Galathea paulae, 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 : 217-219

Galathea paulae n. sp.

( Fig. 78 )

Material examined. Holotype: Tonga. BORDAU 2, Stn CP1578, 19°42'S, 174°25'W, 329–331 m, 11 June 2000: 1 M 5.8 mm (MNHN-IU-2013-8311).

Paratypes: Fiji. MUSORSTOM 10, Stn CP1351, 17°31.14'S, 178°39.96'E, 292–311 m, 11 August 1998: 1 M 4.6 mm (MNHN-IU-2013-8314); 1 ov. F 6.1 mm (MNHN-IU-2013-8315); 2 M 6.2–6.3 mm (MNHN-IU-2013- 8313). BORDAU 1, Stn CP1403, 16°39,60'S, 179°35,96'E, 220–224 m, 25 February 1999: 1 M 7.0 mm (MNHN- IU-2013-8312).

Etymology. This species is dedicated to Paula Martin-Lefèvre of the Muséum nationale d’Histoire Naturelle, Paris, for her support to crustacean research.

Description. Carapace: As long as broad. Cervical groove distinct, laterally bifurcated. Ridges with dense short setae, with a few long plumose setae. Gastric region with 7 transverse ridges; first epigastric, with 2 submedian spines; 2 protogastric ridges, anterior one medially interrupted, posterior ridge scale-like; 2 mesogastric ridges, anterior one laterally not continuous to anteriormost branchial marginal spine, posterior ridge scale-like; 2 metagastric ridges successively shorter posteriorly, uninterrupted. Anterior branchial region with distinct ridges. Mid-transverse ridge uninterrupted, preceded by cervical groove. Posterior branchial region with 5 transverse ridges, 2 of them uninterrupted; some additional scattered scales among ridges. Lateral margins convex medially, with 9 spines: 3 spines in front of and 6 spines behind anterior cervical groove; first anterolateral, well-developed, second very small, and third, located between second and anteriormost spine of branchial margin, accompanying another small spine ventral to between first and second; 3 spines on anterior branchial margin, and 3 spines on posterior branchial margin. External limit of orbit with small spine; infraorbital margin denticulate. Rostrum triangular, 1.8 times as long as broad, length 0.5 postorbital carapace length and breadth 0.3 that of carapace; dorsal surface nearly horizontal in lateral view, with small setiferous ridges; lateral margin with 5 deeply incised teeth.

Pterygostomian flap spineless on surface, with sparse short setae, anterior margin bluntly angular.

Sternun: Plastron about as long as broad, lateral extremities gently divergent posteriorly.

Abdomen: Somites 2–4 each with 2 uninterrupted and 1 medially interrupted transverse ridges on tergite, anterior ridge more distinctly elevated than posterior ridge; somites 5 and 6 with 2 medially interrupted ridges, posterior margin of somite 6 slightly convex. Males with G1 and G2.

Eyes: Ocular peduncles 1.3 times longer than broad, maximum corneal diameter 0.6 rostrum width.

Antennula : Article 1 with 2 spines; well-developed distodorsal and distolateral spines, distodorsal larger; distomesial spine obsolescent. Ultimate article with tuft of fine setae on distodorsal margin.

Antenna: Article 1 hardly visible in dorsal view, with ventral distomesial spine exceeding distal margin of article 2. Article 2 with 2 subequal distal spines, not reaching midlength of article 3. Articles 3–4 unarmed.

Mxp3: Ischium with small spine on flexor distal margin; extensor margin with small but distinct distal spine; crista dentata with 22 or 23 denticles. Merus shorter than ischium; flexor margin with 2 strong subequal spines; extensor margin with distal spine. Carpus unarmed.

P1: 3.0 times carapace length, with setose scales and some long plumose setae. Merus 1.3 times as long as carapace, 2.0–2.1 times as long as carpus, with spines arranged roughly in rows, dorsomesial and ventromesial spines stronger, distal spines prominent. Carpus 0.6–0.7 length of palm, 2.0–2.1 times as long as broad; dorsal surface with some small spines arranged roughly in rows; mesial margin with 3 or 4 spines (distal second largest). Palm 2.4–2.6 times longer than broad, lateral and mesial margins subparallel; spines arranged roughly in dorsolateral and dorsomesial rows, some small spines scattered on dorsal side; dorsolateral row continuing along entire lateral margin of fixed finger. Fingers 0.7–0.8 length of palm, each finger distally with two rows of teeth, spooned; mesial margin of movable finger unarmed.

P2–4: moderately slender, with setose striae, and some long plumose setae. P2 1.7 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 0.8 carapace length, 5.5 times as long as broad, 1.8 times longer than P2 propodus; P3 merus 4.0 times longer than broad, 1.5 times longer than P3 propodus; P4 merus 3.3 times as long as broad, 1.3 length of P4 propodus. Extensor margins with row of 9–11 proximally diminishing small spines on P2–3, distal spine only on P4; flexolateral surface unarmed on P2–4; flexolateral margin distally ending in strong spine followed proximally by several prominences. Carpi with 3 or 4 small spines on extensor margin on P2–3, 1 or 2 minute spines on P4; lateral surface with acute granules sub-paralleling extensor margin on P2–4; flexor distal margin with small distal spine. Propodi 4.6 (P2), 4.3 (P3), 4.0 (P4) 4 times as long as broad; extensor margin unarmed; flexor margin with 6 or 7 slender movable spines on P2–4. Dactyli subequal in length, distally ending in well-curved strong spine, 0.5–0.6 length of propodi; flexor margin with 5 successively diminishing teeth, terminal one prominent.

Epipods on P1, absent on P2–4.

Remarks. Galathea paulae n. sp. is closely related to G. inermis n. sp. from the Solomon Islands (see above) and G. sanctae Macpherson, 2012 from Vanuatu and New Caledonia. Galathea paulae and G. s a n c t a e can be differentiated by the shape of the rostrum, being less than 1.5 times longer than broad in G. s a n c t a e, in contrast more than 1.5 times in G. paulae . Furthermore, the P2 merus is less than 5 times longer than broad in G. s a n c t a e, whereas is more than 5 times in G. paulae .

The genetic divergences between G. sanctae and G. paulae are 12.1% (COI) and 6.4 (16S rRNA), and the divergences between G. paulae and G. inermis are 17.4% (COI) and 7.0% (16S rRNA) ( Tab. 3 ).

Distribution. Fiji, Tonga; 220– 331 m.

Figures

FIGURE 78. Galathea paulae n. sp., holotype, male, 5.8 mm, Tonga (MNHN-IU- 2013 - 8311). 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, left P 2, lateral view; G, left P 4, lateral view. Scale: A, E, F, G = 1 mm; B – D = 0.5 mm.