Euastacus yanga

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Variable spiny cray

Least Concern (IUCN 3.1)[1][2]
Scientific classification edit
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Crustacea
Class: Malacostraca
Order: Decapoda
Family: Parastacidae
Genus: Euastacus
Species:
E. yanga
Binomial name
Euastacus yanga
Morgan, 1997

Euastacus yanga, the variable spiny cray, is a freshwater crayfish endemic to south eastern Australia.

Description[]

Maximum recorded size 61.2 mm (2.41 in) OCL (Occipital Carapace Length).[3]

Rostrum: short, in individuals over 50 mm (2.0 in) OCL usually not reaching the base the third antenna segment; for 20–140 mm (0.79–5.51 in) OCL, to the base or midpoint of that segment; and, in some under 20 mm (0.79 in), to the end of the third segment.[3]

Cephalon: spiny in most individuals, less so on specimens under 20 mm (0.79 in) OCL. Spines larger and more numerous in southern populations.[3]

Thorax: Up to 20 spines on each side in one or two irregular rows although usually absent on smaller individuals (under 20 mm (0.79 in) OCL). Spines generally longer and sharper in southern populations. Tubercles moderately to densely distributed on specimens over 30 mm (1.2 in) OCL, very sparse to moderately on smaller examples, occasionally absent.[3]

Abdomen: one, very occasionally two, dorsal-lateral spines on somite 1 of individuals over 20 mm (0.79 in) OCL. Dorsal spine often present on somite 1, especially on larger specimens. Somite 2 has three to seven (very occasionally two) in lateral line 1, often absent on smaller specimens. Somites 3-5 of larger specimens, over 30 mm (1.2 in) OCL and most over 20 mm (0.79 in), have a single spine in line 1. One to three line 2 spines are usually found on somites 3–6. A single dorsal-lateral spine is usually found on somites 3-5 and occasionally somite 6.[3]

Tailfan: Usually about 17 telsonic spines are present, very large on some specimens over 40 mm (1.6 in). Inner branch of uropod has zero to four median spines of variable size whereas the outer branch has zero to five marginal spines. Uropod and often the telsonic spines absent in northern animals, becoming more numerous to the south.[3]

Claws: chelae or moveable claws are variable in form, sometimes stout, often long, sometime very long. Well developed teeth on most specimens over 30 mm (1.2 in) OCL. Propodus (fixed part of claw) has a well developed row of ventrolateral spines often extending to the tip of the finger, except in small specimens under 20 mm (0.79 in) OCL.[3]

Colour: the body is a deep brown-green or red-brown to brown on the back fading to paler on the belly. Back spines on the thorax are dark, variable in colour and sometimes black. Tubercules pale brown to orange or yellow. Abdominal spines are yellow to pale orange, some larger specimens have a blue tinge. Leg joints red or orange, body of legs generally dark brown, brown-green or blue-green. Fingers deep blue-green, brown or orange. Finger tips sometime red in southern populations.[3]

Distribution[]

Distribution map of Euastacus yanga[4]

New South Wales from the Robertson to Bundanoon area in the Southern Highlands south to just inside the Victorian border near Genoa. E. Yanga is the third most widely distributed Euastacus species behind E. armatus and E. spinifer.[3]

Habitat[]

The species has been collected in streams from 60–720 m (200–2,360 ft) AMSL. Streamside vegetation consisted mainly of temperate rainforest with dry sclerophyll along the ridge-lines but with dry sclerophyll extending to the stream bank in areas lacking rainforest. It is reported that this species prefers smaller streams and is has not been collected at any site together with other members of the genus.[3]

Lifecycle/Reproduction[]

Females in berry have been collected in late October through to November. Eggs numbered between 43 and 164 per female. Eggs are burgundy with white patches where the developing embryo was located.[3]

Conservation[]

Listed as endangered in Victoria[4] otherwise least concern.[1][2]

Utility to humans[]

Not suitable for human consumption due to their small size, never reaching the minimum legal size in both Victoria and New South Wales of 90 mm (3.5 in) OCL.[5][6]

References[]

  1. ^ a b Coughran, J.; Furse, J. (2010). "Euastacus yanga". IUCN Red List of Threatened Species. IUCN. 2010: e.T153631A4523177. doi:10.2305/IUCN.UK.2010-3.RLTS.T153631A4523177.en.
  2. ^ a b Coughran, Jason & Furse, James (2010). An assessment of genus Euastacus (49 species) versus IUCN Red List criteria. Report prepared for the global species conservation assessment of crayfishes for the IUCN Red List of Threatened Species. Researchgate. International Association of Astacology, Alabama, USA. ISBN 9780980545210.
  3. ^ a b c d e f g h i j k Morgan, Gary J. (1997). "Freshwater crayfish of the genus Euastacus Clark (Decapoda: Parastacidae) from New South Wales, with a key to all species of the genus" (PDF). Records of the Australian Museum, Supplement. 23: 99–106. doi:10.3853/j.0812-7387.23.1997.429. ISSN 0812-7387. Retrieved 14 June 2021.
  4. ^ a b "Species List: Victoria : Conservation Status". Atlas of Living Australia. Retrieved 14 June 2021.
  5. ^ "Spiny freshwater crayfish (all species other than Glenelg spiny freshwater crayfish and Murray spiny freshwater crayfish)". Recreational Fishing Guide. Victorian Fisheries Authority. Retrieved 14 June 2021.
  6. ^ "Freshwater bag and size limits". Department of Primary Industries. NSW Government. Retrieved 14 June 2021.
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