Galathea machordomae, 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 : 179-180

Galathea machordomae n. sp.

( Fig. 64 )

Material examined. Holotype: New Caledonia. CHALCAL 2, Stn CP18, 24°47.00'S, 168°09.43'E, 274 m, 27 October 1986: ov. F 4.1 mm (MNHN-IU-2013-13555).

Paratypes: New Caledonia. CHALCAL 2, Stn CP18, 24°47.00'S, 168°09.43'E, 274 m, 27 October 1986: 1 M 3.7 mm (MNHN-IU-2013-13556).

Etymology. This species is dedicated to Annie Machordom of the Museo Nacional de Ciencias Naturales, Madrid, for her support to crustacean taxonomy.

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 4 transverse ridges: 1 epigastric ridge with 2 spines, medially interrupted; 1 protogastric ridge interrupted, with 1 small parahepatic spine on each side; 1 mesogastric ridge medially interrupted, not extending laterally to anteriormost branchial spines; 1 metagastric ridge interrupted and short. Anterior branchial region with distinct ridges. Mid-transverse ridge uninterrupted, preceded by shallow cervical groove. Posterior branchial region with 4 transverse ridges, 1 of them uninterrupted. Lateral margins slightly convex medially, with 5 spines: 1 spine in front of and 4 spines behind anterior cervical groove; first anterolateral, well-developed, slightly behind level of lateral limit of orbit, 1 spine ventral to between first and anterior branch of cervical groove; 2 spines on anterior branchial region, and 2 spines on posterior branchial margin. Small spine on limit of orbit; infraorbital margin with well-developed spine. Rostrum 1.6–1.7 times as long as broad, length 0.7 postorbital carapace length and breadth 0.4 that of carapace; distance between distalmost lateral incisions 0.3 distance between proximalmost lateral incisions; dorsal surface longitudinally concave, with numerous some small setae; lateral margin with 4 deeply incised sharp teeth.

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

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

Abdomen: Somite 2 with 2 uninterrupted transverse ridges on tergite; somites 3–4 with anterior ridge only, and some scattered scales; somites 5–6 smooth. Males with G1 and G2.

Eyes: Ocular peduncles 1.5 times longer than broad, maximum corneal diameter 0.6 rostrum width.

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

Antenna: Article 1 with strong distomesial spine reaching distal margin of article 2. Article 2 with 2 distal spines, distolateral spine slightly longer than distomesial, and barely reaching midlength of article 3. Articles 3 and 4 unarmed.

Mxp3: Ischium with flexor margins ending in small spine, extensor margin ending in acute angle; crista dentata with 24 denticles. Merus shorter than ischium; flexor margin with 3 well-developed spines, proximal spine larger than others; extensor margin blunty produced. Carpus unarmed.

P1: 2.7 times carapace length, somewhat depressed on palm, more so on fingers, with numerous setiferous scales, and some scattered long plumose and some non-plumose setae. Merus slightly longer than carapace, 1.9 times as long as carpus, with some spines, dorsomesial and distal spines stronger than others. Carpus 0.9–1.0 length of palm, 1.7 times as long as broad; dorsal surface with some small spines; mesial margin with row of spines, distal second much stronger than others. Palm 1.8 times longer than broad, lateral and mesial margins subparallel; well-developed spines arranged roughly in dorsal, lateral and dorsomesial rows; dorsolateral row continuing along entire fixed finger. Fingers as long as palm, each finger with two rows of teeth distally spooned; movable finger unarmed.

P2–4: long and slender, with some setose striae and sparse long plumose setae. P2 1.8 times carapace length. Meri successively shorter posteriorly (P3 merus 0.8 length of P3 merus, P4 merus 0.8 length of P3 merus); P2 merus 0.7 carapace length, 3.0 times as long as broad, 1.4 times longer than P2 propodus. P3 merus 2.5 times as long as broad, slightly longer than P3 propodus. P4 merus 2.3 times as long as broad, slightly longer than P4 propodus. Extensor margin with row of 8 or 9 proximally diminishing spines on P2–4; ventral margins distally ending in strong spine, lateral sides unarmed; ventromesial margin with terminal spine on P2–4. Carpi with 5–7 spines on extensor margin on P2–4; lateral surface with 3 or 4 small spines or acute granules sub-paralleling extensor margin; flexor distal margin with small spine. Propodi 3.5–4.0 times as long as broad; extensor margin with 6 or 7 proximal spines; flexor margin with 4or 5 slender movable spines. Dactyli distally ending in wellcurved strong spine, length 0.6–0.7 that of propodi; flexor margin with 5 or 6 proximally diminishing teeth, terminal one prominent.

Epipods present on P1.

Remarks. Galathea machordomae belongs to the group of species having non-scale-like, complete gastric ridges, the carapace lateral margin without a spine between the anterolateral spine and the anteriormost branchial marginal spine, the absence of parahepatic spines and the presence of epipod only on the P1. The closest relatives are G. f o r m o s a De Man, 1902 from Taiwan and Indonesia and G. maculiabdominalis Baba, 1972 from Japan, Palau, the Philippines, Vanuatu, New Caledonia, and Fiji. The new species is easily differentiated from the other two species by the presence of two epigastric spines, which are absent in the other species. No genetic data were obtained from G. machordomae .

Distribution. New Caledonia, 274 m.

Figures

FIGURE 64. Galathea machordomae n. sp., holotype, ovigerous female, 4.1 mm, New Caledonia (MNHN-IU- 2013 - 13555). 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, left P 3, lateral view; H, right P 4, lateral view. Scale: A, F – H = 1 mm; E = 2 mm; B – D = 0.5 mm.