Galathea lepidota, 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 : 162-164

Galathea lepidota n. sp.

( Fig. 57 )

Material examined. Holotype: Philippines. MUSORSTOM 3, Stn CP142, 11°47’N, 123°01’E, 26–27 m, 6 June 1985: ov. F 4.3 mm (MNHN-IU-2013-13321).

Paratypes: Palau. 34 m, 25 May 1995: 5 M 2.5–3.6 mm, 5 ov. F 2.8–4.2 mm (UF5213).—Koror, Lighthouse basin, 48 m, 4 August 1995: 1 M 2.3 mm, 1 ov. F 2.5 mm (UF5220).— 54 m, 5 August 1995: 3 M 1.7–2.8 mm, 1 F 2.2 mm (UF5230).—Koror, Ngerduais channel, 24 m, 14 September 1995: 1 M 4.0 mm (UF5073).— Palau. 33 m, 20 June 1995: 1 ov. F 3.3 mm, 1 F 2.3 mm (UF5209).— Palau, no date: 4 M 2.2–4.3 mm, 4 ov. F 3.3–4.6 mm, 1 F 2.1 mm (UF5218).

Philippines. MUSORSTOM 3, Stn CP142, 11°47’N, 123°01’E, 26–27 m, 6 June 1985: 1 M 3.6 mm (MNHN- IU-2013-13323); 1 ov. F 4.0 mm (MNHN-IU-2013-13324); 29 M 2.5–4.5 mm, 9 ov. F 3.5–4.6 mm, 2 F 2.4–2.5 mm (MNHN-IU-2013-13325).

Indonesia. Makassar Strait. CORINDON, Stn CH 294, 2°38.3'S, 117°50.4'E, 46–57 m, 10 November 1980: 1 M 4.1 mm (MNHN-IU-2013-13322).

Papua New Guinea. Bismark Archipel, NE side Baluam Island, 2.6975°S, 147.5533°E, 3–42 m, 22 June 2003: 1 M 3.3 mm (UF8693).

Solomon Islands. SALOMON 1, Stn CP1810, 9°47.684'S, 160°50.525'E, 53 m, 3 October 2001: 1 M 3.9 mm, 1 F 2.2 mm (MNHN-IU-2013-13326).

Etymology. From the Greek lepidotos, scaly, in reference to the scaly gastric region.

Description. Carapace: 0.9 times as long as broad; ridges with dense short setae, without long plumose setae; cervical groove nearly indistinct, laterally bifurcated; ridges on gastric and anterior branchial regions scale-like or in concentric arcs; epigastric region with 2 median spines; median protogastric scale-ridge unarmed (rarely with 1 or 2 minute spines); 1 parahepatic and 1 anterior branchial spine on each side. Mid-transverse ridge laterally interrupted, preceded by shallow cervical groove, followed by 6 ridges, 2 of them uninterrupted. Lateral margins slightly convex medially, with 8 spines: 2 spines in front of and 6 spines behind anterior cervical groove; first anterolateral, second small, located at midlength between first spine and anteriormost spine of branchial margin; additional spine ventral to between first and second lateral spine; 3 spines on anterior branchial margin, and 3 spines on posterior branchial margin, last smaller than others. External limit of orbit ending in small spine; infraorbital margin with 1 strong spine and a few spinules. Rostrum moderately elongate, 1.6–1.7 times as long as broad, 0.7 carapace length and breadth 0.3 that of carapace, nearly horizontal in lateral view; distance between distalmost lateral incisions 0.25 distance between proximalmost lateral incisions; dorsal surface with small setiferous ridges; lateral margin with 4 deeply incised sharp teeth.

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

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

Abdomen: Somites 2–3 each with 4 transverse ridges on tergite, anterior ridge more distinctly elevated than posterior ridge; tergite of somite 4 with 2 transverse ridges; somites 5 and 6 with 2 uninterrupted or medially interrupted ridges, posteromedian margin of somite 6 nearly 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 3 well-developed spines, distodorsal larger; distomesial spine somewhat smaller and more slender than distolateral. Ultimate article with tuft of fine setae on distodorsal margin.

Antenna: Article 1 with ventral distomesial spine reaching distal margin of article 2. Article 2 with 2 welldeveloped distal spines, distolateral spine longer than distomesial and overreaching midlength of article 3. Articles 3 and 4 unarmed.

Mxp3: Ischium with small distal spine on flexor margin; extensor margin with small but distinct distal spine; crista dentata with 18–20 denticles. Merus shorter than ischium; flexor margin with 2 strong spines of subequal size, proximal one located at midlength, distal one at terminal end; extensor margin with 2 spines. Carpus unarmed.

P1: 2.7–3.5 times carapace length, with numerous short unirramous setae and some long plumose setae. Merus 1.1–1.3 times length of carapace, 1.8 times as long as carpus, with spines arranged roughly in rows, mesial and distal spines prominent. Carpus 0.9 length of palm, 2.3 times as long as broad; dorsal surface with spines arranged roughly in longitudinal rows; mesial margin with 3 or 4 strong spines, distal second largest. Palm 2.8–3.0 times longer than broad, lateral and mesial margins subparallel; spines arranged roughly in rows, dorsolateral row of spines continued on to whole lateral margin of fixed finger. Fingers 1.3 length of palm, each finger with two rows of teeth distally spooned; fingers with row of small spines on dorsal side.

P2–4: Moderately slender, with long sparse plumose setae. P2 2.0–2.1 times 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, 4.4 times as long as broad, 1.4 times longer than P2 propodus; P3 merus 3.4 times longer than broad, 1.3 times longer than P3 propodus; P4 merus 2.5 times as long as broad, as long as P4 propodus. Extensor margins with row of 8 or 9 proximally diminishing spines on P2–3, 3 on P4; lateral surface with 1–2 small spines on P2–3, 5 or 6 on P4; flexor margin distally ending in 2 spines, sometimes absent in small specimens, followed proximally by small spines and several tubercles or eminences. Carpi with 5 or 6 spines on extensor margin on P2–3, 0–1 spines on P4; lateral surface with 4 or 5 spines sub-paralleling extensor margin on P2–4; flexor distal margin with very small distal spine. Propodi 4.1–5.3 times as long as broad; extensor margin with 4–6 spines on proximal half on P2 and P3, with 1 or 2 proximal spines on P4; flexor margin with 4–6 slender movable spines. Dactyli distally ending in well-curved strong spine, 0.5–0.6 length of propodi; flexor margin with 4 or 5 proximally diminishing teeth.

Epipods on P1–3.

Remarks. Galathea lepidota n. sp. is characterized by the presence of scale-like ridges on the gastric area, the carapace with at least one branchial dorsal spine and two epigastric spines, and epipods on P1–3. The new species is closely related to the G. subsquamata Stimpson, 1858 . However, G. lepidota can be easily distinguished from this species by the following aspects:

- The P2–4 meri have two spines on the distal angle of the flexor margin in G. lepidota , instead of only one spine in G. subsquamata .

- The carapace lateral margin has one spine between the anterolateral spine and the anteriormost branchial marginal spine in G. lepidota , but this spine is absent in G. subsquamata .

- The genetic divergences between G. lepidota and G. subsquamata are 20.0% (COI) and 7.1% (16S rRNA).

Distribution. Philippines, Palau, Indonesia (Makassar Strait), Papua New Guinea, Solomon Islands; 3– 57 m.

Figures

FIGURE 57. Galathea lepidota n. sp., holotype, ovigerous female, 4.3 mm, Philippines (MNHN-IU- 2013 - 13321). 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, right P 4, lateral view. Scale: A, E – H = 1 mm; B – D = 0.5 mm.