Euastacus jagabar, 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 : 368-370

Euastacus jagabar n.sp.

Fig. 7

Type material. HOLOTYPE: AM P67933; ♀ (OCL 28.9 mm); a small tributary to Sheepstation Creek (rainforest), Border Ranges National Park, northeastern N.S.W.; 28°23.900'S 153°01.500'E (topographic map); elevation 430 m; J. Coughran and S. Waddington; 16 January 2002 . PARATYPES: AM P67923; 2♀♀ (OCL 18.5, 23.5 mm); Sheepstation Creek (rainforest), Border Ranges NP; 28°24.546'S 153°01.462'E; elevation 330 m; J. Coughran; 17 October 2001 . AM P67924; 13, 1♀ (OCL 18.8 mm, 19.3 mm); Sheepstation Creek (rainforest), Border Ranges NP; 28°24.546'S 153°01.462'E; elevation 330 m; J. Coughran; 5 December 2001 . AM P67922; 1♀ (OCL 22.4 mm); type locality; J. Coughran and S. Waddington; 16 January 2002 .

Type locality. The type locality is in a small gully adjoining the main tributary of Sheepstation Creek on the Rosewood Loop circuit, Border Ranges NP, approximately 25 km north of Kyogle. The stream connects with Sheepstation Ck below the falls.

Other specimens examined. A small male specimen (OCL 12.6 mm; SCU KCK.gd.16) retained on 16 January 2002 from a minor stream feeding Sheepstation Ck was also briefly examined.

Diagnosis. As for E. girurmulayn , except: Rostrum short, often not reaching base of third antennal segment. 2–3 small and rounded rostral spines, extending to rostral base. Antennal squame inflation very pronounced and at midlength, almost triangular in shape. Lateral cephalon poorly spinose, with only a few small, blunt bumps per side. Cervical spines absent. Li abdominal spines absent or present as 1–3 small and blunt bumps on somite 2, occasionally a slight bump on somites 3 and 4 also. 6–8 small dorsal meral spines. 1 dorsal apical propodal spine. Dactylar groove shallow. Keel Pair 2 slightly apart. Keel Pair 3 deflated laterally and with moderate posterior margins.

Description. Maximum OCL: 28.9 mm. — Rostrum. Rostrum short, usually not reaching base of third antennal segment (just reaching on two specimens). Rostral carinae sides convergent and bases divergent. 2–3 small, rounded rostral marginal spines per side, with a distinct gap between first and second spines. Acumen similar in size to marginal spines. Rostral carinae short. OCL/carapace length: 0.87– 0.89. Rostral width/OCL: 0.15–0.18. — Cephalon. A few small or barely discernible, blunt cephalic spines per side. First postorbital spine medium and blunt. Second postorbital spine absent. Basipodite spines absent, holotype with 1 medium and blunt spine on one side. Coxopodite spines small to medium in size and blunt. Interantennal scale elongate (broad on one specimen). Holotype bears a small spine in the centre of the scale, giving the impression of a second broad scale overlying the true scale. Scale margins smooth. Suborbital spine small to medium. Antennal squame lacking marginal spines and inflated at or slightly posterior to midlength, with inflation appearing almost triangular in shape. Interantennal scale length/OCL: 0.06–0.09. — Thorax. Cervical and thoracic spines absent. General tubercles small and moderate to dense. Areola incurved at centre. Areola length/OCL: 0.34–0.38. Areola width/OCL: 0.18–0.19. Carapace width/OCL: 0.48–0.52. Carapace depth/OCL: 0.45–0.47. — Abdomen. Li abdominal spines either absent or present as 1–3 barely discernible bumps or small and blunt spines on abdominal somite 2. Holotype with 1 barely discernible bump on somites 3 and 4. When present, Li spines and bumps often discernible mainly by blue colouration. Lii, D-L and D spines absent. Abdomen width/OCL: 0.44–0.46. OCL/total length: 0.41–0.43. — Tailfan. Standard tailfan spines highly variable, absent or small to medium.Telsonic and uropodal surface and marginal spines absent. Telson length/OCL: 0.3–0.36. — Keel. Pair 1 usually close, slightly apart on paratype, and parallel. Pair 2 slightly apart and parallel to open. Pair 3 narrow to medium breadth, deflated laterally and with moderate posterior margins (i.e. not elongate posteriorly). Pair 4 broad. Keel between pairs 3 and 4 moderate in development. Lateral processes with welldefined margins. — Chelae. Intermediate to stout, paratype with an elongate regenerate chela. Merus . 6–8 small to medium, blunt spines. Carpus. 4 mesial carpal spines, first (distalmost) and third spines offset ventrally to second and fourth. Ventral carpal spine small to medium (absent on one specimen), and blunt. 1–4 small to medium and blunt ventromesial carpal spines, and 1 large ventromesial carpal spine immediately ventral to carpal spines (this large and moderate ventromesial carpal spine is much larger than ventral spine, being similar in size to the mesial carpal spines). Lateral carpal spines absent or insignificant, and discernible mainly by colour. 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. 4 mesial propodal spines, with a distinct gap between first (at distal edge of propodal palm) and second spines. 1 small spine and occasionally some irregular bumps and punctations lateral to dactylar base dorsally. 1 barely discernible to small spine lateral to dactylar base ventrally. 1 small dorsal apical propodal spine on most specimens, holotype with an extra barely discernible spine on one chela only, paratype with an extra barely discernible spine on both chelae. 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 barely discernible spine on one chela of holotype). Propodal length/ OCL: 0.77–0.9. Propodal width/propodal length: 0.43–0.48. Propodal depth/propodal length: 0.29–0.33. Dactylus . 1 small, blunt spine above dactylar cutting edge on dorsal surface. 1 small to medium and blunt apical mesial dactylar spine. Other apical dactylar spines and dactylar basal spines absent. Dactylar groove present. Dactylar length/propodal length: 0.53–0.56. — Punctation. As for E. girurmulayn . — Setation. Sparse 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 on 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 varying from rich tan-brown to dark blue-black, tending to deep green-brown, greenblue or blue on cephalon. Lateral branchiostegites usually paler and tan brown. Small patches of blue in between abdominal pleura and between thorax and abdomen (on first abdominal somite). Prominent, royal blue patches on lateral cephalon above anterior end of cervical groove (“cheek spots”). Body ventrally cream, lavender and/or blue. Walking legs lavender to blue, with pale pink-white coxa. Third, fourth and fifth lateral processes of pereiopods blue to lavender. Carpus and propodus ranging from tan and green to blue-black dorsally. Carpus ventrally with a pink to blue base, tinged green mesially and brown laterally. Apical half of propodal finger pale blue, to a lesser extent on dactylar finger also. Propodus ventrally pale pink to blue, with a deeper blue veining pattern, orange-brown or greenbrown across dactylar articulation and ventrolaterally along propodal finger. Apical 2 ⁄ 3 of both fingers blue ventrally.

Sexes. Males possess a cuticle partition. When examined under the dissecting scope, the only male specimen caught was found to have thick strands of gelatinous material extruding from the gonopores, suggesting that he was mature. This specimen had an OCL of 18.8 mm. This would appear, therefore, to be a very small species of crayfish. However, small “precocious” males have been described in Euastacus (Turvey & Merrick, 1997) , and this specimen may also represent a similar case. The female holotype (28.9 mm OCL) differs only marginally in relative abdomen width to all other specimens, and has only minor setal development around the gonopores, which are still calcified. All other females (18.5–23.5 mm) have closed gonopores lacking setae. Thus, an onset of maturity near 30 mm OCL, at least in females, would seem likely.

Biology. The species occurs in shallow areas at the water’s edge in minor tributaries, sidestreams and shallow edge habitat of Sheepstation Creek, immediately upstream of the falls, and in a major tributary. Sampling activities directly upstream, in the Sheepstation Creek Flora Reserve, yielded only specimens of E. dalagarbe and E. sulcatus . Euastacus jagabar is sympatric with E. sulcatus , a much larger and spinier species. It is likely that the two species partition the stream habitat, with the larger species inhabiting the deeper water in addition to the shallow areas, and the much smaller E. jagabar being restricted to shallower habitat throughout its life-cycle.

Etymology. From the Bundjalung Aboriginal language, jagabar is the same word used to describe blue, black, blueblack and dark (Sharpe, 1985), all of which are true of this species.

Figures

Fig. 7. Euastacus jagabar. Dorsal view, holotype, AM P67933. Photograph: Max Egan. Scale bar is 10 mm.