.
mtCyt B - GenBank (AF109698 - f. connori) also KJ946795 & KJ946796
gb2B - Genbank (AJ003799)
CAD1 - GenBank (KJ946479 - KJ946493)
and other genes.

The basic evidence for the recognition of the forms was given in Martin (2011a).

Found: Australian Capital Territory - Acton (w).
            New South Wales - Barmah Ferry (w); Boggy Swamp Creek, n & e. Putty (w); 13 Km s. Bombala (w); Colo (w); Station Creek,
            Delegate (w); 30 Km n. Holbrook (w); Jeir Creek (w); Kiandra (c, o, w); Macquarie Pass (w); 3 Km s. Nowra (w);
            Tarago Swamp (w); 13 Km n. Tooma Dam (w or c).
            South Australia - Barmera (o); Lake Leake (37.617°S, 140.583°E) (o) and Lake Edward (37.633°S, 140.600°E) (o)
            via Kalangadoo; Warren Gorge, n. Quorn (w). Kangaroo Island: Kingscote (w).
            Tasmania (type locality)(o): - Arthur River (c); Bakers Beach (w); Bellerive (c, o); Bicheno (c); Butler Island, Gordon River (o);
            Cambridge (o); Campbelltown (o); Coles Bay (o); Fossey River (c, w); George Town (c, o); Geeveston (o); Ida Bay (c, o, w);
            Lake Crescent (o); Little Swanport (o); Manning River, Sandy Bay (w); Maydena (c); 15 Km Queenstown (c, o); Smithon (c,o,w);
            Swansea (c, o); Wynyard (c). Flinders Island - Mt. Strezleckie (w): King Island - Porky Lagoon (o); Sea Elephant River (c):
            Victoria - Anglesea (o); Armadale (w); Exhibition Gardens, Carlton (w); Cumberland River (w); Longlea (w); Eildon (w);
            Elphinstone (c, w); Frankston (w); Horden Vale (w); Manns Beach (o); Botanic Gardens, Melbourne (w); Moggs Creek (c, o, w);
            Narbethong (w); North Balwyn (o); Orbost (o); w. Orbost (o); Parker Road, Cape Horn (w); Reedy Creek (c, o); nr. Sale (o);
            Sassafras (w); Upper Clear Spot; Vermont (w); Warrandyte (c, o, w); West Preston (w); Squeaky Beach (c, w),
            Wilsons Promontory.
            Western Australia - Lake Gwellup (e).