Galathea mauritiana Bouvier, 1914

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 : 187-190

Galathea mauritiana Bouvier, 1914

( Figs 67 , 118 C)

Galathea mauritiana Bouvier, 1914: 5 ( Mauritius Islands).— Bouvier, 1915: 200, figs 10, 11 ( Mauritius Islands).— Laurie, 1926: 125 (in part, Farquhar, Coetivy, Saya De Malha, 48 m). — Collins, 1995: 61 (replacement name for Galathea affinis Ortmann, 1892 , preocuppied by the fossil Galathea affinis Ristori, 1886 ).—Baba et al., 2008: 73 (compilation).— Baba et al., 2009: 115, figs. 94–96 ( Taiwan).— Macpherson & Cleva, 2010: 59 , color figs. C, D ( Mayotte and Madagascar, 1–13 m).— Poupin, 2013a: 14, fig. 6d (color) ( Mayotte, 0–22 m).— Poupin et al., 2013b: 6 (Europa island, Mozambique Channel).

Galathea affinis . —Baba, 1990: 953 ( Comoro Islands, 20 m).— Tirmizi & Javed, 1993: 45, fig. 20 ( Madagascar and Mozambique Channel, 1–35 m).

Not Galathea mauritiana .— Poore et al., 2011: 333, pl. 11C (color photo, Taiwan) = (G. s e n t a Macpherson & Robainas-Barcia, 2014).

Material examined. Holotype: Mauritius Island. Le Chaland. M 2.7 mm ( MNHN Ga810, MNHN-IU-2013-9696). Mayotte Island. 12.7605°S, 45.068°E, 2–3 m, 30 May 2008: 1 ov. F 2.8 mm (UF13556).

Madagascar. Nosy Be, off Lokobe reserve, 13.4139°S, 48.3056°E, 1–3 m, 16 May 2008: 1 ov. F 3.6 mm (UF14334). Fort Dauphin, no depth, 1 M 2.1 mm, 1 ov. F 3.3 mm ( MNHN Ga809, MNHN-IU-2013-9695). ATIMO VATAE. Stn TB07, 25°02.5'S, 46°59.7'E, 4–5 m, 9 May 2010: 1 F 2.5 mm (MNHN-IU-2013-9740), 2 M 1.7–2.4 mm, 3 ov. F 2.2–3.3 mm (MNHN-IU- 2010-2741, MNHN-IU-2013-9741).— Stn TS21, 25°01.5'S, 47°00.0'E, 2–4 m, 11 May 2010: 1 F 1.8 mm (MNHN-IU- 2010-2725).— Stn TB12, 25°01.5'S, 47°00.0'E, 4–5 m, 12 May 2010: 1 M 3.2 mm (MNHN-IU- 2010-2748), 1 M 2.1 mm, 4 ov. F 2.5–3.3 mm (MNHN-IU- 2010-2728).

La Réunion. MD32, Stn PL53, 20°55.5’S, 55°17.6’E, 10 m, 21 August 1982: 1 ov. F 2.3 mm, 1 F 2.6 mm (MNHN-IU-2013-13916).

Description. Carapace. As long as broad; anterior cervical groove indistinct. Ridges with dense short setae, and a few scattered long and thick setae. Gastric region with 4 or 5 transverse ridges: 1 epigastric ridge with 2 median spines, medially interrupted; 1 protogastric ridge, slightly convex medially, usually uninterrupted and extending laterally to first marginal spine, laterally interrupted in some specimens; 1 mesogastric ridge uninterruptedly extending laterally to anteriormost of branchial marginal spines; 2 metagastric ridges, anterior one convex and uninterrupted, posterior ridge short, sometimes absent. Mid-transverse ridge uninterrupted, preceded by shallow cervical groove, followed by 5 ridges, 1 or 2 of them uninterrupted. Lateral margins medially convex, with 8 spines: 2 spines in front of and 6 spines behind indistinct anterior cervical groove; first anterolateral, welldeveloped, at level of lateral limit of orbit; second minute, 1 spine ventral to between first and second; 3 spines on anterior branchial region and 3 spines on posterior branchial margin, last small. External limit of orbit unarmed, with well-developed spine between orbit and first anterolateral spine, infra-orbital margin with strong acute process. Rostrum broad triangular, 1.2–1.5 times as long as broad, length 0.5 that of, breadth 0.3–0.4 that of carapace; distance between distalmost lateral incisions 0.3 distance between proximalmost lateral incisions, dorsal surface slightly concave medially; lateral margin with 4 sharp teeth.

Pterygostomian flap rugose, 1 distinct spine on upper margin near linea anomurica, anterior margin ending in well-developed spine.

Sternum: Slightly longer than broad, lateral limits divergent posteriorly.

Abdomen: Somites 2–4 each with 2 uninterrupted transverse ridges on tergite; somites 5–6 each with 2 ridges, medially interrupted. Males with G1 and G2.

Eyes: Ocular peduncles 1.1 times longer than broad, maximum corneal diameter 0.8 rostrum width.

Antennule: Article 1 with 3 well-developed distal spines, distodorsal larger; distomesial smaller than others. Ultimate article with a few short setae not in tuft on distodorsal margin.

Antenna: Article 1 with depressed ventral distomesial process not reaching distal margin of article 2. Article 2 with subequal distal spines, nearly reaching midlength of article 3. Article 3 with distinct distomesial spine. Article 4 unarmed.

Mxp3: Ischium with well-developed distal spine on flexor margin; extensor margin unarmed; crista dentata with 23 or 24 denticles. Merus subequal in length to ischium, with strong proximal spine on flexor margin, located at midlength, and clearly not reaching distal margin of merus; 1 or 2 small or obsolescent distal spines; extensor margin with distal spine. Carpus spineless.

P1: 1.8–2.5 times carapace length, relatively slender, subcylindrical, with numerous short setae and some long setae on dorsal surface and along lateral and mesial margins of all articles. Merus 0.6–0.9 length of carapace, 1.4–1.5 times as long as carpus, with rows of spines, mesial and distal spines strong. Carpus as long as palm, 1.7–2.0 times longer than broad, lateral and mesial margins subparallel, dorsal surface with small spines; mesial surface with row of 3 or 4 well-developed spines; and row of small spines along lateral margin. Palm 1.6–1.7 times longer than broad; spines roughly in rows on dorsal, mesial and lateral; lateral row continued on to whole lateral margin of fixed finger; mesial row continuing along mesial margin of movable finger. Fingers 0.8–1.1 times longer than palm, each finger distally with two rows of teeth, spooned.

P2–4: Relatively slender, somewhat compressed, moderately setose, sparsely with long setae on all articles. P2 1.7 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 0.6 carapace length, 3.0 times as long as broad, 1.6 times longer than P2 propodus; P3 merus 3.0 times as long as broad, 1.2 times length of P3 propodus; P4 merus 2.4 times as long as broad, as long as P4 propodus. Extensor margins with row of 8 or 9 proximally diminishing spines on P2–3, 1 or 2 spines on P4; lateral surface unarmed on P2–4; 2 well-developed spines on terminal flexolateral margin, sometimes obsolescent in P4; flexomesial margin with terminal spine on P2 only. Carpi with 3 or 4 spines on extensor margin of P2–3, 1 minute spine on P4; lateral surface with row of 2 or 3 acute granules paralleling extensor row; flexor distal margin ending in acute angle. P2–4 propodi 4.0 times as long as broad; extensor margin with 3 proximal spines on P2, unarmed on P3–4; flexor margin with 4 slender movable spines on P2–4. Dactyli 0.6–0.7 length of propodi, ending in incurved, strong, sharp spine; flexor margin with prominent triangular terminal tooth preceded by 4 obsolescent teeth.

Epipods absent on pereiopods.

Coloration. Ground color of carapace, abdominal somites 2–4 and pereopods greenish or brownish, with darker transverse ridges; some whitish patches scattered on carapace and abdomen surface; each branchial region with one small black spot near cervical groove. Distal part of P1 palm and proximal portion of P1 fingers whitish; one distinct black spot, encircled by yellow, on distal part of P1 palm. P2–4 with some brownish transverse stripes.

Remarks. Galathea mauritiana was originally described on the basis of one male specimen collected in Mauritius Island. It belongs to the group of species characterized by the pterygostomian flap with one or two spines on the upper margin near the linea anomurica, and an uninterrupted mesogastric ridge between the anteriormost branchial marginal spines. This group contains the following four species other than G. mauritiana : G. a ci s n. sp. from Japan to Australia and New Caledonia, G. aequata n. sp. from French Polynesia, G. ahyongi n. sp. from the Red Sea, and G. s e n t a n. sp. from French Polynesia to Vanuatu and Taiwan.

Galathea mauritiana further differs from G. aequata and G. a c i s by the more slender walking legs (P2–4). For instance, the P2 propodus is 4 times longer than broad in G. mauritiana , whereas this propodus is 3.0–3.5 times in the other two species.

The genetic divergences among G. mauritiana and the other four related species are large: 12.7–16.6% (COI) (only data for 16S rRNA in G. acis and G. s e n t a, 14.0%) ( Tab. 1), although the morphological differences are very subtle.

The synonymy of Galathea mauritiana needs revision after the discovery of several closely related new species. The species was described from Mauritius Island by Bouvier (1914). Previously, the species was named as G. affinis Ortmann, 1892 and cited from numerous localities in the Indian and Pacific oceans (see synonymies under G. acis , G. aequata , and G. ayhongi ). However, the name is preoccupied by the fossil Galathea affinis Ristori, 1886 , and the name G. mauritiana has been used in the recent years (e.g. Baba et al. 2008, 2009). We have revised a small part of the material identified as G. mauritiana or G. affinis and collected by other authors, (e.g. Baba 1979, 1990). However, a more complete study of the material from the different localities will confirm their identity providing the range of the different species.

Distribution. Mauritius, Mayotte, La Réunion Islands, Mozambique Channel and Madagascar, 0– 35 m. Galathea mauritiana seems to be restricted to the SW Indian Ocean, so previous records from other localities of the Indian and Pacific Oceans probably belong to other species, and should be revised.

Figures

FIGURE 67. Galathea mauritiana Bouvier, 1914, female, 2.5 mm, Madagascar (MNHN-IU- 2013 - 9740). 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 1 fingers, ventral view; G, right P 2, lateral view; H, right P 3, lateral view; I, right P 4, lateral view. Scale: A, E, G, H, I = 1 mm; B – D, F = 0.5 mm.

FIGURE 118. Dorsal view. A, Galathea maculiabdominalis Baba, 1972, Vanuatu, male 2.4 mm (MNHN-IU- 2013 - 8344). B, Galathea mariae n. sp., French Polynesia, ovigerous female 3.0 mm (UF 15523). C, Galathea mauritiana Bouvier, 1914, Madagascar, female 2.5 mm (IU- 2013 - 9740). D, Galathea minima n. sp., Papua New Guinea, ovigerous female 2.8 mm (MNHN-IU- 2013 - 704). E, Galathea minima n. sp., Papua New Guinea, ovigerous female 2.5 mm (MNHN-IU- 2013 - 654). F, Galathea ohshimai Miyake & Baba, 1967, Vanuatu, male 2.2 mm (MNHN-IU- 2013 - 13881). G, Galathea parvula n. sp., holotype, ovigerous female 2.9 mm (UF 38286). H, Galathea paulayi n. sp., French Polynesia, male 4.7 mm (UF 15618). I, Galathea peitho n. sp., Papua New Guinea, male 4.0 mm (MNHN-IU- 2013 - 372).