Galathea galene, 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 : 121-123

Galathea galene n. sp.

( Figs 40 , 116 H)

Material examined. Holotype: Vanuatu. SANTO, Stn AT69, 15°40.4'S, 167°17.3'E, 207–229 m, 5 October 2006: M 4.0 mm (MNHN-IU-2013-13963).

Paratypes: Vanuatu. SANTO, Stn AT69, 15°40.4'S, 167°17.3'E, 207–229 m, 5 October 2006: 1 ov. F 5.4 mm (MNHN-IU-2013-9878).

Etymology. The name Galene , calm, 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, and numerous long plumose iridescent setae; cervical groove distinct, laterally bifurcated. Gastric region with 5 transverse ridges: 1 epigastric ridge medially interrupted, with 2 spines, followed by some short scale-like ridges; 1 protogastric ridge medially interrupted, with 1 parahepatic spine on each side, and 1 median scale-like ridge with some long plumose setae; 1 mesogastric ridge, interrupted, not extending laterally to anteriormost of branchial marginal spines; 2 metagastric ridges, anterior ridge uninterrupted, not fused with anterior branchial ridges, posterior ridge short. Anterior branchial region with distinct ridges. Mid-transverse ridge uninterrupted, preceded by shallow cervical groove. Posterior branchial region with 5 transverse ridges, 2 ridges uninterrupted. Lateral margins slightly convex medially, with 5 spines: 1 spine in front of and 4 spines behind anterior cervical groove; first, anterolateral, welldeveloped, behind level of lateral limit of orbit, no spine ventral to between first and anterior branch of cervical groove; 2 spines on anterior branchial region, and 2 spines on posterior branchial margin. Minute spine on limit of orbit; infraorbital margin with well-developed spine. Rostrum twice longer than broad, length 0.6 postorbital carapace length and breadth 0.3 that of carapace; distance between distalmost lateral incisions 0.3 distance between proximalmost lateral incisions; dorsal surface flatish, with numerous small setose scales; lateral margin with 4 deeply incised sharp teeth.

Pterygostomian flap rugose, unarmed.

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

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

Eyes: Ocular peduncles 1.3 times longer than broad; maximum corneal diameter 0.7 rostrum width.

Antennule: Article 1 with 3 well-developed distal spines, distodorsal larger than others. Ultimate article with a few fine setae not in tuft on distodorsal margin.

Antenna: Article 1 with strong distomesial spine not reaching distal margin of article 2. Article 2 with 2 distal spines, distolateral spine longer than distomesial and exceeding midlength of article 3. Article 3 with distomesial spine; article 4 unarmed.

Mxp3: Ischium with flexor margins ending in small spine, extensor margin ending in spine; crista dentata with 23 or 24 denticles. Merus slightly longer than ischium; flexor margin with 3 spines, proximal spine clearly longer than others; extensor margin with distal spine. Carpus unarmed, extensor margin with rugosities.

P1: 3 times carapace length, with setose scales and numerous long iridescent and plumose setae. Merus 1.2 times carapace length, 1.5 times as long as carpus, with spines arranged roughly in rows, dorsomesial and ventromesial spines stronger, distal spines prominent. Carpus as long as palm, 2.3 times as long as broad; dorsal surface with some small spines arranged roughly in rows; mesial margin with some well-developed spines. Palm twice longer than broad, lateral and mesial margins subparallel, with some dorsal, mesial and lateral spines. Fingers as long as palm, each finger distally with two rows of teeth, spooned; fingers unarmed.

P2–4: moderately long and slender, with some setose striae and numerous long plumose and non-plumose setae, some of them iridescent. P2 twice carapace length. Meri successively shorter posteriorly (P3 merus 0.9 length of P3 merus, P4 merus 0.8 length of P3 merus); P2 merus 0.7 carapace length, 4.0 times as long as broad, as long as P2 propodus. P3 merus 3.8 times as long as broad, 1.2 times longer than P3 propodus. P4 merus 3.2 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 or 2 spines on P4; ventral margins distally ending in strong spine, lateral sides unarmed on P2–3, 1 or 2 small spines on P4; ventromesial margins unarmed. Carpi with 4 or 5 spines on extensor margin on P2–3, 1 on P4; lateral surface with a few granules sub-paralleling extensor margin; flexor distal margin acute. Propodi 4.6–5.2 times as long as broad; extensor margin unarmed; flexor margin with 5 or 6 slender movable spines. Dactyli distally ending in well-curved strong spine, length 0.6–0.7 that of propodi; flexor margin with 6 or 7 proximally diminishing teeth, terminal one prominent; each tooth with movable spines.

Epipods absent on pereiopods.

Coloration. Translucent light brown overall. Long setae on carapace and abdomen reddish, those on pereopods whitish.

Remarks. Galathea galene n. sp. is closest to G. raventosae Macpherson, 2012 from the Philippines to New Caledonia but the two species can be easily distinguished by the following characters:

- The rostrum is twice as long as broad in G. galene , whereas it is less than twice in G. raventosae . - The flexor margin of the Mxp3 meri has three spines, instead of two in G. raventosae . - The genetic divergences between G. galene and G. raventosae were 12.2% (16S rRNA) and 13.5% (COI) ( Tab.

1).

Galathea galene is also similar to G. balssi , but easily differentiated from the latter by the following features:

- The branchial regions of the carapace have six to eight ridges in G. balssi , whereas there areonly five ridges in G. g a l e n e.

- The flexor margin of Mxp3 merus has a long median spine in G. balssi , whereas this spine is clearly smaller in G. g a l e n e.

- The genetic divergences between G. g a l e n e and G. balssi were 11.9% (16S rRNA) and 8.6% (COI) ( Tab. 1).

Galathea galene is also close to G. lingadua n. sp. from Fiji (see Remarks of this species). Distribution. Vanuatu, 207– 229 m.

Figures

FIGURE 40. Galathea galene n. sp., holotype, male, 4.4 mm, Vanuatu (MNHN-IU- 2013 - 13963). 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, E – H = 1 mm; B – D = 0.5 mm.

FIGURE 116. Dorsal view. A, Galathea boucheti n. sp., Madagascar, holotype, male 4.0 mm (MNHN-IU- 2013 - 8110). B, Galathea caesariata n. sp., Vanuatu, holotype, male 5.0 mm (MNHN-IU- 2013 - 15938). C, Galathea celiae n. sp., Red Sea, male 2.8 mm (UF 32860). D, Galathea consobrina De Man, 1902, Vanuatu, female 3.2 mm (MNHN-IU- 2013 - 8386). E, Galathea cymo n. sp., Vanuatu, ovigerous female 4.0 mm (MNHN-IU- 2013 - 13343). F, Galathea erythrina n. sp., Red Sea, holotype, female 1.3 mm (UF 36824). G, Galathea eulimene n. sp., Red Sea, Saudi Arabia, male 3.1 mm (UF 35961). H, Galathea galene n. sp., ovigerous female 5.4 mm (MNHN-IU- 2013 - 9878). I, Galathea gladiola n. sp., Vanuatu, holotype, female 4.5 mm (MNHN-IU- 2013 - 8436).