Tina N. Molodtsova

Shallow-Water Sea Anemones (Cnidaria: Anthozoa: Actiniaria) and Tube Anemones (Cnidaria: Anthozoa: Ceriantharia) of the Galápagos Islands

ABSTRACT We provide the first inventory of members of orders Actiniaria (sea anemones sensu stricto) and Ceriantharia (tube anemones) from the Galápagos Islands. Based on observations and collections at 48 localities throughout the archipelago that span nearly a decade, we report on eight species of actiniarians (representing families Actiniidae, Actinostolidae, Aiptasiidae, Hormathiidae, and Isophelliidae) and two of cerianthids (in families Arachnactidae and Botrucnidiferidae). We include live photographs and diagnostic features of the animals, as well as a key and map of their occurrence in the Galápagos. Two actiniarians and one cerianthid are resolved only to genus level; of those identified to species, three of the actiniarians and one of the cerianthids have an eastern Pacific distribution, one actiniarian appears to be endemic to the Galápagos Islands, and two actiniarians are broadly distributed in the Indo-West Pacific.

Anthozoa from the northern Mid-Atlantic Ridge and Charlie-Gibbs Fracture Zone

Abstract An annotated list of deep-sea Anthozoa of the orders Actiniaria, Antipatharia, Scleractinia, Alcyonacea and Pennatulacea collected on the G.O. Sars MAR-ECO cruise to the Mid-Atlantic Ridge between the Azores and the southern tip of the Reykjanes Ridge is given. A total of 33 species is reported of which 32 were identified to species or genus level. The groups most rich in species were Actiniaria (nine species), Scleractinia (eight species) and Pennatulacea (eight species). Scleractinia, Antipatharia and Pennatulacea were mainly represented by species with a wide or cosmopolitan geographical distribution. In contrast, most of the actiniarians had been rarely recorded in the North Atlantic. Three species, Schizopathes affinis Brook, 1889 (Antipatharia), Dendrobrachia multispina Opresko & Bayer, 1991 and Heteropolypus cf. insolitus Tixier-Durivault, 1964 (Alcyonacea) are reported from the North Atlantic for the first time.

Actiniaria and Ceriantharia of the Azores (Cnidaria Anthozoa)

The common shallow water species of sea anemones (Actiniaria) and tube anemones (Ceriantharia) of the Azores are listed. Eight species of sea anemones are mentioned, the species Cereus pedunculatus and Sagartia affinis being new records for the archipelago. Both species of Ceriantharia, namely Arachnanthus nocturnus and Pachycerianthus solitarius, are recorded from the Azores for the first time. Arachnanthus nocturnus is also recorded from the Cape Verde Islands and from Madeira for the first time.

Deep-sea mushroom soft corals (Octocorallia: Alcyonacea: Alcyoniidae) of the Northern Mid-Atlantic Ridge

Abstract In material from the northern Mid-Atlantic Ridge and the Reykjanes Ridge, five species of deep-sea mushroom corals belonging to the genera Anthomastus, Heteropolypus and Pseudoanthomastus were found, including three species new to science. The scope and diagnoses of the genera Heteropolypus and Pseudoanthomastus are re-evaluated based on examination of the type material. The main characteristics to distinguish these three deep-sea genera are tentacular and pharyngeal sclerites. A term sclerome as an inventory of all sclerites of the actual octocoral taxon is proposed. A replacement name Alcyonium pasternaki is proposed for the monomorphic Pseudoanthomastus pacificus Pasternak, 1981. Type materials of Anthomastus grandiflorus Verrill, A. agaricus Studer, A. canariensis Write & Studer, A. purpureus (Koren & Danielssen) and A. agassizii Verrill, all species described or reported from the North Atlantic, confirmed the validity of these species.

Cnidarians and Their Polychaete Symbionts

Cnidarians, especially skeleton-bearing anthozoans and hydrocorals, are known to host abundant and diverse symbiotic fauna encompassing members of the majority of metazoan taxa, ranging from sponges and flat worms to fishes. Members of the class Polychaeta are between the most diverse and perhaps the least studied taxa of coral symbionts. The last revision (Martin and Britayev, Oceanogr Mar Biol 36:217–340, 1998) reckoned about 60 species of symbiotic polychaetes associated with more than 100 species of cnidarian hosts. However, this number is considerably underestimated. Some populations of scleractinians, sea fans and black corals show up to 100 % infestation by symbiotic polychaetes. Close association and inter-relation of highly host-specific symbionts and cnidarian hosts often lead to dramatic changes in the host morphology. At the moment, actual mechanisms of most of mutual relations between host and symbiont in such associations are generally unknown. The objective of the present paper is to summarize data on species composition and ecology of polychaetes associated with cnidarians. In our review, we report 281 species of cnidarian hosts involved in 324 relationships with symbiotic polychaetes. Most polychaete-hosting cnidarians belong to skeleton-bearing taxa, particularly Scleractinia (125 species or 44.48 % of the total cnidarian hosts), Alcyonaria (73 species or 25.97 %) and Hydrozoa (60 species or 21.35 %). About 120 species of symbiotic polychaetes of ten families are reported from cnidarian hosts. Polynoidae include the highest number of cnidarian-associated polychaetes (almost one half of the currently known species), followed by Syllidae and Serpulidae. Host symbiont interrelations, host specificity, location, infestation characteristics and adaptive modifications of symbionts, as well as host reaction on symbionts presence, have been considered. Our review highlights that (1) every group of cnidarians seems to have their own assemblage of symbiotic polychaetes, (2) some deep-sea alcyonaceans and black corals have never been reported without their often undetermined polynoid symbionts so that its presence has been considered as a species-specific, robust taxonomic character, and (3) we certainly expect the polychaete symbionts associated with deep-sea corals to be a hidden hot-spot of diversity, with many species still waiting to be described.

Redescription of Nanacalathis atlantica Zezina, 1991 (Brachiopoda: Chlidonophoridae) from the North Atlantic

The chlidonophorid brachiopod species Nanacalathis atlantica Zezina, 1991 has been identified in material from the north tropical Mid-Atlantic Ridge, between 16°56’ – 16°51’N at the depth range 3227–3474 m, collected during the 37th cruise of the RV Professor Logachev in February-March 2015. This rich new material allows us to redescribe and properly illustrate this poorly known, deep-water species that was established on the basis of one empty shell. The spiculation within the lophophore and tentacles is heavy with the pattern characteristic for the subfamily Eucalathinae.