Euastacus dalagarbe, 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 : 362-364

Euastacus dalagarbe n.sp.

Fig. 4

Type material. HOLOTYPE: AM P67884; male (OCL 35.8 mm); minor gully feeding Brindle Creek (rainforest), Border Ranges National Park, northeastern N.S.W.; 28°22.789'S 153°04.334'E; elevation 760 m; J. Coughran; 22 October 2001 . PARATYPES: AM P67885; 433, 4♀♀ (OCL 9.0– 32.5 mm); type locality; J. Coughran; 27 September 2001 . AM P67886; 13, 1 aberrant male (OCL 25.1–31.3 mm); upper Collins Creek (rainforest), Border Ranges NP; 28°25.978'S 153°07.656'E; elevation 880 m; J. Coughran; 22 October 2001 . AM P67887; 233, 2♀♀ (OCL 18.9–31.7 mm); upper Grady’s Creek , Lost World Wilderness Area (rainforest), Border Ranges NP; 28°22.182'S 153°06.422'E; elevation 890 m; J. Coughran & D. Newell; 2 October 2003 . AM P67888; 433, 3♀♀ (OCL 13.7–30.1 mm); tributary to Sheepstation Ck ; Sheepstation Creek Flora Reserve (rainforest), Border Ranges NP; 28°24.085'S 153°02.247'E; elevation 570 m; J.Coughran & D.Newell; 28 November 2003 . AM P67913; 13, 2♀♀ (OCL 21.4–30.1 mm); un-named wet gully, Bar Mountain (rainforest), Border Ranges NP; 28°27.500'S 153°07.710'E (topographic map); elevation 960 m; J. Coughran & D. Newell; 28 November 2003 .

Type locality. The type locality is in a minor gully feeding Brindle Creek, a westward-flowing tributary of the upper Richmond River, approximately 30 km north of Kyogle. One paratype (32.5 mm male) is the only specimen caught in Brindle Creek itself, despite repeated sampling. While Brindle Creek is large (up to 10 m in width), this animal was collected from a shallow, quiet backwater of Brindle Creek, seasonally fed by a minor gully. All other specimens (including several released after capture) were found in small gullies and tributaries feeding Brindle, Collins, Grady’s and Sheepstation Creeks. These watercourses are typically very small in nature, and often nearly or completely void of surface water for a considerable part of the year.

Other specimens examined. SCU KCK.gd.13; 1 ♀ (OCL 33.6 mm); type locality; J. Coughran; July 2003. SCU KCK.gd.14; 3♀♀ (OCL 14.2–19.3 mm); upper Collins Creek (rainforest); 28°25.978'S 153°07.656'E; elevation 880 m; J. Coughran; 22 October 2001. Several other specimens collected from the Brindle Creek sites were examined briefly before being returned to the water .

Diagnosis. Male cuticle partition present. Rostrum short, usually reaching to base or midlength of third antennal segment. Thoracic spines absent. Li abdominal spines either absent or present as 1–3 barely discernible bumps or small and blunt spines on abdominal somite 2, occasionally 1 bump also on somites 3–4. Lii spines, D-L spines, D spines and abdominal boss absent. 3 mesial carpal spines. 1 ventromesial carpal spine present on normal chelae, distinctly smaller than ventral carpal spine. Ventrolateral propodal spine row absent. Dorsal surface of propodus lateral to dactylar base without bumps, spines or protrusions. Ventrally, 1 small to medium and blunt spine lateral to dactylar base. 0–2 (usually 1) small dorsal apical propodal spines. 0–3 (usually 1–2) spines above propodal and dactylar cutting edges, spines apical in distribution. Spines ventral to propodal and dactylar cutting edges absent. Usually 1 apical mesial dactylar spine. Other apical dactylar spines and dactylar basal spines absent.

Description. Maximum OCL: 35.8 mm. — Rostrum. Rostrum short, reaching to base or midlength of third antennal segment, almost to anterior edge of segment on largest specimen. Rostral margins parallel to slightly convergent. Rostrum broader on specimens from Brindle Creek. Rostral carinae short. Usually 2–4 marginal spines per side (one specimen with 1 spine on one side), rounded and decreasing in size proximally. Acumen similar in size to largest marginal spines. OCL/carapace length: 0.83–0.88. Rostral width/OCL: 0.15–0.21. — Cephalon. Some animals with 1 blunt cephalic spine, absent on some specimens and 2–3 spines on some specimens. Few to numerous smaller, blunt and anteriorly-directed bumps ventral to cephalic spine present on all specimens. First postorbital spine small to medium and blunt. Second postorbital spine absent. Basipodite spines absent. Coxopodite spines generally small. Interantennal spine broad, with 1–3 (usu. 2) bumps or spines per side and a prominent, blue apex. Suborbital spine barely discernible to small. Antennal squame inflated at, or distal to, midlength, and lacking marginal spines. Interantennal scale length/OCL: 0.08–0.13. — Thorax. 3–5 small cervical spines per side, barely discernible on some specimens.Cervical spines flattened and blunt. Thoracic spines absent. General tubercles small to medium in size and moderate to densely distributed.Areola length/OCL: 0.35–0.39.Areola width/OCL: 0.16–0.22. Carapace width/OCL: 0.46–0.54. Carapace depth/ OCL: 0.46–0.52. — Abdomen. Li abdominal spines either absent or present as 1–3 barely discernible bumps or very small and blunt spines on abdominal somite 2. Two specimens with 1 barely discernible bump on somites 3 and 4. Li spines and bumps often discernible mainly by paler colouration. Lii spines, D-L spines and D spines absent. Abdominal boss absent. Abdomen width/OCL:0.46–0.52. OCL/total length:0.38–0.42. — Tailfan. Standard tailfan spines generally small to medium. Telsonic and uropodal surface and marginal spines absent. Telson length/OCL: 0.32–0.38. — Keel. Pair 1 usually close, slightly apart on some specimens, and parallel to slightly closed. Pair 2 close, slightly apart or apart and usually slightly open or parallel, closed on one specimen. Pair 3 narrow to medium breadth and with gradual margins. Pair 4 broad. — Chelae. Usually intermediate in shape, elongate on paratype. Regenerating chelae usually elongate. Merus . 4–8 small and blunt spines. Carpus. 3 mesial carpal spines, distalmost distinctly larger and sharper than, and offset ventrally to, other spines. Two specimens with a fourth minute mesial carpal spine on one claw, and one specimen from Bar Mountain with 2 spines (distalmost absent).Ventral carpal spine large and sharp. A single, blunt ventromesial spine present, much smaller than ventral spine. Regenerate chelae of Collins Creek specimens with 1–2 additional ventromesial carpal spines. Usually 1 (occ. 2) insignificant lateral carpal spines, discernible mainly by pale colour. Dorsal carpal spines absent. Dorsal carpal groove deep. Propodus. Dorsal lateral propodal spine row extending to between ½ and 2 ⁄ 3 of propodal length from apex (reaching entire length of propodus on regenerate chela of one specimen). Ventrolateral propodal spine row absent (1 barely discernible spine on regenerate chela of one specimen from Collins Creek). 3–5 mesial propodal spines (6 on one regenerate chela from Collins Creek). Mesial propodal spines usually numbering 4, with a distinct gap between first spine (at distal edge of propodal palm) and second spine. Spine at distal edge of palm often poorly developed. Specimens from Grady’s Creek, Sheepstation Creek and Bar Mountain with 5 mesial propodal spines. Dorsal propodal surface lateral to dactylar base usually distinctly smooth (some minor development of protuberances on some Bar Mountain specimens). Ventrally, 1 small, blunt spine lateral to dactylar base (absent on one regenerate chela). 1–2 small dorsal apical propodal spines (usually 1), occasionally absent. 2–3 blunt bumps dorsally at dactylar articulation. Spines posterior to dactylar articulation absent. Spines above propodal cutting edge either absent or numbering 1–2 (3 on some regenerate chelae), if present spines small and apical. Spines ventral to propodal cutting edge absent.Propodal length/OCL: 0.89–1.14. Propodal width/propodal length: 0.41– 0.47. Propodal depth/propodal length: 0.25–0.34. Dactylus . Usually 1–2 small spines above dactylar cutting edge on dorsal surface (absent on one specimen; 0 or 3 on some regenerate chelae). Spines ventral to dactylar cutting edge absent. 1 apical mesial dactylar spine, barely discernible or small (absent on one specimen; two specimens with 2 spines on 1 chela). Other apical dactylar spines absent. Dactylar basal spines absent. Dactylar length/propodal length: 0.53–0.59. — Punctation. Sparse to moderate. Punctation especially sparse on dorsal region of cephalon, giving a “polished” appearance on some specimens. — Setation. Sparse to moderate, short, stiff setae on thorax, cervical groove and lateral cephalic regions. — Gastric Mill. TAP count 3.5; TAA count 1.0; spread 2.5. Urocardiac ridges 4–6.

Colouration. Body dark green brown to brown dorsally, tending to brown ventrally. Abdomen brown, with barely discernible Li spines paler than surrounding areas. Walking legs washed pale tan to dull orange ventrally, coxa dull orange. Postorbital spine blue with a yellow tip. Cervical and cephalic spines orange or brown. Merus and carpus of chelae dorsally green-blue, ventrally orange or tan tinged blue along mesial edge. Propodus dorsally brown to greenbrown, mottled on palm and generally darker mesially. Propodus ventrally orange or brown (light blue on one animal from Bar Mountain) with green mottling, bright orange at base of fingers and around dactylar articulation. Fingers of chelae deep green-blue, tending to blue apically, especially on dorsal surface. mesial carpal spines blue with white or yellow tips. Lateral carpal, ventral carpal, ventromesial carpal and ventral meral spines yellow to orange. Mesial and lateral propodal spine rows blue, with pale yellow-green spines with white tips. Propodal and apical dactylar spines white to brown. Spine above cutting edges white to dull yellow-green.

Sexes. Males possess a cuticle partition. A 28.3 mm OCL female specimen from Grady’s Ck has calcified gonopores. A further female from Grady’s Ck with an OCL of 30.5 mm has gonopores which are mostly calcified but are opening (bear a small membranous portion within gonopore).A 29.3 mm OCL female from Brindle Creek has membranous gonopores with light setation around the margins. Thus, it would appear that maturity occurs close to 30 mm OCL.

Biology. The species inhabits moist gullies and small streams which are largely void of surface water for at least part of the year. They are found under rocks in the red clay of the rainforests, where they inhabit burrows into the subsurface water. It would appear that Euastacus dalagarbe to some extent partitions the habitat with the considerably larger and spinier species, E. sulcatus , the former being excluded from the larger habitat of the main creek channel. Both species can, however, occur together in the smaller habitat, and have been collected from under the same rock. Euastacus dalagarbe hosts small, white temnocephala.

Etymology. A blend of the Bundjalung Aboriginal words dalagar (mud) and garbe (gully) (Sharpe, 1985), describing the species’ habitat.

Figures

Fig. 4. Euastacus dalagarbe. Dorsal view, holotype,AM P67884. Photograph: Max Egan. Scale bar is 10 mm.