Galathea lemniscata, 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 : 160-162

Galathea lemniscata n. sp.

( Figs 56 , 117 G)

Material examined. Holotype: New Caledonia. Chesterfield Islands. MUSORSTOM 5, Stn DW348, 19°36.00'S, 158°31.70'E, 260 m, 17 October 1986: F 4.8 mm (MNHN-IU-2013-15873).

Paratypes: Vanuatu. MUSORSTOM 8, Stn DW966, 20°18.80'S, 169°51.91'E, 128–150 m, 21 Septmeber 1994: 1 F 7.6 mm (MNHN-IU-2013-15876).

New Caledonia. Chesterfield Islands. CHALCAL 84, Stn D35, 19°44.84'S, 158°25.83'E, 210 m, 21 July 1984: 1 ov. F 6.9 mm (MNHN-IU-2013-15875). MUSORSTOM 5, Stn DC377, 19°48.60'S, 158°29.10'E, 260–270 m, 20 October 1986: 1 F 4.8 mm (MNHN-IU-2013-15878).

New Caledonia. SMIB 5, Stn DW75, 23°40.90'S, 168°00.80'E, 270 m, 7 September 1989: 1 M 5.4 mm (MNHN-IU-2013-15874). HALIPRO 1, Stn CP851, 21°43.32'S, 166°37.43'E, 314–364 m, 19 March 1994: 1 F 9.3 mm (MNHN-IU-2013-15877).

New Caledonia. Lifou Island. LIFOU, Stn 1462, 20°47.1'S, 167°03.2'E, 70–120 m, 21 November 2000: 1 ov. F 5.2 mm (MNHN-IU-2013-9714).

Etymology. From the Latin lemniscatus, adorned with ribbons, in reference to the whitish bands in the body.

Description. Carapace: 0.9 times as long as broad; ridges with short fine setae, with a few scattered long simple setae; cervical groove slightly distinct, laterally bifurcated; gastric and anterior branchial regions only with scale-like or in concentric arcs; dorsal surface unarmed; mid-transverse ridge interrupted or uninterrupted, preceded by shallow cervical groove, followed by 5 ridges, 1 or 2 uninterrupted. Lateral margins convex medially, with 7 spines: 2 spines in front of, and 5 spines behind, anterior cervical groove; first anterolateral; second, small, at midlength between anterolateral spine and anteriormost spine of branchial margin, accompanying another spine ventral to between first and second; 2 spines on anterior branchial margin, and 3 spines on posterior branchial margin. External limit of orbit with small spine; infraorbital margin with 2 or 3 small spines. Rostrum broad triangular, 1.6 times as long as broad, length 0.6 postorbital carapace length and breadth 0.3 that of carapace, nearly horizontal in lateral view; distance between distalmost lateral incisions 0.3 distance between proximalmost lateral incisions; dorsal surface with a few small scale-like setiferous ridges; lateral margin with 4 deeply incised sharp teeth.

Pterygostomian flap rugose, unarmed, with sparse short setae, anterior margin blunt.

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

Abdomen: Somites 2–4 with 2 transverse ridges, anterior ridge more distinctly elevated than posterior ridge; somites 5 and 6 with 2 medially interrupted ridges, posteromedian margin nearly transversal with setiferous ridge. Males with G1 and G2.

Eyes: Ocular peduncles 1.3 times longer than broad, maximum corneal diameter 0.6 rostrum width.

Antennule: Article 1 with 3 well-developed spines, distodorsal larger; distomesial spine slightly smaller than distoventral. Ultimate article with a few short fine setae on distodorsal margin.

Antenna: Article 1 with ventral distomesial spine reaching midlength of article 2. Article 2 with 2 subequal distal spines, reaching end of article 3. Article 3 with distinct distomesial spine. Article 4 unarmed.

Mxp3: Ischium with well-developed distal spine on flexor margin; extensor and flexor margins ending in spine; crista dentata with 13 or 14 denticles. Merus equally long as ischium; flexor margin with 2 strong subequal spines, proximal one located at midlength, distal one at terminal end; extensor margin with distal spine. Carpus unarmed.

P1: 2.1 times postorbital carapace length, relatively slender, somewhat depressed on palm, more so on fingers. Merus 0.7 times length of carapace, 1.7 times as long as carpus, with spines arranged roughly in rows, distal spines prominent. Carpus 0.7 length of palm, 1.3 times as long as broad; dorsal surface with small spines arranged roughly in longitudinal rows; mesial margin with 3 or 4 strong spines, distal second largest. Palm 1.6 times longer than broad, lateral and mesial margins subparallel; spines arranged roughly in rows; dorsolateral row continuing on to lateral margin of fixed finger; dorsomesial row continuing on to mesial margin of movable finger. Fingers 0.8 length of palm, distally not spooned, with 1 row of teeth, opposable margins nearly straight, with blunt serration.

P2–4: moderately slender, with setose striae and sparse long plumose setae. P2 1.6 times carapace length. Meri successively shorter posteriorly (P3 merus 0.9 length of P3 merus, P4 merus 0.8 length of P3 merus); P2 merus 0.6 carapace length, 2.7 times as long as broad, 1.3 times longer than P2 propodus. Extensor margin with row of 7 or 8 proximally diminishing spines on P2–3, 2 spines on P4; ventral margins distally ending in strong spine followed proximally by 0–1 spines and several eminences, lateral sides with 3 spines on P4. Carpi with 6–7 spines on extensor margin on P2–4; lateral surface with 3 or 4 spines or acute granules sub-paralleling extensor margin; flexor distal margin acute. Propodi 3.5–3.7 times as long as broad; extensor margin with 2–4 proximal spines; flexor margin with 6 or 7 slender movable spines. Dactyli distally ending in well-curved strong spine, length 0.7–0.8 that of propodi; flexor margin with 4 or 5 proximally diminishing teeth, terminal one prominent.

Epipods only on P1.

Coloration. Body color brown, with median longitudinal whitish broad stripe, from base of rostrum to abdominal somite 5; median protogastric-mesogastric regions brown; one whitish or light brown lateral fleck on each branchial region. P1–4 brown or with diffuse brown and whitish bands.

Remarks. Galathea lemniscata n. sp. is characterized by the presence of scale-like ridges on the gastric region and the cutting edges of the cheliped fingers distally not spooned, with one row of teeth only. The closest relative is G. chura Osawa & Higashiji, 2012 from Okinawa Island, Ryukyu Islands, Japan. These two species can be distinguished only by the living coloration. In G. lemniscata , the carapace is brown, sometimes with a broad median longitudinal whitish stripe, extending from the base of the rostrum to the abdominal somite 5 in the new species, whereas in G. chura , the carapace is generally white, with numerous large red spots. Furthermore, the P1–4 are brown in G. lemniscata n. sp., whereas banded with white and red in G. chura .

The genetic divergences between G. lemniscata and other species are always higher than 18.6% ( G. bimaculata n. sp.) (COI) and 4.5% ( G. ploto n. sp.) (16S rRNA) ( Tab. 3 ).

Distribution. Vanuatu, New Caledonia, Chesterfield Islands; 70– 364 m.

Figures

FIGURE 56. Galathea lemniscata n. sp., holotype, female, 4.8 mm, New Caledonia, Chesterfield Islands (MNHN-IU- 2013 - 15873). 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 1 fingers, ventral view; G, right P 2, lateral view; H, right P 3, lateral view; I, right P 4, lateral view. Scale: A, E, G, H, I = 1 mm; B – D, F = 0.5 mm.

FIGURE 117. Dorsal view. A, Galathea halia n. sp., Vanuatu, ovigerous female 3.2 mm (MNHN-IU- 2013 - 8110). B, Galathea halia n. sp., Vanuatu, ovigerous female 3.2 mm (MNHN-IU- 2013 - 13528). C, Galathea imitata n. sp., Western Australia, ovigerous female 3.2 mm (UF 21915). D, Galathea imitata n. sp., Western Australia, male 3.6 mm (UF 22483). E, Galathea inconspicua Henderson, 1885, Vanuatu, male 5.1 mm (MNHN-IU- 2013 - 8507). F, Galathea inflata Potts, 1915, Papua New Guinea, ovigerous female 6.3 mm (MNHN-IU- 2013 - 509). G, Galathea lemniscata n. sp., New Caledonia, Chesterfield islands, holotype, female 4.8 mm (MNHN-IU- 2013 - 15873). H, Galathea leporis n. sp., Papua New Guinea, male 4.3 mm (MNHN-IU- 2013 - 370). I, Galathea longioculata n. sp., Vanuatu, holotype, female 4.8 mm (MNHN- IU- 2013 - 15979).