Erratum: Corrigendum: Salvi D, Al-Kandari M, Oliver PG, Berrilli E, Garzia M (2022) Cryptic marine diversity in the northern Arabian Gulf: an integrative approach uncovers a new species of oyster (Bivalvia: Ostreidae), Ostreaoleomargarita. Journal of Zoological Systematics and Evolutionary Research 2022: 7058975. https://doi.org/10.1155/2022/7058975.

[This corrects the article DOI: 10.1155/2022/7058975.].

Molecular and morphological systematics of a new, reef forming, cupped oyster from the northern Arabian Gulf: Talonostrea salpinx new species.

The rocky northern shores of Kuwait and those of the western, inner shores of Kuwait Bay are dominated by a small, densely encrusting oyster. The identity of this oyster has never been confirmed and was mistaken previously for a small Saccostrea. The shell morphology suggests that this species belongs to the subfamily Crassostreinae, but within that subfamily, the presence of marginal erect trumpet-shaped projections is so far unique. Phylogenetic analyses based on mitochondrial DNA sequence data confirmed that this species belongs to the Crassostreinae and has a sister position to the clade including Talonostrea talonata and T. zhanjiangensis. Genetic distance between this species and Talonostrea species is remarkably high, being ~20% for the cytochrome oxidase I gene and ~7% for the 16S rRNA gene. Based on morphological and molecular analyses, this oyster is therefore described here as Talonostrea salpinx Oliver, Salvi & Al-Kandari, sp. nov. Shell morphology is shown to be variable, and the different forms encountered are described. The wider distribution and origins of this species, whether native or introduced, are discussed.

The Ashtamudi Lake short-neck clam: re-assigned to the genus Marcia H. Adams & A. Adams, 1857 (Bivalvia, Veneridae).

The economically valuable bivalve mollusc, known as the short-neck clam, is the major fishery resource of the brackishwater Ashtamudi Lake in Kerala, India. This fishery carries a Marine Stewardship Council certification for sustainability wherein it and all hitherto published reports identify the short-neck clam or yellow-foot clam as Paphiamalabarica (Dillwyn, 1817). It is noted that this name does not conform with current nomenclature and is now correctly referred to Protapesgallus (Gmelin, 1791). Furthermore, it is shown that the identification is also incorrect. Comparative shell morphology of venerid clams of the subfamily Tapetinae from the south Indian coast demonstrates that the short-neck clam in Ashtamudi Lake is Marciarecens (Holten, 1802). Small numbers of M.opima (Gmelin, 1791) were found in Ashtamudi Lake but appear not to be part of, or contribute significantly to, the fishery. The venerid clams Protapesgallus and P.ziczac (Linnaeus, 1758) are not found in Ashtamudi Lake but are inhabitants of the shallow coastal waters of south India. Descriptions of the four confused species M.recens, M.opima, P.gallus, and P.ziczac are given. On the basis of this study, the species involved in Marine Stewardship Council (MSC) certification may be better considered at the generic level of Marcia or at the species level as Marciarecens, the most dominant species in the Ashtamudi Lake clam fishery zone.

Taxonomy of myid bivalves from fragmented brackish-water habitats in India, with a description of a new genus Indosphenia (Myidae, Myoidea, Myidae).

A group of small bivalves inhabiting Indian brackish-water estuaries and lagoons (known locally as backwaters), variously assigned to Corbula, Cuspidaria, and Sphenia, are reviewed and, based on shell characters, shown to be congeneric. Molecular (COI) and morphological data indicate that this group belongs to the family Myidae. Furthermore, the combined data suggest that these Indian myids are a sister taxon of the genus Sphenia. The Indian material studied herein exhibits a functional morphology typical of infaunal bivalves, whereas typical Sphenia are nestling and epibyssate. A new genus, Indosphenia, is thus erected for the Indian group and includes five species, one of which is named in this study. Indospheniakayalum Oliver, Hallan & Jayachandran, gen. et sp. n. is described from the Cochin Backwater on the western coast of India. Cuneocorbulacochinensis (Preston, 1916) is transferred to Indosphenia. Additionally, the west coast taxa I.abbreviata (Preston, 1907), I.abbreviatachilkaensis (Preston, 1911) and I.sowerbyi (EA Smith, 1893) are recognised herein. Corbulaalcocki Preston, 1907, Corbulagracilis Preston, 1907, Corbulacalcaria Preston, 1907 and Corbulapfefferi Preston, 1907 are placed in synonymy with I.abbreviata, and Cuspidariaannandalei Preston, 1915 is synonymised with I.abbreviatachilkaensis.

Infestation of shore crab gills by a free-living mussel species.

Parasitic and commensal species can impact the structure and function of ecological communities and are typically highly specialized to overcome host defences. Here, we report multiple instances of a normally free-living species, the blue mussel Mytilus edulis Linnaeus, 1758, inhabiting the branchial chamber of the shore crab Carcinus maenas (Linnaeus, 1758) collected from widely separated geographical locations. A total of 127 C. maenas were examined from four locations in the English Channel, one location in the Irish Sea and two locations at the entrance of the Baltic Sea. The branchial chambers of three crabs (one from the English Channel and two from Gullmar Fjord, Sweden) were infested with mussels resembling the genus Mytilus. Sequencing at the Me15/16 locus on the polyphenolic adhesive protein gene confirmed the identity as M. edulis. Bivalve infestation always occurred in larger red male individuals. Up to 16 mussels, ranging from 2 to 11 mm in shell length, were found in each individual, either wedged between gill lamellae or attached to the branchial chamber inner wall. This is one of the first reports of a bivalve inhabiting crustacean gills and is an intriguing case of a normally free-living prey species infesting its predator.

Antonbruunia sociabilis sp. nov. (Annelida: Antonbruunidae) associated with the chemosynthetic deep-sea bivalve Thyasira scotiae Oliver & Drewery, 2014, and a re-examination of the systematic affinities of Antonbruunidae.

Antonbruunia sociabilis sp. nov., an abundant endosymbiont of Thyasira scotiae from a putative sulphidic 'seep' in the Hatton-Rockall Basin (1187-1200 m), North-East Atlantic Ocean, is described. The new species is compared with A. viridis and A. gerdesi from the West Indian Ocean and South-East Pacific Ocean respectively. The three species can be distinguished using a suite of morphological characters, and are associated with geographically separated chemosynthetic bivalve molluscs from different families (Thyasiridae, Lucinidae, Vesicomyidae) living in sediments at different depths. New morphological features are recognized for Antonbruunia and a re-assessment of its systematic affinities indicates a close relationship with the Pilargidae. Previous suggestions of an affiliation with the Nautiliniellidae, recently incorporated into the Calamyzinae (Chrysopetalidae), were not supported. The apparent morphological similarities between the two groups are indicative of convergence related to their shared relationships with chemosynthetic bivalves. The first molecular analyses of Antonbruunia (16S and 18S rDNA) clearly indicate that a close relationship to Pilargidae (represented by Ancistrosyllis sp. and Sigambra sp.) is more likely than an affinity to Calamyzinae (represented by Calamyzas amphictenicola, Natushima sp., and Vigtorniella sp.).

Deep-water Thyasiridae (Mollusca: Bivalvia) from the Oman Margin, Arabian Sea, new species and examples of endemism and cosmopolitanism.

Seven species of Thyasiridae are reported from the Oman Margin of the Arabian Sea at depths between 688 m and 3356 m. Hypoxic conditions exist at depths between 400 and 1200 m and three species are restricted to this zone and to the Arabian Sea. Leptaxinus indusarium has also been recorded from the Indus Fan and Channelaxinus investigatoris from off Sri Lanka. A new species Thyasira anassa sp. nov. is described from the hypoxic zone. Another four species are recorded from the abyssal zone where oxygen levels are typical for the deep ocean. Here another new species is described, Parathyasira bamberi sp. nov. but the other species could not be conclusively identified because of close affinity with populations from other oceans.  Deep water Atlantic species Axinulus croulinensis and Mendicula ferruginosa are apparently present in the abyssal Indian Ocean while another thyasirid shell is very close to Channelaxinus excavatus from the Eastern Pacific and C. perplicata from the Atlantic. Accompanying these abyssal thyasirids were other bivalve species, Deminucula atacellana, Limopsis pelagica and Bentharca asperula that cannot be distinguished by morphology from their Atlantic populations. It is concluded that using morphology alone that the abyssal species may well be cosmopolitan in distribution.

Ascetoaxinus quatsinoensis sp. et gen. nov. (Bivalvia: Thyasiroidea) from Vancouver Island, with notes on Conchocele Gabb, 1866, and Channelaxinus Valentich-Scott & Coan, 2012.

Ascetoaxinus quatsinoensis sp. et gen. nov. is described from deep waters off the coast of Vancouver Island, British Columbia, Canada. The shell of this species is quite unusual in that the margin of the lunule is distinctly scalloped, a feature not reported previously for the Thyasiroidea. Further investigation led to the discovery of another similarly scalloped shell, represented by the unique type specimen of Cryptodon ovoideus Dall, 1890, herein re-classified as Ascetoaxinus ovoidea (Dall, 1890). Results obtained from scanning electron microscopy reveal additional anatomical differences, including distinct gill structure, that distinguish A. quatsinoensis from other thyasirids examined. Morphological comparisons of this new species to closely related taxa has resulted in a re-evaluation of the genera Conchocele Gabb, 1866, and Channelaxinus Valentich-Scott and Coan, 2012.

Shallow marine benthic invertebrates of the Seychelles Plateau: high diversity in a tropical oligotrophic environment.

Soft sedimentary biotopes are extensive in the shallow Western Indian Ocean, especially on the Seychelles Plateau and Mascarene Ridge, yet pro rata compared with coral reefs the research effort devoted to them has been minimal. In this study we examine the benthic mollusc and polychaete worm assemblages of the shallow waters (11-62 m) around Mahe, in the Seychelles, and make direct comparisons with the temperate Irish Sea area and subtropical waters of Hong Kong, China (using identical methodology). Two assemblages were recognized, characterized by depth and sediment type. Of these, assemblage A (in shallow carbonate sands) was the most diverse, with diversity and richness measures exceeding those from the Irish Sea or Hong Kong. Hong Kong generally had the poorest fauna. Considering the Bivalvia alone, estimates of taxonomic distinctness showed this to be least for Seychelles assemblage A. The degree of conformity of the results to the concept of the latitudinal gradient in species richness and the possible underlying causes are discussed. Comparisons with other data suggest that the Seychelles support a benthic fauna at least as diverse as any other described from the tropics. A tentative examination of total bivalve species richness suggests a total of 400-500 for the Seychelles. This is in keeping with other Indian Ocean localities, but higher than known figures for continental east Africa. The findings of this paper support the case for widespread ecological and taxonomic studies of the Western Indian Ocean benthic invertebrates.