Galathea multicristata, 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 : 200-202

Galathea multicristata n. sp.

( Fig. 72 )

Material examined. Holotype: New Caledonia. BATHUS 4, Stn CP889, 21°00.83'S, 164°27.34'E, 416–433 m, 2 August 1994: M 7.4 mm (MNHN-IU-2013-8324).

Etymology. From the Latin, multi, numerous, and crista, ridge, crest, in reference to the numerous ridges on the dorsal surface of the carapace.

Description. Carapace: as long as broad; transverse ridges with dense short setae, and a few scattered long plumose setae; cervical groove distinct, laterally bifurcated. Dorsal surface with numerous interrupted and scalelike ridges, and only mid-transverse and posterior ridge uninterrupted. Three pairs of small epigastric spines; 2 or 3 small hepatic spines on each side. Lateral margins well convex medially, with 10 spines: 2 spines in front of and 8 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, with spine ventral to between first and second; 4 spines on anterior branchial region, second larger than others, and 4 spines on posterior branchial margin, last small. Small frontal spine between lateral limit of orbit and first anterolateral spine; infraorbital margin with 3 spines. Rostrum 2.3 times as long as broad, triangular, length 0.7 postorbital carapace length and breadth 0.3 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 5 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 2–4 each with 3 or 4 uninterrupted or medially interrupted transverse ridges on tergite; somite 5 with 2 uninterrupted ridges; somite 6 with 2 medially interrupted ridges, posteromedian margin slightly convex. 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 well-developed, smaller than others. Ultimate article 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 slightly larger than distomesial and reaching end of article 3. Articles 3 and 4 unarmed.

Mxp3: Ischium with well-developed spine on flexor distal margin; extensor margin unarmed; crista dentata with 27 denticles. Merus shorter than ischium; flexor margin with 2 spines, proximal clearly longer than distal; extensor margin with distal spine. Carpus unarmed.

P1: 3.8 times carapace length, somewhat depressed on palm, more so on fingers, covered with finely setiferous scales, with numerous long plumose and non-plumose setae. Merus 1.3 times length of carapace, 2.0 times as long as carpus, with spines arranged roughly in rows, dorsomesial spines stronger; distal spines prominent. Carpus 0.7 length of palm, 1.6 times as long as broad; dorsal surface with some small spines; mesial margin with 4 spines (distal second strong). Palm 1.7 times as long as broad, lateral and mesial margins slightly divergent; small spines arranged roughly in dorsolateral and dorsomesial rows. Fingers 0.8 length of palm, each finger distally with two rows of teeth, spooned; fingers unarmed.

P2–4: moderately slender, with setose striae and numerous long plumose and non-plumose setae. P2 twice carapace length. Meri successively shorter posteriorly (P3 merus 0.8 length of P2 merus, P4 merus 0.7 length of P3 merus); P2 merus 0.8 carapace length, 4.5 times as long as broad, 1.4 times longer than P2 propodus; P3 merus 4.1 times longer than broad, 1.2 times longer than P3 propodus; P4 merus 2.8 times as long as broad, 0.9 length of P4 propodus. Extensor margin of P2–3 meri with row of 11–13 proximally diminishing spines, and 5 spines on P4; flexor margins distally ending in strong spine followed proximally by 0–1 spines and several eminences; distoflexor angle of P2–4 with one small and one well-developed spines; lateral sides unarmed on P2–3, and with 5 or 6 small spines on P4. Carpi with 5 or 6 spines on extensor margin on P2–4; lateral surface with 2 or 3 small spines or acute granules sub-paralleling extensor margin on P2–4; flexor distal margin with spine. P2–4 propodi 4.6–5.0 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 0.5 that of propodi; flexor margin with 5 or 6 proximally diminishing teeth, terminal one prominent.

Epipods present on P1.

Remarks. Galathea multicristata n. sp. is closely related to G. ciliosa n. sp. from Vanuatu from which it can be distinguished by the following characters:

- The hepatic region has two or three spines in G. multicristata , being unarmed in G. c i l i o s a. - The carapace surface has numerous scale-like ridges in G. multicristata , but only a few ones are present in G. ciliosa .

- The proximal spine on the flexor margin of the Mxp3 merus is clearly larger than the distal spine in G. multicristata , and subequal in G. ciliosa .

No genetic data are available for G. multicristata . Distribution. New Caledonia, 416– 433 m.

Figures

FIGURE 72. Galathea multicristata n. sp., holotype, male, 7.4 mm, New Caledonia (MNHN-IU- 2013 - 8324). 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, left P 4, lateral view. Scale: A, F – H = 1 mm; E = 2 mm; B – D = 0.5 mm.