The species ranges from the Robertson and Bundanoon areas, New South Wales, south to the Victorian border west of Genoa. It occurs in creeks and streams drained by the coastal rivers, particularly the Shoalhaven, Clyde, Tuross, Towamba, Womboyn and Genoa Rivers — a north-south range of approximately 400 km. Most spiny crayfish have a narrow range, usually being restricted to a single river or drainage system, so E. yanga is unusual for its large range. The only other species of spiny crayfish with larger geographic ranges are E. armatus and E. spinifer. (NSW, VIC)
Euastacus yanga resembles a similar species, E. spinifer that may occur in the same habitat in the northern part of the range of E. yanga. Differences between the two species can be subtle, although E. spinifer usually has two large spines on the inner margin of the wrist of the chelae (claws) whereas E. yanga usually has three large spines on the inner margin of the wrist. The body length reaches about 16 cm. The colour of E. yanga varies from north to south. In the north, E. yanga is generally blue-green or brown-green with a yellow-orange underside. Moving south, E. yanga is more red-brown. Northern specimens have a blue patch at the side of the head.
Ecology/Way of Life:
Euastacus yanga live in streams bordered by temperate rainforest, ferns or dry sclerophyll. They occur at altitudes between 60 and 720 m above sea level. Juveniles often live beneath rocks and logs on the stream bed, whereas adults usually burrow in the stream banks. Euastacus yanga is often seen foraging in sheltered or shaded parts of the creek, although as with other spiny crayfish, E. yanga is most active at night when they actively forage for food. The species is an opportunistic omnivore and feeds on decaying plant matter and any type of animal matter that it can scavenge or capture. Euastacus yanga probably mates in late summer or autumn, overwinters with eggs, and hatchlings appear in spring or summer.
Interaction with Humans/Threats:
Euastacus yanga is at greatest risk from habitat destruction such as land clearing and water pollution. Most populations of E. yanga are within National Parks or State Forests, so the status of the species is presently relatively secure.
Euastacus yanga was named by Morgan in 1997. The name is based on yanga, the meaning lobster in the Dharawal and Dhurga languages of south-eastern New South Wales.
Morgan, G. (1997). Freshwater crayfish of the genus Euastacus Clark (Decapoda: Parastacidae) from New South Wales, with a key to all species of the genus. Records of the Australian Museum, Supplement 23: 1–110.
Text, map and photograph by Shane Ahyong.
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