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A new species of the sessile deep-sea barnacle, Heteralepas (Crustacea, Cirripedia), Heteralepas gettysburgensis sp. nov., is described. The specimens were collected at a depth of 225 m at the Gettysburg Seamount on the Gorringe Bank, located in the Portuguese Exclusive Economic Zone, approximately 200 km off the southwestern coast of mainland Portugal. Extensive morphological and molecular (COI, 12S and 16S) analyses were carried out to separate the species from its nearest congeners with similar geographic distribution, i.e., Atlantic waters.
An illustrated checklist of the Mollusca of Galicia Bank, a large and deep seamount off the NW Iberian Peninsula, is provided. The studied material was collected in 8 samples of Seamount 1 cruise (1987), 7 samples of ECOMARG 0709 (2009) and 36 samples of BANGAL 0711 (2011), between 615 and 1768 m. A total of 212 species are known to occur at the Galicia Bank (1 Monoplacophora, 7 Solenogastres, 3 Polyplacophora, 132 Gastropoda, 54 Bivalvia, 6 Scaphopoda, and 9 Cephalopoda), 21 of which from previous studies only. Four species are described as new, 34 species are first record in Spanish waters and another 20 species first record for the Northern Spanish waters. Over 7500 specimens, representing 104 species, were collected alive, and 87 species were represented by empty shells only. Only 53 species were detected in both Seamount 1 and BANGAL 0711; most of the species are rare and more species can be expected if exploration is continued. There is a marked difference in species composition between the summit platform (615‒1000 m) and the deeper part below 1500 m, with some genera (e.g., Colus and Limopsis) represented by alternative species. Endemism, if any, is very low and most of the species are widespread.
A new genus and species of axiid shrimp, Montanaxius mediumquod gen. et sp. nov., is described and illustrated based on three specimens collected from hexactinellid sponges from a seamount in the southwest Indian Ocean. The new genus is characterized by a laterally denticulate rostrum, short lateral carina, absence of submedian carina, a prominent toothed median carina, round pleomere pleura 2–5, pleurobranchs on second to fourth pereopods, and the presence of a male first pleopod and appendix interna on pleopods 3–5. It most closely resembles Levantocaris Galil & Clark, 1993 and Planaxius Komai & Tachikawa, 2008, but differs from the former by being gonochoristic, having a strongly elevated gastric region and well-developed eyes, and from the latter by its toothed median carina and the presence of a median telson spine.