Galathea samadiae, 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 : 271-273

Galathea samadiae n. sp.

( Fig. 97 )

Material examined. Holotype: Philippines. MUSORSTOM 1, Stn 57, 13°53'N, 120°13'S, 96–107 m, 26 March 1976: M 3.2 mm (MNHN-IU-2013-8425).

Paratypes: Philippines. MUSORSTOM 1, Stn 57, 13°53'N, 120°13'S, 96–107 m, 26 March 1976: 1 F 2.8 mm (MNHN-IU-2013-8425).

Etymology. This species is dedicated to Sarah Samadi of the Muséum nationale d’Histoire Naturelle, Paris, for her support to expeditions and crustacean research.

Description. Carapace: 1.2 times as long as broad; anterior and posterior cervical grooves distinct, ridges with dense short setae and some scattered long plumose setae. Gastric region with 6 transverse ridges: 1 epigastric ridge, scale-like, with 4 spines; 2 protogastric ridges, anterior one uninterrupted, with 1 parahepatic spine on each side, posterior ridge scale-like, with plumose stiff setae on median scale; 1 mesogastric ridge uninterrupted but not extending laterally to anteriormost of branchial marginal spines; 2 mesogastric ridges, not continuing laterally to anterior branchial regions. Mid-transverse ridge uninterrupted, preceded by distinct cervical groove, followed by 6 transverse ridges. Cardiac region with 2 median spines. Lateral margins slightly convex, with 7 spines: 2 spines in front of and 5 strong spines behind anterior cervical groove; first anterolateral, well-developed, distinctly posterior to level of lateral limit of orbit; second small, situated at midlength between anterolateral spine and anterior cervical groove, accompanying another small spine ventral to between first and second; 2 spines on anterior branchial region, and 3 spines on posterior branchial margin. Small outer orbital spine; infra-orbital margin with 2 or 3 denticles. Rostrum 1.8 times as long as broad, length 0.5 that of, 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 with 4 sharp teeth.

Pterygostomian flap rugose with sparse setae, anteriorly acute.

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

Abdomen: Somites 2–4 each with 3 uninterrupted transverse ridges on tergite; somites 5 and 6 each with 2 ridges, both medially interrupted. Males with G1 and G2.

Eyes: Ocular peduncles 1.6 times longer than broad, maximum corneal diameter 0.7 rostrum width.

Antennule: Article 1 with 3 distal spines, two well-developed spines, distodorsal larger; distomesial spine very small but distinct; additional 2 small spine on lateral margin. Ultimate article with a few short setae not in tuft on distodorsal margin.

Antenna: Article 1 with depressed ventral distomesial process reaching distal margin of article 2. Article 2 with distolateral spine longer than distomesial, exceeding midlength of article 3. Articles 3 and 4 unarmed.

Mxp3: Ischium with spine on flexor distal margins; crista dentata with 18 or 19 denticles. Merus shorter than ischium, with 3 spines on flexor margin, proximal spine slightly longer than others; extensor margin with 2 small spines. Carpus spineless, extensor margin rugose.

P1: 3.3 times carapace length, with long stiff setae on striae of all articles, and some scattered long and thick plumose setae. Merus 1.5 times length of carapace, twice longer than carpus, with several rows of spines, dorsomesial row with strong spines, distal spine stronger than others. Carpus as long as palm, 2.8 times longer than broad, dorsal surface with row of small spines; mesial surface with well-developed spines; and some small spines along lateral margin. Palm 2.7 times longer than broad; small dorsal spines roughly in rows: mesial, dorsal and lateral. Fingers 0.8 as long as palm, each finger distally with two rows of teeth, spooned; fingers unarmed.

P2–4: relatively short, setose, sparsely with thick long plumose setae on all articles. P2 1.7 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 0.7 carapace length, 4.0 times as long as broad, 1.4 times longer than P2 propodus; P3 merus 3.0 times as long as broad, as long as P3 propodus; P4 merus 2.7 times as long as broad, as long as P4 propodus. Extensor margins of meri with row of 5–7 proximally diminishing spines on P2–4; lateral surface with 3 small spines on P4; flexolateral margins ending in strong terminal spine proximally followed by 1 or 2 smaller spines; flexomesial margins unarmed. Carpi each with 5 or 6 spines on extensor margin on P2–4; lateral surface with row of 3–5 small spines or acute granules paralleling extensor row; flexor distal margins with very small distal spine. Propodi 4.5–5.3 times as long as broad; extensor margin with 1–3 proximal spines on P2–4; flexor margin with 5 or 6 movable spines. Dactyli subequal in length, 0.6–0.7 length of propodi, ending in incurved, strong, sharp spine; flexor margin with 4 or 5 successively diminishing teeth, terminal tooth prominent.

Epipods present only on P1.

Remarks. Galathea samadiae n. sp. is closest to G. echinata Macpherson, 2012 from New Caledonia. The two species can be distinsguished by the following characters:

- The parahepatic spines are present in G. s a m a d i a e, whereas they are absent in G. echinata ; the protogastric and megatastric spines are absent in G. samadiae , while these spines are present in G. echinata . Furthermore, the postcervical spines are present in G. echinata , rather than absent in G. samadiae .

- The branchial margin has two spines on the anterior part, and three spines on the posterior part in G. samadiae , whereas there are one spine on the anterior part, and two spines on the posterior part in G. echinata . - The Mxp3 merus has three weak spines on the flexor margin in G. samadiae , instead of one strong median spine in G. echinata .

No genetic data are available for G. samadiae . Distribution. Philippines, 96– 107 m.

Figures

FIGURE 97. Galathea samadiae n. sp., holotype, male, 3.2 mm, Philippines (MNHN-IU- 2013 - 8425). 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, left P 2, lateral view; G, right P 3, lateral view; H, right P 4, lateral view. Scale: A, E – H = 1 mm; B – D = 0.5 mm.