Started in 2005 the quest to rediscover the Orbost Spiny Crayfish Euastacus diversus has been a long and intriguing journey cumulating in the publication of this paper.
This story began back in 1959 when one of Australia’s foremost expert on freshwater crayfish at that time, Edgar Riek, discovered this small freshwater crayfish species in the east Gippsland region of Victoria. Then in 1969 he described the species and named it Euastacus diversus. Since that day this crayfish has remained a rare and elusive species.
In 1986, the then current expert on the genus Euastacus, Gary Morgan, searched for this species but was unable to find any in the wild. As a consequence he redescribed the handful of original specimens collected by Riek in 1959 that are held at the Australian Museum. Gary Morgan’s detailed description, published in the Memoirs of the Museum of Victoria 30th May 1986, was the latest scientific publication on this species and forms the basis of all current information and opinions until now.
In 2005, the Australian Crayfish Project (ACP) was started, involving one of the largest projects researching freshwater crayfish ever seen in Australia. Between 2005 and 2007 we also failed to find any specimens of Euastacus diversus for the type locality general area 40 miles north of Orbost. Then in 2007 we changed our methods and successfully started finding more and more specimens. Up to 2011 a considerable number of E. diversus and other Euastacus species were found in the wild. The project has been very successful in finding this and other crayfish species, and large areas of southern NSW and eastern Victoria were systematically biologically surveyed specifically for freshwater crayfish. We found Euastacus specimens everywhere and most did not match the description for the known species leading to much confusion. However, genetic analysis by the Carnegie Museum of Natural History in the USA helped clarify the situation resulting in the thorough redescription of E. diversus and the discover of a number of new species.
The research culminated in this paper titled “Re-description of the Orbost Spiny Crayfish, Euastacus diversus Riek 1969 (Decapoda: Parastacidae), in Eastern Victoria, Australia” published in the journal “Freshwater Crayfish”. The paper redescribes Euastacus diversus to include the Bonang River crayfish (previously thought to be a new species).
The Bonang taxon represent a morphologically distinct population of Euastacus diversus that is genetically 1.95% divergent from the E. diversus type locality populations.
The research extends the distribution of the species to the Brodribb, Yalmy, Rodger and Bonang River drainages at elevations ranging from 350 – 950 m a.s.l., with an overall Extent of Occurrence of 465 km2. Research continues on E. diversus which will surely increase the Extent of Occurrence. Research also continues on the new Euastacus species and hopefully the first of the new species descriptions will be published later this year.
Coughran J, McCormack RB and Fetzner Jr. JW (2015). Re-description of the Orbost spiny crayfish, Euastacus diversus Riek 1969 (Decapoda: Parastacidae), in eastern Victoria, Australia. Freshwater Crayfish 21(1): 185-197.