Galathea simulata, 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 : 285-288

Galathea simulata n. sp.

( Fig. 103 )

Material examined. Holotype: New Caledonia. Lagon East. Stn 613, 22°07.3'S, 166°59.5'E, 45–50 m, August 1986: ov. F 5.1 mm (MNHN-IU-2013-8024).

Paratypes: New Caledonia. Chesterfield Islands. CORAIL 2, Stn DW46, 19°18.54'S, 158°20'E, 21 m, 23 July 1988: 1 F 2.7 mm (MNHN-IU-2013-8049).—Stn DW94, 19°06'S, 158°50'E, 36–53 m, 27 July 1988: 1 M 3.8 mm (MNHN-IU-2013-8048).—Stn CP124, 19°29'S, 158°20'E, 53–56 m, 29 July 1988: 1 M 4.3 mm, 1 ov. F 4.4 mm (MNHN-IU-2013-8029). Lifou Island. LIFOU, Stn 1420, 20°47.7'S, 167°09.35'E, 4–5 m, 18–19 November 2000: 1 F 3.0 mm (MNHN-IU-2013-8032).—Stn 1421, 20°52.4'S, 167°08.5'E, 4 m, 27 November 2000: 1 M 2.0 mm (MNHN-IU-2013-8030). Goro. 22°19.23'S, 167°00.65'E, 0 m, 5 November 1965: 1 M 1.8 mm (MNHN-IU-2013- 8023).—Noumea, Stn 34, 22°12'S, 166°24'E, 10 m, May 1984: 1 M 5.8 mm (MNHN-IU-2013-8041).—Tie, 5–7 m, 9 September 1993: 1 ov. F 4.0 mm (MNHN-IU-2013-8035).—Touho, 20°47'S, 165°13'E, no depth, September 1993: 2 M 3.3–4.1 mm (MNHN-IU-2013-8040). Lagon East. Stn 606, 22°12.8'S, 167°00.5'E, 46–48 m, August 1986: 1 M 5.7 mm (MNHN-IU-2013-8042).—Stn 607, 22°12.1'S, 167°02.5'E, 48–54 m, August 1986: 1 M 3.8 mm (MNHN-IU-2013-8037).—Stn 612, 22°08.9'S, 167°00.5'E, 46–48 m, August 1986: 1 M 3.0 mm, 2 ov. F 4.2–4.6 mm (MNHN-IU-2013-8045).—Stn 613, 22°07.3'S, 166°59.5'E, 45–50 m, August 1986: 1 M 5.8 mm, 1 ov. F 4.6 mm (MNHN-IU-2013-8025).—Stn 616, 22°05.5'S, 166°58.8'E, 34–38 m, August 1986: 2 ov. F 4.7–5.5 mm (MNHN-IU-2013-8027).—Stn 617, 22°04.0'S, 166°57.5'E, 49 m, August 1986: 1 M 4.9 mm (MNHN-IU-2013- 13956).—Stn 619, 22°03.2'S, 166°54.2'E, 27–42 m, August 1986: 1 F 4.4 mm (MNHN-IU-2013-8026).—Stn 625, 21°59.2'S, 166°53.6'E, 34–40 m, August 1986: 1 M 3.6 mm (MNHN-IU-2013-8033).—Stn 627, 21°58.9'S, 166°50.7'E, 45–47 m, August 1986: 1 ov. F 5.1 mm (MNHN-IU-2013-8034).—Stn 648, 21°52.8'S, 166°35.2'E, 22–25 m, August 1986: 1 ov. F 5.4 mm (MNHN-IU-2013-8047).—Stn 692, 21°32'S, 166°12.3'E, 44–48 m, August 1986: 1 ov. F 3.6 mm (MNHN-IU-2013-8043).—Stn 735, 22°05.1'S, 166°57.2'E, 15–34 m, August 1986: 1 ov. F 3.7 mm (MNHN-IU-2013-8038).—Stn 736, 22°06.7'S, 166°58.4'E, 44–45 m, August 1986: 1 ov. F 4.8 mm (MNHN-IU-2013-8044).—Stn 737, 22°08.4'S, 166°59.1'E, 49–50 m, August 1986: 1 M 4.9 mm (MNHN-IU- 2013-8046).—Stn 738, 22°09.8'S, 167°00.2'E, 59–61 m, August 1986: 1 F 3.8 mm (MNHN-IU-2013-8031).—Stn 739, 22°11.6'S, 167°01'E, 41–44 m, August 1986: 1 M 5.0 mm (MNHN-IU-2013-8036). South Reef, Stn 305, 22°41.5'S, 166°46.3'E, 26 m, January 1985: 1 ov. F 4.8 mm (MNHN-IU-2013-8039).—Stn 409, 22°41.5'S, 167°24.2'E, 18 m, 24 January 1985: 1 M 4.7 mm, 2 ov. F 5.0– 5.1 mm (MNHN-IU-2013-8028).

Etmology. From the Latin, simulo, imitate, copy, in reference to the similarity with G. aegyptiaca .

Description. Carapace: As long as broad; anterior cervical groove indistinct. Six ridges on gastric region: 1 epigastric ridge medially interrupted, with 2 median spines; 2 protogastric ridges, anterior one strongly convex medially, uninterrupted, with 1 parahepatic spine at each side, posterior ridge short, scale-like and placed medially; 1 mesogastric ridge uninterruptedly extending laterally to anteriormost of branchial marginal spines, no posterior ridge scale-like; 2 metagastric ridges, anterior ridge uninterrupted and fused with anterior branchial ridges. Midtransverse ridge uninterrupted, preceded by shallow cervical groove, followed by 5 transverse ridges, 2 of them uninterrupted. Lateral margins medially convex, with 7 spines: 2 spines in front of, and 5 spines behind, indistinct anterior cervical groove; first anterolateral, well-developed, at same level of lateral limit of orbit; second, small, at midlength between anterolateral spine and anterior cervical groove, accompanying another spine ventral to between first and second; 2 spines on anterior branchial region, and 3 spines on posterior branchial margin, last small. External orbital limit ending in small spine; infra-orbital margin with strong spine. Rostrum broad triangular, as long as broad, length 0.5 that of, breadth 0.4 that of carapace; distance between distalmost lateral incisions 0.2 distance between proximalmost lateral incisions; dorsal surface nearly horizontal in lateral view, with some thick long plumose setae; lateral margin with 4 sharp spines. Ridges with numerous unirramous setae, and some thick long plumose setae on dorsal surface of rostrum, between epigastric spines and on median convexity of second gastric ridge.

Pterygostomian flap rugose, unarmed.

Sternum: Lateral limits divergent posteriorly.

Abdomen: Somites 2–3 each with 2 uninterrupted transverse ridges on tergite; somite 4 with posterior ridge medially interrupted; somite 5 and 6 each with 2 medially interrupted ridges, posteromedian margin of somite 6 straight. Males with G1 and G2.

Eyes: Ocular peduncles 1.1 times longer than broad, maximum corneal diameter 0.5 rostrum width.

Antennule: Article 1 with 3 well-developed distal spines, distodorsal larger. Ultimate article elongate, 2.5 times longer than broad, with tuft of setae on distodorsal margin.

Antenna: Article 1 with depressed ventral distomesial process slightly exceeding distal margin of peduncle. Article 2 with distomesial spine as long as distolateral, reaching midlength of article 3. Articles 3 and 4 unarmed.

Mxp3: Ischium with well-developed distal spine on flexor margin; extensor margin unarmed; crista dentata with 23–26 denticles. Merus subequal in length to ischium, with 2 strong spines of subequal size on flexor margin, proximal one located at midlength, distal one at terminal end; extensor margin with small distal spine. Carpus spineless.

P1: 3.0–3.5 times carapace length, with numerous short setae and some scattered long plumose setae on dorsal surface and along lateral and mesial margins of all articles. Merus 1.1 times length of carapace, 1.7 times as long as carpus, with rows of spines, mesial and distal spines strong. Carpus 0.8 length of palm, 2.7 times longer than broad, lateral and mesial margins subparallel, dorsal surface with small spines in 2 longitudinal rows; mesial surface with row of well-developed spines; and row of small spines along lateral margin. Palm 3.0 times longer than broad, spines roughly in rows on dorsal, mesial and lateral sides; lateral row continued on to whole lateral margin of fixed finger. Fingers 0.7 as long as palm, each finger distally with two rows of teeth, spooned; mesial margin of movable finger with proximal spines.

P2–4: Relatively slender, moderately setose, sparsely with long setae on all articles. P2 1.7 times carapace length. P3 merus 1.2 length of P2 merus, P4 merus 0.8 length of P3 merus), equally broad on P2–4; P2 merus 0.7 carapace length, 3.3 times as long as broad, 1.3 times longer than P2 propodus; P3 merus 3.4 times as long as broad, 1.2 times length of P3 propodus; P4 merus 3.3 times as long as broad, 1.1 length of P4 propodus. Extensor margins with row of 8 or 9 proximally diminishing spines on P2–3, only distal spine on P4; lateral surface unarmed on P2–3, row of 3 spines on P4; flexolateral margins with strong terminal spine; flexomesial margin with terminal spine on P2 only. Carpi with 4 spines on extensor margin; lateral surface with row of 2 or 3 small spines paralleling extensor row; flexor distal margins with spine. Propodi subequal in length on P3 and P4, slightly shorter on P2, equally broad on P2–4 and ca. 5 times as long as broad; extensor margin with 3 proximal spines on P2–4; flexor margin with 5 slender seta-like movable spine on P2, 4 on P3–4; 2 proximal spines on lateral side of P3–4, unarmed on P2. Dactyli subequal in length, 0.5–0.6 length of propodi, ending in incurved, strong, sharp spine; flexor margin with prominent triangular terminal tooth preceded by obsolescent 5 teeth.

Epipods present on P1, absent on P2–3.

Remarks. Galathea simulata is close to G. aegyptiaca Paul’son, 1875 and other related species, e.g. G.

corbariae n. sp., G. homologa n. sp., G. imitata n. sp. However, G. simulata can be differentiated from the other 4 species by having the P2–3 propodi more elongate, 5 times longer than broad, whereas they are less slender, equal or less than 4 times longer than broad, in the other species.

The genetic divergences between G. simulata and the other related species are quite large (10.0–17.1% COI, 5.7–9.0% 16S rRNA, see Tab. 1).

Distribution. New Caledonia, Chesterfield Islands, 4– 56 m.

Figures

FIGURE 103. Galathea simulata n. sp., holotype, ovigerous female, 5.1 mm, New Caledonia (MNHN-IU- 2013 - 8024). A, carapace and abdomen, dorsal view; B, sternal plastron; 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; I, ultimate article of antennular peduncle. Scale: A, E – H = 1 mm; B – D, I = 0.5 mm.