Galathea ahyongi, 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 : 34-37

Galathea ahyongi n. sp.

( Figs 7 , 115 E)

Galathea affinis — Lewinsohn, 1969: 112, fig. 21 (Red Sea, 0–2 m). Galathea mauritiana . — Laurie, 1926: 125 (in part, Chagos, 48 m).

Material examined. Holotype: Red Sea. Farasan Banks, Dolphen Lagoon, 19.0053°N, 40.1482°E, 1–7 m, 4 March 2013: 1 ov. F 3.5 mm (UF36149).

Paratypes: Red Sea. Gulf of Aqaba. Nahorst Expedition'77, 10 km Aqaba, 20 March 1977: 1 F 3.5 mm ( SMF). Ferry Port, 5–10 m, 22 July 1995: 2 M 2.5–3.0 mm, 1 ov. F 3.0 mm ( SMF). Rabigh, Stn 1, 7 April 2011: 2 M 2.9–3.0 mm, 1 ov. F 3.1 mm ( SMF). Jeddah, Stn 1, 17 April 2011: 1 ov. F 2.6 mm ( SMF).

Red Sea. Sudan, Al Bahr al Ahmar, Sanganeb. SAN49, 1 m, 26 March 1991: 1 ov. F 3.6 mm ( SMF).—SAN50, 26 March 1991: 2 M 3.5–3.8 mm, 3 ov. F 3.8–4.0 mm ( SMF).— SAN36, 28 March 1991: 1 ov. F 3.5 mm ( SMF).— SAN39, 5 m, 28 March 1991: 2 M 2.0– 2.3 mm, 2 F 2.0– 2.1 mm ( SMF).— SAN51, 1 m, 30 March 1991. 2 M 2.9–3.3 mm, 2 ov. F 3.8–4.0 mm ( SMF).— SAN12, 1 m, 4 April 1991: 8 M 2.2–3.4 mm, 10 ov. F 2.8–4.6 mm, 7 F 1.8–2.5 mm ( SMF).—SAN3, 1 m, 5 April 1991: 15 M 2.4–3.5 mm, 13 ov. F 2.5–3.6 mm, 8 F 2.0– 2.7 mm ( SMF).—SAN35, 5 April 1991: 1 M 2.7 mm ( SMF).—SAN 2, 1 m, 6 April 1991: 1 M 1.6 mm, 3 ov. F 2.1–2.4 mm, 2 F 1.6–1.8 mm ( SMF).—SAN8, 1 m, 6 April 1991: 34 M 2.2–3.6 mm, 27 ov. F 2.6–4.0 mm, 16 F 2.1–2.9 mm ( SMF).—SAN38, 1 m, 8 April 1991: 1 F 2.8 mm ( SMF).— SAN13, 1 m, 8 April 1991: 16 M 1.6–3.5 mm, 21 ov. F 3.0– 4.5 mm, 7 F 2.1–2.6 mm ( SMF).— SAN166, 5 m, 21 September 1992: 3 M 2.2–2.6 mm, 2 ov. F 2.2–2.5 mm ( SMF).— SAN133, 1 m, 25 September 1992: 1 ov. F 3.5 mm ( SMF).— SAN154, 1 m, 25 September 1992: 2 M 3.0– 3.4 mm, 1 ov. F 3.6 mm, 1 F 3.0 mm ( SMF).— SAN101, 1 m, 26 September 1992: 4 M 2.0– 2.6 mm, 8 ov. F 2.4–2.9 mm, 1 F 2.2 mm ( SMF).— SAN113, 1 m, 27 September 1992: 1 M 3.0 mm, 1 ov. F 3.2 mm ( SMF).— SAN144, 8 m, 1 October 1992: 1 ov. F 2.3 mm ( SMF).— SAN120, 6– 10 m, 3 October 1992: 1 M 3.0 mm ( SMF).—SAN57, 1 m, no date: 5 M 2.8–3.6 mm, 3 ov. F 2.3–4.1 mm ( SMF). Red Sea. Al Wajh, 26°15.769'N, 36°26.034'E, 0.5 m, 11 April 2011: 1 ov. F 2.8 mm ( SMF).— Al Maqunah, 28°27.239'N, 34°45.799'E, 0–5 m, 12 April 2011: 10 M 1.9–3.8 mm, 11 ov. F 2.5–3.1 mm ( SMF).— Jeddah, 21°53.09'N, 38°58'22"E, 0.5 m, 17 April 2011: 8 M 1.8–3.3 mm, 7 ov. F 2.8–4.0 mm, 3 F 1.8–2.7 mm ( SMF).—Farasan Islands, Saso Island, 16°52.211'N, 41°35.545'E, 0.5–1 m, 21 February 2012: 8 M 1.9–4.1 mm, 6 ov. F 3.2–3.7 mm, 1 F 3.1 mm ( SMF).— Thuwai, Al- Fahal reef, 1–15 m, 6 October 2012: 1 ov. F 2.7 mm (UF32937).— Al Lith, 20°12.012'N, 40°07.104'E, 0–5 m, 6 March 2012: 1 M 2.1 mm ( SMF).— Al Wajh, 26°14'47'N, 36°26'47"E, 0–5 m, 12 June 2013: 1 ov. F 3.2 mm ( SMF).— 25°12'39"N, 37°12.22"E, 0–5 m, 14 June 2013: 1 ov. F 3.6 mm ( SMF).— Duba, 27°20'39"N, 35°41'41"E, 0.5 m, 21 June 2013: 1 M 4.0 mm ( SMF).— Alkhuraybath, 28°06'27"N, 34°59'27"E, 0–1 m, 23 June 2013: 1 M 2.1 mm ( SMF). Saudi Arabia. Yanbu, 24.4427°N, 37.2477'E, 3–22 m, 4 October 2013: 1 M 2.1 mm (UF38284).

Oman. Gulf of Oman. SE of Muscat, Bandar Karyan, 23°31.623'N, 58°44.367'E, 4–15 m, 28 January 2005: 1 M 3.2 mm (UF7578).

Etymology. Named for Shane T. Ahyong, for his major contributions to Anomuran systematics and decapod crustacean phylogeny.

Description. Carapace: Slightly longer than broad; anterior cervical groove indistinct; transeverse ridges with dense short setae, and a few scattered long and thick setae. Gastric region with 5 transverse ridges: 1 epigastric ridge with 2 submedian spines, medially interrupted; 1 protogastric ridge, slightly convex medially, uninterrupted and extending laterally to carapace margin; 1 mesogastric ridge interrupted laterally by cervical groove; 2 metagastric ridges, anterior one convex and usually medially interrupted, posterior ridge scale-like. 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 spine anterolateral, well-developed, behind of lateral limit of orbit; second minute, 1 spine ventral to between first and second; 3 spines on anterior branchial margin and 3 spines on posterior branchial margin, last small. External limit of orbit unarmed, 1 well-developed frontal spine between external limit of orbit and first anterolateral spine, infra-orbital margin with strong spine. Rostrum broadly triangular, 1.4–1.5 times as long as broad, length 0.4 that of, breadth 0.3–0.4 that of carapace, distance between distalmost lateral incisions 0.3 of distance between proximalmost lateral incisions, dorsal surface slightly concave medially; lateral margin with 4 sharp teeth.

Pterygostomian flap rugose, with 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 and 6 each with 2 ridges, medially interrupted. Males with G1 and G2.

Eyes: Ocular peduncles 1.3–1.4 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 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 distal spine on flexor margin; extensor margin unarmed; crista dentata with 22–24 denticles. Merus subequal in length to ischium, with strong proximal spine on flexor margin, located at midlength, and reaching distal margin of merus; 1 small distal spine; extensor margin with small distal spine. Carpus spineless.

P1: 1.8–2.2 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 0.6–0.8 length of carapace, 1.5 times as long as carpus, with rows of spines, mesial and distal spines strong. Carpus as long as palm, 1.8–2.1 times longer than broad, lateral and mesial margins subparallel, dorsal surface with small spines; mesial surface with row of 3–5 well-developed spines; and row of small spines along lateral margin. Palm 1.5–1.7 times longer than broad; spines arranged in irregular longitudinal rows on dorsal, mesial and lateral surfaces; lateral row continued onto whole lateral margin of fixed finger; mesial row continuing along mesial margin of movable finger. Fingers 0.9–1.1 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 1.6–1.7 times carapace length. Meri successively shorter posteriorly (P3 merus 0.9 length of P2 merus, P4 merus 0.8 length of P3 merus); P2 merus 0.6–0.7 carapace length, 3.0–3.2 times as long as broad, 1.6–1.7 times longer than P2 propodus; P3 merus 2.8–3.0 times as long as broad, 1.2–1.3 times length of P3 propodus; P4 merus 2.1–2.2 times as long as broad, 1.0–1.1 length of P4 propodus; extensor margins each with row of 11–13 proximally diminishing spines on P2–3, 2–4 spines on P4; lateral surfaces unarmed on P2–4; 2 well-developed spines on terminal flexor margin, sometimes obsolescent in P4; flexor mesial margin with terminal spine on P2 only. Carpi each with 4 or 5 spines on extensor margin in P2–3, 0–1 minute spine in P4; lateral surfaces each with row of 2 or 3 acute granules paralleling extensor row of spines; flexor distal margin ending in acute angle. P2–4 propodi 3.5–3.7 times as long as broad; extensor margin with 3 or 4 proximal spines in P2–3, unarmed in P4; flexor margin with 4 or 5 slender movable spines in 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 obsolescent 4 teeth.

Epipods absent on pereiopods.

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

Remarks. The new species resembles G. mauritiana Bouvier, 1914 and other 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 (e.g. G. a c i s n. sp., G. aequata and G. s e n t a n. sp.). Galathea ahyongi n. sp. is easily distinguished from the other species of the group by having the anterior mesogastric ridge interrupted medially and/or laterally, instead of uninterrupted in the other species.

The genetic divergences among G. ahyongi and the other closely related species are always larger than 9.8% (COI) ( Tab. 1).

Distribution. Red Sea, Oman, on Stylophora sp., Pocillopora sp. and Pavona decussata , 0– 15 m.

Figures

FIGURE 7. Galathea ahyongi n. sp., holotype, ovigerous female, 3.5 mm, Red Sea (UF 36149). 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, left P 1, dorsal view; F, left P 2, lateral view; G, left P 3, lateral view; H, left P 4, lateral view. Scale: A, E – H = 1 mm; B – D = 0.5 mm.

FIGURE 115. Dorsal view. A, Galathea acis n. sp., Vanuatu, male 3.7 mm (MNHN-IU- 2013 - 15899). B, Galathea aegyptiaca Paul’son, 1875, Red Sea, female 4.2 mm (UF 37107). C, Galathea aegyptiaca Paul’son, 1875, Madagascar, male 3.4 mm (MNHN-IU- 2010 - 2739). D, Galathea aequata n. sp., French Polynesia, male 4.1 mm (UF 15761). E, Galathea ahyongi n. sp., Red Sea, Saudi Arabia, ovigerous female 3.5 mm (UF 36149). F, Galathea amamiensis Miyake & Baba, 1966, Vanuatu, female 2.9 mm (MNHN-IU- 2013 - 8182). G, Galathea amamiensis Miyake & Baba, 1966, Papua New Guinea, female 3.1 mm (MNHN-IU- 2013 - 356). H, Galathea autahi n. sp., French Polynesia, male 4.8 mm (MNHN-IU- 2013 - 13569). I, Galathea bimaculata Miyake & Baba, 1966, Papua New Guinea, ovigerous female 2.5 mm (MNHN-IU- 2013 - 13907).