A Day in the Swamps of Katoomba Chasing the Giant Dragonfly Petalura gigantea
In late December 2014, I met up with Dr Ian Baird one of Australia’s foremost experts on Giant Dragonflies and we spent the day together wandering selected swamps of the Blue Mountains hunting this rare and elusive species. This was an eye opener for me and I had a fantastic day learning all about Giant Dragonflies. The following information on the species was provided by Ian.
Petalura gigantea, commonly known as the Giant Dragonfly or Southeastern Petaltail is a very large dragonfly which may have a wingspan up to 13 cm. It is recorded from selected peat swamps, bogs and seepages (mires) along the coast and ranges of NSW from Nadgee Nature Reserve near the Victorian border, to near the Qld border in and around Basket Swamp National Park and Boonoo Boonoo State Forest. It has also been observed in nearby Girraween National Park in southeastern Qld.
It has been recorded in swamp habitats from near sea level to 1240 m elevation. Listed as endangered in NSW under the NSW Threatened Species Conservation Act 1995, with habitat loss and degradation identified as the main threats to the species.
In addition to the large size and widely separated dark eyes, the species (and genus) is characterised by a long pterostigma (darkened cell) towards the distal end of the leading edge of the wings, and large petaloid superior anal appendages in adult males. Adult females lack the conspicuous petaloid appendages and are somewhat bulkier than males.
The family is unique amongst dragonflies, in that larvae excavate burrows which extend below the water table in soft peaty soils in mires, seepages or along stream margins. The larvae (mudeyes) occupy and maintain these burrows for their entire larval period, generally surviving on creatures captured within the burrow system, or perhaps ambushed at the burrow entrance. Larvae may leave their burrows to hunt under favorable conditions, but this behaviour has not been confirmed. Petalurid dragonflies have very long larval stages, which are known to extend for at least five years in two overseas species. Extrapolation from recent studies by Ian and Dr John Trueman, suggest, respectively, a larval stage of at least six years, and possibly 10 or more, in P. gigantea. Ian was extremely skilled at locating burrows and he found 10:1 to what I did. I was desperately searching for an occupied burrow but only ever found those recently vacated.
After this extended larval stage they emerge (October-January) and climb the nearest shrub or sedgeland vegetation to undergo emergence, usually leaving their larval skin (exuvia) attached to their shrub or sedge emergence supports. Ian and I surveyed the Katoomba swamp and I was astounded at the number of exuvia we found amongst the sedges. Ian indicated that this was an unusually large emergence event for this swamp patch.
Adults live for a maximum of one summer flying season, which extends into February at least, with occasional late flying individuals having been observed on one occasion as late as mid-March in the Blue Mountains.
My thanks to Ian for a most enjoyable and informative day. I’ll certainly be keeping an eye out for Giant Dragonflies in the future.Cheers Rob McCormack
Selected references for Petalura gigantea
Baird I. R. C. (2012) The wetland habitats, biogeography and population dynamics of Petalura gigantea (Odonata: Petaluridae) in the Blue Mountains of New South Wales. PhD thesis, University of Western Sydney, Australia. Available from http://handle.uws.edu.au:8081/1959.7/509925.
Baird I. R. C. (2013) Emergence behaviour in Petalura gigantea (Odonata: Petaluridae): confirmation of upright emergence. International Journal of Odonatology 16, 213-8. doi:10.1080/13887890.2013.798975
Baird, I.R.C. (2013). Larval habitat and behaviour of Phenes raptor (Odonata: Petaluridae): a review of current knowledge, with new observations. International Journal of Odonatology, 16, 79-91. doi:10.1080/13887890.2012.757723
Baird, I.R.C. (2014). Larval burrow morphology and groundwater dependence in a mire-dwelling dragonfly, Petalura gigantea (Odonata: Petaluridae). International Journal of Odonatology, 17, 101-121. doi:10.1080/13887890.2014.932312
Baird, I.R.C. (2014). Mate guarding and other aspects of reproductive behaviour in Petalura gigantea (Odonata: Petaluridae). International Journal of Odonatology, 17, 223-236. doi:10.1080/13887890.2014.979333
Baird I. R. C. & Burgin S. (2013) An emergence study of Petalura gigantea (Odonata: Petaluridae). International Journal of Odonatology 16, 193-211. doi:10.1080/13887890.2013.798580
Baird I. R. C. & Ireland C. (2006) Upright emergence in Petalura gigantea (Odonata: Petaluridae). International Journal of Odonatology 9, 45-50.
Benson D. & Baird I. R. C. (2012) Vegetation, fauna and groundwater interrelations in low nutrient temperate montane peat swamps in the upper Blue Mountains, New South Wales. Cunninghamia 12, 267-307. Available from http://www.rbgsyd.nsw.gov.au/science/Scientific_publications/cunninghamia/contents_by_volume/volume_12#twelvefour
Davies, D.A.L. (1998). The genus Petalura: field observations, habits and conservation status (Anisoptera: Petaluridae). Odonatologica, 27, 287-305.
Fleck G. (2011) Phylogenetic placement of Petaluridae and basal Anisoptera families (Insecta: Odonata). Stuttgarter Beiträge zur Naturkunde A Neue Series 4, 83-104.
Hawking J. H. & Theischinger G. (2004) Critical species of Odonata in Australia. International Journal of Odonatology 7, 113-32.
NSW Scientific Committee. (1998) Giant dragonfly – endangered species listing. NSW Scientific Committee final determination. Available from http://www.environment.nsw.gov.au/determinations/GiantDragonflyEndSpListing.htm
NSW Scientific Committee. (2007). Petalura gigantea – endangered species listing amendment. NSW Scientific Committee determination to add Petalura litorea to Part 1 of Schedule 1 (Endangered species) of the Threatened Species Conservation Act. Available from http://www.environment.nsw.gov.au/listings/PetaluraGiganteaAmendment.htm
Theischinger G. (1975) Ein “Dreigespann” von Petalura gigantea Leach. Tombo 18, 45. (In German, with English summary).
Theischinger G. (1999) A new species of Petalura Leach from south-eastern Queensland (Odonata: Petaluridae). Linzer biologische Beiträge 31, 159-66.
Theischinger G. & Endersby I. (2009) Identification Guide to the Australian Odonata. Department of Environment, Climate Change and Water NSW, Hurstville, NSW.
Theischinger G. & Hawking J. H. (2006) The Complete Field Guide to Dragonflies of Australia. CSIRO, Collingwood, Vic.
Tillyard, R.J. (1909). Studies in the life-histories of Australian Odonata. 1. The life-history of Petalura gigantea Leach. Proceedings of the Linnean Society of NSW, 34, 256-267.
Tillyard, R.J. (1911). Studies in the life-histories of Australian Odonata. 4. Further notes on the life-history of Petalura gigantea Leach. Proceedings of the Linnean Society of NSW, 36, 86-96.
Ware, J.L., Beatty, C.D., Sanchez Herrera, M., Valley, S., Johnson, J., Kerst, C., May, M.L. & Theischinger, G. (2014). The petaltail dragonflies (Odonata: Petaluridae): Mesozoic habitat specialists that survive to the modern day. Journal of Biogeography, 41, 1291-1300. doi:10.1111/jbi.12273