Sansibia claereboudti Samimi-Namin, Benayahu & McFadden, 2022

Benayahu, Yehuda, Ekins, Merrick, Van Ofwegen, Leen P., Samimi-Namin, Kaveh & Mcfadden, Catherine S., 2022, On some encrusting Xeniidae (Octocorallia): Re-examination of the type material of Sansibia flava (May, 1898) and a description of new taxa, Zootaxa 5093 (4), pp. 421-444 : 428-429

Sansibia claereboudti Samimi-Namin, Benayahu & McFadden sp. nov.

Figures 1 , 5C–D , 6 , 7

http://zoobank/ urn:lsid:zoobank.org:act:E8115341-B5FE-40A7-A1D8-3B7D7B1DB628

Material. Oman, Holotype: RMNH Coel. 42915, Oman Sea , Bandar Al-Khiran (23.501662° N, 58.763671° E), 8– 10 m, 2013, coll. K. Samimi-Namin & M. Claereboudt ; Paratypes: RMNH Coel. 42916, same details; SMNHTAU_ Co _38229, same details .

Description. The holotype has a stoloniferous growth form and encrusts a limestone fragment ( Fig. 5 C–D , 6A ). Polyps are monomorphic, and their distribution varies from well-spaced to dense clumps. They arise from anastomosing stolons that criss-cross the substrate Fig. (6 A–B). The polyps are flabby and lie horizontally on the colony surface. The polyp body is up to 2 mm long and the tentacles are> 1 mm long. There is a single row of 5–7 plump pinnules along each side of a tentacle. The smaller polyps may have fewer pinnules or even none, probably representing young ones. The stolons are rather thin and delicate, up to 1 mm thick.

The sclerites of the holotype are ellipsoid platelets, highly abundant throughout the colony, measuring 0.010 – 0.016 x 0.014 –0.020 mm ( Fig. 7A ). Some sclerites tend to fracture due to the SEM preparation. They are composed of calcite rods whose tips provide a granular appearance to the sclerite surface ( Fig. 7B ).

Color. The ethanol-preserved samples are cream or light brown.

Etymology The species is named after Michel Claereboudt, Sultan Qaboos University, Oman, for his contributions to knowledge of the marine biodiversity of the Middle East.

Variation. The morphological features of the paratype colonies ( Fig. 6C ) resemble the holotype, except in size.

Remarks. S. claereboudti sp. nov. is the second confirmed species of this genus. Although Alderslade (2000) included Anthelia boquetei Roxas, 1933 , Anthelia formosana Utinomi, 1950 , and? Anthelia lineata Stimpson, 1855 in the genus Sansibia , all three of those species need re-examination prior to a concrete decision on their taxonomic status. The morphology of S. claereboudti sp. nov. differs markedly from that of S. flava whose polyps are not contractile, while those of S. claereboudti sp. nov. can completely contract. S. flava has a spreading membrane, while S. claereboudti sp. nov. has stolons growing over the reef substrate. S. claereboudti sp. nov. features tentacles with a single row of 5–7 pinnules compared to S. flava which has 3–4 rows and up to 25 pinnules in the outermost row. The sclerites of both species are ellipsoid platelets, highly abundant throughout the colony, and those of S. claereboudti sp. nov. are a bit smaller in diameter compared to S. flava (0.008 –0.013 x 0.013 –0.018 and 0.010 –0.016 x 0.014 – 0.020 mm, respectively). S. flava has sclerites with a rather smooth and roundish margin except for some cracks, while S. claereboudti sp. nov. has some sclerites with a waist. Despite these morphological differences between the two congeners, the molecular data suggest a close genetic relationship between S. flava and S. claereboudti sp. nov. Based on the description of the latter two species an updated diagnosis of Sansibia is presented. So far, these two species exhibit restricted, non-overlapping geographic ranges: Oman Sea vs. SW Indian Ocean.

Living features. The live colonies are iridescent blue-purple or green due to the light-refraction properties of the sclerites ( Fig. 5C, D ). In situ photographs show the polyps in various states, from moderately expanded to completely contracted. Expanded polyps are 2–6 mm in width when alive and the tentacles are up to 4 mm long and 2 mm wide. Polyps contract when stimulated physically.

Distribution. Oman Sea, Arabian Sea ( Fig. 1 ).

Figures

FIGURE 1. Distribution map of the material examined in the current study. Color shades on the background represent different marine realms. TA = Tropical Atlantic, TSAM = Temperate Southern America, TSA = Temperate Southern Africa, WI-P = Western Indo-Pacific, CI-P = Central Indo-Pacific, and TAA = Temperate Australasia.

FIGURE 5. Live colonies of Sansibia species. S. flava (May, 1898) on the reef: (A) Colony with expanded brown polyps and bright, almost white polyp body. (B) Colony with expanded polyps. S. claereboudti sp. nov.: (C, D) Encrusting colonies with expanded polyps and distinct pinnules along the margins of the tentacles (photos C, D: courtesy of M. Claereboudt).

FIGURE 6. Sansibia claereboudti sp. nov.: (A) Holotype (RMNH Coel. 42915). (B) Enlarged portion of (A) marked by dashed rectangle, arrows indicate clusters of polyps. (C) Paratype colonies (RMNH Coel. 42916) attached to calcareous substrate.

FIGURE 7. Scanning electron micrographs of sclerites of Sansibia claereboudti sp. nov. Holotype (RMNH Coel. 42915): (A) Ellipsoid platelets. (B) Tips of calcite rods provide uniform granular appearance to the sclerite surface.