Euastacus morgani, Coughran, Jason & McCormack, Robert B., 2011

Coughran, Jason & McCormack, Robert B., 2011, Euastacus morgani sp. n., a new spiny crayfish (Crustacea, Decapoda, Parastacidae) from the highland rainforests of eastern New South Wales, Australia, ZooKeys 85, pp. 17-26 : 18-22

Euastacus morgani sp. n. Figures 12

Material Examined.

HOLOTYPE. AM P.84263, Australia, New South Wales, tributary of Little Nymboida River, upstream of Eastern Dorrigo Way road crossing near Lowanna, on periphery of Bindarri National Park, rainforest, 30.2288°S, 152.9203°E, 25 March 2008, J. Coughran and R. B. McCormack, 30.88 mm OCL, female. PAR ATYPES. AM P.84264-P.84266, type locality, 25 March 2008, J. Coughran and R. B. McCormack, 29.94-39.87 mm OCL, 2 females, 1 male.

Other Material.

ACP 1101-1105, type locality, 25 March 2008, J. Coughran and R. B. McCormack, 22.41-31.65 mm OCL, 3 females, 2 males. ACP 1095-1096, type locality, 25 March 2008, J. Coughran and R. B. McCormack, 17.17-19.77 mm OCL, 1 male, 1 female. ACP 1098, type locality, 25 March 2008, J. Coughran and R. B. McCormack, 14.85 mm OCL, 1 male.

Diagnosis.

Male cuticle partition present. Rostrum with 3 or 4 small marginal spines per side, extending to midlength. Suborbital spine of medium size. Thorax with 10-20 very small to small thoracic spines per side. Abdominal somites with tiny to small, moderately sharp to sharp Li and Lii spines. D-L and D abdominal spines present on somites 2-3 of some large specimens. Apical propodal spines absent. Ventral lateral propodal spine row moderately developed, usually with 4-5 centrally located spines. Spines above propodal cutting edge absent. Dactylus with 1 apical mesial spine and 1 dorsal mesial basal spine. Marginal dactylar basal spines absent. Dactylar finger with 1 or 2 tiny apical spines above cutting edge. Carpus with 3 mesial and 2 lateral spines. Ventromesial carpal spines smaller than ventral carpal spine. Setation light.

Size.

The maximum size of specimens collected was 39.9 mm OCL.

Description.

Rostrum. Rostrum short, usually reaching base of third antennal segment (occasionally not quite reaching base, and rarely extending as far as midlength of segment). Rostral sides slightly convergent to convergent, rostral bases divergent. Rostrum with 3 or 4 small marginal spines, extending to approximately rostral midlength, or beyond. Acumen similar in size to marginal spines. OCL/Carapace Length: 0.83-0.89. Rostrum Width/OCL: 0.16-0.19.

Cephalon. Numerous bumps and protrusions in cephalic region, with 1 (occasionally 2) on each side developed into more prominent, but small and blunt cephalic spine. First post-orbital ridge spine distinct but small. Second post-orbital ridge spine barely discernible to small; posterior to spine each ridge poorly developed initially, with large and swollen bump at posterior end. Suborbital spine medium in size, and acute.

Antenna. Basipodite spines small to medium. Coxopodite without distinct spines but with large, rounded development of coxopodal plate at mesial end. Interantennal spine of medium width and usually with slightly scalloped margins. Antennal squame lacking marginal spines, with near triangular inflation at midlength. Scale Length/OCL: 0.09-0.12.

Thorax. Thorax with 1-3 barely discernible to small cervical spines on each side, flattened and triangular in shape with moderate to sharp point. Dorsal thoracic spines present and numbering 10-20 on each side. Dorsal thoracic spines very small to small but distinct, and larger than general tubercles; spines highlighted against the carapace by profile (raised, but blunt) and/or colour (yellow-brown, grey-brown, grey or blue-grey). General tubercles small to medium in size (very small on specimens <25 mm OCL), and of moderate density. Areola Length/OCL: 0.35-0.39. Areola Width/OCL: 0.16-0.21. Carapace Width/OCL: 0.53-0.62. Carapace Depth/OCL: 0.44-0.50.

Sternal Keel. Lateral processes to first pereiopods (LPr1) slightly apart, slightly open to open in orientation, and with semi-abrupt posterior margins. LPr2 apart and with slightly open to open orientation. LPr3 narrow, and LPr4 of medium width. LPr2 to LPr4 all with distinctive, sharply defined margins, and sternal keel between both LPr2-LPr3 and LPr3-LPr4 entire and sharply developed.

Abdomen. Abdominal somite 1 lacking spines. Somite 2 with 3-5 tiny to small, moderately sharp to sharp Li spines. Somites 3-6 with 1 Li spine, decreasing in size posteriorly to be barely discernible on somite 6 (absent on some specimens <25 mm OCL). Frequently 1 or 2 small Lii spines on somites 3-6 of specimens> 20 mm OCL. Abdominal D-L spines present on somites 2-3 of one specimen, and on somites 2-6 of the largest specimen. Abdominal D spines also present on somites 2-3 of these two specimens only. Abdomen Width/OCL: 0.48-0.54 (male), 0.50-0.55 (female). OCL/Total Length: 0.39-0.43.

Tailfan. Standard tailfan spines small. Telson and uropods lacking surface and marginal spines. Telson Length/OCL: 0.33-0.37.

First Cheliped. Chelae usually intermediate in shape, occasionally elongate or stout.

Propodus. Dorsal lateral propodal spine row extending from apex to base of propodus. Ventral lateral propodal spine row less developed, with 1-6 (usually 4 or 5) more or less centrally located spines. Numerous bumps and protrusions lateral to dactylar base dorsally, of which 1 or 2 are usually distinctly larger. Bumps and protrusions also present on ventral surface of propodus lateral to dactylar base, often including 1-4 more prominently developed spines extending along propodal finger. Propodus with 5-7 mesial spines. Dorsal apical propodal spines absent. Two blunt spines at dactylar articulation. Propodal surface posterior to dactylar articulation lacking spines, with 2 or 3 distinctly deep punctuations. Pre-carpal area lacking spines, with occasional distinct punctuations. Spines above propodal cutting edge absent on both dorsal and ventral surfaces (2 barely discernible apical spines on dorsal surface of one specimen ACP1099). Prominent tooth near dactylar articulation. Propodus Length/OCL: 0.81-0.90 (male), 0.80-0.94 (female). Propodus Width/PropL:0.46-0.50. Propodus Depth/Propodus Length: 0.26-0.31.

Dactylus. Usually 1 or 2 barely discernible to small apical spines above dactylar cutting edge (absent on one specimen). Spines above cutting edge absent on ventral surface. Dactylus with 1 apical mesial spine and 1 dorsal mesial basal spine. All other dactylar spines absent (one regenerate chela with a small marginal dactylar basal spine). Dactylar groove distinct. Dactylus Length/Propodus Length: 0.55-0.61.

Carpus. Carpus with 3 mesial spines, decreasing in size posteriorly; generally produced to sharp point. Lateral margin of carpus with 2 spines. Ventral surface of carpus with large, sharp ventral spine and 1 or 2 tiny to medium, blunt ventromesial spines. Dorsal surface with deep groove; bearing 1-3 large, bluish-green, blunt bumps or spines (occasionally merging to effectively form raised ridge or boss) on dorsal surface mesial to groove.

Merus. Merus with 6 or 7 small to medium dorsal spines, and a barely discernible or small distolateral spine.

Third Maxilliped. Laterodistal corner of ischium produced to a distinct point. Exopodite shorter than or about as long as ischium (average 0.93 × ischium length).

Gastric Mill. Gastric mills were carefully extracted and examined for three specimens ranging in size from 29.94 to 39.87 mm OCL. Zygocardiac ossicle with 1.0-1.5 teeth anterior to ossicle ear (TAA), and 4.0-4.5 teeth anterior to posterior margin of ear (TAP), with tooth spread of 2.5-3.0. Urocardiac ossicle with 6 or 7 ridges.

Setation and Punctation. Setae sparse and short. Sparse to moderate and fine punctation on body. Chelae with occasional deep punctuations.

Colouration. Dorsally brown or green-brown with pale cream cephalic and cervical spines. Thoracic spines usually distinct from thorax background, and varying in colour (cream, grey, grey-brown or blue-grey). Abdominal somites marked heavily with blue laterally, with cream Li spines. First chelae mesially blue, with cream-tipped mesial propodal spines. Dorsal carpal bumps blue (often forming a raised, blue ridge). Walking legs blue-grey. Lateral propodal spines cream. Ventrally, a varying wash of pale blue-green, pink and orange, with a dull grey abdomen and tailfan. Merus of first cheliped and antennal bases vivid orange.

Sexes.

Males with cuticle partition. Female specimens without fully mature gonopores. All female specimens have calcified gonopores that lack marginal setation. Gonopores of four largest female specimens (29.9-39.9 mm OCL) with slightly incised rims, those of largest specimen appear to be in state of decalcification, being partially membranous on mesial margins. Thus, it would seem that female maturity occurs close to 40 mm OCL.

Etymology.

Named to honour Gary J. Morgan, whose landmark research on the Australian spiny crayfish genus Euastacus ( Morgan 1983, 1986, 1988, 1989, 1991, 1997) has been pivotal to our understanding of these animals.