Galathea corbariae, 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 : 91-94

Galathea corbariae n. sp.

( Fig. 28 )

Material examined. Holotype: Vanuatu. SANTO, Stn FB61, 15°34.4'S, 167°12.6'E, 2–3 m, 7 October 2006: 1 ov. F 2.8 mm (MNHN-IU-2013-8020).

Paratypes: Japan. Ryukyu Islands. Yaeyama Islands, Iriomote Island, Hoshizuna Beach, 24.44°N, 123.7769°E, 17 m, 10 July 2010: 1 M 4.1 mm (UF26922): 1 ov. F 5.0 mm (UF26923); Mitara Beach, 24.3738°N, 123.7505°E, 2–3 m, 11 July 2010: 1 ov. F 5.0 mm (UF26929); Unari-Zaki, 24.4259°N, 123.7659°E, 3–21 m, 8 July 2010: 1 M 5.3 mm (UF26896).

Indonesia. Moluccas Islands. Ternate, 1894: 1 M 3.5 mm, 2 ov. F 3.9–4.1 mm (SM4571). East coast of Marsegu Island. 18 January 1975: 1 M 4.7 mm (MNHN-Ga1139, MNHN-IU-2013-14267). Gorong Island. 26 January 1975: 3 M 3.0– 4.9 mm, 1 ov. F 2.5 mm, 1 F 2.2 mm (MNHN-Ga1140, MNHN-IU-2013-14266). 27 January 1975: 1 ov. F 2.4 mm, 1 F 2.3 mm (MNHN-Ga1141, MNHN-IU-2013-14268).

Vanuatu. SANTO, Stn DB48, 15°38.7'S, 167°5.2'E, 10–17 m, 21 September 2006: 1 ov. F 3.9 mm (MNHN- IU-2013-8022).—Stn FB61, 15°34.4'S, 167°12.6'E, 2–3 m, 7 October 2006: 6 M 2.2–4.1 mm, 6 ov. F 2.5–3.8 mm (MNHN-IU-2013-8021).

Etymology. This species is dedicated to Laure Corbari of the Muséum nationale d’Histoire Naturelle, Paris, for her support to crustacean research.

Description. Carapace: Slightly longer than broad; anterior cervical groove indistinct. Five ridges on gastric region: 1 epigastric ridge medially interrupted, with 2 epigastric spines; 1 protogastric ridge, strongly convex medially, uninterrupted, with 1 parahepatic spine at each side; 1 mesogastric ridge uninterruptedly extending laterally to anteriormost of branchial marginal spines; 2 uninterrupted metagastric ridges. Mid-transverse ridge uninterrupted, preceded by shallow cervical groove, followed by 5 transverse ridges, 2 of them uninterrupted. Lateral margins medially convex, with 7 spines: 2 spines in front of, and 5 spines behind, indistinct 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, accompanying another spine ventral to between first and second; 2 spines on anterior branchial region, and 3 spines on posterior branchial margin, last small. External limit of orbit ending in small spine; infra-orbital margin with strong spine. Rostrum broad triangular, as long as broad, length 0.5 that of, 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 some thick long plumose setae; lateral margin with 4 sharp spines. Ridges with numerous unirramous setae, and some thick long plumose setae more dense on dorsal surface of rostrum, between epigastric spines, on median convexity of anterior protogastric ridge and cardiac region.

Pterygostomian flap rugose, anterior margin ending in well-developed spine.

Sternum: As long as broad, lateral limits divergent posteriorly.

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

Eyes: Ocular peduncles 1.1 times longer than broad, maximum corneal diameter 0.5 rostrum width.

Antennule: Article 1 with 3 well-developed distal spines, distodorsal larger. Ultimate article elongate, 2.5 times longer than broad, with tuft of setae on distodorsal margin.

Antenna: Article 1 hardly visible from dorsal view, with depressed ventral distomesial process slightly exceeding distal margin of peduncle. Article 2 with distomesial spine as long as distolateral, reaching midlength of article 3. Articles 3 and 4 unarmed.

Mxp3: Ischium with well-developed distal spine on flexor margin; extensor margin unarmed; crista dentata with 23–27 denticles. Merus subequal in length to ischium, with 2 strong spines of subequal size on flexor margin, proximal one located at midlength, distal one at terminal end; extensor margin with small distal spine. Carpus spineless.

P1: 2.6–3.0 times carapace length, with numerous short setae and some scattered long plumose setae on dorsal surface and along lateral and mesial margins of all articles. Merus 0.9 times length of carapace, 1.6 times as long as carpus, with rows of spines, mesial and distal spines strong. Carpus 0.8 length of palm, 2.2 times longer than broad, lateral and mesial margins subparallel, dorsal surface with small spines in longitudinal row; mesial surface with row of well-developed spines; and row of small spines along lateral margin. Palm 2.5 times longer than broad, lateral and mesial margins subparallel; spines roughly in rows on dorsal, mesial and lateral; lateral row continued on to whole lateral margin of fixed finger. Fingers 0.8 as long as palm, each finger distally with two rows of teeth, spooned, mesial margin of movable finger unarmed.

P2–4: Relatively slender, moderately setose, sparsely with long setae on all articles. P2 1.7 times carapace length. P2–3 meri subequal in length, P4 merus 0.8 length of P3 merus, equally broad on P2–4. P2 merus 0.7 carapace length, 3 times as long as broad, 1.5 times longer than P2 propodus; P3 merus 3 times as long as broad, 1.3 times length of P3 propodus; P4 merus 2.4 times as long as broad, as long as P4 propodus. Extensor margins with row of 8 or 9 proximally diminishing spines on P2–3, only distal spine on P4; lateral surface unarmed on P2–3, row of 2 or 3 spines on P4; flexor margins with strong terminal spine; ventromesial margin with terminal spine on P2 only. Carpi with 4 spines on extensor margin; lateral surface with row of 2 or 3 small spines paralleling extensor row; flexor distal margins with small spine. Propodi subequal in length on P3 and P4, slightly shorter on P2, equally broad on P2–4, and 4 times as long as broad; extensor margin with 2 or 3 proximal spines on P2–4; flexor margin with 4 slender movable spines on P2–4; 1 proximal spine on lateral side of P4, unarmed on P2–3. Dactyli subequal in length, 0.6 length of propodi, ending in incurved, strong, sharp spine; flexor margin with prominent triangular terminal tooth preceded by 4 or 5 obsolescent teeth.

Epipods present on P1, absent on P2–3.

Remarks. The new species is closely related to G. aegyptiaca Paul’son, 1875 (see the differences under Remarks for this species) and G. homologa n. sp. Galathea corbariae resembles G. homologa from which it can be distinguished by the more slender ultimate article of the antennular peduncle, 2.5 times longer than broad in G. corbariae , versus at most twice longer than broad in G. homologa . Furthermore, the rostrum is longer than broad in G. homologa , instead of as long as broad in G. corbariae .

The genetic divergences between G. corbariae and G. homologa are 11.3% COI, and 1.2% 16S rRNA, see Tab. 1).

Distribution. Japan (Ryukyu Islands), Indonesia ( Moluccas Islands) and Vanuatu, 2– 21 m.

Figures

FIGURE 28. Galathea corbariae n. sp., holotype, ovigerous female, 2.8 mm, Vanuatu (MNHN-IU- 2013 - 8020). 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, left P 1, dorsal view; F, left P 2, lateral view; G, right P 3, lateral view; H, right P 4, lateral view; I, ultimate article of antennular peduncle. Scale: A, E – H = 1 mm; B – D = 0.5 mm.