Galathea cymothoe, 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 : 99-102

Galathea cymothoe n. sp.

( Fig. 31 )

Material examined. Holotype: New Caledonia. Chesterfield Islands. CORAIL 2, Stn CP131, 19°25'S, 158°38'E, 215-217 m, 29 July 1988: M 4.3 mm (MNHN-IU-2013-15820).

Paratypes: Vanuatu. SANTO, Stn EP36, 15°33.1/33.3'S, 167°12.4–12.7'E, 20–60 m, 15 October 2006: 3 M 2.0– 2.3 mm (MNHN-IU-2013-15822).

New Caledonia. Chesterfield Islands. CHALCAL 84, Stn CP12, 20°34.30'S, 158°47.40'E, 67 m, 23 July 1984: 1 ov. F 3.2 mm (MNHN-IU-2013-8459). CORAIL 2, Stn DW3, 20°50.42'S, 161°34.19'E, 58 m, 20 July 1988: 1 M 4.0 mm (MNHN-IU-2013-13970).—Stn DW117, 19°25'S, 158°32'E, 52 m, 28 July 1988: 1 ov. F 3.5 mm (MNHN- IU-2013-15821).—Stn DW144, 19°28'S, 158°23'E, 50 m, 30 July 1988: 1 ov. F 3.2 mm (MNHN-IU-2013-15824), 1 M 3.2 mm (MNHN-IU-2013-13946), 1 F 3.3 mm (MNHN-IU-2013-13947).—Stn DW160, 19°46'S, 158°23'E, 35–41 m, 1 August 1988: 1 M 4.1 mm (MNHN-IU-2013-13959).—Stn DW166, 19°41'S, 158°25'E, 56 m, 2 August 1988: 1 M 3.6 mm (MNHN-IU-2013-15826).

New Caledonia. SMIB 5, Stn DW99, 23°24.70'S, 168°05.40'E, 58 m, 14 September 1989: 2 ov. F 5.3–6.2 mm (MNHN-IU-2013-15823).

Etymology. The name Cymothoe , running waves, 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 moderately long unirranous setae, and a few scattered moderately long non-plumose setae; cervical groove distinct, laterally bifurcated. Gastric region with 9 transverse ridges: 2 epigastric ridges, anterior one medially interrupted, with 2 spines, posterior ridge medially interrupted; 2 protogastric ridges, anterior ridge uninterrupted, not extending laterally to second lateral spine, convex medially, with 1 parahepatic spine on each side; 2 mesogastric ridges, anterior ridge not extending laterally to anteriormost of branchial marginal spines, posterior ridge scale-like; 3 metagastric ridges not extending laterally to anterior branchial ridges; a few additional scattered scale-ridges. Anterior branchial region with distinct ridges. Mid-transverse ridge uninterrupted, preceded by shallow cervical groove, followed by 6 transverse ridges, 3 of them uninterrupted. Lateral margins convex medially, with 8 spines: 2 spines in front of and 6 spines behind anterior cervical groove; first anterolateral, well-developed, at level of lateral limit of orbit; second, small, at midlength between anterolateral spine and anteriormost spine of branchial margin, with accompanying spine ventral to between first and second; 3 spines on anterior branchial region, and 3 spines on posterior branchial margin, last small. Small spine between lateral limit of orbit and anterolateral spine; infraorbital margin with strong spine. Rostrum 1.8 as long as broad, length 0.6–0.7 postorbital carapace length and breadth 0.3 that of carapace; distance between distalmost lateral incisions 0.3 distance between proximalmost lateral incisions; dorsal surface nearly horizontal in lateral view, with numerous setae; lateral margin with 4 deeply incised sharp teeth.

Pterygostomian flap rugose, with spine on anterior ridge, ridges with short setae, anterior margin ending in acute angle.

Sternum: 0.8 times as long as broad, lateral extremities gently divergent posteriorly.

Abdomen: Somites 2–3 each with 3 or 4 uninterrupted transverse ridges on tergite; somite 4 with 4 ridges, 2 interrupted and 2 uninterrupted; somites 5 with 2 uninterrupted ridges; somite 6 each with 2 medially interrupted ridges, posteromedian margin straight. Males with G1 and G2.

Eyes: Ocular peduncles 1.5 times longer than broad, maximum corneal diameter 0.8 rostrum width.

Antennule: Article 1 with 2 spines; well-developed distodorsal and distolateral spines, distodorsal larger; distomesial spine minute or obsolescent. Ultimate article with a few short fine setae, not in tuft on distodorsal margin.

Antenna: Article 1 with ventral distomesial spine not reaching distal margin of article 2. Article 2 with 2 welldeveloped distal spines, distolateral spine slightly longer than distomesial and reaching midlength of article 3. Articles 3 and 4 unarmed.

Mxp3: Ischium with well-developed spine on flexor distal margin; extensor margin ending in acute angle; crista dentata with 20 or 21 denticles. Merus as long as ischium; flexor margin with 2 subequal spines; extensor margin with 1-2 minute spines. Carpus unarmed.

P1: 3.0 times carapace length, covered with finely setiferous scales, with numerous long non-plumose setae. Merus 1.2 times length of carapace, 1.4 times as long as carpus, with spines arranged roughly in rows, dorsomesial spines stronger; distal spines prominent. Carpus 0.9 length of palm, 2.3 times as long as broad; dorsal surface with some small spines; mesial margin with row of well-developed spines. Palm 2.3 times longer than broad, lateral and mesial margins subparallel; a few small spines arranged roughly in dorsolateral and dorsomesial rows, some small spines scattered on dorsal side; dorsolateral spines continuing along fixed finger. Fingers 0.6 length of palm, each finger with two rows of teeth distally spooned; movable finger with 2 or 3 small proximal spines.

P2–4: Moderately slender, with setose striae and numerous 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, 1.4 times longer than P2 propodus; P3 merus 3.1 times longer than broad, 1.2 times longer than P3 propodus; P4 merus 3.0 times as long as broad, 1.2 length of P4 propodus. Extensor margin of P2–3 meri with row of 8 proximally diminishing spines, and 1 distal spine on P4; ventral margins distally ending in strong spine followed proximally by several tubercles or eminences; lateral sides unarmed on P2–3, with 3 small spines on P4. Carpi with 5 or 6 spines on extensor margin on P2–4; lateral surface with 3 or 4 spines (on P2) or acute granules (P3–4) sub-paralleling extensor margin on P2–4; flexor distal margin ending in acute angle. P2–4 propodi 4.5–4.7 times as long as broad; extensor margin with 0–2 proximal spines; flexor margin with 6 or 7 slender movable spines on P2–4. 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 on P1 and rarely on P2.

Remarks. The closest relative of the present new species is G. clarki n. sp. from the South China Sea, from which G. cy m o t h o e can be distinguished by the following characters:

- The epipods are present on P 1–3 in G. clarki , but only on P1 (rarely on P2) in G. cymothoe .

- The rostrum is narrower in G. clarki (nearly twice longer than broad, and length 0.5 postorbital carapace length) than in G. cymothoe (clearly less than twice longer than broad, and length 0.6–0.7 postorbital carapace length).

No genetic data are available for this species.

Distribution. Vanuatu, New Caledonia, Chesterfield Islands, 20– 217 m.

Figures

FIGURE 31. Galathea cymothoe n. sp., holotype, male, 4.3 mm, New Caledonia, Chesterfield Islands (MNHN-IU- 2013 - 15820). 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, right P 4, lateral view. Scale: A, F – H = 1 mm; E = 2.0 mm; B – D = 0.5 mm.