Galathea subsquamata Stimpson, 1858

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 : 295-298

Galathea subsquamata Stimpson, 1858

( Figs 106 , 120 I, 121A)

Galathea subsquamata Stimpson, 1858: 90 (Amami-oshima).— Baba, 1989: 130 (Oshima Strait, Amami-oshima, 25–40 m). Dubious identifications:

Galathea subsquamata .— Henderson, 1888: 118, pl. 12, fig. 4 (Off Tablas Island, Philippines, 183–210 m).— Yokoya, 1933: 58 (S of Inuboe-zaki, 238 m).— Miyake, 1938: 40, fig. 3 (Oshima, Kii Peninsula, 6 m).— Baba, 1977a: 247 (east side of Sibutu Strait, Sulu Islands and Ternate, 4–27 m).— Baba, 1979a: 525 (Noumea, New Caledonia, 20–23 m).— Baba, 1982b: 60 ( Palau Islands, 0–50 m).— Baba, 1988: 79 (Sulu Archipelago, between Burias and Luzon, shore to 53 m).— Wu et al., 1998: 100, figs 16, 21C ( Taiwan).— Komai, 2000: 353 (list).— Davie, 2002: 62 (no record).— Poore, 2004: 232 (compilation).—Macpherson, 2008: 292 (Dampier Archipelago, 2–38 m).—Baba et al., 2008: 79 (compilation).

Material examined. Neotype: Japan. Amami-oshima Island. Oshima Strait, Atetsu Bay, Stn 6, 40 m, 4 August 1988: M 4.3 mm (MNHN-IU-2013-15933)

Japan. Amami-oshima Island. Oshima Strait, Atetsu Bay, Stn 6, 40 m, 4 August 1988: 1 ov. F 3.4 mm (MNHN-IU-2013-15934).—Near Tawara, Stn 18, 30 m, 6 August 1988: 1 ov. F 3.6 mm (MNHN-IU-2013-15932).

Mariana Islands. Guam Island. East Agana Bay, 1–2 m, 1 February 1997: 1 F 5.0 mm (UF318).—Apra harbour, Drydock Shoal, 0.5–3.5 m, 24 June 2002: 1 M 3.8 mm (UF2817).—Apra harbour, Sasa Bay, 3.5–5.0 mm, 9 July 1997: 1 ov. F 3.7 mm (UF317).

Papua New Guinea. PAPUA NIUGINI, Stn PD06, 05°12.7'S, 145°47.9'E, 10–20 m, 8 November 2012: 2 M 2.6–3.5 mm, 2 ov. F 2.4–3.3 mm (MNHN-IU-2013-13495).—Stn PD14, 05°12.3'S, 145°47.9'E, 10–15 m, 11 November 2012: 1 M 3.4 mm (MNHN-IU-2013-353); 7 M 2.8–3.5 mm, 7 ov. F 3.0– 3.9 mm (MNHN-IU-2013- 13497).—Stn PD31, 05°05.3'S, 145°48.1'E, 1–6 m, 12–13 December 2012: 1 F 2.1 mm (MNHN-IU-2013- 14043).— Stn PD32, 05°04.4'S, 145°48.7'E, 18 m, 17 November 2012: 1 M 3.3 mm (MNHN-IU-2013- 13499).—Stn PD35, 05°01.3'S, 145°47.9'E, 1–12 m, 19–20 November 2012: 1 M 2.2 mm (MNHN-IU-2013- 496); 1 juv. 1.2 mm (MNHN-IU-2013-726).— Stn PR35, 05°06.3'S, 145°49.3'E, 0 m, 15 November 2012: 1 M 4.4 mm, 1 F 4.5 mm (MNHN-IU-2013-13501).—Stn PR71, 05°10.8'S, 145°49.7'E, 0 m, 21 November 2012: 1 M 2.0 mm, 1 ov. F 3.0 mm, 1 F 5.5 mm (MNHN-IU-2013-13502).—Stn PR76, 05°01.6'S, 145°47.9'E, 2–15 m, 21 November 2012: 1 M 3.8 mm (MNHN-IU-2013-13503).—Stn PB01, 05°11.3'S, 145°49.4'E, 6–10 m, 30 December 2012: 1 M 4.1 mm (MNHN-IU-2013-773).— Stn PB08, 05°11'S, 145°48.4'E, 4–5 m, 30 December 2012: 10 M 1.8–2.5 mm, 3 ov. F 3.2–3.4 mm, 7 F 1.8–2.0 mm (MNHN-IU-2013-376).—Stn PB12, 05°11.8'S, 145°48.8'E, 7–15 m, 30 December 2012: 1 ov. F 3.1 mm (MNHN-IU-2013-13496).—Stn PB17, 05°04.9'S, 145°49.3'E, 26 m, 30 December 2012: 1 M 3.5 mm, 1 ov. F 3.4 mm (MNHN-IU-2013-13500).—Stn PB19, 05°05.1'S, 145°48.6'E, 10 m, 30 December 2012: 4 M 1.9–3.8 mm, 1 ov. F 2.5 mm, 2 F 2.5–3.1 mm (MNHN-IU-2013-13494).—Stn PS15, 05°05.79'S, 145°48.194'E, 12 m, 30 December 2012: 2 M 2.8–4.1 mm (MNHN-IU-2013-13498).

Description. Carapace: As long as broad; ridges with dense short setae, without long setae; cervical groove laterally bifurcated; ridges on gastric and anterior branchial regions scale-like or in concentric arcs; epigastric and protogastric regions with 2 median spines; 1 parahepatic, 1 or 2 anterior branchial, and 1 postcervical spine on each side. Mid-transverse ridge laterally interrupted, preceded by shallow cervical groove, followed by 4 or 5 transverse ridges, 1 or 2 of them uninterrupted. Lateral margins slightly convex medially, with 8 spines: 2 spines in front of and 6 spines behind anterior cervical groove; 1 well-developed first anterolateral spine, second spine minute, located at midlength between first anterolateral spine and anterior cervical groove; additional spine ventral to between first and second anterolateral 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, with 1 frontal spine; infraorbital margin with 1 strong spine. Rostrum moderately elongate, triangular, 1.7–1.8 times as long as broad, 0.6 carapace length and breadth 0.3–0.4 that of carapace, nearly horizontal in lateral view; distance between distalmost lateral incisions 0.3 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 2–4 each with 2 transverse ridges on tergite, anterior ridge more distinctly elevated than posterior ridge; 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 1.3 times longer than broad, maximum corneal diameter 0.8 rostrum width.

Antennule: Article 1 with 3 well-developed spines, distodorsal larger; distomesial spine somewhat smaller and more slender than distolateral. Ultimate article with a few setae, not in tuft, 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 21–23 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: 2.7–3.0 times carapace length, with numerous short and long setae. Merus 1.0–1.2 times length of carapace, 1.7 times as long as carpus, with spines arranged roughly in rows, mesial and distal spines strong. Carpus 0.8–0.9 length of palm, 1.9–2.4 times as long as broad; dorsal surface with spines arranged roughly in longitudinal rows; mesial margin with 3 or 4 strong spines. Palm 2.1–3.1 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 0.8–1.1 length of palm, each finger with two rows of teeth distally spooned; fingers with row of small spine on dorsal side.

P2–4: Moderately slender, with numerous long setae. P2 2.0–2.1 times carapace length. Meri successively shorter posteriorly (P3 merus 0.9 length of P2 merus, P4 merus 0.7–0.8 length of P3 merus); P2 merus 0.8–0.9 carapace length, 4.2–4.9 times as long as broad, 1.5–1.6 times longer than P2 propodus; P3 merus 4.0–4.8 times longer than broad, 1.3 times longer than P3 propodus; P4 merus 2.7–3.2 times as long as broad, as long as P4 propodus. Extensor margins with row of 9 or 10 proximally diminishing spines on P2–3, 3 on P4; lateral surface with 1 or 2 small spines on P2–3, 5 or 6 on P4; flexor margin distally ending in spine followed proximally by small spines and several tubercles or eminences. Carpi with 4 or 5 spines on extensor margin on P2–3, 1–3 small spines on P4; lateral surface with 4 or 5 spines sub-paralleling extensor margin on P2–4; flexor distal margin with small distal spine. Propodi 4.5–5.5 times as long as broad; extensor margin with 3 or 4 spines on proximal half on P2–4; flexor margin with 5 or 6 slender movable spines. Dactyli distally ending in well-curved strong spine, 0.4–0.5 length of propodi; flexor margin with 5 proximally diminishing teeth.

Epipods on P1–3.

Coloration. Base color greenish. Carapace and abdomen with some whitish flecks. Carapace ridges and spines reddish or brownish. P1 with rounded large white spots, encircled by dark brown, on distal part of merus, carpus and palm; proximal third of fingers greenish, distal two-thirds white; spines with red tips. P2–4 with numerous small white spots on merus and carpus; distal orange spot on merus; distal half of propodus whitish.

Remarks. Stimpson (1858) described Galathea subsquamata on the basis of material from “Ousima” (= Amami-oshima Island, northern Ryukyu Islands). The type material of the species was lost in the Great Fire of Chicago in 1871 ( Evans 1967). We have obtained new material from the type locality (Amami-oshima Island, Oshima Strait) (see Baba 1989) and have selected a neotype to facilitate further studies. Galathea aculeata Haswell, 1882 has been placed in the synonymy of G. subsquamata , but these two species are easily distinguished by the presence of one postcervical spine on each side of the carapace in G. subsquamata , which is always absent in G. aculeata . Unfortunately, we have studied a small portion of the material previously identified as G. subsquamata . Therefore, a revision of the individuals of this species cited along Japan, Taiwan, Philippines and other localities in the Western Pacific, would be desirable.

The closest relative of G. subsquamata is G. c ym o n. sp. from Vanuatu, New Caledonia and Chesterfield Islands but the two can be easily distinguished by the following characters:

- The anterior branchial region is armed with one or two spines in G. subsquamata , rather than unarmed in G. cymo .

- Epipods are present on P 1–3 in G. subsquamata , instead of only P 1 in G. cymo . - The genetic divergences between the two species are 20.0% (COI) and 4.3% (16S rRNA) ( Tab. 3 ).

Distribution. Known with certainty from the Ryukyu Islands, Japan, Mariana Islands, and Papua New Guinea; 0– 32 m.

Figures

FIGURE 106. Galathea subsquamata Stimpson, 1858, neotype, male, 4.3 mm, Japan, Oshima Strait (MNHN-IU- 2013 - 15933). 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, E – H = 1 mm; B – D = 0.5 mm.

FIGURE 120. Dorsal view. A, Galathea pubescens Stimpson, 1858, Vanuatu, male 6.2 mm (MNHN-IU- 2013 - 15948). B, Galathea punctata n. sp., Vanuatu, ovigerous female 5.0 mm (MNHN-IU- 2013 - 8491). C, Galathea rubrispina n. sp., Papua New Guinea, holotype, male 2.4 mm (MNHN-IU- 2013 - 377). D, Galathea schnabelae n. sp.. Maldives, holotype, male 3.3 mm (UF 40283). E, Galathea scolopia n. sp., Papua New Guinea, male 3.8 mm (MNHN-IU- 2011 - 4479). F, Galathea senta n. sp., Vanuatu, ovigerous female 3.4 mm (MNHN-IU- 2013 - 14361). G, Galathea sinensis Dong & Li, 2010, Vanuatu, ovigerous female 5.7 mm (MNHN-IU- 2013 - 8229). H, Galathea spinosorostris Dana, 1852, Hawaii, female 2.2 mm (UF 12200). I, Galathea subsquamata Stimpson, 1858, Papua New Guinea, male 3.8 mm (MNHN-IU- 2013 - 13503).