Galathea atua, 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 : 48-50

Galathea atua n. sp.

( Fig. 12 )

Material examined. Holotype: French Polynesia. Austral Islands, RAPA, Stn 5, 27°05.6'S, 144°18.5'W, 8 m, 4 November 2002: 1 ov. F 3.8 mm (MNHN-IU-2013-13218).

Etymology. Atua is the family god in Polynesian mythology. It is considered as a substantive in apposition.

Description. Carapace: Slightly broader than long; transverse ridges with dense very short setae, without long setae; posterior cervical groove distinct, anterior branch indistinct. Gastric region with 4 transverse ridges: 1 epigastric ridge medially interrupted, with 2 submedian spines; 1 protogastric ridge uninterrupted, without parahepatic spines; 1 mesogastric ridge medially interrupted and laterally extending to anteriormost branchial spines; 2 metagastric ridges, anterior one medially interrupted, not continuing to anterior branchial regions, posterior ridge scale-like. Anterior branchial region with distinct ridges. Mid-transverse ridge uninterrupted, preceded by cervical groove, followed by 4 ridges, 2 of them uninterrupted. Lateral margins slightly convex, with 7 spines: 2 spines in front of, and 5 spines behind, anterior cervical groove; first (anterolateral) well-developed, at same level of lateral limit of orbit; second small, additional spine present ventral to between first and second spines; 2 spines on anterior branchial margin, and 3 spines on posterior branchial margin, last small. Lateral limit of orbit with spine; infraorbital margin with strong spine. Rostrum 1.2 times as long as broad, length 0.5 of postorbital carapace length and breadth 0.4 of carapace width; distance between distalmost lateral incisions 0.25 distance between proximalmost lateral incisions; dorsal surface nearly horizontal in lateral view, with some short setae; lateral margin with 4 deeply incised sharp teeth.

Pterygostomian flap rugose, unarmed, ridges with short setae, anterior margin acutely pointed.

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

Abdomen: Somite 2 with 2 transverse uninterrupted ridges; somites 3–6 with anterior margin only, tergites smooth; posteromedian margin of somite 6 straight.

Eyes: Ocular peduncles 1.3 times longer than broad, maximum corneal diameter 0.6 rostrum width. Antennule: Article 1 with 3 well-developed distal spines, distodorsal larger, distomesial spine slightly smaller. Ultimate article with a few short fine setae not in tuft on distodorsal margin.

Antenna: Article 1 with distomesial spine reaching distal margin of article 2. Article 2 with 2 subequal distal spines, reaching midlength of article 3. Article 3 with distomesial spine. Article 4 unarmed.

Mxp3: Ischium with small spine on flexor and extensor distal margins; crista dentata with 27 or 28 denticles. Merus as long as ischium; flexor margin with 2 subequal well-developed spines; extensor margin with distinct spine. Carpus unarmed, rugose along extensor margin.

P1: 2.2 times carapace length, covered with finely setiferous scales, with scattered long non-iridescent setae. Merus 0.8 length of carapace, 1.4 times as long as carpus, with spines arranged in longitudinal rows, dorsomesial spines stronger. Carpus as long as palm, 3.0 times as long as broad; dorsal and lateral surfaces with some spines; mesial margin also with some spines. Palm 3.0 times longer than broad, lateral and mesial margins subparallel; spines arranged in dorsolateral and dorsomesial rows, dorsolateral row continuing along proximal half of fixed finger; a few small spines scattered on dorsal side. Fingers 0.8 length of palm, each finger with 2 rows of teeth distally spooned; movable finger without spines.

P2–4: moderately slender, with setose striae and sparse long setae (setae non-iridescent). P2 twice carapace length. Meri successively shorter posteriorly (P3 merus 0.9 length of P3 merus, P4 merus 0.7 length of P2 merus); P2 merus 0.8 of carapace length, 3.8 times as long as broad, 1.4 times longer than P2 propodus; P3 merus 3.4 times as long as broad, 1.3 times longer than P3 propodus; P4 merus 3.0 times as long as broad, as long as P2 propodus; extensor margins each with row of 10 or 11 proximally diminishing spines on P2–3, unarmed in P4; ventral margins distally ending in strong spine followed proximally by 0–1 spines and several transverse ridges; lateral sides unarmed. Carpi each with 2–4 spines on extensor margin in P2–3, unarmed in P4; lateral surfaces with some acute granules sub-paralleling extensor margin; flexor distal margins acute. P2–4 propodi 4.8–5.0 times as long as broad; extensor margins each with 0–1 proximal spines; flexor margins each with 4 or 5 slender movable spines. Dactyli distally ending in noticeably curved strong spine, 0.5 times as long as propodi; flexor margins each with 4 proximally diminishing teeth, terminal one prominent.

Epipod present only on P1.

Remarks. This species resembles G. eridani n. sp. from Mozambique and New Caledonia, G. m a r i a e n. sp. from French Polynesia, New Caledonia and the Maldives, and G. whiteleggii Grant & McCulloch 1906 from Australia (see below under Remarks for these species).

No molecular data are available from G. atua .

Distribution. French Polynesia, Austral Islands, 8 m.

Figures

FIGURE 12. Galathea atua n. sp., holotype, ovigerous female, 3.8 mm, French Polynesia (MNHN-IU- 2013 - 13218). 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, 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.