Two new deepwater sea anemones (Cnidaria: Anthozoa: Actiniaria) Sicyonis heliodiscus sp.n. (Actinostolidae) and Hormathia pacifica sp.n. (Hormathiidae) from Pacific

Abstract

Sicyonis heliodiscus sp.n. and Hormathia pacifica sp.n. are described from the Taney Seamounts, NE Pacific. The species belonging to these two genera are known mainly from N Atlantic and Antarctic locations, and only a few species were recorded from the Pacific. Sicyonis heliodiscus sp.n. is a large species which has unusual exterior with short column hidden in live specimens under the wide oral disk and short marginal tentacles directed downward. It is a rare species, which have been observed only a few occasions during more than 25 years of research by the Monterey Bay Aquarium Research Institute. In contrast, Hormathia pacifica sp.n. is common at the Taney Seamounts. It has a common appearance for the genus and can be distinguished from other Hormathia species by a combination of features including the morphology of the body and cnidom. How to cite this article: Sanamyan N.P., Sanamyan K.E., Lundsten L. 2015. Two new deepwater sea anemones (Cnidaria: Anthozoa: Actiniaria) Sicyonis heliodiscus sp.n. (Actinostolidae) and Hormathia pacifica sp.n. (Hormathiidae) from Pacific // Invert. Zool.

Distribution of Megabenthic Communities Under Contrasting Settings in Deep-Sea Cold Seeps Near Northwest Atlantic Canyons

“…Hormathia sp. anthozoans had higher densities in hard habitats than soft habitats which agrees with findings on Hormathia pacifica recorded living upon manganese encrusted basalt and dead sponge tissue in the Taney Seamounts (Sanamyan et al, 2015). Our results fit well with previous studies on Belgica Province carbonate mounds where on-mound habitat had higher biodiversity than off-mound (Henry and Roberts, 2007).…”

Deep-Sea Anemones (Cnidaria: Anthozoa: Actiniaria) from the South Atlantic

“…The differences in number of mesenteries could be due to the different size of specimens or the difficulty in counting mesenteries in general, but especially in badly preserved deep-sea specimens. It is important to note that S. erythrocephala falls into a group within Actinostolidae that, in general, does not follow the Actinostola rule, even indistinctly (Sanamyan et al, 2015). This is seen in our specimens of S. erythrocephala in which small differences within a pair can be observed only in the histological sections (fig.…”

“…lacunifera (Stephenson, 1918a); H. marioni (Haddon,TABLE 7 Size ranges of the cnidae of Chondrophellia coronata (Verrill, 1883) Abbreviations and symbols: SD, standard deviation; N, Total number of capsules measured; S, proportion of specimens in which each cnidae was found; F, frequency; +++, very common; ++, common; +, rather common; -, rare. (Fabricius, 1780); H. pacifica Sanamyan et al, 2015;H. pectinata (Hertwig, 1882); H. spinosa (Hertwig, 1882) (Fautin, 2016).…”

Sea anemones (Actiniaria, Corallimorpharia and Zoantharia) from the Western Bering Sea (Northwest Pacific)

“…Short, conical, with pointed tips tentacles are all of the same shape and arranged in a single cycle on the margin of the disc, that makes this anemone unusually looking and easily recognizable in underwater photographs. Its shape somewhat resembles Sicyonis heliodiscus Sanamyan et al, 2015, another disc-shaped species recently described from material collected by Monterey Bay Aquarium Research Institute (USA) in the eastern Pacific Ocean (Sanamyan et al, 2015a). Sicyonis heliodiscus, however, has much more numerous tentacles and they are blunt and arranged in two cycles.…”