Galathea rangi, 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 : 263-265

Galathea rangi n.sp.

( Fig. 94 )

Material examined. Holotype: French Polynesia. Austral Islands. BENTHAUS, Stn DW1997, 22°29.14'S, 151°22.30'W, 700–1350 m, 23 November 2002: M 3.5 mm (MNHN-IU-2013-8304).

Etymology. In the Pacific mythology, Rangi is the Polynesian sky-god creator. The name is considered as a substantive in apposition.

Description. Carapace: as long as broad; transverse ridges with dense short setae, and some scattered long non-plumose setae; cervical groove distinct, laterally bifurcated. Gastric region with 6 transverse ridges: 1 epigastric ridge uninterrupted, unarmed; 2 protogastric ridges, anterior extending laterally to second marginal spines, posterior ridge scale-like, median scale convex, with some long non-plumose setae; 1 mesogastric ridge uninterrupted but not extending laterally to anteriormost of branchial marginal spines; 2 metagastric uninterrupted ridges, not extending laterally to anterior branchial regions. One small hepatic spine near first marginal spine (anterolateral). Anterior branchial region with distinct ridges. Mid-transverse ridge uninterrupted, preceded by shallow cervical groove, followed by 5 ridges, 2 uninterrupted. Lateral margins well convex medially, with 7 spines: 2 spines in front of, and 5 spines behind, anterior cervical groove; first spine on anterolateral angle, at same level of lateral limit of orbit; second small, at midlength between anterolateral spine and anterior cervical groove, with spine ventral to between first and second; 1 additional small spine between lateral limit of orbit and first anterolateral spine; 2 spines on anterior branchial region, and 3 spines on posterior branchial margin, last small. Small spine on lateral limit of orbit, 1 minute frontal spine; infraorbital margin with 3 or 4 small spines. Rostrum 1.6 as long as broad, length 0.7 postorbital carapace length and 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 numerous scale-like setose ridges; lateral margin with 4 deeply incised sharp teeth.

Pterygostomian flap rugose, unarmed, ridges with short setae, anterior margin bluntly angular.

Sternum: 0.8 times as long as broad, lateral extremities gently divergent posteriorly.

Abdomen: Somites 2–3 each with 3 uninterrupted or medially interrupted transverse ridges on tergite; somites 4–5 each with 2 uninterrupted ridges, somite 6 with 2 medially interrupted ridges, posteromedian margin transverse. Males with G1 and G2.

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

Antennule: Article 1 with 3 well-developed distodorsal and distolateral spines, distodorsal larger; distomesial spine smaller than others. Ultimate article twice longer than broad, with a few short fine setae not in tuft on distodorsal margin.

Antenna: Article 1 with ventral distomesial spine nearly reaching distal margin of article 2. Article 2 with 2 well-developed distal spines, distolateral spine larger than distomesial and nearly reaching end of article 3. Article 3 with small distomesial spine. Article 4 unarmed.

Mxp3: Ischium with well-developed spine on flexor distal margin; extensor margin unarmed; crista dentata with 8 strong denticles. Merus shorter than ischium; flexor margin with 2 subequal strong spines; extensor margin with distal spine. Carpus unarmed.

P1: 2.7 times carapace length, covered with finely setiferous scales, with scattered long non-plumose setae. Merus as long as carapace, 2.5 times as long as carpus, with spines arranged roughly in rows, dorsomesial spines stronger; distal spines prominent. Carpus 0.5 length of palm, 1.3 times as long as broad; dorsal surface with some small spines; mesial margin with 3 spines (distal second strong). Palm twice longer than broad, lateral and mesial margins slightly convex; spines arranged roughly in dorsolateral and dorsomesial rows, some small spines scattered on dorsal side; dorsolateral row continuing along entire fixed finger. Fingers 0.6 length of palm, each finger with 1 row of teeth, distally not spooned, prehensile distal edges close fitting with small blunt teeth; mesial margin of movable finger with distal spine.

P2–4: moderately slender, with setose striae and sparse long non-plumose setae. P2 1.8 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 0.7 carapace length, 3.6 times as long as broad, 1.4 times longer than P2 propodus; P3 merus 3.2 times longer than broad, 1.1 times longer than P3 propodus; P4 merus 2.8 times as long as broad, 1.0–1.1 length of P4 propodus. Extensor margin of P2–3 meri with row of 9 or 10 proximally diminishing spines, and 1 distal spine on P4; ventral margins distally ending in strong spine followed proximally by 0–1 spines and several eminences; lateral sides unarmed on P2–3, and with 2 or 3 small lateral spines on P4. Carpi with 5 or 6 spines on extensor margin on P2–4; lateral surface with 2 or 3 small spines sub-paralleling extensor margin on P2–4; flexor distal margin with spine. P2–4 propodi 4.2–4.5 times as long as broad; extensor margin with 2–4 proximal spines on P2–4; flexor margin with 5 or 6 slender movable spines on P2–4. Dactyli subequal in length, distally ending in well-curved strong spine, length 0.4–0.5 that of propodi; flexor margin with 5 proximally diminishing teeth, terminal one prominent.

Epipods present on P1–3.

Remarks. Galathea rangi n. sp. is easily differentiated from the closest relative G. leptocheir Baba & Fujita, 2008 from the Ryuku Islands, Japan, by the following features:

- The P1 palm is more than 3 times as long as broad in G. leptocheir , whereas twice in G. r a n g i. - The crista dentata of the Mxp3 ischium has 14–20 teeth in G. leptocheir Baba & Fujita, 2008 instead of only eight teeth in G. rangi .

Distribution. French Polynesia, Austral Islands, 700–1350 m

Figures

FIGURE 94. Galathea rangi n. sp., holotype, male, 3.5 mm, French Polynesia (MNHN-IU- 2013 - 8304). 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.