Galathea phalangis, 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 : 230-232

Galathea phalangis n. sp.

( Fig. 83 )

Material examined. Holotype: Madagascar. Tulear, Stn D37, 23°29'42"S, 43°39'30"E, 50 m, 12 September 1963: ov. F 3.6 mm (MNHN-Ga788, MNHN-IU-2013-9693).

Paratypes: Madagascar. Tulear, Stn D18, 23°30'57"S, 43°42'18"E, 170 m, 31 August 1963: 1 ov. F 3.1 mm (MNHN-Ga787, MNHN-IU-2013-9692). MIRIKY, Stn CP3260, 15°35'S, 45°45'E, 179–193 m, 10 July 2009: 1 M 2.5 mm (MNHN-IU-2013-14304).—Stn CP3282, 14°52'S, 46°58'E, 215-261 m, 13 July 2009: 1 M 3.8 mm (MNHN-IU-2013-14305).

Etymology. From the Latin phalanx, line, battle-array, in reference to the numerous ridges on the carapace.

Description. Carapace: As long as broad; cervical groove distinct, laterally bifurcated. Ridges with dense short setae, with some long thick iridescent setae. Gastric region with 9 transverse ridges: 2 epigastric ridges medially interrupted, anterior with 2 submedian spines; 2 uninterrupted protogastric ridges, without parahepatic spines; 2 uninterrupted mesogastric ridges, anterior ridge, laterally not continuous to anteriormost branchial marginal spine; 2 metagastric ridges successively shorter posteriorly, uninterrupted and not continuing with anterior branchial ridges. Anterior branchial region with distinct ridges. Mid-transverse ridge uninterrupted, preceded by cervical groove. Posterior branchial region with 6 transverse ridges, 2 or 3 ridges uninterrupted; some additional scattered scales among ridges. Lateral margins subparallel, with 8–10 spines: 2–4 spines in front of and 6 spines behind anterior cervical groove; first anterolateral, well-developed, situated in frontal margin, second very small, 0–2 minute spines between them and accompanying another small spine ventral to between first and second; 3 spines on anterior branchial margin, and 3 spines on posterior branchial margin. External orbital limit ending in minute spine; infraorbital margin with strong spine. Rostrum spatulate, 2.0 times as long as broad, length 0.7 postorbital carapace length and breadth 0.3 that of carapace; distance between distalmost lateral incisions 0.3 distance between proximalmost lateral incisions; dorsal surface nearly horizontal in lateral view, with small setiferous ridges; lateral margin convex, with 4 relatively small, shallowly incised teeth.

Pterygostomian flap spineless on surface, with sparse short setae, anterior margin bluntly angular.

Sternun: Plastron about as long as broad, lateral extremities gently divergent posteriorly.

Abdomen: Somites 2–4 each with 5 uninterrupted transverse ridges on tergite, anterior ridge more distinctly elevated than posterior ridge; some thick long iridescent setae on median portion of somites; somites 5 and 6 with 2 ridges, posterior margin of somite 6 slightly convex. Males with G1 and G2.

Eyes: Ocular peduncles as long as broad, maximum corneal diameter 0.6 rostrum width.

Antennula : Article 1 with 2 spines; well-developed distodorsal and distolateral spines; distomesial spine obsolescent. Ultimate article with tuft of fine setae on distodorsal margin.

Antenna: Article 1 hardly visible in dorsal view, with ventral distomesial spine exceeding distal half of article 2. Article 2 with 2 subequal distal spines, not reaching midlength of article 3. Articles 3–4 unarmed.

Mxp3: Ischium with small spine on flexor distal margin; extensor margin with small but distinct distal spine; crista dentata with 18 denticles. Merus as long ischium; flexor margin with 2 strong subequal spines; extensor margin with distal spine. Carpus unarmed.

P1: 2.5 times carapace length, subcylindrical, with setose scales and numerous long simple setae. Merus as long as carapace, 1.8 times as long as carpus, with small spines arranged roughly in rows, dorsomesial and ventromesial spines stronger, distal spines prominent. Carpus 0.9 length of palm, 2.6 times as long as broad; dorsal surface with some small spines arranged roughly in rows; mesial margin with 1 or 2 well-developed spines. Palm 3.0 times longer than broad, lateral and mesial margins subparallel; small spines arranged roughly in dorsolateral and dorsomesial rows. Fingers as long as palm, each finger distally with two rows of teeth, spooned; fingers unarmed.

P2–4: moderately slender, with setose striae, and numerous long simple setae. P2 1.8 times carapace length. Meri successively shorter posteriorly (P3 merus 0.8 length of P2 merus, P4 merus 0.8 length of P3 merus; P2 merus 0.8 carapace length, 4.5 times as long as broad, 1.7 times longer than P2 propodus; P3 merus 3.5 times longer than broad, 1.3 times longer than P3 propodus; P4 merus 3.5 times as long as broad, 1.1 length of P4 propodus. Extensor margins with row of 10–12 proximally diminishing small spines on P2–3, 1 or 2 spines on P4; lateral surface with 1 or 2 small spines on P4; flexolateral margin distally ending in 1 spine followed proximally by several prominences. Carpi with 4 or 5 small spines on extensor margin on P2–3, unarmed on P4; lateral surface with granules sub-paralleling extensor margin on P2–4; flexor distal margin with small distal spine. Propodi 4.5 times as long as broad; extensor margin unarmed; flexor margin with 5 or 6 slender movable spines on P2–4, terminal one paired with another seta mesial to it. Dactyli distally ending in well-curved strong spine, 0.6–0.7 length of propodi; flexor margin with 5 or 6 successively diminishing teeth, terminal one prominent; each tooth with articulating seta.

Epipod present only on P1.

Remarks. Galathea phalangis n. sp. resembles G. punctata n. sp. from the Philippines to New Caledonia (see Remarks for G. punctata ).

Distribution. Madagascar, 50– 261 m.

Figures

FIGURE 83. Galathea phalangis n. sp., holotype, ovigerous female, 3.6 mm, Madagascar (MNHN-Ga 788, MNHN-IU- 2013 - 9693). 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, left P 2, lateral view; G, left P 3, lateral view; H, left P 4, lateral view. Scale: A, F – H = 1 mm; E = 2 mm; B – D = 0.5 mm.