Non-native coral species dominate the fouling community on a semi-submersible platform in the southern Caribbean.

A coral community was examined on a semi-submersible platform that was moored at the leeward side of Curaçao, in the southern Caribbean, from August 2016 until August 2017. This community included several non-native or cryptogenic species. Among them were two scleractinian corals (Tubastraea coccinea and T. tagusensis) and two octocorals (Chromonephthea sp. and an unidentified Nephtheidae sp.). This is the first reported presence of T. tagusensis in the southern Caribbean, and the genus Chromonephthea in the Caribbean region. An ascidian, Perophora cf. regina, is also reported from the southern Caribbean for the first time, as well as a coral-associated vermetid gastropod, Petaloconchus sp., first recorded in the Caribbean in 2014. Lack of biofouling management could potentially harm indigenous marine fauna through the introduction of non-native species. Therefore monitoring communities associated with semi-submersible platforms is essential to track the presence and dispersal of non-native, potentially invasive species.

The genus Litophyton Forskål, 1775 (Octocorallia: Alcyonacea: Nephtheidae) from Australia.

The Litophyton species of Australia are described. Of the 33 species dealt with three were previously described and 30 are considered new. For convenience the species described are divided into five distinct morphological groups. The new species are compared with previously described species from neighbouring Indonesia. L. pyramidalis (Kükenthal, 1895) is synonymized with L. elongatum (Kükenthal, 1895).

A revision of the genus Calcigorgia (Cnidaria, Octocorallia, Acanthogorgiidae) with the description of three new species.

Octocorals of the Acanthogorgiid genus Calcigorgia have been examined, from Japan, Sea of Okhotsk, and Bering Sea. The four known species are re-described and scanning electron microscopy (SEM) images of sclerites presented. Three other species are described and depicted, bringing the total number of Calcigorgia species to seven. Calcigorgia simushiri, Dautova 2018 is synonymized with C. spiculifera Broch, 1935. A neotype for C. spiculifera has been designated.

A new name for Dendronephthya kukenthali Gravier, 1908 (Octocorallia, Nephtheidae): Dendronephthya perezi nom. n.

The World Register of Marine Species (WoRMS) is an online resource, which provides the most comprehensive database of scientific names of marine organisms (WoRMS, 2018). WoRMS is regularly retrieved by multidisciplinary researchers around the globe, regarded as a source of reliable taxonomic information. The database is continuously improved by taxonomic experts, which frequently have to address issues raised by users and other editors (Costello et al., 2013). This study is a result of one of these exchanges of knowledge stimulated by WoRMS.

Evaluating the genus Cespitularia MilneEdwards & Haime, 1850 with descriptions of new genera of the family Xeniidae (Octocorallia, Alcyonacea).

Several species of the family Xeniidae, previously assigned to the genus Cespitularia Milne Edwards & Haime, 1850 are revised. Based on the problematical identity and status of the type of this genus, it became apparent that the literature has introduced misperceptions concerning its diagnosis. A consequent examination of the type colonies of Cespitularia coerulea May, 1898 has led to the establishment of the new genus Conglomeratuscleragen. n. and similarly to the assignment of Cespitularia simplex Thomson & Dean, 1931 to the new genus, Caementabundagen. n. Both new genera are described and depicted and both feature unique sclerite morphology, further highlighting the importance of sclerite microstructure for generic position among Xeniidae. Freshly collected material was subjected to molecular phylogenetic analysis, whose results substantiated the taxonomic assignment of the new genera, as well as the synonymies of several others.

Search for mesophotic octocorals (Cnidaria, Anthozoa) and their phylogeny. II. A new zooxanthellate species from Eilat, northern Red Sea.

An octocoral survey conducted in the mesophotic coral ecosystem (MCE) of Eilat (Gulf of Aqaba, northern Red Sea) yielded a new species of the speciose reef-dwelling genus Sinularia. It features encrusting colony morphology with a thin, funnel-shaped polypary. Sinularia mesophoticasp. n. (family Alcyoniidae) is described and compared to the other congeners with similar morphology. Both the morphological and molecular examination justified the establishment of the new species, also assigning it to a new genetic clade within Sinularia. The results highlight its unique phylogenetic position within the genus, and this is the first described species of a mesophotic zooxanthellate octocoral.

A new species of Melithaea (Anthozoa, Octocorallia, Melithaeidae) from the Oman Sea, off Oman.

A new species, Melithaea davidisp. n., is described from the eastern coast of Oman, Oman Sea, in the northwestern Indian Ocean, where it differs from its congeners in lacking capstans and having predominantly spindles in the coenenchyme. A molecular phylogenetic analysis of mtMutS and 28S rDNA genes suggests that it is genetically distinct from similar species in the Red Sea. Furthermore, a species previously reported as Acabaria sp. from the Arabian Sea is now identified as Melithaea mabahissi (Hickson, 1940).

The genus Bebryce (Cnidaria, Octocorallia, Plexauridae) at Japan, with descriptions of three new species.

Three new deep-water species of Bebryce from Japan are described and depicted using Scanning Electron Microscopy: Bebryce otsuchiensis sp. n., Bebryce rotunda sp. n., and Bebryce satsumaensis sp. n. Bebryce studeri Whitelegge, 1897, was reported from Japanese waters for the first time, bringing the total of Japanese Bebryce species to six. Five of these six species seem to be endemic to Japanese waters and all occur in deep water up to 213 m. A key to the Bebryce species is presented.

Species of Elasmogorgia and Euplexaura (Cnidaria, Octocorallia) from Japan with a discussion about the genus Filigella.

Octocorals with thread-like colony shape have been re-examined, mainly from Japanese waters. The holotypes of Elasmogorgia filiformis and Filigella boninensis and a syntype of Filigella mitsukurii have been studied. Euplexaura arbuscula is identified and Euplexaura yayoii sp. n. described.

Sinularia polydactyla (Ehrenberg, 1834) (Cnidaria, Octocorallia) re-examined, with the description of a new species.

Sinularia polydactyla (Ehrenberg, 1834) is re-described and a lectotype assigned. This led to examination of related material from various Indo-Pacific regions. Consequently, Sinularia levi sp. n. is described from Eilat, Israel (Gulf of Aqaba, northern Red Sea) and Sinularia compressa Tixier-Durivault, 1945 and Sinularia candidula Verseveldt and Benayahu, 1983 are synonymized with Sinularia polydactyla. Additional specimens identified in the literature as Sinularia polydactyla are provisionally reassigned to other taxa.

The genus Litophyton Forskål, 1775 (Octocorallia, Alcyonacea, Nephtheidae) in the Red Sea and the western Indian Ocean.

The Litophyton species of the Red Sea and the western Indian Ocean are revised, which includes species previously belonging to the genus Nephthea, which is synonymized with Litophyton. A neotype for both Litophyton arboreum, the type species of Litophyton, and Nephthea chabrolii, the type species of Nephthea, are designated. The new species Litophyton curvum sp. n. is described and depicted, and a key to all Litophyton species is provided. Of the 26 species previously described from the western Indian Ocean and Red Sea, 13 species are considered valid and 13 have been synonymized or placed in other genera.

Overview of the genus Briareum (Cnidaria, Octocorallia, Briareidae) in the Indo-Pacific, with the description of a new species.

The status of Indo-Pacific Briareum species (Cnidaria, Octocorallia, Briareidae) is reviewed by presenting their sclerite features and habitus descriptions. Following the re-examination of type material, museum specimens and newly collected specimens, a species identification key is provided. The species distributions are discussed and updated distribution ranges are depicted. Moreover, a new taxon, Briareum cylindrum sp. n. is described and depicted, whereas Briareum excavatum (Nutting, 1911) is synonymised with Briareum stechei (Kükenthal, 1908). Briareum hamrum (Gohar, 1948) is recorded from the Persian Gulf and Oman Sea for the first time. Consequently, in total four Briareum species are recognized in the Indo-Pacific; Briareum hamrum from the western Indian Ocean, and Briareum cylindrum sp. n., Briareum stechei, and Briareum violaceum from the central and eastern Indo-Pacific region.

Melithaeidae of Japan (Octocorallia, Alcyonacea) re-examined with descriptions of 11 new species.

Japanese melithaeid type material is re-examined and re-described. The sclerites of the different species are depicted using Scanning Electron Microscopy. All Japanese species of the family Melithaeidae treated here belong to the genus Melithaea and are endemic to Japanese waters. Old museum material and newly collected specimens from Japanese waters are identified after comparison with this type material. Acabaria modesta var. abyssicola is regarded a separate species, here named Melithaea abyssicola (Kükenthal, 1909). In addition, 11 new species are described: Melithaea boninensis sp. n., Melithaea doederleini sp. n., Melithaea isonoi sp. n., Melithaea keramaensis sp. n., Melithaea oyeni sp. n., Melithaea ryukyukensis sp. n., Melithaea sagamiensis sp. n., Melithaea satsumaensis sp. n., Melithaea suensoni sp. n., Melithaea tanseii sp. n., and Melithaea tokaraensis sp. n.. Pleurocorallium confusum Moroff, 1902, Pleurocoralloides formosum Moroff, 1902, Melitodes flabellifera Kükenthal, 1908, and Melitodes densa Kükenthal, 1908 are synonymized with Melithaea japonica (Verrill, 1865). We have designated a neotype for Melithaea mutsu Minobe, 1929. A key to the Japanese melithaeids is presented.

A new genus of soft coral (Cnidaria, Octocorallia) from the Republic of Congo (Pointe-Noire Region).

A new genus of soft coral from the Republic of Congo is described, Complexum gen. n. Nine West African octocoral species previously described in the genus Alcyonium by Tixier-Durivault (1955) are referred to this new genus, and a new species is described and figured, Complexumpusillum sp. n. The new species is characterized by having encrusting growth form and abundant spiny clubs in the surface of the polyparium. It colonizes shallow calcareous rocky banks (5 to 20 m depth) existing in coastal water of the region of Pointe-Noire. Based on molecular phylogeny this new genus is well separated from Alcyonium species.

Molecular phylogenetic evidence supports a new family of octocorals and a new genus of Alcyoniidae (Octocorallia, Alcyonacea).

Molecular phylogenetic evidence indicates that the octocoral family Alcyoniidae is highly polyphyletic, with genera distributed across Octocorallia in more than 10 separate clades. Most alcyoniid taxa belong to the large and poorly resolved Holaxonia-Alcyoniina clade of octocorals, but members of at least four genera of Alcyoniidae fall outside of that group. As a first step towards revision of the family, we describe a new genus, Parasphaerasclera gen. n., and family, Parasphaerascleridae fam. n., of Alcyonacea to accommodate species of Eleutherobia Pütter, 1900 and Alcyonium Linnaeus, 1758 that have digitiform to digitate or lobate growth forms, completely lack sclerites in the polyps, and have radiates or spheroidal sclerites in the colony surface and interior. Parasphaerascleridae fam. n. constitutes a well-supported clade that is phylogenetically distinct from all other octocoral taxa. We also describe a new genus of Alcyoniidae, Sphaerasclera gen. n., for a species of Eleutherobia with a unique capitate growth form. Sphaerasclera gen. n. is a member of the Anthomastus-Corallium clade of octocorals, but is morphologically and genetically distinct from Anthomastus Verrill, 1878 and Paraminabea Williams & Alderslade, 1999, two similar but dimorphic genera of Alcyoniidae that are its sister taxa. In addition, we have re-assigned two species of Eleutherobia that have clavate to capitate growth forms, polyp sclerites arranged to form a collaret and points, and spindles in the colony interior to Alcyonium, a move that is supported by both morphological and molecular phylogenetic evidence.

Sinularia leptoclados (Ehrenberg, 1834) (Cnidaria, Octocorallia) re-examined.

Sinularia leptoclados (Ehrenberg, 1834) is re-described. Sinularia leptoclados var. gonatodes Kolonko, 1926 is synonymized with Sinularia maxima Verseveldt, 1977. Two new species of Sinularia with digitiform lobules, leptoclados-type surface clubs and unbranched interior spindles, are described. An updated maximum likelihood tree of Sinularia species with leptoclados-type clubs (clade 5C) based on two mitochondrial genes (mtMutS, COI) and a nuclear gene (28S rDNA) is presented.

Fish, fans and hydroids: host species of pygmy seahorses.

An overview of the octocoral and hydrozoan host species of pygmy seahorses is provided based on literature records and recently collected field data for Hippocampus bargibanti, Hippocampus denise and Hippocampus pontohi. Seven new associations are recognized and an overview of the so far documented host species is given. A detailed re-examination of octocoral type material and a review of the taxonomic history of the alcyonacean genera Annella (Subergorgiidae) and Muricella (Acanthogorgiidae) are included as baseline for future revisions. The host specificity and colour morphs of pygmy seahorses are discussed, as well as the reliability of (previous) identifications and conservation issues.

Patterns of distribution of calcite crystals in soft corals sclerites.

The gross morphology of soft coral surface sclerites has been studied for taxonomic purposes for over a century. In contrast, sclerites located deep in the core of colonies have not received attention. Some soft coral groups develop massive colonies, in these organisms tissue depth can limit light penetration and circulation of internal fluids affecting the physiology of coral tissues and their symbiotic algae; such conditions have the potential to create contrasting calcifying conditions. To test this idea, we analyzed the crystal structure of sclerites extracted from different colony regions in selected specimens of zooxanthellate and azooxanthellate soft corals with different colony morphologies, these were: Sarcophyton mililatensis, Sinularia capillosa, Sinularia flexibilis, Dendronephthya sp. and Ceeceenus levis. We found that the crystals that constitute polyp sclerites differ from those forming stalk sclerites. We also observed different crystals in sclerites located at various depths in the stalk including signs of sclerite breakdown in the stalk core region. These results indicate different modes of calcification within each colonial organism analyzed and illustrate the complexity of organisms usually regarded as repetitive morphological and functional units. Our study indicates that soft corals are ideal material to study natural gradients of calcification conditions.