Galathea clarki, 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 : 83-85

Galathea clarki n. sp.

( Fig. 25 )

Material examined. Holotype: South China Sea. Macclesfield Bank, Stn 24, 15°26'30"N, 114°14'E, 24–63 m, May 1892: 1 M 4.2 mm ( NHMUK).

Paratypes: South China Sea. Macclesfield Bank, Stn 19, 15°32'N, 113°45'E, 24 m, May 1892: 1 ov. F 3.5 mm ( NHMUK).—Stn 24, 15°26'30"N, 114°14'E, 24–63 m, May 1892: 1 ov. F 3.3 mm, 1 F 2.8 mm ( NHMUK).

Etymology. This species is dedicated to Paul Clark from the Natural History Museum, London, for his important contribution to the decapod taxonomy.

Description. Carapace: 1.3 times longer than broad; transverse ridges with dense moderately long unirranous setae, and a few scattered long non-plumose setae; cervical groove distinct, laterally bifurcated. Gastric region with 7 transverse ridges: 1 epigastric ridge with 2 spines; 2 protogastric ridges, anterior one laterally interrupted, with 1 parahepatic spine on each side, posterior ridge scale-like; 2 mesogastric ridges, anterior ridge interrupted, not extending laterally to anteriormost of branchial marginal spines, posterior ridge short; 2 metagastric ridges, anterior one not extending laterally to anterior branchial ridges. Anterior branchial region with distinct ridges. Midtransverse ridge uninterrupted, preceded by shallow cervical groove, followed by 5 transverse ridges, 2 of them uninterrupted. Lateral margins convex medially, with 8 spines: 2 spines in front of and 6 spines behind anterior cervical groove; first anterolateral, well-developed, at level of lateral limit of orbit; second, small, at midlength between anterolateral spine and anteriormost spine of branchial margin, with accompanying spine ventral to between first and second; 3 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 1.9 as long as broad, length 0.5 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 numerous setae; lateral margin with 4 deeply incised sharp teeth.

Pterygostomian flap rugose, ridges with short setae, anterior surface with spine, anterior margin ending in acute angle.

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

Abdomen: Somites 2–5 each with 2 uninterrupted transverse ridges on tergite, additional interrupted ridge on somite 2; somite 6 each with 2 medially interrupted ridges, posteromedian margin 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 2 spines; well-developed distodorsal and distolateral spines, distodorsal larger; distomesial spine obsolescent. Ultimate article with a few short fine setae not in tuft on distodorsal margin.

Antenna: Article 1 with ventral distomesial spine not reaching distal margin of article 2. Article 2 with 2 welldeveloped distal spines, distolateral spine clearly longer than distomesial and exceeding midlength of article 3. Articles 3 and 4 unarmed.

Mxp3: Ischium with well-developed spine on flexor distal margin; extensor margin ending in acute angle; crista dentata with 18–21 denticles. Merus shorter than ischium; flexor margin with 2 subequal spines; extensor margin unarmed. Carpus unarmed.

P1: 2.6 times carapace length, covered with finely setiferous scales, with scattered long non-plumose setae. Merus 1.1 times length of carapace, 1.3 times as long as carpus, with spines arranged roughly in rows, dorsomesial spines stronger; distal spines prominent. Carpus 0.9 length of palm, 2.3 times as long as broad; dorsal surface with some small spines; mesial margin with row of well-developed spines. Palm 2.3 times longer than broad, lateral and mesial margins subparallel; a few small spines arranged roughly in dorsolateral and dorsomesial rows, some small spines scattered on dorsal side; dorsolateral spines continuing along fixed finger; dorsomesial spines continuing along movable finger. Fingers 0.7 length of palm, each finger distally with two rows of teeth, spooned.

P2–4: moderately slender, with setose striae and numerous long non-plumose setae. P2 1.6 times carapace length. Meri successively shorter posteriorly (P3 merus 0.9 length of P2 merus, P4 merus 0.9 length of P3 merus); P2 merus 0.6 carapace length, 2.9 times as long as broad, 1.4 times longer than P2 propodus; P3 merus 2.8 times longer than broad, 1.1 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 9 or 10 proximally diminishing spines, and 7 or 8 spines on P4; ventral margins distally ending in strong spine followed proximally by several tubercles or eminences; lateral sides unarmed on P2–4. Carpi with 6 or 7 spines on extensor margin on P2–4, 1 distal spine on P4; lateral surface with 3 or 4 spines (on P2) or acute granules (P3–4) sub-paralleling extensor margin on P2–4; flexor distal margin ending in acute angle. P2–4 propodi 4 or 5 times as long as broad; extensor margin with 2 proximal spines; flexor margin with 7 or 8 slender movable spines on P2–4. Dactyli distally ending in well-curved strong spine, length 0.6- 0.7 that of propodi; flexor margin with 5 proximally diminishing teeth, terminal one prominent.

Epipods on P1–3.

Remarks. The new species belongs to the group of species only with two well-developed terminal spines on the antennular basal article (the distomesial spine is greatly reduced, obsolescent). The closest relative is G. cymothoe n. sp. from Vanuatu, New Caledonia and Chesterfield Islands (see Remarks of G. cymothoe ).

No genetic data are available.

Distribution. South China Sea. Macclesfield Bank, 24– 63 m.

Figures

FIGURE 25. Galathea clarki n. sp., holotype, male, 4.2 mm, South China Sea (NHMUK). 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, F – H = 1 mm; E = 2.0 mm; B – D = 0.5 mm.