Theischinger, G. and Endersby, I. 2009. Identification guide to the Australian Odonata. Department of Environment, Climate Change and Water NSW.
Previous IUCN Red Lists had the genus name spelled as Acanthaeshna; this was corrected in 2005 to Acanthaeschna. See Theischinger and Endersby (2009) for an account of the taxonomic history of this species.
Justification: Acanthaeschna victoria has only ever definitely been recorded from seven locations, and already appears to be extinct at two of them. Although its area of occupancy (AOO) is difficult to estimate, it is certainly less than 500 km² based on current known locations. Only one location where the species is believed to still be present is within a national park, and even there fire is a potential threat. Overall the species is threatened by habitat loss due to conversion for agriculture and development for housing or other uses; there is strong evidence of a continuing decline in populations, AOO and habitat quality, and it appears that the overall population is severely fragmented. The species is assessed as Endangered under criterion B2 (EN B2ab(ii,iii,iv)) and taking the reasonable precautionary approach advocated by the IUCN.
Acanthaeschna victoria is endemic to Australia, where it is known only from a relatively small number of sites along the coast of New South Wales and Queensland. At most, 10 sites for the species have ever been recorded, comprising seven locations for extinction risk assessment purposes. One of these locations has already been lost in the expansion of Brisbane and the site at Broadwater was cleared shortly after the species was found there; it has not been found there subsequently. Therefore only five locations for the species can be considered as currently known. With scattered records over a large distance it is very difficult to give a sensible estimate of area of occupancy, but based on the known sites it is certainly less than 500 km². One population appears to be within Great Sandy National Park.
There is insufficient information to make any definitive statements about current population sizes. On the paucity of records of this species, Theischinger and Endersby (2009) state: “It is not clear if the poor collecting record of A. victoria is due to its rareness or due to its patterns of behaviour and ecology. As most of its supposed larval habitats appear to be at least potentially temporal, they are rather unlikely to be sampled in projects monitoring the health of streams, and the probability to get new information from such work is low”. However, from known loss of sites and threats to the habitats of the species, whatever the current population is, it is certainly declining, it also appears to be severely fragmented (based not just on records of the species, but the known loss of suitable habitat).
Theischinger and Endersby (2009: 247) summarize the available information: “The available collecting data indicate that A. victoria is a spring/early summer species with adults emerging early in October in the north of its range, possibly considerably later in the south. It seems to be partly diurnal, partly crepuscular (this may be reflected in the extremely contrasting eye colouration). At this stage it appears that temporary low-altitude swamps, slow streams and rivers near the coastline are its habitats. The only available larvae were found in what is known in New South Wales as ‘black water streams’. This is a type of stream known for very low dissolved oxygen content. The Queensland equivalent is apparently the ‘wallum stream’. The latter term pretty well covers the situations where A. victoria was found in north-eastern New South Wales.” And “It is obvious that land containing habitats as described above has been extensively transformed this century by human activities. This land is now settlements, pasture and sugar cane country, and ... these and other kinds of development continue.”
Continuing decline in area, extent and/or quality of habitat:
More information on distribution and habitat is urgently needed for this species, and on threats at individual sites. The species would undoubtedly benefit from the granting of totally protected status to some of its known locations, and management plans will be needed at other locations in order to ensure that habitat remains suitable.