Galathea polyphemus, 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 : 246-248

Galathea polyphemus n. sp.

( Figs 88 , 119 H)

Galathea pilosa . — Poore et al., 2011: 333, pl. 11E (color photo, Moorea).

Material examined. Holotype: French Polynesia, Society Islands. Moorea, outer reef slope, 12 October 2008: ov. F 4.0 mm (UF15464).

Paratypes: French Polynesia, Society Islands. Moorea, June–August 2006: 1 M 5.6 mm (UF13856).

French Polynesia, Society Islands. Moorea, outer reef slope, 12 October 2008: 1 M 4.4 mm (UF15414); 1 M 4.4 mm (UF15427); 1 M 3.4 mm (UF15455); 1 ov. F 4.0 mm (UF15463); 1 F 3.9 mm (UF18867).

Etymology. Polyphemus , one of the Cyclopes, was in love of the sea-nymph Galathea . The name is considered as a substantive in apposition.

Description. Carapace: Slightly broader than long; transverse ridges with dense short setae, and numerous long plumose setae, some iridescent, and denser on rostrum surface; cervical groove distinct, laterally bifurcated. Gastric region with some transverse ridges: 1 epigastric ridge medially interrupted, with 5–7 spines; 2 protogastric ridges, anterior ridge usually uninterrupted, medially convex, with minute parahepatic spine on each side, posterior ridge scale-like; 1 mesogastric ridge uninterrupted but not extending laterally to anteriormost of branchial marginal spines; 2 metagastric ridges, anterior ridge usually uninterrupted, not continuing laterally to anteriorbranchial ridges, posterior ridge moderately short. Hepatic region unarmed. Anterior branchial region with distinct ridges, 1 spine on each side. One post-cervical spine usually on each side. Mid-transverse ridge uninterrupted, preceded by shallow cervical groove, usually followed by 5 ridges before posterior ridge, 2 or 3 ridges uninterrupted. Lateral margins well convex medially, 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, at midlength between anterolateral spine and anteriormost spine of branchial margin, without spine ventral to between first and second; 3 spines on anterior branchial region, last small, and 2 spines on posterior branchial margin, last small and obsolescent in some specimens. Lateral limit of orbit unarmed; infraorbital margin with small spine. Rostrum truncate, as long as broad, length 0.6 postorbital carapace length and breadth 0.4 that of carapace; distance between distalmost lateral incisions 0.15 distance between proximalmost lateral incisions; dorsal surface nearly horizontal in lateral view, with numerous small scale-like setose ridges; lateral margin with 4 deeply incised teeth, distal pair small.

Pterygostomian flap rugose, unarmed, ridges with short setae, anterior margin ending in spine.

Sternum: As long as broad, lateral extremities gently divergent posteriorly. Sternite 3 2.2 times as broad as long, with median knot bordering left and right lobes, each lateral margin with convex margin. Sternite 4 1.9 times longer and 3.6 times broader than sternite 3, 0.9 as long as broad; surface of sternites 4–7 with setiferous scale-like ridges.

Abdomen: Somites 2–4 each with 2 or 3 uninterrupted and 0–1 interrupted transverse ridges on tergite; somite 5 with 4 uninterrupted or interrupted ridges; somite 6 with 2 uninterrupted ridges. Males with G1 and G2.

Eyes: Ocular peduncles 1.1 times longer than broad, maximum corneal diameter 0.7 rostrum width.

Antennule: Article 1 with 4 well-developed distal spines, distodorsal larger, distomesial and distoventral spines smaller than others. Ultimate article with tuft of fine setae on distodorsal margin.

Antenna: Article 1 with ventral distomesial spine exceeding distal margin of article 2. Article 2 with 2 welldeveloped distal spines, distolateral spine slightly longer than distomesial, and reaching midlength of article 3. Article 3 with small distomesial spine. Article 4 unarmed.

Mxp3: Ischium with flexor margin ending in small spine, extensor margin ending in acute point; crista dentata with 24 or 25 denticles. Merus slightly shorter than ischium; flexor margin with 3 subequal spines; extensor margin with distal spine. Carpus unarmed.

P1: 1.7 times carapace length, with numerous scales with numerous long setae, some of them iridescent. Merus 0.7 times carapace length, 2.7 times as long as carpus, with some spines, dorsomesial and distal spines stronger than others. Carpus 0.9 length of palm, 0.8 times as long as broad; dorsal surface with some spines; mesial margin with row of spines, distal stronger than others. Palm 0.8 times as long as broad, lateral and mesial margins slightly divergent; small spines arranged roughly in dorsal, dorsolateral and dorsomesial rows. Fingers 1.3 times as long as palm, each finger distally with two rows of teeth, spooned; fixed finger with some proximal spines along lateral margin; movable finger with 1 or 2 proximal spines.

P2–4: long and slender, with setose striae and numerous long plumose setae, some of the iridescent. P2 1.7 times carapace length. Meri successively shorter posteriorly (P3 merus 0.9 length of P3 merus, P4 merus 0.9 length of P3 merus); P2 merus 0.7 carapace length, 2.6 times as long as broad, 1.5 times longer than P2 propodus. Extensor margin with row of 9 or 10 proximally diminishing spines on P2–3, 1 distal spine on P4; ventral margins distally ending in strong spine, lateral sides with 2 or 3 small spines on P4. Carpi with 3 or 4 spines on extensor margin, distalmost smaller than distal second, sometimes absent; lateral surface with 3 or 4 small spines or acute granules sub-paralleling extensor margin; flexor distal margin with small spine. Propodi 2.5–2.9 times as long as broad; extensor margin with 2 or 3 proximal spines on P2–3, 0–1 spines on P4; flexor margin with 4–7 slender movable spines. Dactyli distally ending in well-curved strong spine, length 0.7–0.8 that of propodi; flexor margin with 4 or 5 proximally diminishing teeth, terminal one moderately prominent.

Epipods absent on pereopods.

Coloration. Base color of carapace and abdomen purple, with numerous white spots, each spot encircled by dark purple. Large yellow fleck on each hepatic, anterior branchial and lateral gastric regions; yellow fleck on each posterolateral branchial region. Rostrum yellowish. P1 with numerous small red spots, usually on spines, merus bluish. P2–4 with transverse bluish and yellowish bands.

Remarks. Galathea polyphemus n. sp. and G. pilosa De Man, 1888 are closely related. There are not clear morphological differences between the two species, but the living coloration provides the differentiation of them. In this new species, the base color of the carapace and abdomen is purple, whereas it is red in G. pilosa . In spite of the morphological proximity, the genetic divergences between the two are enough great to recognize them as distinct species (15. 3 % for COI, 9.4 % for 16S rRNA). ( Tab. 1).

Distribution. French Polynesia, Society Islands; depth not recorded.

Figures

FIGURE 88. Galathea polyphemus n. sp., holotype, ovigerous female, 4.0 mm, French Polynesia (UF 15464). 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 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.

FIGURE 119. Dorsal view. A, Galathea pilosa De Man, 1888, Papua New Guinea, ovigerous female 4.5 mm (MNHN-IU- 2013 - 1055). B, Galathea pilosa De Man, 1888, Maldives, male 3.6 mm (UF 39675). C, Galathea platycheles Miyake, 1953, Madagascar, female 2.2 mm (MNHN-IU- 2013 - 13822). D, Galathea platycheles Miyake, 1953, Western Australia, ovigerous female 1.9 mm (UF 22402). E, Galathea politula n. sp., Vanuatu, holotype, M 3.5 mm (MNHN-IU- 2013 - 9707). F, Galathea polydora n. sp., Vanuatu, male 3.3 mm, (MNHN-IU- 2013 - 9871). G, Galathea polydora n. sp., Vanuatu, ovigerous female 2.5 mm (MNHN-IU- 2013 - 13476). H, Galathea polyphemus n. sp., French Polynesia, male 4.4 mm (UF 15427). I, Galathea providentia Laurie, 1926, Madagascar, female 3.0 mm (MNHN-IU- 2013 - 13802).