Euastacus guruhgi, 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 : 366-368

Euastacus guruhgi n.sp.

Fig. 6

Type material. HOLOTYPE: AM P67926; ♀ (OCL 25.2 mm); Korrumbyn Creek , adjacent to visitor carpark (rainforest), Mount Warning National Park, northeastern N.S.W.; 28°23.875'S 153°16.893'E; elevation 410 m; J. Coughran and A. Coughran; 12 April, 2002 . PARATYPES: AM P67918; male (OCL 23.5 mm); type locality; J. Coughran and A. Coughran; 12 April 2002 . AM P67919; 13, 2♀ (OCL 17.0– 32.5 mm); un-named creek running parallel to Brummies Rd (rainforest), Wollumbin National Park, northeastern N.S.W.; 28°23.587'S 153°13.875'E; elevation 320 m; J. Coughran; 5 September 2002 . AM P67920; 13, 1♀ (OCL 24.8 mm, 22.4 mm); un-named gully along North Wollumbin Rd (rainforest), Wollumbin NP; 28°23.304'S 153°14.013'E; elevation 440 m; J. Coughran; 5 September 2002 . AM P67921; 1♀ (OCL 17.5 mm); Palmer Creek (rainforest), Wollumbin NP; 28°24.723'S 153°13.705'E; elevation 430 m; J. Coughran; 5 September 2002 .

Type locality. The type locality is in the main creek adjacent to the visitor carpark at Mt Warning National Park, approximately 15 km southwest of Murwillumbah. The holotype was collected approximately 200 m upstream of the intersection of the creek and the walking track.

Diagnosis. As for E. girurmulayn , except: Rostrum varying in length, extending to the midlength of the second antennal segment or as far as the anterior tip of the third antennal segment. 2–4 small, blunt rostral spines per side. Antennal squame lacking marginal spines and inflated at or slightly distal to midlength. Li abdominal spines usually just discernible. 4–8 just discernible or small dorsal meral spines. 1 dorsal apical propodal spine. Dactylar groove absent or shallow. Lateral processes with blunt to moderate margins.Keel Pair 2 slightly apart and slightly open. Keel posterior to pair 3 usually broad and strongly developed, and fusing smoothly with the lateral processes of the third and fourth pereiopods.

Description. Maximum OCL: 32.5 mm. — Rostrum. Rostrum varying considerably in length, extending to midlength of second antennal segment or as far as the anterior end of the third antennal segment. Rostral carinae short, convergent at sides and divergent at base. 2–4 small to medium and blunt rostral marginal spines per side. Acumen usually similar in size to, or slightly larger than, marginal spines (acumen smaller than marginal spines on the specimen from Palmer Ck). Rostral carinae short to medium length. OCL/carapace length: 0.87–0.90. Rostral width/OCL: 0.12–0.18. — Cephalon. 2–4 medium cephalic spines, and a few smaller bumps, per side. First postorbital spine usually medium to large and blunt (small on specimens from North Wollumbin gully). Second postorbital spine absent. 1 small to medium basipodite spine present. Specimens from Mt Warning and Palmer Ck have basipodite spines on the right hand side only. Coxopodite irregular, either with 2 large spines (Mt Warning specimens), or a broad zone of small spines giving a serrate edge. Interantennal scale broad, margins smooth. Suborbital spine small to medium.Antennal squame lacking marginal spines and inflated at or slightly distal to midlength. Inflation narrow to moderate and reduced on left hand side on some animals from “Brummies” Ck and the North Wollumbin Rd gully. Interantennal scale length/OCL: 0.06–0.10. — Thorax. Cervical spines usually barely discernible, but largest animal with 4 small spines. Thoracic spines absent. General tubercles small to medium and moderately distributed. Areola incurved at centre. Areola length/OCL: 0.35–0.39. Areola width/OCL: 0.14–0.16. Carapace width/ OCL: 0.49–0.54. Carapace depth/OCL: 0.38–0.44. — Abdomen. Usually 1 just discernible Li spine or bump on abdominal somites 3–6 (absent on small specimens). Somite 2 with 2–4 just discernible or small Li spines (absent on some specimens). Lii spines, D-L spines and D spines absent. Abdomen width/OCL: 0.44–0.52. OCL/total length: 0.40–0.44. — Tailfan. Standard tailfan spines medium. Telsonic and uropodal surface and marginal spines absent. Telson length/OCL: 0.3–0.37. — Keel. Pair 1 close and parallel. Pair 2 slightly apart and slightly open (apart and open on Mt Warning specimens). Pair 3 narrow to medium breadth, and with gradual posterior margins (more elongate). Pair 4 medium to broad. Keel between pairs 3 and 4 broad and strongly developed, and fusing with the lateral processes of the pereiopods, giving a swollen appearance. Lateral processes with blunt to moderate margins, in extreme situations giving a swollen appearance to the sternum. — Chelae. Intermediate to stout (regenerate chelae more elongate). Merus . 4–8 just discernible to small, and poorly developed, dorsal meral spines. Carpus. Usually 4 mesial carpal spines, first (distalmost) and third spines offset ventrally to second and fourth. Some regenerate chelae have 3 spines, and one animal has 3 spines on a normal chela and 4 on a regenerate chela. Ventral carpal spine small to medium, barely discernible on some small animals. Some regenerate chelae lack ventral carpal spines. 3–4 small to medium and blunt ventromesial carpal spines on normal chelae (regenerate chelae usually with two spines, although one regenerate chela with 5 spines). Ventromesial spines extending in a row from ventral spine towards the second mesial carpal spine, and 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 as far as 2 ⁄ 3 of propodal length (to around midlength on most specimens). Ventrolateral propodal spine row absent. Usually 4 mesial propodal spines, with a distinct gap between first (at distal edge of propodal palm) and second spines. One specimen from Mt Warning has 5 distinct mesial propodal spines, and some regenerate cheale have 3 or 5 spines. Usually 1 spine lateral to dactylar base dorsally. Some chelae with 2 spines, and one specimen from “Brummies” Ck has 5 spines on a normal chela. Another specimen from “Brummies” Ck has 1–2 spines and some additional small bumps lateral to the dactylar base. Usually 1 barely discernible to small spine lateral to dactylar base ventrally (one specimen from “Brummies” Ck has 2 spines; spines usually smaller or absent on regenerate chelae). 1–2 small to medium dorsal apical propodal spines (absent on small animal from Palmer Ck). 2 large, blunt bumps at dactylar articulation dorsally. Spines posterior to dactylar articulation absent. Precarpal spines absent. Spines above propodal cutting edge (dorsal surface) absent (1 spine on one chela of one specimen from “Brummies” Ck). Propodal length/OCL: 0.78–0.98. Propodal width/ Propodal length: 0.45–0.52. Propodal depth/propodal length: 0.31–0.37. Dactylus . Usually 1 small and blunt spine above dactylar cutting edge on dorsal surface. The large specimen from “Brummies” Ck bears 3 spines above dactylar cutting edge on its normal chela. 1 small to medium apical mesial dactylar spine (absent on one normal chela, and 2 spines on one regenerate chela). Other apical dactylar spines and dactylar basal spines absent. Dactylar groove absent or shallow. The dactylus is proportionally longer in the specimens from Mt Warning. Dactylar length/propodal length: 0.51–0.53 (Palmer Ck, “Brummies” Ck, North Wollumbin Rd gully); 0.62–0.66 (Mt Warning). — Punctation. As for E. girurmulayn . — Setation. Light on body, moderate on abdomen. Dense clumps of long, but 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 1.0–2.0; spread 1.5–2.5. Urocardiac ridges 3–6.

Colouration. Body dorsally brown to green-brown. Cephalothorax (and to a lesser extent abdomen) laterally lighter, often a rich golden-brown. Body ventrally pink and cream. Walking legs blue-grey. Carpus and propodus brown or green-brown dorsally and with a darker veining pattern (less distinct than in E. girurmulayn ). Fingers bluish apically. Carpus, propodus and fingers variable in ventral colour: specimens from Mt Warning NP predominantly brown, with small and varying amounts of blue; specimens from Wollumbin NP predominantly blue with only minor brown wash across palm near dactylar articulation. Darker veining pattern evident on ventral propodal surface of all specimens.

Sexes. Males possess a cuticle partition. The female from Mt Warning (25.2 mm OCL) has soft, membranous gonopores with lightly setose margins. All other females (17.5–22.4 mm OCL) have calcified gonopores which lack setae. It would appear that female maturity occurs near 25 mm OCL.

Biology. Euastacus guruhgi occurs in rainforested gullies and streams draining the Tweed volcanic plug. Specimens were collected from under rocks and debris, and were found together with E. sulcatus at all sites. Euastacus guruhgi hosts small, white temnocephala.

Etymology. From the Bundjalung Aboriginal word guruhgi (swollen) (Sharpe, 1985), describing the inflated, swollen appearance of the sternal keel and lateral processes.

Figures

Fig. 6. Euastacus guruhgi. Dorsal view, holotype, AM P67926. Photograph: Max Egan. Scale bar is 10 mm.