Originally, Edgar Riek described two giant spiny crayfish species, firstly in 1956 E. spinosus from the upper reaches of the Hastings River, New South Wales, then secondly in 1969 E. clydensis, from a side stream of the Clyde River near Brooman, and paratypes from near Conjola, New South Wales.
Morgan (1997) revised the taxonomy of Euastacus; more recent sampling indicated continuous morphological variation between E. spinosus, E. spinifer and E. clydensis, this led to Morgan considering all three species to be synonymous. In 1997 he syonymised E. clydensis into Euastacus spinifer (Heller, 1865).
Fortuitously, we had done a huge amount of surveying of both the Shoalhaven and Clyde river basins as well as the more unusual sites like Beecroft Peninsular. This surveying as part of the Australian Crayfish Project supplied a broad Euastacus spinifer sample from this southern region for genetic analysis.
An extensive molecular phylogenetic and population genomic analysis of Euastacus spinifer sensu lato from across its geographical range revealed strong population structure corresponding to several major geographically correlated clades, the southernmost clade being the most genetically divergent (Van Der Wal et al. 2022).
In Van Der Wal et al. 2022, we formally remove E. clydensis from the synonymy of E. spinifer, increasing the recognised number of species of Euastacus. With formal recognition of E. clydensis as a valid species separate from E. spinifer, we increase the number of Euastacus species to 54
Euastacus clydensis ranges from the Southern Highlands in the vicinity of Moss Vale (~35°S), south to the vicinity of Batemans Bay (~35.6°S) in the southern Shoalhaven and Clyde River drainages
For Further Information see:
Wal, Cara Van Der, Ahyong, Shane T., Lo, Nathan, Ho, Simon Y. W. & McCormack, Robert B., 2022, Redescription of Euastacus clydensis Riek, 1969 (Crustacea: Parastacidae), a valid species of spiny crayfish from southern New South Wales, Australia, pp. 285-297 in Zootaxa 5222 (3): https://doi.org/10.11646/zootaxa.5222.3.6