Euastacus girurmulayn, Coughran, 2005

Coughran, Jason, 2005, New Crayfishes (Decapoda: Parastacidae: Euastacus) from Northeastern New South Wales, Australia, Records of the Australian Museum 57 (3), pp. 361-374 : 365-366

Euastacus girurmulayn n.sp.

Fig. 5

Type material. HOLOTYPE: AM P67914; ♀ (OCL 33.9 mm); Tuntable Creek , above falls (wet sclerophyll with rainforest understorey), Nightcap National Park, northeastern N.S.W.; 28°33.234'S 153°17.785'E; elevation 460 m; J. Coughran and A. Coughran; 14 October 2002 . PARATYPES: AM P67915; 13, 1♀ (OCL 22.4 mm, 26.8 mm); type locality; J. Coughran; 20 September 2002 . AM P67916; 13, 1♀ (OCL 22.5, 22.6 mm); Gibbergunyah Creek (rainforest gully), Whian Whian National Park, northeastern N.S.W.; 28°34.786'S 153°20.305'E; elevation 580 m; J. Coughran; 18 October 2002 ; AM P67917; 1♀ (OCL 30.6 mm); unnamed gully in the Cooper’s Ck catchment along North Rocks Rd (rainforest gully), Whian Whian NP; 28°33.809'S 153°21. 033'E; elevation 550 m; J. Coughran; 18 October 2002 .

Type locality. The type locality is in Tuntable Creek, above the falls, in Nightcap National Park, approximately 30 km north of Lismore. The holotype was collected from a large rock at the stream margins, approximately 500 m upstream of the falls.

Diagnosis. Male cuticle partition present. Rostrum short, but usually reaching base of third antennal segment. 2–3 small and rounded rostral spines. Suborbital spine small to medium. Inflation of antennal squame narrow. Lateral cephalon with 1–4 small cephalic spines and a few smaller bumps per side. Coxopodal plate irregular, usually with a broad zone of spines forming a jagged edge to the plate. Thoracic spines absent. Usually 1–4 cervical spines per side. General tubercles small and moderately distributed. 1–4 Li spines (or bumps) usually present on abdominal somites 2– 6, with large specimens bearing more spines. Other abdominal spines and abdominal boss absent. 7–12 dorsal meral spines. 4 mesial carpal spines, the distalmost being the largest, with variation in the alignment of spines. Ventrolateral propodal spine row absent. Spines above propodal cutting edge usually absent (1 specimen with 1 spine). 0–1 dorsal apical propodal spines. 4–5 mesial propodal spines. 1 small and blunt spine above dactylar cutting edge. 1 apical mesial dactylar spine. A single spine lateral to dactylar base ventrally. Dactylar groove distinct. Lateral processes with moderate to well-defined margins. Keel Pair 2 close and parallel to open. Keel posterior to pair 3 reduced and deflated at sides, forming a narrow ridge.

Description. Maximum OCL: 33.9 mm. — Rostrum. Rostrum short, usually just reaching base of third antennal segment (extending only to midway of second antennal segment on one animal from Gibbergunyah Ck). Rostral carinae short to medium length, convergent at sides and divergent at base. 2–3 rostral marginal spines per side. Spines varying in location along the rostrum, with four possible spine locations evident and all animals lacking spines in some positions (and often unequal on different sides of the rostrum). Acumen slightly larger than marginal spines and rounded. Rostral carinae short. OCL/carapace length: 0.87–0.90. Rostral width/OCL: 0.15–0.18. — Cephalon. Usually 1–4 small cephalic spines, and a few smaller bumps. First postorbital spine small to medium and blunt to moderately pointed. Second postorbital spine absent. Basipodite spines usually absent, but animals from Tuntable Ck with a small spine on one or both sides. Coxopodal plate irregular, usually with a broad zone of spines forming a jagged edge to the plate, or with two large, triangular teeth; in extreme cases, plate looking grossly misshaped (North Rocks gully animal). Interantennal scale elongate to medium. Scale margins usually smooth (one animal from Tuntable Ck slightly toothed). Suborbital spine small to medium. Antennal squame lacking marginal spines and with narrow inflation, at or slightly posterior to midlength. Interantennal scale length/OCL: 0.07–0.10. — Thorax. 1–4 cervical spines per side on most specimens (absent on specimen from North Rocks gully). Thoracic spines absent. General tubercles small and moderately distributed. Areola parallel or only slightly incurved at centre. Areola length/OCL: 0.34–0.38. Areola width/OCL: 0.15–0.18. Carapace width/OCL: 0.47–0.51. Carapace depth/OCL: 0.37–0.42. — Abdomen. Li spines absent on somite 1. Usually 1–4 vague bumps or blunt spines in the Li position on abdominal segments 2–6, although all specimens bar the holotype lack spines on some segments. Holotype with 2–4 small spines on somite 2, 3–4 small spines on somites 3–5 and 1 spine on somite 6. Li spines absent on one small specimen from Gibbergunyah Ck. Lii spines, D-L spines and D spines absent on all specimens. Abdomen width/OCL: 0.44–0.48. OCL/total length: 0.41. — Tailfan. Standard tailfan spines medium. Telsonic and uropodal surface and marginal spines absent. Telson length/ OCL: 0.3–0.34. — Keel. Pair 1 close and parallel. Pair 2 close and parallel to open. Pair 3 narrow to medium breadth, and with gradual posterior margins (elongate). Pair 4 broad. Keel posterior to pair 3 reduced and deflated at sides, forming a narrow ridge. All lateral processes with moderate to well-defined margins. — Chelae. Elongate to stout. Regenerate chelae usually more elongate than normal chelae. Merus . 7–12 small and poorly developed spines. Carpus. 4 mesial carpal spines, with some differentiation between populations as to the alignment. In animals from Tuntable Ck, only the first (distalmost) spine is offset ventrally. The first and third mesial carpal spines are offset ventrally in the animal from North Rocks gully, and only the fourth spine is offset ventrally in the Gibbergunyah Ck animals. Ventral carpal spine small and blunt. 1–3 ventromesial carpal spines on normal chelae, extending in a row from ventral spine towards the second mesial carpal spine.Ventromesial carpal spines increasing in size mesially, with the outermost being immediately ventral to, and similar in size to, the second mesial carpal spine. A single lateral spine present at distal edge of carpus, insignificant or small. Dorsal carpal spines absent. Dorsal carpal groove deep. Propodus. Dorsal lateral propodal spine row extending from apex to midlength or as far as 2 ⁄ 3 of propodal length (spines notably smaller and blunter on the specimen from North Rocks gully). Ventrolateral propodal spine row absent. 4–5 mesial propodal spines, usually 4 with a distinct gap between first (at distal edge of propodal palm) and second spines. Spines in some positions indistinct or damaged. 1 spine lateral to dactylar base dorsally (absent on one regenerate chela). 1 small spine lateral to dactylar base ventrally. 1 small dorsal apical propodal spine on most specimens, absent on some animals. Holotype with 1 large spine on one chela and 2 small spines on the other. 2 large, blunt bumps at dactylar articulation dorsally, more pronounced on the specimens from Tuntable Ck. Spines posterior to dactylar articulation absent. Precarpal spines absent. Spines above propodal cutting edge (dorsal surface) usually absent (holotype with 1 apical spine on one chela and 1 at midlength on other). Propodal length/OCL: 0.75–0.92. Propodal width/propodal length: 0.43–0.48. Propodal depth/ propodal length: 0.28–0.33. Dactylus . 1 small, blunt spine above dactylar cutting edge on dorsal surface, absent on smaller specimens. 1 medium and blunt apical mesial dactylar spine (spines small on one specimen from Gibbergunyah Ck). Other apical dactylar spines and dactylar basal spines absent. Dactylar groove distinct. Dactylar length/propodal length: 0.56–0.62. — Punctation. Sparse and shallow on cephalon, less distinct and sparser laterally. Punctation on chelae also sparse but more distinct. — Setation. Setation light on body and abdomen, moderate on walking legs. Dense clumps of long, uneven setae protruding from punctures in chelae, especially on fingers. Distinctive bristly setation around and on lateral processes of pereiopods, and around coxa of pereiopods of some animals. — Gastric Mill. TAP count 3.0–3.5; TAA count 1.0; spread 2.0–2.5. Urocardiac ridges 4.

Colouration. Body dorsally brown, with lateral branchiostegites lighter (often a rich tan colour). Animals often with blue patches on lateral cephalon above anterior end of cervical groove. Body ventrally cream. Walking legs cream or pale purple-grey, with cream coxa. Carpus and propodus light brown dorsally with a distinct, darker veining pattern. Fingers dark brown, tending blue or cream apically. Carpus ventrally orange-brown, tinged blue-brown mesially and brown laterally. Propodus ventrally cream-brown or pale bluish-grey with a darker veining pattern of brown or blue, orange-brown or green-brown near dactylar articulation and with blue or cream finger-tips.

Sexes. Males possess a cuticle partition.The large female from Tuntable Ck (33.9 mm OCL) is mature, with soft, membranous gonopores heavily fringed with setae. Other females, including the 30.6 mm OCL animal from North Rocks gully, have closed gonopores without setae, suggesting that maturity occurs in females after reaching 30 mm OCL.

Biology. The species was collected from somewhat different habitats at each of the three populations. Tuntable Ck is a small, permanent stream with a gravel and cobble bed overlying solid bedrock. The animals were collected from under rocks at the stream margins or on exposed shoulders. The gully along North Rocks Road lacks surface water entirely, and the animal was collected from under a rock next to the road culvert. The Gibbergunyah Ck site is high in the headwaters of the creek, and the habitat consists of a few basaltic cobbles and boulders and dense vegetative debris over fine, red earth. At this site, animals were collected from under cobbles and palm fronds, and even from under the same frond as a larger specimen of E. sulcatus , which is also present at Tuntable Ck. Euastacus girurmulayn hosts small, white temnocephala.

Etymology. From the Bundjalung Aboriginal words girur (smooth, slippery) and mulayn (crayfish) (Sharpe, 1985). In general terms, this is the least spinose member of the setosus complex.

Figures

Fig. 5. Euastacus girurmulayn. Dorsal view, holotype, AM P67914. Photograph: Max Egan. Scale bar is 10 mm.