Galathea homologa, 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 : 139-140

Galathea homologa n. sp.

( Fig. 47 )

Material examined. Holotype: Vanuatu. SANTO, Stn DB1, 15°33.1'S, 167°17.8'E, 15–25 m, 10 September 2006: F 3.0 mm (MNHN- IU-2013-8050).

Etymology. From the Greek homologos, agreeing, in reference to the close relationship with the G. aegyptiaca species group.

Description. Carapace: Slightly broader than long; anterior cervical groove indistinct. Five ridges on gastric region: 1 epigastric ridge with 2 median epigastric spines, medially interrupted; 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, anterior ridge sometimes fused with anterior branchial ridges. Mid-transverse ridge uninterrupted, preceded by shallow cervical groove, usually followed by 5 ridges. 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, 1.3 times as long as broad, length 0.6 that of, breadth 0.4 that of carapace; distance between distalmost lateral incisions 0.25 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 between epigastric spines and on median convexity of second gastric ridge.

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 slightly convex.

Eyes: Ocular peduncles 1.1 times longer than broad, maximum corneal diameter 0.6 rostrum width.

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

Antenna. Article 1 with depressed ventral distomesial process slightly exceeding distal margin of peduncle. Article 2 with distomesial spine as long as distolateral, exceeding 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 22 denticles. Merus slightly shorter than ischium, with 2 strong spines of subequal size on flexor margin, proximal one located at midlength, distal one at terminal end; extensor margin with distal spine. Carpus spineless.

P1: missing.

P2–4: Relatively slender, moderately setose, with long plumose setae on all articles. P2 1.7 times carapace length. P2–3 meri subequal in length, P4 merus 0.9 length of P3 merus, equally broad on P2–4. P2 merus 0.7 carapace length, 3.3 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 3 times as long as broad, 1.2 length of 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 4 spines on P4; flexor margins with strong terminal spine; ventromesial margin with terminal spine on P2–3. Carpi with 3 or 4 spines on extensor margin; lateral surface with row of 2–4 small spines paralleling extensor row; flexor distal margins with small spine. Propodi subequal in length on P2 and P4, slightly longer on P3, equally broad on P2–4, each about 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; lateral side unarmed on P2–4. Dactyli subequal in length, 0.5–0.6 length of propodi, ending in incurved, strong, sharp spine; flexor margin with prominent triangular terminal tooth preceded by obsolescent 4 teeth.

Epipods present only on P1.

Remarks. The species is close to G. aegyptiaca and G. corbariae n. sp. (see Remarks for these species).

Distribution. Vanuatu, 15– 25 m.

Figures

FIGURE 47. Galathea homologa n. sp., holotype, female, 3.0 mm, Vanuatu (MNHN-MNHN-IU- 2013 - 8050). A, carapace and abdomen, dorsal view; B, sternal plastron; 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 2, lateral view; F, right P 3, lateral view; G, right P 4, lateral view; H, ultimate article of antennular peduncle. Scale: A, E, F, G = 1 mm; B – D = 0.5 mm.