Eucalliaxiopsis paradoxa, Poore, 2021

Poore, Gary, 2021, Indo-West Pacific and Australian species of Eucalliacidae with descriptions of four new species (Crustacea: Axiidea), Memoirs of Museum Victoria 80, pp. 1-41 : 28-33

Eucalliaxiopsis paradoxa sp. nov.

http://zoobank.org/urn:lsid:zoobank.org:act:2EEAC4EC-C3EA-

4D17-9102-4090CA6DF02E

Figures 20 , 21 , 25h, i

Material examined. Holotype. Australia, Qld , Great Barrier Reef, Rib Reef, 18.48° S, 146.86° E, October 1985, shallow lagoon, 4 m, (M. Riddle stn R/10 /2), NMV J71683 (male, 9.4 mm).

Paratypes. Collected with holotype. NMV J71679 (ovigerous female, 9.4 mm), NMV J71684 (3 females, 9.8–10.9 mm). Australia, Qld , Great Barrier Reef, Myrmidon Reef, 18.27° S, 147.38° E, October 1985, lagoon with “ Callianassa ” mounds, 8 m, (M. Riddle stn M/10/1), NMV J71680 (7 males, 3.9–10.3 mm; 7 females, 4.4–10.4 mm) .

Diagnosis. Pleonite 1 with pleopods attached to pair of sternal plates. Eyestalk about twice as long as wide. Antennule peduncle reaching to midpoint of antenna peduncle article 5. Maxilliped 3 exopod absent. Cheliped carpi distolateral margin with 3 acute teeth near lower margin separated by submarginal oblique grooves, second tooth with prominent rounded ridge, propodi lateral face with short horizontal longitudinal ridge extending from beyond mid-length of palm to base of finger, upper mesial face with row of clusters of long setae. Male pleopod 1 article 1 linear, with distal setae; article 2 blade-like with subapical medial notch. Female pleopod 2, appendix interna absent. Uropod endopod ovate with excavate apex. Telson with row of spiniform setae on ridge.

Description of holotype male. Carapace length 9.4 mm, smooth; gastric–abdominal regions together 4.7 times as long as wide; branchiostegite fully calcified; cervical groove at 0.63 carapace length, scarcely obvious on branchiostegite; cardiac sulcus at 0.8 carapace length, not meeting mid-dorsally, extending transversely across quarter of branchiostegite.

Rostrum acute, tapering evenly over most of length, length 0.5 width of eyestalks. Anterolateral carapace lobe 0.6 length rostrum, with rounded apex, anteriorly directed, with numerous submarginal dorsal setae.

Thoracic sternite 7 1.3 times as long as wide, with well-defined median sulcus over posterior half, lateral groove anterior to coxal articulation shallow, oblique, meeting medially, with 7 posterolateral clusters of 2 or 3 long setae. Pleonal sternite 1with pair of swollen relatively unchitinised areas anterior to ridge bearing pleopods. Pleonite 6 with small lateral blunt hook-like process at midpoint.

Eyestalk 2.2 times as long as wide at base, tapering to cornea and acute apical lobe; cornea subcircular; apical lobe extended dorsally. Antennular peduncle 3 times as long as width of both eyestalks; article 2 3.5 times as long as wide; article 3 half as long as article 2; articles 2 and 3 with ventrolateral row of long setae, continued onto flagellum. Antennal peduncle 3.4 times as long as width of both eyestalks, overreaching antennule peduncle by half of article 5; scaphocerite wider than long, with acute apex; article 4 c. 5 times as long as wide; article 5 0.6 length of article 4. Maxilliped 3 ischium with slightly convex mesial margin, expanding from narrow proximomesial corner; ischium– merus upper margin 1.7 times as long as greatest width; crista dentata of 12 spines, the most proximal reflexed; carpus– dactylus together almost as long as ischium–merus.

Chelipeds unequal, major propodus 1.2 times as long as that of minor, both of similar widths, major dactylus stouter than that of minor. Major cheliped (right in holotype) ischium twice as long as distal width, lower margin with short spines becoming more distinct distally; merus twice as long as broad, lower margin mostly straight, unarmed, upper margin with distal tooth; carpus 1.2 times as wide as upper length, upper margin carinate, unarmed except for distal tooth, distomesial margin with prominent lobe near lower margin, distolateral margin with acute tooth near upper margin, with 3 acute teeth near lower margin separated by submarginal oblique grooves, second tooth with prominent rounded ridge, 3 short setae in lower groove; propodus widest proximally, tapering, upper palm length barely exceeding greatest width, upper margin straight, carinate, with rounded lobe not projecting over dactylus, lower margin carinate, strongly curved mesially, mesial face with short distal uneven setose ridge below upper margin, distomesial margin of palm almost straight, lateral face of palm with short horizontal ridge, about fifth length of palm, extending on to finger, 4 rimmed tubercles near proximal margin, 1 at midpoint of palm, 1 near lower margin, each perforated for cluster of setae; fixed finger half length of upper margin of palm, cutting edge with denticles over proximal half, blunt triangular tooth near midpoint; dactylus as long as fixed finger, twice as long as wide at base, cutting edge with blunt proximal molar, with straight tip; submarginal tufts of long setae on upper and lower mesial margins of carpus and propodus, opposing mesial margins of fingers.

Minor cheliped (left in holotype) ischium twice as long as distal width, lower margin with distal spines; merus twice as long as broad, lower margin mostly straight, unarmed; carpus 1.2 times as wide as upper length, upper margin carinate, unarmed except for distal tooth, distomesial face with lower submarginal ridge, distolateral margin with acute tooth near upper margin, with 3 teeth near lower margin separated by submarginal oblique grooves, second tooth acute with prominent rounded ridge, 2 short setae in lower groove; propodus greatest width proximally, tapering, upper palm length equal to greatest width, palm tapering, upper margin carinate, overhanging mesial face, with rounded lobe projecting over dactylus, lower margin carinate, strongly curved mesially, mesial face with 4 blunt teeth at associated with upper row of clusters of setae, distomesial margin of palm almost straight, lateral face of palm with prominent ridge running from two-thirds length of palm to middle of finger, 5 rimmed tubercles near proximal margin of which 1 near midpoint of palm is more distal, each perforated for cluster of setae; fixed finger 0.7 length of upper margin of palm, width at base half width of palm, cutting edge smooth; dactylus as long as fixed finger, 3.2 times as long as wide at base, cutting edge straight; submarginal tufts of long setae on upper and lower mesial margins of carpus and propodus, opposing mesial margins of fingers.

Pereopod 2 merus twice as long as maximum width; dactylus c. 3 times as long as upper margin of propodus. Pereopod 3 merus twice as long as maximum width; carpus 1.8 times as long as wide; propodus with lower margin concave, twice as long overall as mid-length; dactylus 0.7 times length of axial length of propodus. Pereopod 4 merus length 2.2 times maximum width; carpus 2.5 times as long as wide; propodus as long as wide, typically setose, with 1 long distal seta overlapping dactylus.

Pleopod 1 article 1 distally setose; article 2 as long as article 1, 4 times as long as wide, with apex curved, appendix interna lobe-like, not produced, unarmed. Pleopod 2 endopod twice as long as wide; appendix masculina overreaching endopod by about third its length, triangular in cross-section, setose along posterior face and distally; appendix interna near base of appendix masculina without hooks.

Uropodal endopod anterior margin convex, posterior margin convex, widest about third way along, 1.4 times as long as wide, apex excavate, with rows of long setae at ends of anterior and posterior margins, with 8 short setae between in excavation, with subdistal group of facial setae; exopod ovate, anterior margin straight, distal and posterior margins continuous, greatest dimension 2.2 times anterior margin, with row of blade-like distal setae on distal margin, c. 6 not overlapping with densely setose distal margin; dorsal plate extending almost half of exopod width, distal margin with spiniform setae. Telson 1.6 times as wide as long, broadest at midpoint, posterolateral corner rounded; posterior margin sinuous, lateral regions most prominent, with posterolateral cluster of long setae plus 2 short spiniform setae; dorsal surface with sharp transverse ridge at anterior third, with 36 short spiniform setae, few long setae at midpoint

Female. Essentially as male except: major cheliped palm tapering, upper length 0.9 greatest width, upper margin convex, depressed distally, lateral ridge longer than in male, fixed finger broader than in male, crenellate proximal and distal to tooth. Pleonal sternite 1with pair of oval plates supporting pleopods, each with longitudinal row of setae. Pleopod 1 peduncle with mesial setose lobe longer than base. Pleopod 2 peduncle with similar mesial setose lobe; endopod without appendix interna.

Etymology. Paradoxa (Latin) , reflecting the subtle differences from E. panglaoensis and co-occurring E. dworschaki , and a tribute to the collector’s name, Martin Riddle.

Distribution. Australia, Qld, central Great Barrier Reef (18° S). Subtidal coral reef lagoons.

Remarks. Eucalliaxiopsis paradoxa shares several features with E. panglaoensis and E. dworschaki (see remarks under Eucalliaxiopsis above).The new species differs from these two in having eight short setae in the uropodal endopod excavation (fig. 21e; 11 in the other species), a short longitudinal ridge at the base of the finger on the lateral face of the chelipeds, the propodus of the male cheliped tapering (more rectangular in the others), and the middle distolateral cheliped carpal tooth being oblique and sharply ridged (figs 20g, i, 21m, o, r, 25h). In E. dworschaki , the ridge on the palm extends almost its entire length, and the middle carpal lobe is perpendicular and with a median groove. Besides having fewer short setae at the end of the uropodal endopod, Eucalliaxiopsis paradoxa differs from E. panglaoensis in the upper margin of the male major cheliped palm being as long as wide (vs 1.3 times as long as palm width), the palm of the female major cheliped being relatively longer (1.1 vs 0.9 times as long as greatest width), the uropodal endopod being more tapered (more oval in E. panglaoensis ) and the sinuous posterior margin of the telson (vs straight).

Figures

Figure 20. Eucalliaxiopsis paradoxa sp. nov. Holotype, NMV J71683 (male, 9.4 mm): a, b, carapace, dorsal and lateral views; c, d, anterior carapace, eyestalks, antennule, antenna, dorsal and lateral views; e, maxilliped 3; f, g, major cheliped (left), mesial and lateral views, with detail of distolateral corner of carpus; h, i, minor cheliped (right), mesial and lateral views, with detail of distolateral corner of carpus; j, k, m, pereopods 2, 3, 5. Paratype, NMV J71680 (female, 9.3 mm): l, pereopod 4. Scale bars = 1 mm.

Figure 21. Eucalliaxiopsis paradoxa sp. nov. Holotype, NMV J71683 (male, 9.4 mm): a, thoracic sternite 7; b, pleonite1 sternite, right pleopod 1 (anterior uppermost); c, pleonite 6, telson, lateral view; d, pleonite 6, left lateral oblique view; e, right uropod; f, telson; g, h, pleopod 1, mesial and posterior views; i, pleopod 2, posterior view. Paratype, NMV J71679 (ovigerous female, 9.4 mm): j, k, anterior carapace, eyestalks, antenna, dorsal and lateral views; l, m, major cheliped (left), mesial and lateral views; n, o, minor cheliped (right), mesial and lateral views; p, q, pleopods 1, 2. Paratype, NMV J71684 (female, 10.4 mm): r, minor cheliped carpus, distolateral margin. Scale bars = 1 mm.

Figure 25. Eucalliaxiopsis spp. E. aequimana: a, b, major cheliped, mesial. E. dworschaki, Papua New Guinea, MNHN-IU-2013-10003: c, d, major cheliped lateral, upper margin. E. dworschaki, Philippines, NHMW 20923: e, f, major cheliped carpus lower lateral angle, upper margin. E. panglaoensis, NHMW 20922: g, minor cheliped, lateral. E. inaequimana: h, major cheliped, mesial. E. paradoxa: h, i, major cheliped lateral, mesial. Photos e–g: P.C. Dworschak. Various scales.