Galathea gruis, 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 : 131-133

Galathea gruis n. sp.

( Fig. 44 )

Material examined. Holotype: Indonesia. Kei Islands. KARUBAR, Stn DW18, 05°18'S, 133°01'E, 205–212 m, 24 October 1991: M 3.6 mm (MNHN-IU-2013-8356).

Paratypes: Indonesia. Kei Islands. KARUBAR, Stn DW18, 05°18'S, 133°01'E, 205–212 m, 24 October 1991: 1 M 3.4 mm (MNHN-IU-2013-8357), 1 M 3.2 mm (MNHN-IU-2013-8364), 4 M 3.0– 3.6 mm, 1 F 2.5 mm (MNHN-IU-2013-8358).

Philippines. MUSORSTOM 2, Stn CP41, 13°15'N, 122°46'E, 166–172 m, 25 November 1980: 1 M 3.3 mm (MNHN-IU-2013-8359), 1 M 4.1 mm (MNHN-IU-2013-8360), 1 M 3.0 mm (MNHN-IU-2013-8361), 1 M 2.8 mm (MNHN-IU-2013-8362), 3 M 3.0– 4.1 mm (MNHN-IU-2013-8363).

Etymology. The name Grus , the crane, refers to one of the southern hemisphere constellations.

Description. Carapace: as long as broad; transverse ridges with dense short setae, without long iridescent setae; cervical groove distinct, laterally bifurcated. Gastric region with 6 transverse ridges: 1 epigastric ridge with 2 spines, medially interrupted, minute or absent in a few specimens; 2 protogastric ridges, anterior ridge medially interrupted, without parahepatic spines, posterior ridge short, arcuate; 1 mesogastric ridge medially interrupted, not extending laterally to anteriormost of branchial marginal spines; 2 metagastric ridges, anterior ridge medially interrupted, not extending laterally to anterior branchial region, posterior ridge short. Hepatic region unarmed. Anterior branchial region with distinct ridges. Mid-transverse ridge uninterrupted, preceded by shallow cervical groove, followed by 5 transverse ridges. Lateral margins well convex medially, with 5 or 6 spines: 1 spine in front of and 4 or 5 spines behind anterior cervical groove; first anterolateral, well-developed, at same level of lateral limit of orbit, without spine ventral to between first and anterior end of cervical groove; 2 spines on anterior branchial region, last small, and 2 or 3 spines on posterior branchial margin, last small. Small spine on lateral limit of orbit; infraorbital margin with strong spine. Rostrum 1.7–1.9 as long as broad, length 0.6–0.7 postorbital carapace length and breadth 0.3–0.4 that of carapace; distance between distalmost lateral incisions 0.3 distance between proximalmost lateral incisions; dorsal surface nearly horizontal in lateral view, with numerous short unirramous setae; lateral margin with 4 deeply incised sharp teeth.

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

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

Abdomen: Somites 2–3 each with 2 uninterrupted transverse ridges on tergite; somites 4–6 smooth or with scattered scales. Telson incompletely subdivided. Males with G1 and G2.

Eyes: Ocular peduncles 1.3 times longer than broad, maximum corneal diameter 0.7–0.8 rostrum width.

Antennule: Article 1 with 3 well-developed distal spines, distodorsal larger, distomesial spine smaller than others; small lateral spine at base of distodorsal spine. Ultimate article with a few short fine setae not in tuft on distodorsal margin.

Antenna: Article 1 with strong distomesial spine exceeding distal margin of article 3. Article 2 with 2 welldeveloped distal spines, distolateral spine larger than distomesial spine, nearly reaching end of article 3. Articles 3 and 4 unarmed.

Mxp3: Ischium with flexor margin ending in strong spine, extensor margin ending in acute angle; crista dentata with 20 or 21 denticles. Merus shorter than ischium; flexor margin with 2 spines, proximal clearly stronger than distal; extensor margin with minute distal spine.

P1: 2.4–3.5 times carapace length, with numerous setiferous scales, and a few scattered long setae. Merus 1.1–1.3 times carapace length, 1.7–1.9 times as long as carpus, with some spines, dorsomesial and distal spines stronger than others. Carpus 0.8–1.1 times length of palm, 1.7–2.1 times as long as broad; dorsal surface with some small spines; mesial margin with 4 spines, distal second largest. Palm 1.7–1.9 times longer than broad, lateral and mesial margins slightly convex; spines arranged roughly in dorsolateral and dorsomesial rows, and some small spines on dorsal side. Fingers 0.9–1.1 times palm length, unarmed; each finger distally with two rows of teeth, spooned.

P2–4: moderately long and slender, with some setose striae and sparse long plumose setae. P2 1.7–2.0 times carapace length. Meri successively shorter posteriorly (P3 merus 0.9 length of P2 merus, P4 merus 0.8 length of P3 merus). P2 merus 0.7 carapace length, 3.6–3.9 times as long as broad, 1.3–1.4 times longer than P2 propodus; P3 merus 3.2–3.5 times longer than broad, 1.3 times longer than P3 propodus; P4 merus 2.8–3.3 times as long as broad, 1.1 times longer than P4 propodus. Extensor margin of P2–3 meri with row of 6 or 7 proximally diminishing spines, 1 distal spine on P4; ventral margins distally ending in strong spine followed proximally by 0–1 spines and several eminences; lateral sides unarmed on P2–4. Carpi with 4 or 5 spines on extensor margin on P2–4, distalmost smaller than distal second, sometimes absent; lateral surface with some acute granules sub-paralleling extensor margin on P2–4; flexor distal margin ending in acute angle. P2–4 propodi 3.6–4.5 times as long as broad; extensor margin unarmed; flexor margin with 4–6 slender movable spines. Dactyli distally ending in well-curved strong spine, length 0.5–0.8 that of propodi; flexor margin with 4–6 proximally diminishing teeth, terminal one prominent.

Epipods absent on pereiopods.

Remarks. Galathea gruis n. sp. belongs to the group of species having an interrupted transverse ridge between the anteriormost branchial marginal spines, the carapace with two epigastric spines, the lateral margin without a spine between the anterolateral spine and the anteriormost branchial marginal spine, and the absence of epipods on P1–3.

The new species is closely related to G. anepipoda Baba, 1990 , from Madagascar (see above), but can be easily distinguished by the following characters:

- The palm is distinctly longer than the fingers in G. anepipoda , whereas the fingers are longer or as long as the palm in the new species.

- The distomesial spine of the antennal article 1 exceeds the antennal article 3 in G. g r u i s, rather than reaching the end of the antennal article 3 in G. anepipoda .

The genetic divergence between G. g r u i s and G. anepipoda are 10.1% (COI) ( Tab. 1). Distribution. Philippines, Indonesia (Kei Islands); 166– 212 m.

Figures

FIGURE 44. Galathea gruis n. sp., holotype, male, 3.6 mm, Indonesia, Kei Islands (MNHN-IU- 2013 - 8356). 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.