Euastacus vesper Mccormack & Ahyong, 2017, sp. n.
Creators: name: Mccormack, Robert B.
name: Ahyong, Shane T.
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Parastacidae
Euastacus
Euastacus vesper

description: Euastacus vesper sp. n.
(Figs 1–6)
Material Examined. HOLOTYPE. AM P99506, male (CL 74.78 mm, OCL 64.74 mm), 127 g, Cudgegong River, Coricudgy Road, New South Wales, 32°52.009’S, 150°18.295’E, 743 m above sea level (asl), coll. R. McCormack, 19 April 2008.
PARATYPES. Collected with holotype: AM P99541, 1 male (CL 55.39 mm, OCL 46.78 mm), 53 g; ACP 1136, 1 male (CL 71.52 mm, OCL 61.47 mm), 117 g; ACP 1137, 1 female (OCL 55.63 mm), 79 g; AM P99507, 1 female (CL 50.72 mm, OCL 42.74 mm), 41 g; ACP 1139, 1 juv female (CL 14.26, OCL 10.69 mm), 1 g; ACP 1140, 1 juv male (CL 12.47 mm, OCL 9.17 mm), 0.5 g; CMNH 37973.67, 1 male (OCL 57.75 mm), 94 g; AM P99508, 1 male (CL 69.49 mm, OCL 59.93 mm), 107 g; CMNH 37973.68, 1 female (OCL 55.63 mm).
Upper Cudgegong River, Coricudgy State Forest, NSW: ACP 1130, male, Kelgoola Picnic Area, Coricudgy Rd, 32°51.569’S, 150°18.862’E, 794 m asl, coll. R. McCormack, 19 April 2008; ACP 1131, 1 female (CL 19.24 mm, OCL 15.27 mm), 2 g, Kelgoola Picnic Area, Coricudgy Rd, 32°51.569’S, 150°18.862’E, 794 m asl, coll. R. McCormack, 19 April 2008; ACP 1132, 1 male (CL 49.82 mm, OCL 42.30 mm), 36 g, Kelgoola Picnic Area, Coricudgy Rd, 32°51.569’S, 150°18.862’E, 794 m asl, coll. R. McCormack, 19 April 2008; AM P99509, 1 female (CL 51.8 mm, OCL 44.04 mm), 44 g, Kelgoola Picnic Area, Coricudgy Rd, 32°51.569’S, 150°18.862’E, 794 m asl, coll. R. McCormack, 19 April 2008; ACP 1134, 1 male (CL 60.47 mm, OCL 51.08 mm), 65 g, Kelgoola Picnic Area, Coricudgy Rd, 32°51.569’S, 150°18.862’E, 794 m asl, coll. R. McCormack, 19 April 2008; ACP 3984, 1 male (CL 42.43 mm, OCL 35.94 mm), 22 gram, 32°50.731’S, 150°21.272’E, 1123 m asl, coll. R. McCormack, 28 April 2012; ACP 5874, 1 male (CL 72.56 mm, OCL 62.85 mm), 125 g, 32°51.581’S, 150°18.842’E, 761 m asl, coll. R. & C. McCormack, 19 September 2016; ACP 5875, 1 female (CL 78.92 mm, OCL 67.91 mm), 143 g, 32°51.581’S, 150°18.842’E, 761 m asl, coll. R. & C. McCormack, 19 September 2016; ACP 5876, 1 ovigerous female (CL 64.09 mm, OCL 54.95 mm), 80 g, 32°51.581’S, 150°18.842’E, 761 m asl, coll. R. & C. McCormack, 19 September 2016; ACP 5877, 1 male (CL 75.94 mm, OCL 67.08 mm), 140 g, 32°51.581’S, 150°18.842’E, 761 m asl, coll. R. & C. McCormack, 19 September 2016; ACP 5878, 1 ovigerous female (OCL 53.77 mm), 79 g, 32°51.581’S, 150°18.842’E, 761 m asl, coll. R. & C. McCormack, 19 September 2016.
Tributary of the Cudgegong River: ACP 5872, 1 ovigerous female (OCL 58.44 mm), 94 g, 32°51.572’S, 150°18.894’E, 763 m asl, coll. R. & C. McCormack, 19 September 2016; ACP 5870, 1 male (OCL 60.54 mm), 105 g, 32°51.626’S, 150°18.943’E, 764 m asl, coll. R. & C. McCormack, 19 September 2016; ACP 5871, 1 male (CL 37.42 mm, OCL 31.66 mm), 16.02 g, 32°51.626’S, 150°18.943’E, 764 m asl, coll. R. & C. McCormack, 19 September 2016; ACP 5873, 1 female (CL 47.33 mm, OCL 40.04 mm), 31.67 g, 32°51.626’S, 150°18.943’E, 764 m asl, coll. R. & C. McCormack, 19 September 2016.
Diagnosis. Male cuticle partition absent. Thoracic spines present. Rostrum reaching midlength to end of the ultimate antennal article, with 2 or 3 marginal spines or blunt tubercles. Carapace with first and second postorbital ridges unarmed in adults; 1 medium sharp spine, 1 small sharp spines in addition to several protrusions ventral to postorbital ridges; suborbital spine medium sized; 2–4 medium sized and sharp cervical spines; 14–27 large sized and pointed thoracic spines; general tubercles medium to large sized and moderately distributed. Antennular basipodite spines absent. Antennal coxopodite spine absent in adults. Interantennal spine triangular, margins irregularly tuberculate, apex acute; scaphocerite widest proximal to midlength, reaching anteriorly as far as rostral apex. Abdomen with 3–4 large sized sharp Li spines on somite 2; 1 large sharp Li spine somites 3–5; Lii spines present on somites 3–6; 1 large sharp D & D-L spine on somite 1; D spines on somites 2–5 usually sharp, those of somites 4–5 sometimes blunt in large specimens; 1 large sharp D-L spine on somites 2–5; somite 6 with small, scattered D & D-L spines over dorsal surface; dorsal boss absent or weakly developed> 40 mm ocl. Cheliped lateral propodal spine rows well developed; 5 or 6 mesial propodal spines; 1 dorsal apical propodal spine; 1 or 2 spines above propodal cutting edge; 1 small blunt tubercle lateral to dactylar base dorsally; 1–3 blunt tubercles lateral to dactylar base ventrally; 1 dorsal apical dactylar spine; 0–2 spines above dactylar cutting edge; 2 or 3 apical mesial dactylar spines; 0–1 marginal mesial dactylar basal spines; dactylar groove distinct; 2 mesial carpal spines; ventral carpal spine large; 1–6 low ventromesial carpal spines; 2 medium lateral carpal spines.
Description. Cephalothorax: Rostrum reaching to midlength or end of antennular peduncle article 3. Rostral sides convergent or parallel, rostral bases parallel or divergent, carinae long. Rostrum with 2 or 3 marginal spines or blunt tubercles along distal half; apical spine similar size to first marginal spine, other marginal spines reducing in size posteriorly, more acute in smaller specimens; OCL/CL 0.74–0.88. Rostrum length 0.13–0.36 OCL (proportionally shortest in larger specimens), width 0.12–0.14 OCL. OCL 0.42–0.45 total body length.
Anterior cephalothorax moderately spinose in specimens <55 mm OCL with 1 medium large spine, 1 smaller spine and several protrusions ventral to post orbital ridges; large specimens> 65 mm OCL with 10–20 large spines or tubercles. First post-orbital ridge well-defined, slender, unarmed in adults, with small anterior spine in small juveniles (~ 15 mm OCL). Second post-orbital ridge unarmed in adults, indicated by 2 low swellings, posterior larger, in juveniles with small anterior spine. Suborbital spine medium sized.
Branchial surfaces with 14–27 large, prominent dorsal thoracic spines, arrayed in 3 irregular rows (in specimens> 40 mm OCL) with the dorsal row consisting of medium spines, the central large and ventral row consisting of smaller spines, spines blunter, more rounded in smaller specimens, tending pointed in specimens> 60 mm OCL; branchial surface with numerous small spines; general tubercles medium to large in size and moderately distributed; 2–4 sharp, medium sized, cervical spines, dorsalmost largest, sharpest. Areola length 0.33–0.36 OCL. Areola width 0.15–0.18 OCL. Carapace width 0.54–0.59 OCL. Carapace depth 0.50–0.55 OCL.
Epistome pilose in adults, anteriorly produced to form interantennal spine; interantennal spine triangular, slightly longer than wide in adults (Fig. 6 B, D, F), as long as wide in juveniles (Fig. 6 H), surface glabrous, margins irregularly tuberculate, apex acute.
Thoracic sternal keel. Sternal processes of pereopod 1 with posterior margins oblique; ventral edges cristate; processes closely spaced to separated, parallel; unarmed; median keel following pereopod 1 slightly concave. Sternal processes of pereopods 2–4 triangular, increasing in size posteriorly, posterior margins oblique, processes widely separated, open, unarmed, anterior margins straight, scoops absent; median keel following pereopods 2 slightly concave, that following pereopod 4 slightly convex.
Abdomen. Abdominal spines developing in specimens> 40 mm OCL. Medium to large D spine on somite 1, spine variable from large and rounded to small and sharp; 1 small to large D spine on somite 2–5, spine varying from rounded to sharp. Large, sharp D-L spine somite 1; 1 large sharp D-L spine on somites 2–5. Somite 6 with array of 9–14 small sharp D and D-L spines covering dorsal surface (specimens> 60 mm OCL). Somite 2 with 1– 5 large sharp Li spines (usually 3 or 4), 0–2 spines in specimens <40 mm OCL. Somites 3–5 with 1 large sharp Li spine. Somite 6 with 0–1 small sharp Li spines. Lii spines generally absent on somite 2 (one specimen with 1 each side); somite 3–6 with 1–2 Lii spines (specimens <60 mm OCL), 1–3 (specimens> 60 mm OCL), medium sized and sharp. Dorsal boss absent or weakly developed in specimens> 40 mm OCL. Abdomen width 0.45–0.50 OCL (male), 0.49–0.51 (female).
Tailfan. Strong tailfan spination, standard spines medium to large in size. Telson with 7–10 surface spines (specimens <50 mm OCL), 10–17 spines (specimens> 40 mm OCL); lateral margin with 2 spines, proximal present in specimen> 50 mm OCL. Uropodal exopod with 0–3 lateral marginal spines, inner with 0–1, spines small, sometimes along margin or just above. Uropodal endopod with 0–3 surface spines, usually along longitudinal median carina. Telson length 0.28–0.33 OCL.
Antenna. Scaphocerite unarmed laterally, lateral margin straight to slightly concave distally, widest at or slightly proximal to midlength, length 0.11–0.14 OCL; basipodite spines absent, at most with blunt angular lobe; coxa with prominent outer spine, distal articulated sclerite mesial to scaphocerite articulation unarmed in adults, at most with small rounded tubercle (Fig. 6 B), juveniles ~ 15 mm OCL with small spine (“coxopodite spine”) (Fig. 6 H).
Pereopod 1 (First Cheliped). Chelae with propodal teeth becoming medium to well developed in specimens> 60 mm OCL.
Propodus lateral spine row well developed; dorsolateral propodal spine row extending from apex to base of propodus; ventrolateral propodal spine row slightly less developed, falling just short of apex of propodus; 5 or 6 mesial propodal spines, 0 or 1 small dorsal apical propodal spine on specimens> 60 mm OCL, absent on smaller specimens; 1 or 2 small distal spines or tubercles (usually 2) above dorsal cutting edge developing> 50 mm OCL, 3 spines> 65 mm OCL; 1 (occasionally 2) large rounded tubercles and numerous bumps and protrusions lateral to dactylar base dorsally; 1–3 tubercles or blunt spines lateral to dactylar base ventrally; prominent, blunt spine at ventral dactylar articulation; precarpal spine absent; angular tubercles posterior to dactylar articulation sometimes present on specimens> 40 mm OCL (typically 1 side only); ventral propodal surface usually densely setose in specimens under 35 mm OCL, sparsely setose in larger specimens. Propodus length 0.72–0.87 OCL (male), 0.77– 0.82 (female). Propodus width/propodus length: 0.37–0.54 (male), 0.41–0.52 (female). Propodus depth/propodus length: 0.26–0.36 (male), 0.28–0.34 (female).
Dactylus with 1 dorsal apical spine or tubercle followed proximally by 0–2 small spines or tubercles above dactylar cutting edge (1 specimen with 2 apical spines on one side; ACP 5875). Spines above cutting edge absent on ventral surface. 2–4 (usually 3) apical mesial dactylar spines. Basal mesial margin with 1 dorsal, occasionally 1 marginal mesial dactylar basal spine (usually absent; one specimen with 2). Dactylar groove distinct. Dactylus length/propodus length: 0.53–0.59 (male), 0.53–0.54 (female).
Carpus with 2 large mesial spines (1 specimen with 3 on one side; ACP 3984), distalmost spine distinctly larger and sharper than proximal; 2 short, medium sized lateral carpal spines. Ventral carpal spine large sharp, group of 1–6 small rounded to medium-large sharp ventromesial spines. Articular condyle unarmed. Carpal groove deep.
Merus with 5–8 small to medium dorsal spines, the first 2 distal spines medium sized, the remainder small in specimens <50 mm OCL, all medium sized in specimens> 50 mm OCL. Outer meral spine small to absent.
Pereopods 2–3: chelate, dactylus, propodus, carpus smooth, unarmed; merus extensor margin with 3 or 4 spines, flexor margin unarmed; ischium extensor margin with 0–3 spines (usually absent on pereopod 2), flexor margin unarmed.
Pereopod 4: simple. Propodus flexor margin multispinose; anterior surface smooth, posterior surface multispinose. Carpus distal and flexor margins with scattered spines. Merus extensor margins with 3–5 spines; flexor margin with 2–4 spines. Ischium with 2–4 extensor spines.
Pereopod 5: simple. Propodus flexor margin multispinose; posterior surface smooth, anterior surface multispinose. Carpus distal and flexor margins with scattered spines. Merus extensor margins with 1–4 spines; flexor margin with 2–5 spines. Ischium unarmed. Male gonopore without cuticle partition.
Maxilliped 3. Laterodistal corner of ischium produced to a distinct point, mesial margin broadly rounded. Exopod distal article reaching to about midlength of ischium, flagellum overreaching ischium.
Gastric mill. (9 specimens OCL 31.66–67.91 mm) TAA count 0.5. TAP count 7–9 (usually 7–8). Spread 6.5– 8.5. Secondary zygocardiac ossicle ear absent. Urocardiac ossicle with 8–11 ridges.
Setation and punctation. Setae moderate. Moderate and fine punctation on body. Chelae with deep setose tubercles with tufts of bristle setae.
Colouration. (Fig. 1 B–D). Dorsally green-brown with pale cream or yellow general tubercles, cephalic and cervical spines. Large thoracic spines very dark green to black. Abdominal spines highlighted in yellow to orange. First chelae mesially blue, with white to cream-tipped mesial propodal spines; propodal and dactylar apex generally blue with some specimens displaying unique vivid purple-pink colouration (Fig. 1 D); lateral propodal spines cream or blue. Walking legs green, tending towards lighter blue green towards tips. Cream to orange ventrally.
Size. Male (n = 14) OCL 9.17–67.08 mm (0.5–140 g); female (n = 11) OCL 10.69–67.91 mm (1–143 g).
Etymology. Named vesper (Latin), meaning “western”, alluding to the western distribution of the new species relative to its closest relative, E. spinifer. Suggested common Name: the Cudgegong Giant Spiny Crayfish
Distribution. Presently known only from the Cudgegong River and its tributaries; 743–1123 m a.s.l.
Ectocommensals. In addition to unidentified parasitic mites on thin parts of the cuticle (e.g., uropods and telson) and arthrodial membranes, numerous temnocephalans and oligochaetes were present on most crayfish specimens. Two species of temnocephalan (Fig. 1 C) were recorded from E. vesper: a larger brown form with 5 anterior tentacles (Temnosewellia sp.) occurring in very high numbers, and a smaller white form with 6 anterior tentacles (Temnohaswellia sp.) in very smaller numbers. The small numbers of Temnohaswellia sp. was unexpected given its typical prevalence on other species of Euastacus (McCormack 2012).
Colonies of phreodrilid oligochaetes (2–30) were present on most crayfish in grooves and cavities of the exoskeleton. Up to 25 worms were found in the orbital cavities around the eyes and rostrum and are possibly a different species from those found on the more exposed external surfaces. Phreodrilids were also found between the folds of the sternal keel processes, in the cervical groove and other carapace grooves, uropod joints and attached to the abdominal pleura below the Li spines and between the Li and Lii spines of somite 2. External worms are large, 4–10 mm long, and are usually within protective detritus domiciles attached to the exoskeleton. They may heavily infest crayfish of both sexes. Pinder & Brinkhurst (1997) regard these worms as ectocommensals.
The rates of phreodrilid infestation were very high. The smallest specimens (OCL 31.36 mm; ACP 5871) carried worms only in the orbital area but not on the body. All specimens larger than OCL 35 mm also had worms on the body surface. All large specimens of E. vesper (except ACP3984 from 1183 m asl), carried numerous worms in the orbital cavities as well as on the body surface including the thoracic sternum. Although the species of oligochaete on E. vesper is yet to be confirmed, Pinder & Brinkhurst (1997) identified Astacopsidrilus jamiesoni Brinkhurst, 1991, from Euastacus in the rainforest streams of the Gold Coast, southern Queensland, and McCormack & Coughran (2008) reported the same oligochaete from E. maccai McCormack & Coughran, 2008 from northeastern New South Wales. Pinder (2001) records Astacopsidrilus notabilis Goddard, 1909, and A. fusiformi Goddard, 1909, as also occurring in New South Wales and preliminary identification according to keys in Pinder (2013) would indicate the worms are one of these two species.
Remarks. Although E. vesper and E. armatus both occur in the Cudgegong system, the new species is most closely related to E. spinifer, whose distribution is centred east of the Great Dividing Range in the Sydney basin (including the drainages of Hunter and Hawkesbury Rivers). Euastacus vesper, included in the molecular phylogenetic analysis of the genus (Shull et al. 2005) as “ E. sp.”, was derived as sister to E. spinifer, with 3.3% sequence divergence in COI, well within the recognized range separating other species of the genus (Furse et al. 2013). Like E. spinifer and E. armatus, E. vesper belongs to the group within the genus of giant spiny crayfish (McCormack 2012), characterized by their generally large body size, prominent abdominal spination (Fig. 2, 3) and typically two mesial carpal spines on the first chelipeds (Fig. 4 B. C). Euastacus vesper can be distinguished from E. spinifer by its greater degree of thoracic spination (14–27 spines in three irregular rows (Fig. 3 A, B; 5B, D); versus 6–20 thoracic spines in two irregular rows in E. spinifer), and the absence of the antennal basipodite and coxopodite spines (Fig. 4 A, 6B, H). Euastacus vesper may also differ from E. spinifer in colouration. Although E. spinifer shows considerable variation in colour throughout its range, none has the vivid pink and purple colouration overlying the blue-green base colour of the cheliped fingers and palm often evident in E. vesper (Fig. 1 D). From E. armatus, E. vesper is readily distinguished by the green-blue (versus white) chelipeds and straight, less prominent D and D-L spines, which in E. armatus are large and anteriorly recurved.
Apart from normal allometric variation, specimens of E. vesper are morphologically largely consistent. The rostrum becomes proportionally shorter and broader, and tubercles relatively more blunt with increasing body size (Fig. 6 A, C, E, G). In adults, the pereopod 2 ischium is usually unarmed but may have 1 or 2 small extensor spines; the anterior margin of the antennal basipodite is straight, with at most a low blunt projection (Fig. 6 B, H). The antennal coxopodite spine is absent except in small juveniles (~ 15 mm OCL) (Fig. 6 H). Of the 25 specimens examined, all were clearly either male or female. No intersex specimens were observed. Setal development around the female gonopores along with the developmental condition of the gonopores indicates that female maturity occurs at 50–55 mm OCL; given the high proportion of ovigerous females observed, the majority of mature females apparently breed each year. Female Euastacus spinifer across the species’ range mature at a larger size (60–80 mm OCL), with one southern specimen of 80.2 mm OCL recorded with closed gonopores (Morgan 1997). Females are ovigerous by OCL 53.77 mm, with eggs counts for five females as follows: ACP 5878, OCL 53.77 mm, 148 eggs; ACP 5876, OCL 54.84 mm, 164 eggs; ACP 5872, OCL 58.44 mm, 154 eggs; ACP 5870, OCL 60.54 mm, 220 eggs; ACP 5875, OCL 67.91 mm, 3 eggs. As in E. spinifer, newly released juveniles of E. vesper are characterized by distinctive cream-coloured bands across the first and last abdominal somites.
Horwitz & Richardson (1986) classified Australian crayfish burrows into three categories based on the relationship to the water-table (Types 1–3). Euastacus vesper constructs “ Type 1” burrows, which are in, or connected to open water, in both clear flowing forested streams and streams through grazing paddocks with open canopy and grassy banks. The Cudgegong River and its tributary streams are perennially flowing, though with seasonally varying flow strength. The streams in which E. vesper was collected typically consist of deeper pools 0.5–1.2 m deep with shallow riffles and cascades. The larger crayfish may use the shallow riffle areas to forage but they do not construct burrows there. Juveniles tend to construct burrows in the shallow margins and under rock along the sides of riffles and in the shallow feeder streams; greatest numbers occur along undercut banks with vegetation cover, such as Lomandra sp. overhanging the stream edge (Fig. 1 E). Larger individuals favour deeper water with the largest adults in the deepest pools. Available burrow sites are very limited within the banks of these pools; burrows are close together, many with entrances within 100 mm of the other. Given the limited available habitat for construction of new burrows, it is possible that burrows are utilised by successive generations of crayfish.
description: Published as part of Mccormack, Robert B. & Ahyong, Shane T., 2017, Euastacus vesper sp. nov., a new giant spiny crayfish (Crustacea, Decapoda, Parastacidae) from the Great Dividing Range, New South Wales, Australia, pp. 556-567 in Zootaxa 4244 (4) on pages 557-565, DOI: 10.11646/zootaxa.4244.4.6, http://zenodo.org/record/437272