Pristine Gahnia filum habitat on southern Yorke Peninsula.
The large grass-like tussocks are G. filum, which are about 1.5 m high.
Partly cleared Gahnia filum wetland on southern Yorke Peninsula
G. filum wetland on southern Yorke Peninsula that has been historically cleared, and the saw-sedge allowed to grow back.
G. filum wetlands on southern Yorke Peninsula that have been subject to overgrazing.
Due to kangaroos (left) and to cattle (right)
G. filum wetlands on the west side of Lake Alexandrina.
Ungrazed regrowth on left, but severely overgrazed and trampled by cattle on the right.
(The two photos are separated only by a fence! )
Gahnia deusta tussocks, which are 0.6 m high
Regrowth Gahnia trifida tussocks, which are 2 m high,
present in the Lower Southeast
G. trifida wetland severely overgrazed and trampled
by cattle, at Black Swamp, near Finniss
Forest habitat of Gahnia radula in the Lower Southeast
Left view photographed in 1996, of pristine Gahnia filum wetland (the large tussocks), original habitat of the endangered skipper, Hesperilla donnysa donnysa form flavescens (Yellowish Sedge-skipper). This was the last remaining extensive wetland of its type left on the Adelaide Plains. Each tussock is well over 100 years old.
Right view taken one year later after clearance for urban development. Clearance permission was not sought, nor was it required since Federal lands are not subject to State conservation laws. It set a bad example for developers. The clearance caused the extinction of the original, type (flavia) population of the butterfly.
The wine-red coloured area around the neck
The new head for the larva is forming directly behind the old black coloured head
This is a male larva indicated by the pair of pale yellow, small organs present on the dorsal side about midway along the body.
Final instar larva from the Lower Southeast
This larva is a female as it does not have the pair of posterior, dorsal yellow organs.
Different coloured forms of the head
for the mature instar larvae
Forms without the side stripe are
very rare.
This larva has just moulted and the pale areas are still green, but which later turn brown.
Posterior end of a mature larva (dark form delos), showing the rear anal plate and the tiny dark secondary setae.
Anal plate secondary setae on mature larvae of the dark form delos
Anal plate secondary setae on a mature larva of form flavescens
Opened pupa shelter of dark form skipper
The pupa is a black coloured form typical for the dark form skipper.
The pupa would normally be pointing upwards.
Black coloured pupa of the dark form skipper
Pale pupa colour forms of form flavescens from coastal Adelaide
Operculum (anterior end of pupa) of dark form skipper
The hardened and thickened processes probably help prevent small predators from attacking the pupa through the open entrance of the shelter.
Detail of cremaster
(posterior end of pupa)
The cremaster is strengthened by the two longitudinal dorso-lateral ridges.
Closeup of bristles on the cremaster, which are flattened for strength and hooked at the ends so that the pupa can anchor itself to the silk lined shelter (in the same manner as velcro).
Posteriorly directed bristles on the posterior parts of the pupa abdomen that
help position the pupa and prevent it from sliding down inside the shelter.
The hairs are strengthened by the half-conical bases which stop the bristles
from bending over.
The anterior side of the bases is to the left.
All photography by R. Grund unless stated otherwise.
