Galathea pauxilla, 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 : 223-225

Galathea pauxilla n. sp.

( Fig. 80 )

Material examined. Holotype: Vanuatu. SANTO, Stn AT86, 15°31.9'S, 167°16.2'E, 176–246 m, 12 October 2006: ov. F 4.3 mm (MNHN-IU-2013-13998).

Etymology. From the Latin pauxillus, dim, in reference to the small size of the species.

Description. Carapace: As slightly longer than broad; transverse ridges with numerous short fine setae, without long setae; cervical groove distinct, laterally bifurcated. Gastric region with 9 ridges; 1 epigastric scale-like ridge, with 5 small median spines; 3 protogastric ridges, anterior ridge uninterrupted, with 1 small parahepatic spine on each side, median ridge uninterrupted, posterior ridge scale-like; 2 mesogastric ridges, not continuing laterally with anterior branchial ridges; 3 metagastric ridges, medially uninterrupted and not continuing laterally with anterior branchial ridges. One small spine on each hepatic region. Mid-transverse ridge uninterrupted, preceded by shallow cervical groove, followed by 6 ridges, 4 uninterrupted. Lateral margins slightly convex medially, with 7 spines: first anterolateral, well-developed, second very small but distinct, located at midlength between first spine and anteriormost spine of branchial margin, 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. Rostrum triangular, 1.8 times as long as broad, length 0.5 that of, breadth 0.3 that of carapace; distance between distalmost lateral incisions 0.3 distance between proximalmost lateral incisions, dorsal surface nearly horizontal in lateral view, with some thick long plumose setae; lateral margin with 4 shallowly incised 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 4 uninterrupted transverse ridges on tergite, anterior ridge more elevated than posterior ridge; somites 4–5 with 3 ridges; somite 6 each with 2 medially interrupted ridges, posteromedian margin of somite 6 straight.

Eyes: Ocular peduncles 1.4 times longer than broad, maximum corneal diameter 0.9 rostrum width.

Antennule: Article 1 with 2 well-developed spines, distodorsal larger; distomesial spine obsolescent; lateral margin with 2 small spines. Ultimate article elongate, more than 2.5 times longer than broad, with a few short fine setae not in tuft on distodorsal margin.

Antenna: Article 1 with distomesial spine barely reaching distal margin of article 2. Article 2 with 2 subequal distal spines, reaching midlength of article 3. Article 3 with minute distomesial spine. Article 4 unarmed.

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

P1: 3.3 times carapace length, with numerous finely setiferous scales, with scattered long thick setae. Merus 1.6 times length of carapace, 2.2 times as long as carpus, with spines arranged roughly in rows, dorsomesial and ventromesial spines stronger; distal spines prominent. Carpus 0.9 length of palm, 4 times as long as broad; dorsal surface with small spines arranged roughly in longitudinal rows; mesial spines slightly stronger than dorsal spines. Palm 4 times longer than broad, lateral and mesial margins with small spines arranged roughly in dorsolateral and dorsomesial rows, some minute spines scattered on dorsal side. Fingers as long as palm, each finger distally ending in two rows of teeth, incurved to cross each other when closed, mesial margin of movable finger and lateral margin of fixed finger unarmed.

P2–4: Moderately long and slender, with setose striae and long setae. P2 twice carapace length. Meri successively shorter posteriorly (P3 merus 0.9 length of P2 merus, P4 merus 0.7 length of P3 merus); P2 merus 0.8 carapace length, 9 times as long as broad, 1.5 times longer than P2 propodus; P3 merus 7 times longer than broad, 1.5 times longer than P3 propodus; P4 merus 6 times as long as broad, as long as P4 propodus. Extensor margins of P2–3 meri with row of 10 or 11 proximally diminishing spines, P4 merus with 4 spines and 1 small dorsal spine; flexor margins distally ending in strong spine followed proximally by 1 or 2 small spines and several tubercles or eminences. P2–4 carpi with 6 small spines on extensor margin; lateral surface with 5 or 6 small spines or acute granules sub-paralleling extensor margin on P2–4; flexor distal margin sometimes with small spine. P2, P3 and P4 propodi 5.5, 6.0 and 5.5 times as long as broad, respectively; extensor margin with 1–3 small proximal spines; flexor margin with 5–7 slender movable spines on P2–4. Dactyli subequal in length, distally ending in well-curved strong spine, length 0.6 that of propodi; flexor margin with 7 or 8 proximally diminishing teeth, terminal one prominent.

Epipods present on P1.

Remarks. The new species resembles G. albatrossae Baba, 1988 from Taiwan, Philippines to New Caledonia. The two species can be distinguished by the anterior metagastric ridge. This ridge is uninterrupted and continuing laterally with the anterior branchial ridges in G. albatrossae , whereas this ridge is not continuing laterally in G. pauxilla .

No genetic data are available for G. pauxilla .

Distribution. Vanuatu, 176– 246 m.

Figures

FIGURE 80. Galathea pauxilla n. sp., holotype, ovigerous female, 4.3 mm, Vanuatu (MNHN-IU- 2013 - 13998). 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, left P 3, lateral view; H, right P 4, lateral view. Scale: A, F – H = 1 mm; E = 2 mm; B – D = 0.5 mm.