Galathea raventosae, 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 : 418-422

Galathea raventosae n. sp.

( Figs 4 ; 6A )

HOLOTYPE. — Vanuatu. SANTO 2006 , stn AT34, 15°35.9’S, 167°17.1’E, 234-270 m, 23.IX.2006, 1 ♂, 4.5 mm (MNHN-IU-2009-605).

PARATYPES. — Vanuatu. SANTO 2006, stn AT22, 15°32.3’S, 167°16.0’E, 180-227 m, 22.IX.2006, 1 ♂, 3.5 mm, 1 ovig. ♀, 5.0 mm (MNHN-IU-2009-606). — Stn AT69, 15°40.4’S, 167°17.3’E, 207-229 m, 5.X.2006, 1 ovig. ♀, 5.4 mm (MNHN-IU-2009-607).

New Caledonia. HALIPRO 1, stn CP853, 21°45’S, 166°37’E, 241-250 m, 19.X.1993, 1 ovig. ♀, 4.6 mm (MNHN-IU-2009-608).

DISTRIBUTION. — Vanuatu and New Caledonia, in 180- 270 m.

ETYMOLOGY. — Named for Nuria Raventos, CEAB, for her support and advocacy for marine research.

DESCRIPTION

Carapace, exclusive of rostrum, as long as broad; dorsal surface nearly horizontal from anterior to posterior; transverse ridges with sparse long plumose setae among short fine setae; cervical groove distinct, laterally bifurcated; most ridges on gastric region interrupted, with some scattered scale-like ridges; small parahepatic spine lateral to second transverse ridge; epigastric region with pair of submedian spines; anterior branchial region with distinct ridges; mid-transverse ridge uninterrupted, preceded by shallow cervical groove, followed by three interrupted and three uninterrupted transverse ridges placed alternately. Lateral margins well convex medially, with six spines: two spines in front of and four spines behind anterior cervical groove; first anterolateral, well developed, second very small but distinct, located at midlength between first spine and anterior cervical groove, without small spine ventral to between first and second; two spines on anterior branchial margin, and two spines on posterior branchial margin.Small outer orbital spine; infraorbital margin with strong spine. Rostrum 1.6-1.7 as long as broad, length 0.6-0.7 postorbital carapace length and breadth 0.3 that of carapace; dorsal surface nearly horizontal in lateral view, with small setiferous ridges; lateral margin with four deeply incised sharp teeth.

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

Sternal plastron about as long as broad, lateral extremities gently divergent posteriorly. Sternite 3 twice as broad as long, with median depression bordering left and right lobes, anterior margin of each lobe convex, with minute dentitions. Sternite 4 3.4 times longer and 3.3 times broader than sternite 3, 0.5 as long as broad; surface with setiferous interrupted transverse ridges, not reaching lateral margin. Following sternites smooth.

Abdominal somites 2-3 each with two uninterrupt- ed transverse ridges on tergite, anterior ridge more distinctly elevated than posterior ridge; somite 4 with two ridges, posterior ridge medially interrupted; somites 5 and 6 each with uninterrupted anterior ridge and two medially interrupted ridges. Telson 0.8 as long as broad, incompletely subdivided. Male gonopods on abdominal somites 1-2.

Ocular peduncles 1.3 times longer than broad; eyestalk (other than cornea) with lateral margin straight, dorsally with some long setae; cornea not dilated, as broad as the peduncle.

Basal article of antennular peduncle with three spines; well-developed distodorsal and distolateral spines, distodorsal larger; distomesial spine somewhat shorter than distolateral. Ultimate article with a few short fine setae not in tuft on distodorsal margin.

Antennal peduncle with article 1 hardly visible in dorsal view, with ventral distomesial spine not reaching distal margin of article 2. Article 2 with two well-developed distal spines, distolateral spine terminating in or slightly overreaching midlength of article 3, distomesial spine slightly shorter than distolateral. Article 3 with distinct distomesial spine. Article 4 unarmed.

Mxp3 basis with several denticles on mesial ridge, distalmost larger. Ischium with well-developed spine on flexor distal margin; extensor margin with small but distinct distal spine; crista dentata with 20-21 denticles. Merus shorter than ischium; flexor margin with one strong spine at midlength, and one small distal spine; extensor margin with two obsolescent distal spines. Carpus unarmed.

P1 2.5-2.6 (females), 3.0-3.7 (male) times postorbital carapace length, subcylindrical, somewhat depressed on palm, more so on fingers, covered with finely setiferous scales, with scattered long thick plumose setae. Merus 1.3 times length of carapace, 1.7 times as long as carpus, with spines arranged roughly in rows, dorsomesial and ventromesial spines stronger; distal spines prominent. Carpus 0.9-1.2 length of palm, 1.7-1.9 times as long as broad; dorsal surface with small spines arranged roughly in two longitudinal rows; mesial margin with 3-4 strong spines (distal second largest). Palm 1.7-2.1 times longer than broad, lateral and mesial margins slightly convex; spines arranged roughly in dorsolateral and dorsomesial rows, some small spines scattered on dorsal side. Fingers 0.7-0.8 length of palm, distally spooned, prehensile distal edges close fitting with intermeshing teeth when closed; opposable margins slightly gapping, with blunt serration; mesial margin of movable finger unarmed.

P2-4 moderately slender, with setose striae and sparse long plumose setae. Meri successively shorter posteriorly (P3 merus 0.9 length of P2 merus, P4 merus 0.8 length of P3 merus); P2 merus 0.8 carapace length, 4.2 times as long as broad, 1.3 times longer than P2 propodus; P3 merus 3.7 times longer than broad, equally broad as P4 merus, 1.2 times longer than P3 propodus; P4 merus 3.1 times as long as broad, 0.9-1.0 length of P4 propodus. Dorsal margins of propodi with row of 7-10 proximally diminishing spines on P2-3, three or four distal spines on P4; ventral margins distally ending in strong spine followed proximally by small spine and several tubercles or eminences. Carpi with five spines on extensor margin on P2- 3, one or two spines on P4, distal-most smaller than distal second; dorsolateral surface with acute granules sub-paralleling extensor margin on P2-4; flexor distal margin with small distal spine. Propodi subequal in length on P2-4, each about 5.0 times as long as broad; extensor margin unarmed; flexor margin with 5-7 slender movable spines on P2-4, terminal one paired with another smaller spine mesial to it. Dactyli subequal in length, distally ending in well-curved strong spine, length 0.7 that of propodi; flexor margin 6 proximally diminishing teeth, terminal one prominent; each tooth with seta-like movable spine.

Epipods absent on pereopods 1-3.

Colouration

Ground colour of carapace, abdominal somites 2-4 and pereopods light brownish or pale; abdominal somites 5-6, telson and uropods whitish or translucent. Long thick plumose setae of carapace, abdomen and P1 mostly brown. P2-4 dactyli whitish.

REMARKS

The new species resembles G. consobrina from Indonesia, the Philippines, South China Sea and southwestern Australia ( De Man 1902; Baba 1988; Poore et al. 2008; Dong & Li 2010). Both species have 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 anterolateral and anteriormost branchial marginal spines, gastric striae not scale-like, the antennular basal article with three spines, epigastric spines present, and epipods absent on P1-3. However, the two species can be distinguished by the following: – one hepatic spine is distinct on each side in G. consobrina , whereas it is absent in the new species; – the small spine ventral to between first and second lateral spines of the carapace is well developed in G. consobrina , whereas it is absent in the new species; – the branchial lateral margin of the carapace has five spines in G. consobrina , four spines in the new species;

– the flexor margin of the Mxp3 merus bears two well-developed spines of subequal size in G. consobrina , instead of one strong median and one minute distal spines as in the new species.

Figures

FIG. 4. — Galathea raventosae n. sp., holotype ♂, 4.5 mm (MNHN-IU-2009-605): 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, C, D, F, 1 mm; E, G, H, I, 0.5 mm.

FIG. 6.— A, Galathea raventosae n.sp.,holotype ♂, 4.5 mm,dorsal view;B, Galathea sanctae n. sp.,holotype ovig.♀, 5.5 mm,dorsal view.