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| Anthomastus nanhaiensis Li & Xu, 2023 |
Abstract
Members of the subfamily Anthomastinae Verrill, 1922, commonly known as mushroom soft corals, are some of the most typical examples of octocorals in the deep sea. However, their diversity and spatial distribution in the northwestern Pacific are poorly known. Here, two species of mushroom soft corals were obtained from the Zhenbei Seamount in the South China Sea, one described as Anthomastus nanhaiensis, new species, and the other identified as Bathyalcyon robustum Versluys, 1906. Anthomastus nanhaiensis is characterised by highly tuberculated double spheroids, clubs and spindles in capitulum and stalk, and the absence of sclerites from neck zone of anthocodial wall. It is the first species of Anthomastus Verrill, 1878 recorded from the South China Sea, and the second one known from the northwestern Pacific. Bathyalcyon robustum Versluys, 1906 is a remarkable octocoral originally reported from the western Pacific by having a single large autozooid, a peculiar feature within the subfamily Anthomastinae Verrill, 1922. We describe its live morphology for the first time and the detailed structure of sclerites, particularly the rodlets in pharynx and the multiradiates in tentacles, which can be used to distinguish the monotypic genus Bathyalcyon Versluys, 1906 from Anthomastus Verrill, 1878 (vs. platelets in pharynx and the absence of multiradiates in tentacles).
Key words. Anthomastinae, Scleralcyonacea, Anthozoa, dimorphic, taxonomy, deep sea
TAXONOMY:
Class Octocorallia Haeckel, 1866
Order Scleralcyonacea McFadden, van Ofwegen & Quattrini, 2022
Family Coralliidae Lamouroux, 1812
Subfamily Anthomastinae Verrill, 1922
Anthomastus Verrill, 1878
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| Morphology of the holotype of Anthomastus nanhaiensis, new species. A, the animal in situ; B, an autozooid; C, the colony in top view; D, the colony in lateral view; E, the longitudinal section of the colony, showing large cavities of autozooids (au) and small cavities of siphonozooids (arrows). Scale bars = 1 mm (B), 10 mm (C‒E). |
Anthomastus nanhaiensis, new species
Diagnosis. Anthomastus with capitate-shaped colony divided into a spherical capitulum and an inconspicuous stalk. Polyps dimorphic. Autozooids sterile, large, retractile, 92 in number. Siphonozooids fertile, minute, scattered among autozooids and forming a continuous layer. Sclerites including rods, platelets, highly tuberculated double spheroids, clubs and spindles. Anthocodial wall devoid of sclerites.
Etymology. The specific name nanhaiensis refers in Chinese to the South China Sea, the type locality of the species.
Yang Li and Kuidong Xu. 2023. Anthomastus nanhaiensis, new species, and Bathyalcyon robustum Versluys, 1906, Two mushroom Soft Corals (Octocorallia: Coralliidae) from Zhenbei Seamount in the South China Sea. RAFFLES BULLETIN OF ZOOLOGY. 71: 669–680.
