Latissimia opalia Ekins, 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 : 430-433

Latissimia opalia Ekins, Benayahu & McFadden , sp. nov.

Figures 1 , 8–10

http://zoobank/ urn:lsid:zoobank.org:act:7CA36992-98F8-478D-BE5A-A2318722193D

Material. Australia. Holotype: QM G339447 , Shelly Beach, Caloundra , Queensland (26.79972° S, 153.150278° E), Intertidal pools of beach rock, 0.1–1 m, 23 February 2021, coll. M. Ekins ; Paratypes: QM G339756 - QM G339762 and QM G339448 - QM G339450 , all same details ; QM G333523 , same location as the holotype, 4 June 2013, coll. M. Ekins & J. Johnson ; QM G317135 , same location as the holotype, 30 June 2000, coll. S. Cook , & D.

Edson; QM G317204 , Dunwich , North Stradbroke Island, Queensland, Australia (27.494167° S, 153.400000° E), 0.1–1 m, 23 September 2000, coll. J. Hooper, S. Cook, J. Kennedy, S. List-Armitage, D. Edson and G. Wörheide.

Description. The holotype measures 30 x 23 mm and is 8 mm in height ( Fig. 8A ), featuring polyps attached to an encrusting 3 mm thick spreading membrane. The polyps are up to 11 mm in length with the majority being around this size, and a few contracted ones of only 2 mm in length. The lower part of the polyps below the tentacles is 1–1.5 mm in width. The expanded tentacles are approximately 1.5 mm long with two rows of 24–30 pinnules on either side of the tentacle.

The sclerites of the holotype are ellipsoid platelets, a few with a waist-like median narrowing, either on one or both sides of the sclerite ( Fig. 9A ). Under an incident light microscope they are opalescent blue and abundant throughout the colony, measuring 0.008 –0.013 x 0.016 –0.019 mm in diameter. The sclerites are composed of calcite rods whose tips provide a uniform granular appearance to the sclerite surface ( Fig. 9B ). Some sclerites tend to fracture during the dehydration process necessary for SEM.

Color. The ethanol-preserved holotype is cream/light orange.

Etymology. The species name, opalia , is derived from the Latin opalus, referring to the opal-blue color of the live colonies.

Variation. The morphological features of the paratype colonies resemble the holotype, except in size ( Fig. 8 B–H ).

Remarks. L. opalia is characterized by large non-retractile blue polyps when alive ( Fig. 10 ) and a relatively thick spreading membrane providing a fleshy appearance. Another xeniid, Sympodium caeruleum Ehrenberg, 1834 , similarly has encrusting colonies with a bluish tinge when alive (Benayahu et al. 2021). However, it differs from L. opalia by having a much thinner and more delicate spreading membrane and fully retractile polyps. All of the sequenced samples of L. opalia were assigned to MOTU72, thus indicating that the geographic distribution of L. opalia includes the Queensland (eastern Australia) intertidal rock platforms and mudflats ( Fig. 1 ).

Living features. The live colonies are blue/brown in color ( Fig. 10 A–B ). Higher magnification of the polyps and tentacles clearly demonstrates the characteristic blue coloration of the sclerites ( Fig. 10 C–F ). At low tide the polyps in direct sunlight contract such that their sclerites form an almost complete barrier blocking out the sunlight and giving the colonies their blue color, with the creamy-brown color of the underlying tissue apparent between the sclerites.

Distribution. South-eastern Queensland and northern New South Wales, Australia ( 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 8. Latissimia opalia gen. nov. sp. nov. (A) Holotype (QM G339447) with expanded polyps emerging from the encrusting spreading membrane. (B–H) Paratype colonies.

FIGURE 9. Scanning electron micrographs of sclerites of Latissimia opalia gen. nov. sp. nov. Holotype (QM G339447): (A) Ellipsoid platelets. (B) Tips of calcite rods provide a uniform granular appearance to the sclerite surface.

FIGURE 10. Live colonies of Latissimia opalia gen. nov. sp. nov.: (A, B) View of encrusting colonies. (C, D) Polyps exhibiting characteristic blue coloration of sclerites with creamy brown color of underlying tissue containing symbiotic algal cells. (E, F) Magnified tentacles with pinnules exhibiting the above coloration features.