Galathea lingadua, 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 : 167-168

Galathea lingadua n. sp.

( Fig. 59 )

Material examined. Holotype: Fiji. MUSORSTOM 10, Stn CP1349, 17°31.07'S, 178°38.79'E, 244–252 m, 11 August 1998: F 5.1 mm (MNHN-IU-2013-13962).

Etymology. Lingadua is a Fijian god of the drums; used as a noun in apposition.

Description. Carapace: Slightly longer than broad; transverse ridges with dense short setae, and some scattered long plumose and iridescent setae; cervical groove distinct, laterally bifurcated. Gastric region with 5 transverse ridges: 1 epigastric ridge medially interrupted, with 2 spines; 1 protogastric ridge, uninterrupted, with small parahepatic spine on each side (minute on right side); 1 mesogastric ridge, interrupted, not extending laterally to anteriormost of branchial marginal spines; 2 metagastric ridges, anterior ridge, not fused with anterior branchial ridges, posterior ridge scale-like. Anterior branchial region with distinct ridges. Mid-transverse ridge uninterrupted, preceded by shallow cervical groove. Posterior branchial region with 5 transverse ridges, 2 ridges 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, behind level of lateral limit of orbit, no spine ventral to between first and anterior branch of cervical groove; 2 spines on anterior branchial region, and 2 spines on posterior branchial margin. Minute spine on limit of orbit; infraorbital margin with well-developed spine. Rostrum twice as long as broad, length 0.6 postorbital carapace length and breadth 0.3 that of carapace; distance between distalmost lateral incisions 0.35 distance between proximalmost lateral incisions; dorsal surface flatish, with numerous small setose scales; 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; somite 3–4 with 2 ridges, posterior medially interrupted ridge; somites 5–6 smooth, posteriormedian margin of somite 6 straight. 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 subequal distal spines, reaching midlength of article 3. Article 3 with distomesial spine; article 4 unarmed.

Mxp3: Ischium with flexor margins ending in small spine, extensor margin ending in acute angle; crista dentata with 23 denticles. Merus shorter than ischium; flexor margin with strong proximal spine, and 2 (median and distal) minute spines; extensor margin unarmed, with median tubercle. Carpus unarmed.

P1: 3 times carapace length, relatively slender, with setose scales and numerous long iridescent and noniridescent setae. Merus 1.3 times as long as carapace, 1.8 times as long as carpus, with spines arranged roughly in rows, dorsomesial and ventromesial spines stronger, distal spines prominent. Carpus as long as palm, 2.2 times as long as broad; dorsal surface with some small spines arranged roughly in rows; mesial margin with 2 welldeveloped spines. Palm 2.3 times longer than broad, lateral and mesial margins subparallel; small spines arranged roughly in dorsal, dorsolateral and dorsomesial rows. Fingers 0.9 length of palm, each finger distally with two rows of teeth, spooned; fingers unarmed.

P2–4: moderately long and slender, with some setose striae and numerous long plumose and non-plumose setae, some of them iridescent. P2 2.0 times carapace length. Meri successively shorter posteriorly (P3 merus 0.9 length of P3 merus, P4 merus 0.9 length of P3 merus); P2 merus 0.7 carapace length, 3.8 times as long as broad, as long as P2 propodus. P3 merus 3.0 times as long as broad, as long as P3 propodus. P4 merus 3.5 times as long as broad, as long as P4 propodus. Extensor margin with row of 7 or 8 proximally diminishing spines on P2–3, 2 or 3 spines on P4; ventral margins distally ending in strong spine, lateral sides unarmed on P2–3, 1 or 2 spines on P4; ventromesial margins unarmed. Carpi with 4 or 5 spines on extensor margin on P2–3, 2 on P4; lateral surface with 4 or 5 granules sub-paralleling extensor margin; flexor distal margin blunty produced. Propodi 5.2–6.0 times as long as broad; extensor margin with 0–2 proximal spines; flexor margin with 4 or 5 slender movable spines. Dactyli distally ending in well-curved strong spine, length 0.6–0.7 that of propodi; flexor margin with 6 or 7 proximally diminishing teeth, terminal one prominent.

Epipods present on P1.

Remarks. Galathea lingadua n. sp. is easily differentiated from the two most closely related species, G. galene n. sp. and G. raventosae Macpherson, 2012 , by the different structure of the anterior protogastric ridge on the carapace. This ridge is uninterrupted in G. lingadua , instead of interrupted and usually with one median scalelike ridge in the other two species.

No genetic data are available for G. lingadua .

Distribution. Fiji, 244– 252 m.

Figures

FIGURE 59. Galathea lingadua n. sp., holotype, female, 5.1 mm, Fiji (MNHN-IU- 2013 - 13962). 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.