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1. On some encrusting Xeniidae (Octocorallia): Re-examination of the type material of Sansibia flava (May, 1898) and a description of new taxa

   https://doi.org/10.11646/zootaxa.5093.4.3  

   BENAYAHU, YEHUDA; EKINS, MERRICK; OFWEGEN, LEEN P.; SAMIMI-NAMIN, KAVEH; MCFADDEN, CATHERINE S. (January 2022, Zootaxa)

   The type of the xeniid soft coral Sansibia flava (May, 1898) is re-described for the first time and its morphological diagnosis is presented. A subsequent integrated analysis of molecular and morphological characters of related Xeniidae, including species indigenous to the Indo-Pacific Ocean and invasive in the Atlantic (Brazil), led to the description of a new Sansibia species, as well as two new genera comprising an additional three new species. All of these taxa are encrusting, with polyps arising directly from a spreading basal membrane. Molecular phylogenetic analyses show that these genera are not sister taxa, thus further emphasizing the remarkable phylogenetic diversity of xeniids with such a growth form. The sclerites of all species are uniformly ellipsoid platelets, abundant throughout the colony. The species exhibit restricted, non-overlapping geographic ranges, with distinct genotypes (molecular operational taxonomic units) found in different marine realms. The results emphasize the importance of re-examination of original old type material while applying molecular phylogenetic analyses in order to delineate species boundaries and to recognize biodiversity patterns. 

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2. Revisiting the type of Cespitularia stolonifera Gohar, 1938 leads to the description of a new genus and a species of the family Xeniidae (Octocorallia, Alcyonacea)

   https://doi.org/10.11646/zootaxa.4964.2.5  

   BENAYAHU, YEHUDA; OFWEGEN, LEEN P.; ALLAIS, J. P.; MCFADDEN, CATHERINE S. (April 2021, Zootaxa)

   null (Ed.)

   Because of the problematical identity and status of the type of the xeniid soft coral genus Cespitularia Milne-Edwards & Haime, 1850, the species C. stolonifera Gohar, 1938 is revised. Examination of the type colonies has led to the establishment of the new genus Unomia gen. n. which is described and depicted. This genus features a stalk, commonly divided into branches featuring a diffuse polypiferous part consisting of distal clustered polyps and proximal individual ones on the stalk or the basal membranous part of the colonies. The sclerites are ellipsoid platelets composed of dendritic calcite rods whose tips are distinct on the surface of the platelets. Freshly collected material from Venezuelan reefs where the species is invasive was subjected to molecular phylogenetic analysis, the results of which substantiate the taxonomic assignment of the new genus under U. stolonifera comb. n. A new species, U. complanatis, from Japan and Green Island (Taiwan) is described and further illustrates the extent of the interspecific morphological variation within the genus. The results reveal that the biogeographic distribution of Unomia gen. n. includes Pacific Ocean reefs in addition to the previously reported invaded Caribbean reefs. 

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3. 50 Shades of Red: the red-reticulate group of Goniobranchus (Heterobranchia: Nudibranchia: Chromodorididae)

   Bonomo, L; Soong, GY; Reimer, J; Gosliner, T (August 2022, World Congress of Malacology Spixiana)

   The Chromodorididae family tree has been refined in recent years via molecular phylogenetic analyses which have clarified many relationships between taxa. The genus Goniobranchus is one clade within Chromodorididae that was previously included within the genus Chromodoris. However, based on recent molecular phylogenetic results, Chromodoris was determined to be non-monophyletic and Goniobranchus was resurrected. In this study, we performed molecular and morphological analyses to resolve the internal relationships among Goniobranchus species, specifically the red-reticulate species complex of three previously described species, Goniobranchus tinctorius, G. reticulatus, and G. alderi, which display a red network of lines over a white mantle and are widely distributed across the Indo-Pacific Ocean. We sequenced two mitochondrial genes (COI and 16S) and one nuclear gene (H3) for 339 Goniobranchus specimens, and in our phylogenetic analyses the red-reticulate species group emerged as a monophyly. This current work has indicated there are at least eleven distinct species within this species complex, including the only three previously described species and another described species, G. splendidus, was added to this clade. The molecular data and the morphological differences among species will be discussed, and we present a possible way forward to clarify the taxonomy of the red-reticulate species complex. 

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4. Diversification and distribution of gall crabs (Brachyura: Cryptochiridae: Opecarcinus) associated with Agariciidae corals.

   https://doi.org/https://doi.org/10.1007/s00338-021-02163-1  

   Xu, T.; Bravo, H.; Paulay, G.; van der Meij, S.E.T. (August 2021, Coral Reefs - this is not a proceedings, it is a journal, but it is not in your dropdown!?)

   null (Ed.)

   Coral reefs are home to the greatest diversity of marine life, and many species on reefs live in symbiotic associations. Studying the historical biogeography of symbiotic species is key to unravelling (potential) coevolutionary processes and explaining species richness patterns. Coral-dwelling gall crabs (Cryptochiridae) live in obligate symbiosis with a scleractinian host, and are ideally suited to study the evolutionary history between heterogeneous taxa involved in a symbiotic relationship. The genus Opecarcinus Kropp and Manning, 1987, like its host coral family Agariciidae, occurs in both Indo-Pacific and Caribbean seas, and is the only cryptochirid genus with a circumtropical distribution. Here, we use mitochondrial and nuclear DNA gene fragments of Opecarcinus specimens sampled from 21 Indo-Pacific localities and one Atlantic (Caribbean) locality. We applied several species delimitation tests to characterise species diversity, inferred a Bayesian molecular-clock time-calibrated phylogeny to estimate divergence times and performed an ancestral area reconstruction. Time to the most recent common ancestor (tMRCA) of Opecarcinus is estimated at 15−6 Mya (middle Miocene—late Miocene). The genus harbours ~ 15 undescribed species as well as several potential species complexes. There are indications of strict host-specificity patterns in certain Opecarcinus species in the Indo-Pacific and Atlantic, however, a robust phylogeny reconstruction of Agariciidae corals—needed to test this further—is currently lacking. The Indo-West Pacific was inferred to be the most probable ancestral area, from where the Opecarcinus lineage colonised the Western Atlantic and subsequently speciated into O. hypostegus. Opecarcinus likely invaded from the Indo-West Pacific across the East Pacific Barrier to the Atlantic, before the full closure of the Isthmus of Panama. The subsequent speciation of O. hypostegus, is possibly associated with newly available niches in the Caribbean, in combination with genetic isolation following the closure of the Panama Isthmus. 

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5. Seven new species of Tetranemertes Chernyshev, 1992 (Monostilifera, Hoplonemertea, Nemertea) from the Caribbean Sea, western Pacific, and Arabian Sea, and revision of the genus

   https://doi.org/10.3897/zookeys.1181.109521  

   Cherneva, Irina; Ellison, Christina I.; Zattara, Eduardo E.; Norenburg, Jon L.; Schwartz, Megan L.; Junoy, Juan; Maslakova, Svetlana A. (October 2023, ZooKeys)

   Andreas Schmidt-Rhaesa (Ed.)

   The marine ribbon worm genusTetranemertesChernyshev, 1992 currently includes three species: the type speciesT. antonina(Quatrefages, 1846) from the Mediterranean Sea,T. rubrolineata(Kirsteuer, 1965) from Madagascar, andT. hermaphroditica(Gibson, 1982) from Australia. Seven new species are described:T. bifrostsp. nov.,T. ocelatasp. nov.,T. majinbuuisp. nov., andT. pastafariensissp. nov.from the Caribbean Sea (Panamá), and three species,T. unistriatasp. nov.,T. paulayisp. nov., andT. arabicasp. nov., from the Indo-West Pacific (Japan and Oman). As a result, an amended morphological diagnosis of the genus is offered. To improve nomenclatural stability, a neotype ofTetranemertes antoninais designated from the Mediterranean. The newly described species, each characterized by features of external appearance and stylet apparatus, as well as by DNA-barcodes, form a well-supported clade withT. antoninaon a molecular phylogeny of monostiliferan hoplonemerteans based on partial sequences of COI, 16S rRNA, 18S rRNA, and 28S rRNA. Six of the seven newly described species, as well asT. rubrolineata, possess the unusual character of having a central stylet basis slightly bilobed to deeply forked posteriorly in fully grown individuals, a possible morphological synapomorphy of the genus. In addition, an undescribed species ofTetranemertesis reported from the Eastern Tropical Pacific (Panamá), increasing the total number of known species in the genus to eleven. 

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