The Holocene to Recent ostracods of the Azores archipelago (NE Atlantic): Systematics and biogeography

• First report on the Holocene to Recent marine Ostracoda of the Azores
• Twenty species reported, with eight new taxa (5 new records and 3 new species)
• Strong biogeographic relationships with the Eastern Atlantic and the Mediterranean
• Weak biogeographic relationships between the Azores and Madeira and Canaries
• Systematic studies should be a key objective of the marine research in islands.

This is the first report on the systematics and the biogeography of the Holocene to Recent shallow marine Ostracoda of the Azores archipelago (Portugal). Twenty species are herein reported, comprising 10 families and 14 genera (Neonesidea, Leptocythere, Callistocythere, Cyprideis, Carinocythereis, Aurila, Heterocythereis, Urocythereis, Loxoconcha, Semicytherura, Xestoleberis, Sclerochilus, Lanceostoma and Cylindroleberis). Eight new taxa are reported for the Azores: 5 new records — the species Neonesidea longisetosa (Brady, 1902), Cyprideis torosa (Jones, 1850), Aurila prasina Barbeito-Gonzàlez, 1971, Semicytherura aff. cornuta (Brady, 1868) and Sclerochilus hicksi Athersuch and Horne, 1987 (cf. also online Supplementary data) — and 3 new species, Callistocythere insularis n. sp., Semicytherura brandaoae n. sp. and Lanceostoma simplex n. sp., which are here described. Based on our results, the Azorean shallow-water marine ostracod communities (from the intertidal down to circa 90 m depth) appear to be less diverse than similar communities found elsewhere.The biogeographical relationships of the Azorean shallow water marine ostracods are mainly with the Eastern Atlantic, with only a few species occurring on the Western Atlantic shores of America. In contrast with the usual pattern of strong biogeographical relationships of the Azorean marine fauna and flora with the Mediterranean and the Macaronesian archipelagos, the similarity of the ostracod fauna between the Azores and the Macaronesian archipelagos (Madeira and Canary Islands) is very weak, probably as a result of a gap in the taxonomic knowledge of the benthic ostracods of the latter archipelagos.