Eucalliaxiopsis patio, 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 : 33-38

Eucalliaxiopsis patio sp. nov.

http://zoobank.org/urn:lsid:zoobank.org:act:F5884500-4430-

493B-9BCD-CA5E769F846E

Figures 22–24

Eucalliaxiopsis PNG-1153C.— Robles et al., 2020.

Material examined. Holotype. Papua New Guinea, New Ireland Province, Patio Island , 02° 36.2' S, 150° 31.6' E, 6–8 m, coral rubble (KAVIENG 2014 stn KB38), MNHN-IU-2014-2536* (female, cl. 4.6 mm).

Paratype. Collected with holotype (MNHN-IU-2014-2539 (male, cl. 4.3 mm, with male and female bopyrid isopods under left branchiostegite).

Diagnosis. Pleonite 1 without pair of sternal plates. Eyestalk 1.5 times as long as wide. Antennule peduncle reaching to midpoint of antenna peduncle article 5. Maxilliped 3 exopod absent. Cheliped carpi distolateral margin square at lower angle, propodi lateral face without longitudinal ridge, upper mesial face with row of short transverse ridges associated with more distal clusters of setae. Male pleopod 1 of single article with narrower distal lobe. Female pleopod 2, appendix interna present. Uropod endopod ovate. Telson without transverse row of spiniform setae.

Description of holotype female. Carapace length 4.6 mm, smooth; gastric–abdominal regions together 4.2 times as long as wide; branchiostegite fully calcified; cervical groove at 0.67 carapace length, scarcely obvious on branchiostegite; cardiac sulcus at 0.83 carapace length, not meeting mid-dorsally, extending transversely across two-thirds of branchiostegite.

Rostrum broadly rounded-triangular, length about 0.2 width of eyestalks. Anterolateral carapace lobe as long as rostrum, with rounded apex, depressed anteriorly, with c. 5 submarginal dorsal setae. Pleonites 1–6 lengths relative to cl: 0.46: 0.67: 0.45: 0.33: 0.41: 0.51; pleonite 1 with strong dorsal transverse groove, without pair of sternal plates; pleonites 3–5 with lateral tufts of setae; pleonite 6 with 8 lateral rows of setae.

Thoracic sternite 7 1.2 times as long as wide, with well-defined median sulcus over posterior half, smooth over medial half, lateral ridge anterior to coxal articulation crossing pit at quarter of width, meeting medially, with 3 posterolateral clusters of long setae.

Eyestalk 1.7 times as long as wide at base, swollen laterally, tapering to cornea and acute apical tubercle; cornea wider than long, depressed anteriorly. Antennular peduncle twice as long as width of both eyestalks; article 2 twice as long as wide; article 3 as long as article 2; articles 2 and 3 with ventrolateral row of long setae, continued onto flagellum. Antennal peduncle 2.4 times as long as width of both eyestalks, overreaching antennule peduncle by half of article 5; scaphocerite ovoid, longer than wide; article 4 c. 5 times as long as wide; article 5 0.8 length of article 4. Maxilliped 3 ischium with slightly convex mesial margin, expanding from narrow proximomesial corner; ischium–merus upper margin twice as long as greatest width; crista dentata of 6 spines, the 2 most proximal largest; carpus–dactylus together almost as long as ischium–merus.

Chelipeds unequal, major carpus-propodus upper margin 1.1 length of minor, propodus 1.2 times as wide as minor. Major cheliped (left in holotype) ischium twice as long as distal width, lower margin with needle-like spines becoming more distinct distally; merus 1.7 times as long as broad, lower margin convex, unarmed; carpus 1.2 times as wide as upper length, margins carinate; propodus greatest width in middle of palm, upper palm length 1.15 times greatest width, distomesial margin of palm with submarginal group of 2 setae, small tubercle, distolateral margin of palm with submarginal group of c. 6 setae between fingers; fixed finger 0.4 length of upper margin of palm, cutting edge with microdenticles over proximal half, blunt triangular tooth at about midpoint; dactylus as long as fixed finger, twice as long as wide at base, cutting edge with deflected tip; submarginal tufts of long setae on upper and lower mesial margins of carpus and propodus, opposing mesial margins of fingers; 3 short transverse ridges associated with setae on submesial upper margin.

Minor cheliped (right in holotype) ischium c. 2.3 times as long as distal width, lower margin with needle-like spines becoming more distinct distally; merus 1.7 times as long as broad, lower margin convex, unarmed; carpus 1.2 times as wide as upper length, margins carinate; propodus palm more tapering than major, 0.95 times as wide as upper palm length, distomesial margin of palm with submarginal group of 4 12 setae, distolateral margin of palm with submarginal group of c. 4 setae; fixed finger half length of upper margin of palm, mesial cutting edge straight, smooth, cutting edge straight, fixed finger with smooth lateral ridge defining edge of lateral concavity at base of fixed finger, without granules; dactylus as long as fixed finger, 3 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; 2 short transverse ridges associated with setae on submesial upper margin, more prominent distally.

Pereopod 2 merus 1.8 times as long as maximum width; dactylus c. 3 times as long as upper margin of propodus. Pereopod 3 merus 2.2 times as long as maximum width; carpus 1.8 times as long as wide; propodus with lower margin almost straight, 1.8 times as long as mid-length; dactylus half as long as axial length of propodus. Pereopod 4 merus twice as long as maximum width; carpus 3 times as long as wide; propodus typically setose, with distal spiniform setae among setose margin, with 2 long distal setae overlapping dactylus.

Pleopod 1 article 1 without distal projection beyond article 2; article 2 longer than article 1. Pleopod 2 endopod 3 times as long as wide; appendix interna at midpoint of endopod.

Uropodal endopod ovoid, anterior margin more convex than posterior margin, widest about third way along, 1.5 times as long as wide, 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 over anterior half, posterolateral corner evenly rounded to posterior margin; posterior margin barely convex, with posterolateral clusters of long setae; dorsal surface with obscure rounded transverse ridge at anterior third, without median notch.

Paratype male. Carapace length 4.3 mm. Eyestalks 1.5 times as long as wide at base, swollen laterally, tapering to cornea and acute apical tubercle; cornea wider than long, depressed anteriorly Postrostral dorsal area with pair of shallow pits.

Chelipeds unequal, major carpus-propodus upper margin 1.1 length of minor, propodus 1.3 times as wide as minor. Major cheliped (right) ischium twice as long as distal width, lower margin with denticles, 1 distal spine; merus 1.7 times as long as broad, lower margin convex, unarmed; carpus 1.4 times as wide as upper length, margins carinate; propodus greatest width in middle of palm, upper palm length 1.15 times greatest width, distomesial margin of palm with submarginal group of 2 setae plus tubercle; fixed finger 0.35 length of upper margin of palm, cutting edge with microdenticles over proximal half, blunt triangular tooth near midpoint; dactylus as long as fixed finger, twice as long as wide at base, cutting edge irregular, with deflected tip; submarginal tufts of long setae on upper and lower mesial margins of carpus and propodus, opposing mesial margins of fingers; 4 short transverse ridges associated with setae on submesial upper margin.

Minor cheliped (left) ischium c. 2.3 times as long as distal width, lower margin with denticles, 1 distal spine; merus 1.8 times as long as broad, lower margin convex, unarmed; carpus 1.1 times as wide as upper length, margins carinate; propodus palm more tapering than major, 0.95 times as wide as upper palm length, distomesial margin of palm with 2 submarginal groups of 2–3 setae; fixed finger 0.4 length of upper margin of palm, mesial cutting edge straight, smooth; dactylus as long as fixed finger, 2.8 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; 3 short transverse ridges associated with setae on submesial upper margin, more prominent distally.

Pleopod 1 articles indistinguishable; article 1 with 1 short, 4 long distal setae; article 2 a short triangle, half as wide as article 1. Pleopod 2 endopod 2.7 times as long as wide; appendix masculina attached at mid-length, 5 times as long as width, distal margin rounded, exceeding endopod by fifth of its length, with c. 9 facial setae near midpoint, c. 14 subdistal setae; appendix interna rod-like, about 0.4 length of appendix interna.

Etymology. From Patio Island, Papua New Guinea, the type locality (noun in apposition).

Distribution. Papua New Guinea. Coral rubble, 6– 8 m.

Remarks. The holotype was sister taxon to five individuals of E. inaequimana on the phylogenetic tree of Robles et al. (2020). Both species have submarginal mesial transverse ridges on the cheliped propodi from which tufts of long setae emerge; in other species of Eucalliaxiopsis the same tufts are not supported in this way. The male pleopod 1 of both species has a simple second article, free or fused, a form seen too in E. madagassa (see Poore and Dworschak, 2017: fig. 1C, D), Eucalliax quadracuta and Calliaxina bulimba (see above). The typical article 2 of species of Eucalliaxiopsis is flattened with a distal oblique notch. Eucalliaxiopsis patio differs from E. inaequimana in shorter, more swollen eyestalks (1.5 vs 1.8 times as long as wide), slightly shorter rostrum (quarter vs fifth length of eyestalk), shorter antenna peduncle (2.4 vs 3.0 times as long as base of both eyes), more compact antennular and antennal peduncular articles, the telsonic ridge being only slightly elevated and complete (vs clearly elevated, with median notch), and a broader uropodal endopod (1.5 vs 1.8 times as long as wide). The appendix interna on the female pleopod 2 is present while it is absent in E. inaequimana . It is possible that this difference may be related to the female’s small size; Dworschak (2006) noted that the smallest female of E. panglaoensis possessed an appendix interna while larger ones did not. Two individuals were collected from the type locality, with carapace lengths of 4.3 and 4.6 mm. The largest known specimen of E. inaequimana has a carapace length of 9.1 mm.

Identification of these specimens using Sakai’s (2011) key to species of Calliaxina leads to C. aequimana , a southern Australian species. This species, now Eucalliaxiopsis aequimana , lacks mesial ridges on the chelipeds and has a female-like male pleopod 1.

Figures

Figure 22. Eucalliaxiopsis patio sp. nov. Holotype, MNHN-IU-2013-2536 (female, 4.1 mm): a, habitus, dorsal; b, carapace, lateral view; c, thoracic sternite 7; d, pleonite1 sternite, right pleopod 1; e, f, anterior carapace, eyestalks, antennule, antenna, dorsal and lateral views; g, pleonite 6, telson, uropod; h, uropod exopod, margin, dorsal plate; i, j, telson, lateral and dorso-anterior views; k, maxilliped 3; l, maxilliped 3, crista dentata, basis, ischium. Scale bars = 1 mm.

Figure 23. Eucalliaxiopsis patio sp. nov. Holotype, MNHN-IU-2013-2536 (female, 4.1 mm): a, major cheliped (left), mesial; b, major cheliped (left), distal propodus, dactylus, lateral; c, minor cheliped (right), mesial view; d, minor cheliped (right), distal propodus, dactylus, lateral; e–h, pereopods 2–5; i, j, pleopods 1, 2. Scale bars = 1 mm.

Figure 24. Eucalliaxiopsis patio sp. nov. Paratype, MNHN-IU-2013-2539 (male, 4.6 mm): a, b, anterior carapace, eyestalks, dorsal and lateral views; c, major cheliped (right), mesial; d, major cheliped (right), propodus, dactylus, upper; e, minor cheliped (left), mesial view; f, minor cheliped (left), propodus, dactylus, upper; g, h, pleopods 1, 2. Scale bars = 1 mm.