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The taxonomic study of Great Amazon Reef System sponges yielded three Oceanapia-like (Phloeodictyidae, Haplosclerida) species of similar gross morphology, two preliminarily identified as O. bartschi and another as Coelocarteria (Poecilosclerida), due to the presence of common palmate isochelae. The remarkable overall similarity of all three species in gross morphology necessitated an integrative assessment of the phylogenetic affinities. A selection of haplosclerid and poecilosclerid sequences (18S and 28S rRNA) was gathered from Genbank and compared to sequences mapped to reference from metagenome of two Oceanapia-like species from the Amazon River mouth, one of which matched O. bartschi. Both Brazilian species clustered with Coelocarteria singaporensis (Singapore). These species nest in the Poecilosclerida, far from Oceanapia (sp. and isodictyiformis) and other haplosclerids (Amphimedon, Petrosia, Siphonodictyon and Xestospongia) but also far from the poecilosclerid Isodictya that is currently classified in the same family as Coelocarteria, the Isodictyidae. Specimens with chelae are named Coelocarteria alcoladoi sp. nov. herein, while those without chelae represent the other two species. One matched Inflatella bartschi (O. bartchi’s holotype, here re-examined), thereby supporting the transfer of this species to Coelocarteria. The other is proposed as C. amadoi sp. nov. and is the second known lipochelous species in this genus. The 28S phylogenies recovered Coelocarteria bartschi comb. nov. (formerly Oceanapia bartschi) in the Poecilosclerida clade that clustered with Coelocarteria spp., including the type species of this genus, C. singaporensis, with 100% support. Coelocarteria alcoladoi sp. nov., also without chelae, grouped in the same clade, thereby corroborating the classification in this genus. The clade composed of Coelocarteria spp. grouped with Cornulella sp., suggesting an affinity between these genera. Coelocarteria is currently situated within Isodictyidae and Cornulella in Acarnidae. Isodictya (Isodictyidae) grouped with Amphilectus (Esperiopsidae) with high support and is only distantly related to Coelocarteria. Acarnus (Acarnidae) grouped with Clathria, also with high support, far from Coelocarteria and Cornulella. These results suggest the polyphyletic nature of Isodictyidae and Acarnidae, for which reason we preferred to propose a new, currently monotypic family for Coelocarteria spp., Coelocarteriidae fam. nov.
Snorkel snails (genus Rhiostoma) are widely distributed in Indo-China and on the Malay Peninsula. The shell morphology is traditionally used for species identification yet in Thailand, the common snorkel snail, Rhiostoma housei, shows considerable variation in shell morphology within and between populations. Therefore species identifications and delimitations are difficult. We used two mitochondrial DNA fragments (COI and 16S rRNA) and morphological characters to delimit species and infer phylogenetic relationships of Rhiostoma housei s.l. from eight localities in Thailand, representing potential cryptic species suggested by earlier allozyme and karyological data. Results revealed four distinct clades from different geographic areas in Thailand. Species delimitation analyses confirmed the clades as four separate species and a geometric morphometric analysis demonstrated subtle but consistent conchological differences between the four clades. The high COI sequence divergences among the four clades (mean: 14.8%; range: 10.3–16.5%) further supported the species level recognition. As a consequence, three new species are described from Thailand: R. khoratense, sp. nov., R. nakwangense, sp. nov. and R. phunangense, sp. nov.
Magdalena N. Georgieva, Nadezhda N. Rimskaya-Korsakova, Varvara I. Krolenko, Cindy Lee Van Dover, Diva J. Amon, Jonathan T. Copley, Sophie Plouviez, Bernard Ball, Helena Wiklund, Adrian G. Glover
The vestimentiferan tubeworm genera Lamellibrachia and Escarpia inhabit deep-sea chemosynthesis-based ecosystems, such as seeps, hydrothermal vents and organic falls, and have wide distributions across the Pacific, Atlantic and Indian Oceans. In 2010–2012 during initial explorations of hydrothermal vents of the Mid-Cayman Spreading Centre (MCSC), both genera were found to co-occur at the Von Damm Vent Field (VDVF), a site characterised by diffuse flow, therefore resembling a ‘hydrothermal seep’. Here, we erect two new vestimentiferan tubeworm species from the VDVF, Lamellibrachia judigobini sp. nov. and Escarpia tritentaculata sp. nov. Lamellibrachia judigobini sp. nov. differs genetically and morphologically from other Lamellibrachia species, and has a range that extends across the Gulf of Mexico, MCSC, off Trinidad and Tobago, and Barbados, and also across both vents and seeps and 964–3304-m water depth. Escarpia tritentaculata sp. nov. is distinguished from other Escarpia species primarily based on morphology and is known only from vents of the MCSC at 2300-m depth. This study highlights the incredible habitat flexibility of a single Lamellibrachia species and the genus Escarpia, and historic biogeographic connections to the eastern Pacific for L. judigobini sp. nov. and the eastern Atlantic for E. tritentaculata sp. nov.
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