Galathea submagnifica Laurie, 1926

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 : 293-295

Galathea submagnifica Laurie, 1926

( Fig. 105 )

Galathea submagnifica Laurie, 1926: 128 , pl. 8, figs 5–10 (Providence, 92–143 m).—Baba et al., 2008: 79 (compilation).

Material examined. Madagascar. ATIMO VATAE, Stn DW3518, 24°50.7'S, 47°28.7'E, 99–101 m, 30 April 2010: 1 M 4.2 mm (MNHN-IU-2013-8340).

La Réunion, MD32, Stn FA25, 21°21.8’S, 55°45.9’E, 90–95 m, 16 August 1982: 1 ov. F 1.8 mm (MNHN-IU- 2013-8339).— Stn CP55, 21°05.3’S, 55°12.5’E, 97–110 m, 22 August 1982: 1 ov. F 2.3 mm, 1 F 2.5 mm (MNHN- IU-2013-8338).

Description. Carapace: As long as broad; ridges with dense short setae, with scattered long plumose setae; cervical groove distinct, laterally bifurcated. Ridges on gastric, cardiac and branchial regions scale-like or in concentric arcs, with 2 epigastric spines, and 1 parahepatic spine on each side. Mid-transverse ridge interrupted, preceded by shallow cervical groove. Lateral margins slightly convex, with 6 spines: 1 spine in front of and 5 spines behind anterior cervical groove; first anterolateral, well-developed, behind level of lateral limit of orbit, with well-developed spine ventral to between first and second spines; 2 spines on anterior branchial region, and 3 spines on posterior branchial margin, last small. Small spine between lateral limit of orbit and anterolateral spine; infraorbital margin with strong spine. Rostrum 1.8–2.0 as long as broad, length 0.7 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 some short setae; lateral margin with 4 deeply incised sharp teeth.

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

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

Abdomen: Somite 2 with 2 transverse uninterrupted ridges; somites 3 or 4 with anterior transverse ridge only; somites 5 and 6 smooth, posteromedian margin of somite 6 straight. Males with G1 and G2.

Eyes: Ocular peduncles 1.3 times longer than broad, maximum corneal diameter 0.7 rostrum width.

Antennule: Article 1 with 3 well-developed distal spines, distodorsal larger, distomesial spine slightly smaller than others. Ultimate article with a few short fine setae not in tuft on distodorsal margin.

Antenna: Article 1 with ventral distomesial spine slightly exceeding distal margin of article 2. Article 2 with distolateral spine slightly longer than distomesial, 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 19–21 denticles. Merus as long as ischium; flexor margin with 2 well-developed spines, proximal stronger than distal; extensor margin with distinct spine. Carpus unarmed.

P1: 2.9 times carapace length, covered with finely setiferous scales, with scattered long setae. Merus 0.9 times length of carapace, 1.3 times as long as carpus, with spines arranged roughly in rows, dorsomesial spines stronger; distal spines prominent. Carpus 0.8 length of palm, 1.8 times as long as broad; dorsal and lateral surfaces with some spines; mesial margin with some spines. Palm 1.8 times longer than broad, lateral and mesial margins slightly divergent; spines arranged roughly in dorsolateral and dorsomesial rows; dorsolateral spines continuing along fixed finger; a few small spines scattered on dorsal side. Fingers 0.9 length of palm, distally spooned, gapping, prehensile distal edges close fitting with small blunt teeth; movable finger with 1 proximal spine.

P2–4: Moderately slender, with setose striae and sparse long plumose setae. P2 twice carapace length. Meri successively shorter posteriorly (P3 merus 0.9 length of P2 merus, P4 merus 0.9 length of P3 merus. P2 merus 0.7 carapace length, 3.5 times as long as broad, 1.5 times longer than P2 propodus; P3 merus 3.1 times as long as broad, 1.3 times longer than P3 propodus; P4 merus 3.5 times as long as broad, 1.3 times longer than P2 propodus. Extensor margin of P2–3 meri with row of 5–8 proximally diminishing spines, 1 or 2 spines on P4; ventral margins distally ending in strong spine followed proximally by 0–1 spines and several eminences; lateral sides unarmed, or with 1 small spine. Carpi with 5 or 6 spines on extensor margin on P2–3, 2 spines on P4; lateral surface with 4 or 5 spines sub-paralleling extensor margin; flexor distal margin acute. Propodi 3.1–3.5 times as long as broad; extensor margin with 1 or 2 proximal spines on P2–4; flexor margin with 5 or 6 slender movable spines. Dactyli distally ending in well-curved strong spine, length 0.7–0.8 that of propodi; flexor margin with 4–6 proximally diminishing teeth, terminal one prominent.

Epipods present on P1.

Remarks. Laurie (1926) described Galathea submagnifica on the basis of four female specimens caught in Providence Island. The present material from Madagascar and La Reunion agrees very well with the type description. This species is characterized by numerous scale-like ridges on the carapace, and the dorsal surface of the carapace without postcervical spines. G. furfurea n. sp. from New Caledonia and South China Sea (Macclesfield Bank) and G. waiora n. sp. from French Polynesia are quite similar to G. submagnifica . Galathea submagnifica can be easily distinguished from G. furfurea by the following characters:

- The gastric region has two epigastric spines in G. submagnifica , rather than four in G. f u r f u re a. - The carapace lateral margin has one small spine between the anterolateral spine and the anteriormost spine on the branchial margin in G. furfurea , whereas this spine is absent in G. submagnifica . - The genetic divergences between G. submagnifica and G. f u r f u re a are 12.9 % (COI) and 9.7% (16S rRNA) ( Tab. 3 ).

Differentiating characters between G. magnifica and G. waiora are discussed under Remarks for G. waiora . Distribution. Previously known only from Providence Island; newly recorded from Madagascar, La Réunion; 90– 143 m.

Figures

FIGURE 105. Galathea submagnifica Laurie, 1926, male, 4.2 mm, Madagascar (MNHN-IU- 2013 - 8340). 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.