Galathea echinata, Macpherson, 2012

Macpherson, Enrique, 2012, New deep-sea squat lobsters of the genus Galathea Fabricius, 1793 (Decapoda, Galatheidae) from Vanuatu and New Caledonia, Zoosystema 34 (2), pp. 409-427 : 412-416

Galathea echinata n. sp.

( Fig. 2 )

HOLOTYPE. — New Caledonia. NORFOLK 2, stn DW2024, 23°27.92’S, 167°50.90’E, 370-371 m, 21.X.2003, 1 ♂, 5.1 mm (MNHN-IU-2009-591).

PARATYPES. — New Caledonia. SMIB 5, stn DW88, 22°18.60’S, 168°40.20’E, 350 m, 13.IX.1989, 1 ♂, 4.6 mm, 1 ovig. ♀, 5.0 mm (MNHN-IU-2009-592).

DISTRIBUTION. — New Caledonia, in 350- 371 m.

ETYMOLOGY. — From the Latin “echinatus”, spiny, in reference to the numerous spines on the dorsal surface of the carapace.

DESCRIPTION

Carapace, exclusive of rostrum, 1.2 times as long as broad; dorsal surface of gastric region slightly convex, anterior cardiac region concave; anterior and posterior cervical grooves distinct; ridges on gastric and anterior branchial regions scale-like, not well defined; mid-transverse ridge interrupted, preceded by cervical groove, followed by scale-like ridges and interrupted transverse ridge; all ridges finely setose, with some scattered long and thick plumose setae.Two pairs of small epigastric spines; one median protogastric, and one parahepatic spine on each side; two submedian metagastric spines; one postcervical spine on each side and two cardiac spines. Lateral margins medially convex, with five spines: two spines in front of and three strong spines behind indistinct end of anterior cervical groove; first anterolateral, strong, distinctly posterior to level of lateral limit of orbit; second small, just anterior to lateral end of anterior cervical groove, accompanying another small spine ventral to between first and second; one spine on anterior branchial region, and two spines on posterior branchial margin, last slightly smaller than others, situated at level of cardiac spines. Small spine on lateral limit of orbit; infra-orbital margin with one spine. Rostrum 2.2-2.3 times as long as broad, length 0.6 that of, breadth 0.3 that of carapace, dorsal surface nearly horizontal in lateral view, with small setiferous ridges; lateral margin with four relatively small teeth.

Pterygostomian flap rugose with sparse setae, anteriorly rounded.

Sternal plastron 1.3 times as long as broad, lateral limits divergent posteriorly. Sternite 3 1.3 times as broad as long, anterior margin bilobated. Sternite 4 6.2 times longer and 4.7 times broader than preceding sternite, 0.5 as long as broad; surface with a few short transverse ridges bearing long setae. Following sternites smooth.

Abdominal somites 2-4 each with two uninterrupted transverse ridges on tergite; somite 5 and 6 each with two ridges, posterior one uninterruped on somite 5 and both medially interrupted on somite 6. Telson 0.8 as long as broad, incompletely subdivided. Two pairs of male gonopods.

Ocular peduncles 1.8 times longer than broad; cornea not dilated, as broad as peduncle.

Basal article of antennular peduncle with two well-developed distal spines, distodorsal larger than distolateral, distomesial obsolete. Ultimate article with a few short setae not in tuft on distodorsal margin.

Article 1 of antennal peduncle with depressed ventral distomesial process not reaching distal margin of article 2. Article 2 with distolateral spine clearly larger than distomesial, barely reaching midlength of article 3. Articles 3 and 4 unarmed.

Mxp3 ischium with well-developed distal spine on extensor margin; crista dentata with 21 or 22 denticles. Merus subequal in length to ischium, with one strong spine at midlength of flexor margin; extensor margin with very small spine. Carpus spineless.

P1 4.9 (males), 4.0 (females) times postorbital carapace length, relatively slender, subcylindrical, with long stiff setae on striae of all articles, and some scattered long and thick plumose setae. Merus 1.6- 1.9 times length of carapace, 1.8-2.3 times as long as carpus, with several rows of spines, dorsomesial row with strong spines. Carpus 0.7-0.9 length of palm, 2.4 (males), 1.5 (females) times longer than broad, dorsal surface with row of small spines; mesial surface with well-developed spines; some small spines along lateral margin. Palm 2.9-3.8 (males), 4.5 (females) times longer than broad; small dorsal spines roughly in three rows: mesial, dorsal and lateral; lateral row not continued on to fixed finger. Fingers 0.7 (males), 0.6 (females) as long as palm, distally spooned, touching each other with intermeshing teeth when closed; opposable margins gaping (holotype); when gaping, fixed finger with eminence at distal third and movable finger with process at proximal third; mesial margin of movable finger unarmed.

P2-4 relatively short, somewhat compressed, setose, sparsely with thick long plumose setae on all articles. Meri successively shorter posteriorly (P3 merus 0.8 length of P2 merus, P4 merus 0.9 length of P3 merus), equally broad on P2-4; P2 merus 0.6 carapace length, 3.2 times as long as broad, 1.2 times longer than P2 propodus; P3 merus 2.9 times as long as broad, 1.0 times length of P3 propodus; P4 merus 2.5 times as long as broad, 0.8 length of P4 propodus; dorsal margins with row of 5-6 proximally diminishing spines on P2-3, with terminal spine only on P4; dorsolateral surface unarmed on P2-4; ventrolateral margins with strong terminal spine; ventromesial margin with small terminal spine on P2 only. Carpi with four or five (on P2-3) and 1-3 (on P4) spines on extensor margin, distal-most larger; dorsolateral surface with row of 3-4 small granules paralleling extensor margin on P2-4; flexor distal margins with very small distal spine. Propodi subequal in length on P2-4, each 4.5-5.0 times as long as broad; extensor margin with one or two proximal spines on P2-3, unarmed on P4; flexor margin with 6-8 spines, terminal one paired with another smaller spine mesial to it. Dactyli subequal in length, 0.6 length of propodi, ending in incurved, strong, sharp spine; flexor margin with five or six proximally diminishing teeth, terminal one prominent; each tooth with seta-like movable spine.

Epipods absent on pereopods.

REMARKS

Galathea echinata n. sp. belongs to the group of species having an interrupted ridge between the anteriormost branchial marginal spines directly behind the anterior cervical groove, the rostrum with four lateral spines, the carapace lateral margin with a small spine between the anterolateral and anteriormost branchial marginal spines, gastric striae not scale-like, and the antennular basal article with two spines. The closest relative is G. robusta Baba, 1990 from Madagascar (see above for the comparative material used), from which it is easily distinguished by the following ( Table 1):

– the branchial margin of the carapace has three strong spines instead of five spines of moderate size; – the ridges on gastric and anterior branchial regions are scale-like and not well defined in the new species, whereas some of these ridges are uninterrupted and well defined in G. robusta ;

– the flexor margin of the Mxp3 merus bears a strong spine at midlength, instead of three spines of moderated size (proximal and median subequal).

Figures

FIG. 2. — Galathea echinata n. sp., holotype ♂, 5.1 mm (MNHN-IU-2009-591): A, carapace and abdomen, dorsal view; B, anterior part of sternal plastron; C, cephalic region, showing antennular and antennal peduncles, ventral view; D, right Mxp3, lateral view; E, right P1, dorsal view; F, distal part of P1 fingers, ventral view; G, right P2, lateral view; H, right P3, lateral view; I, right P4, lateral view. Scale bars: A, B, D, F, 2 mm; C, 1.5 mm; E, G, H, I, 1 mm.