Galathea eione, Macpherson, Enrique & Robainas-Barcia, Aymee, 2015

Macpherson, Enrique & Robainas-Barcia, Aymee, 2015, Species of the genus Galathea Fabricius, 1793 (Crustacea, Decapoda, Galatheidae) from the Indian and Pacific Oceans, with descriptions of 92 new species, Zootaxa 3913 (1), pp. 1-335 : 102-104

Galathea eione n. sp.

( Fig. 32 )

Material examined. Holotype: Fiji. SUVA 2, Stn CP66, 17°45.1'S, 177°13.7'E, 37 m, 21 October 1998: M 4.2 mm (MNHN-IU-2013-13606).

Paratypes: Fiji. MUSORSTOM 10, Stn CP1358, 17°48,49'S, 178°46,70’E, 80–120 m, 13 August 1998: 5 M 2.5–3.5 mm, 2 ov. F 3.3–3.5 mm, 4 F 3.1–3.5 mm (MNHN-IU-2013-13607). SUVA 2, Stn CP46, 17°52.5'S, 177°15.5'E, 25 m, 19 October 1998: 1 ov. F 2.8 mm (MNHN-IU-2013-13609).— Stn CP48, 17°56.2'S, 177°14.3'E, 16 m, 19 October 1998: 20 M 3.3–5.6 mm, 17 ov. F 3.5–5.7 mm, 3 F 3.0– 3.1 mm (MNHN-IU-2013-13611).—Stn DW53, 17°44.2'S, 177°18.4'E, 28 m, 20 October 1998: 1 ov. F 4.0 mm (MNHN-IU-2013-13610).—Stn CP66, 17°45.1'S, 177°13.7'E, 37 m, 21 October 1998: 19 M 3.0– 5.3 mm, 12 ov. F 2.8–3.7 mm, 4 F 2.4–3.4 mm (MNHN- IU-2013-13612); 1 ov. F 3.5 mm (MNHN-IU-2013-13613); 1 ov. F 3.4 mm (MNHN-IU-2013-13614); 1 ov. F 3.7 mm (MNHN-IU-2013-13615); 1 ov. F 3.5 mm (MNHN-IU-2013-13616). BORDAU 1, Stn CP1438, 17°13.2'S, 178°48'E, 97-104 m, 3 March 1999: 1 ov. F 4.0 mm, 1 F 3.0 mm (MNHN-IU-2013-13608).

Etymology. The name Eione , strand, refers to one of the Nereids of Greek mythology. The name is considered as a substantive in apposition.

Description. Carapace: As long as broad; transverse ridges with dense short setae, without long setae; cervical groove distinct, laterally bifurcated. Gastric region with some transverse ridges: 1 epigastric ridge unarmed, uninterrupted, medially convex; 2 protogastric ridges, anterior one uninterrupted, medially convex, posterior ridge scale-like; 1 mesogastric ridge uninterrupted but not extending laterally to anteriormost of branchial marginal spines; 2 metagastric ridges, anterior one uninterrupted, not continuing laterally to anteriorbranchial ridges, posterior ridge short; some additional scattered scales in some specimens. Hepatic region unarmed. Anterior branchial region with distinct ridges. Mid-transverse ridge uninterrupted, preceded by shallow cervical groove, followed by 5 ridges, 3 of them uninterrupted. Lateral margins well convex medially, with 7 spines: 2 spines in front of, and 5 spines behind, anterior cervical groove; first anterolateral, well-developed, at same level of lateral limit of orbit, second, small, at midlength between anterolateral spine and anteriormost spine of branchial margin, with small spine ventral to between first and second; 2 spines on anterior branchial region, last small, and 3 spines on posterior branchial margin, last small and obsolescent in some specimens. Small spine on lateral limit of orbit; infraorbital margin with strong spine. Rostrum 1.8–1.9 times as long as broad, length 0.6 postorbital carapace length and breadth 0.4 that of carapace; distance between distalmost lateral incisions 0.3 distance between proximalmost lateral incisions; dorsal surface nearly horizontal in lateral view, with numerous small scale-like setose ridges; lateral margin with 4 deeply incised teeth.

Pterygostomian flap rugose, unarmed, ridges with short setae, anterior margin acute.

Sternum: As long as broad, lateral extremities gently divergent posteriorly. Abdomen: Somites 2–4 each with 2 or 3 uninterrupted transverse ridges on tergite; somites 5 and 6 each with 2 medially interrupted ridges, sometimes anterior ridge uninterrupted. Males with G1 and G2.

Eyes: Ocular peduncles 1.5 times longer than broad, maximum corneal diameter 0.7 rostrum width.

Antennule: Article 1 with 3 well-developed distal spines, distodorsal larger, distomesial spine slightly smaller than others. Ultimate article with some fine setae, not in tuft, on distodorsal margin.

Antenna: Article 1 with ventral distomesial spine exceeding distal margin of article 2. Article 2 with 2 small distal spines, distolateral spine longer than distomesial, and reaching midlength of article 3. Articles 3 and 4 unarmed.

Mxp3: Ischium with flexor and extensor margins ending in blunt angle or with small spine; crista dentata with 20 or 21 denticles. Merus as long as ischium; flexor margin with 2 subequal spines; extensor margin unarmed. Carpus unarmed.

P1: 3.2–3.6 times carapace length, with numerous setiferous scales, and some scattered long non-plumose setae. Merus 1.5 times carapace length, 2.0 times as long as carpus, with some spines, dorsomesial and distal spines stronger than others. Carpus 0.8 length of palm, twice longer than broad; dorsal surface with some small spines; mesial margin with row of spines, distal slightly stronger than others. Palm 2.3–2.6 times longer than broad, lateral and mesial margins slightly divergent; small spines arranged roughly in dorsal, dorsolateral and dorsomesial rows. Fingers 0.8 times palm length, each finger with two rows of teeth distally spooned; fixed finger with some proximal spines along lateral margin; movable finger unarmed.

P2–4: Long and slender, with some setose striae and some long non-plumose setae. P2 1.8 times carapace length. Meri successively shorter posteriorly (P3 merus 0.9 length of P2 merus, P4 merus 0.8 length of P3 merus); P2 merus 0.7 carapace length, 3.6 times as long as broad, 1.3 times longer than P2 propodus; P3 3.6 times as long as broad, slightly longer than P3 propodus; P4 merus 3.7 times as long as broad, as long as P4 propodus. Extensor margin with row of 7 or 8 proximally diminishing spines on P2–3, 1 distal spine on P4; ventral margins distally ending in strong spine, lateral sides with 0–2 small spines on P4. Carpi with 3–5 spines on extensor margin on P2- 3, 0–1 distal spine on P4, distalmost smaller than distal second, sometimes absent; lateral surface with 3 or 4 small spines or acute granules sub-paralleling extensor margin; flexor distal margin acute. Propodi 4.9–5.1 times as long as broad; extensor margin with 0–3 minute proximal spines; flexor margin with 4–6 slender movable spines. Dactyli distally ending in well-curved strong spine, length 0.5–0.6 that of propodi; flexor margin with 4 or 5 proximally diminishing teeth, terminal one prominent.

Epipods present on P1.

Remarks. Galathea eione n. sp. appears close to G. providentia Laurie, 1926 and G. ternatensis De Man, 1902 These species are characterized by an interrupted mesogastric ridge, non-scale-like gastric ridges, the carapace lateral margin bearing one small but distinct spine between the anterolateral spine and the anteriormost branchial marginal spine, the antennular basal article with three well-developed terminal spines, the lack of epigastric spines, and the presence of epipod only on P1. Galathea eione is easily distinguished from these species by the absence of hepatic spines, which is always present in G. providentia and G. ternatensis (see Remarks of G. providentia and G. ternatensis ).

Distribution. Fiji, 16– 120 m.

Figures

FIGURE 32. Galathea eione n. sp., holotype, male, 4.2 mm, Fiji (MNHN-IU- 2013 - 13606). A, carapace and abdomen, dorsal view; B, thoracic sternites 3 and 4; C, left part of cephalothorax, ventral view, showing antennular and antennal peduncles, and anterior part of pterygostomian flap; D, ischium, merus and carpus of right Mxp 3, lateral view; E, right P 1, dorsal view; F, right P 2, lateral view; G, right P 3, lateral view; H, left P 4, lateral view. Scale: A, F – H = 1 mm; E = 2.0 mm; B – D = 0.5 mm.