Galathea tagaloa, 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 : 298-299

Galathea tagaloa n. sp.

( Figs 107 , 121 B)

Material examined. Holotype: Fiji. BORDAU 1, Stn DW1493, 18°43.02'S, 178°23.74'W, 429–440 m, 11 March 1999: M 5.1 mm (MNHN-IU-2013-8089).

Paratypes: Vanuatu. BOA 1, Stn CP2414, 15°41.28'S, 167°02.897'E, 309–402 m, 5 September 2005: 1 M 6.7 mm, 1 ov. F 5.5 mm (MNHN-IU-2013-8103). SANTO, Stn AT58, 15°33.0'S, 167°19.3'E, 364–390 m, 0 3 October 2006: 1 M 6.5 mm (MNHN-IU-2013-13983).

Fiji Islands. BORDAU 1, Stn CP1395, 16°45.13'S, 179°59.20'E, 423–500 m, 23 February 1999: 1 F 5.0 mm (MNHN-IU-2013-8099).— Stn CP1406, 16°39.47'S, 179°36.93'E, 360–380 m, 25 February 1999: 1 ov. F 5.3 mm (MNHN-IU-2013-8093).—Stn DW1421, 17°07.95'S, 178°59.25'W, 403–406 m, 28 February 1999: 1 M 4.7 mm (MNHN-IU-2013-8091).— Stn CP1444, 17°11.13'S, 178°41.41'W, 398–409 m, 0 3 March 1999: 1 M 4.6 mm, 1 ov. F 5.1 mm (MNHN-IU-2013-8102).—Stn CP1467, 18°11.80'S, 178°35.80'W, 417–427 m, 0 6 March 1999: 2 M 4.7–4.8 mm, 3 ov. F 4.5–5.4 mm (MNHN-IU-2013-8098).—Stn DW1492, 18°43.12'S, 178°22.63'W, 430–450 m, 11 March 1999: 1 ov. F 5.1 mm (MNHN-IU-2013-8097).— Stn DW1493, 18°43.02'S, 178°23.74'W, 429–440 m, 11 March 1999: 1 ov. F 4.9 mm (MNHN-IU-2013-8096).—Stn CP1500, 18°41.74'S, 178°26.20'W, 366–389 m, 12 March 1999: 1 M 4.5 mm, 1 ov. F 4.3 mm (MNHN-IU-2013-8090).—Stn CP1501, 18°39.68'S, 178°29.90'W, 350–357 m, 12 March 1999: 3 M 4.7–5.1 mm, 2 F 4.2–4.6 mm (MNHN-IU-2013-8092).

Tonga Islands. BORDAU 2, Stn CP1525, 21°17'S, 174°59'W, 349–351 m, 0 2 June 2000: 2 ov. F 3.4–3.5 mm (MNHN-IU-2013-8095).—Stn CP1561, 19°52'S, 174°40'W, 383–393 m, 0 8 June 2000: 1 M 5.5 mm (MNHN-IU- 2013-8101).— Stn CP1572, 19°42'S, 174°31'W, 391–402 m, 11 June 2000: 1 ov. F 4.9 mm (MNHN-IU-2013- 8094), 1 ov. F 3.1 mm (MNHN-IU-2013-8100).

Etymology. The name refers to Tagaloa , the ocean-god, that according the Samoan tradition created the Fiji islands. The name is considered as a substantive in apposition.

Description. Carapace: As long as broad; transverse ridges with sparse long setae among numerous short fine setae; cervical groove distinct, laterally bifurcated; most ridges on gastric region uninterrupted, with some scattered scale-like ridges; epigastric region with 8 or 9 spines; protogastric with 4 or 5 small median spines; 3 or 4 small hepatic spines on each side near anterolateral spine, sometimes 1 or 2 very near lateral margin; 1 or 2 small parahepatic spines lateral to anterior protogastric ridge; anterior branchial region with distinct ridges, sometimes with 1 or 2 minute spines on each side. Anterior mesogastric ridge not extending laterally to anteriormost of branchial marginal spines; anterior metagastric ridge not extending laterally to anterior branchial ridges. Midtransverse ridge uninterrupted, preceded by shallow cervical groove, followed by 5 ridges. Lateral margins slightly convex medially, with 7 spines: first anterolateral, well-developed, second very small but distinct, located at midlength between first spine and anterior cervical groove, with small spine ventral to between first and second; 2 spines on anterior branchial margin, and 3 spines on posterior branchial margin. Small outer orbital spine; infraorbital margin with 1 strong spine, and 1 or 2 spines; sometimes 1 small spine between orbital and anterolateral spines. Rostrum triangular, 2.0–2.1 times as long as broad, length 0.6 that of, breadth 0.3–0.4 that of carapace; distance between distalmost lateral incisions 0.25 distance between proximalmost lateral incisions; dorsal surface nearly horizontal in lateral view, with some thick long plumose setae; lateral margin with 4 deeply incised sharp spines.

Pterygostomian flap rugose, with sparse short setae, anterior margin bluntly angular.

Sternum: About as long as broad, lateral limits divergent posteriorly.

Abdomen: Somites 2–3 each with 2 uninterrupted and 1 scale-like transverse ridges on tergite, anterior ridge more elevated than posterior ridge; somite 4 with 2 ridges, posterior ridge medially interrupted; somites 5 and 6 each with 2 medially interrupted ridges; posteromedian margin of somite 6 straight. Males with G1 and G2.

Eyes: Ocular peduncles 1.5 times longer than broad, maximum corneal diameter 0.7 rostrum width.

Antennule: Article 1 with 2 well-developed spines, distodorsal and distolateral spines, distodorsal larger; distomesial spine distinct but very small; 2 small spines along lateral margin. Ultimate article moderately elongate, twice longer than broad, with a few short fine setae not in tuft on distodorsal margin.

Antenna: Article 1 with distomesial spine reaching distal margin of article 2. Article 2 with 2 well-developed distal spines, distomesial spine slightly longer than distolateral reaching end of article 3, additional small spine at midlength of mesial margin. Articles 3 and 4 unarmed.

Mxp3: Basis with several denticles on mesial ridge, distalmost larger. Ischium with well-developed spine on flexor distal margin; crista dentata with 22 or 23 denticles. Merus shorter than ischium; flexor margin with 3 spines, proximal stronger than others; extensor margin with 1 or 2 spines, distal spine well-developed. Carpus unarmed.

P1: 4.4 times carapace length, with numerous finely setiferous scales, with scattered long thick plumose setae. Merus 1.6 times length of carapace, 2.0 times as long as carpus, with spines arranged roughly in rows, dorsomesial and ventromesial spines stronger; distal spines prominent. Carpus 0.7 length of palm, 2.3 times as long as broad; dorsal surface with small spines arranged roughly in 2 longitudinal rows; mesial spines slightly stronger than dorsal spines. Palm 2.7 times longer than broad, lateral and mesial margins with small spines arranged roughly in dorsolateral and dorsomesial rows, some small spines scattered on dorsal side. Fingers 0.7 length of palm, each finger distally with two rows of teeth, spooned, mesial margin of movable finger and lateral margin of fixed finger unarmed.

P2–4: Moderately long and slender, with setose striae and long plumose setae. P2 2.1 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 0.8 carapace length, 4.5 times as long as broad, 1.2 times longer than P2 propodus; P3 merus 3.5 times longer than broad, 1.0–1.1 times longer than P3 propodus; P4 merus 3.5 times as long as broad, 1.1 length of P4 propodus. Extensor margins of meri with row of 8–10 proximally diminishing spines; flexor margins distally ending in strong spine followed proximally by 1 or 2 small spines and several tubercles or eminences. Carpi with 5 or 6 spines on extensor margin, distalmost longer than distal second; lateral surface with 1 or 2 small spines and acute granules sub-paralleling extensor margin on P2–4; flexor distal margin sometimes with small spine. P2, P3 and P4 propodi 6.5, 6 and 5 times as long as broad, respectively; extensor margin with 3 or 4 small proximal spines on P2–4; flexor margin with 5 or 6 slender movable spines on P2–4. Dactyli subequal in length, distally ending in well-curved strong spine, length 0.5 that of propodi; flexor margin with 5 or 6 proximally diminishing teeth, terminal one prominent.

Epipods on P1.

Coloration. Base color light orange. Ridges on carapace and abdomen reddish.

Remarks. Galathea tagaloa is closely related to G. pubescens Stimpson, 1858 from Japan to New Caledonia from which it can be distinguished by the following characters:

- The rostrum is twice longer than wide in G. tagaloa , whereas it is clearly less than twice in G. pubescens . - The carapace has numerous anterior branchial and postcervical spines in G. pubescens , whereas these spines are absent (rarely 1 or 2 minute spines) in G. tagaloa .

- The genetic divergences between G. pubescens and G. tagaloa are 16.2% (16S rRNA) and 19.3% (COI) ( Tab. 2 ).

Distribution. Fiji, Tonga Islands, Vanuatu, 309– 450 m.

Figures

FIGURE 107. Galathea tagaloa n. sp., holotype, male, 5.1 mm, Fiji (MNHN-IU- 2013 - 8089). 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.

FIGURE 121. Dorsal view. A, Galathea subsquamata Stimpson, 1858, Papua New Guinea, male 3.4 mm (MNHN-IU- 2013 - 353). B, Galathea tagaloa n. sp., Vanuatu, M 6.5 mm (MNHN-IU- 2013 - 13983). C, Galathea tagaro n. sp., Vanuatu, holotype, female 4.7 mm (MNHN-IU- 2013 - 8365). D, Galathea tanegashimae Baba, 1969, Papua New Guinea, male 2.3 mm (MNHN- IU- 2013 - 375). E, Galathea ternatensis De Man, 1902, Papua New Guinea, male 3.5 mm (MNHN-IU- 2013 - 13664). F, Galathea tongi n. sp., French Polynesia, ovigerous female 3.0 mm (UF 15686).