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Bryozoan records from the shores and upper shelf (≤50 m depth) of the remote Azores Archipelago (central North Atlantic) have been analyzed, along with unpublished data and data from recent surveys. A checklist of 67 shallow-water species is hereby compiled for the region, of which more than one third represent records from campaigns conducted during the last 20 years. A classification on the origin of the species indicates that the majority (62%) are cryptogenic while 27% (n = 18) are considered native. Given the natural limitations for genetic exchange between the archipelago’s bryozoan populations and those from neighboring shores, the taxa presently considered as cryptogenic may yield a considerable amount of endemic species after taxonomic revision. The remaining 11% are confirmed as non-indigenous species, highlighting the importance of human-mediated transport in considerably enhancing the diversity of bryozoans in remote oceanic archipelagos, which would otherwise be off-limits to their natural dispersal capacity. In view of the need to quantitatively evaluate the certainty of species-level identification when assembling such biodiversity inventories, we have developed a method to attribute a degree of certainty to species records. The application of this method to the current checklist highlights the importance of further studies to ascertain the identification of many species recorded for the Azores, and to be able to categorize them confidently as either native, cryptogenic or non-indigenous.

The Azores, Madeira, Selvagens, Canary Islands and Cabo Verde are commonly united under the term “Macaronesia”. This study investigates the coherency and validity of Macaronesia as a biogeographic unit using six marine groups with very different dispersal abilities: coastal fishes, echinoderms, gastropod molluscs, brachyuran decapod crustaceans, polychaete annelids, and macroalgae. We found no support for the current concept of Macaronesia as a coherent marine biogeographic unit. All marine groups studied suggest the exclusion of Cabo Verde from the remaining Macaronesian archipelagos and thus, Cabo Verde should be given the status of a biogeographic subprovince within the West African Transition province. We propose to redefine the Lusitanian biogeographical province, in which we include four ecoregions: the South European Atlantic Shelf, the Saharan Upwelling, the Azores, and a new ecoregion herein named Webbnesia, which comprises the archipelagos of Madeira, Selvagens and the Canary Islands., SCOPUS: ar.j, info:eu-repo/semantics/published

The diversity of calcareous epiliths along a bathymetrical transect spanning the intertidal to bathyal (0–500 m) was investigated during a two-year carbonate cycling experiment deployed in the Faial Channel, Azores. The epilith inventory comprises 47 taxa of bryozoans, 9 serpulids, 3 bivalves, 3 cirripeds, 3 foraminiferans, 2 vermetid gastropods, and 1 scleractinian coral, along with 6 rhodophyte morphotypes. Colonised surface area, carbonate accretion rates, and biodiversity peak in the deeper euphotic zone (15 and 60 m), where mature biocoenoses were established after 2 years exposure, whereas colonisation was retarded at dysphotic and aphotic depths. Particularly in the photic zone, colonised surface area, accretion rates, as well as species richness and abundance were higher on down-facing compared to up-facing surfaces. Analyses of similarity (ANOSIM) and non-metrical multidimensional scaling (NMDS) of species abundance data revealed that water depth and substrate orientation were the dominant factors controlling the community structure as a result of direct (photosynthesis) and indirect (bioerosion pressure; nutrient supply) effects of the light regime, while exposure time and substrate type had little influence. The same hierarchy applies for the ichnodiversity of bioerosion traces, but with an inverse pattern in case of substrate orientation, reflecting the interaction of encrustation and bioerosion. Positive net carbonate production rates support the development of oyster bioherms and heterozoan-dominated carbonate/volcaniclastic sediments accumulating in the Faial Channel and adjacent slope. A comparison with biogenic sediments from other Macaronesian archipelagos and seamounts demonstrates the abundance and diversity of non-tropical heterozoan carbonates in oceanic islands.

Shallow marine gastropod assemblages from Chattian, Aquitanian and Burdigalian sections in the Indian Kutch Basin are described. They provide insight into the composition and biogeographic relations of the gastropod assemblages at this junction between the Western Tethys and Proto-Indo-Pacific Ocean. For the first time, an improved biostratigraphy allows a clear separation of the assemblages, especially for the hitherto undifferentiated Early Miocene faunas. Throughout the Oligocene, about one-third of the species are also frequently found in the Western Tethys, documenting a passable Tethyan Seaway for nearshore molluscs. A considerable provincialism is evident as well. The expected turnover during the Early Miocene, due to the closing of the Tethyan Seaway, is reflected in the Miocene assemblages. Surprisingly, however, the cut appears very early, i.e. already during the Aquitanian, when the West–East interrelation drops to zero despite the passage having been open during this interval. In contrast, the Burdigalian assemblages witness a minor re-appearance of Western Tethys taxa, suggesting the re-establishment of rather ineffective migration pathways prior to the final closure of the Tethyan Seaway. Cerithium bermotiense and Lyria (Indolyria) maniyaraensis are introduced as new species.

Considering the diversity and abundance of larger foraminifera examined from a wide range of Late Oligocene to Early Miocene palaeoenvironments in the Tethyan Seaway, encrusting bryozoans make extremely little use of their tests as substratum. Significant encrustations by bryozoans were exclusively found on large (o c. 6 cm), undulating tests of Lepidocyclina spp., on which, however, a remarkable 34 taxa of encrusting bryozoans were recorded. This shallow-water fauna of Chattian age was analyzed in respect of the bryozoan taxa present, colony growth type, and mode of budding, colony size, as well as onset of reproduction. Taxic and morphological similarities between the fossil assemblage and modern faunas encrusting mobile substrata indicate a long history of bryozoans as part of the interstitial habitat, while the tests of certain larger foraminifera may have played a significant role in the evolution of shallow-water bryozoans by providing substrata for encrusting species in otherwise unfavorable environments.

Sessile barnacle assemblages, dominated by Concavus concavus (Bronn) and Balanus perforatus Bruguiere, are very abundant in the Lower Pliocene deposits of the Almeria-Nijar and Carboneras basins (southeastern Spain). They occur in shallow-coastal siliciclastic and mixed siliciclastic-carbonate sediments, forming dense concentrations in two contexts: (1) sheltered shallow-marine depressions and (2) the mouth of distributary channels feeding a delta lobe. Extensive colonization took place during periods of quiescence with a high nutrient and food supply inducing the formation of hummocks. Crowding of high morphotypes was presumably triggered by a high larval supply and recruitment rate. The barnacles are exceptionally well preserved, often as in situ clusters, many with opercula, and include a range of ontogenetic stages with some specimens preserving original colouration. Good preservation is probably due to sudden burial without further reworking.

In the central Iranian Esfahan-Sirjan and Qom basins sedimentation of the Oligo-/Miocene Qom Formation took place on extensive mixed carbonate–siliciclastic ramps. During this time, both basins were positioned at the Eurasian margin of the Tethyan Seaway, which connected the western and eastern regions of the Tethys Ocean at least until the late Burdigalian. During the so-called Terminal Tethyan Event the Tethyan Seaway was then closed due to the collision of the African/Arabian and Iranian/Eurasian plates. Facies analysis of the sedimentary record of both basins indicates paleoenvironments ranging from terrestrial to open marine settings, including mangrove, restricted inner shelf lagoon, seagrass meadow, reefal, and deeper offshore environments. Recognition of eight depositional sequences and elaboration of an integrated biostratigraphic framework (calcareous nannoplankton, planktic and larger benthic foraminifers, gastropods, and pectinids) allow us to construct a basin-spanning stratigraphy. The assignment of the recognized sea-level lowstands to the Ru 3 to Bur 3 lowstands of the global sea-level curve enables a comparison with time-equivalent sections from the Zagros Basin, which was part of the African/Arabian Plate on the opposing southern margin of the Tethyan Seaway. The so calibrated sections display restrictions of the Tethyan Seaway and interruption of the south Iranian gateways between the Qom Basin and the Proto-Indopacific in relation to ongoing plate collision during the early Burdigalian.