Numerous new records of tropical non-indigenous species in the Eastern Mediterranean highlight the challenges of their recognition and identification Author Albano, Paolo G. https://orcid.org/0000-0001-9876-1024 Department of Palaeontology, University of Vienna, Althanstrasse 14, 1090, Vienna, Austria pgalbano@gmail.com Author Steger, Jan Department of Palaeontology, University of Vienna, Althanstrasse 14, 1090, Vienna, Austria Author Bakker, Piet A. J. Naturalis Biodiversity Center, Darwinweg 2, 2333, CR Leiden, The Netherlands Author Bogi, Cesare Gruppo Malacologico Livornese, c / o Museo di Storia Naturale del Mediterraneo, via Roma 234, 57127, Livorno, Italy Author Bosnjak, Marija Department of Palaeontology, University of Vienna, Althanstrasse 14, 1090, Vienna, Austria & Croatian Natural History Museum, Demetrova 1, Zagreb, Croatia Author Guy-Haim, Tamar National Institute of Oceanography, Israel Oceanographic and Limnological Research (IOLR), Haifa 3108001, Israel Author Huseyinoglu, Mehmet Fatih Faculty of Maritime Studies, University of Kyrenia, Karakum, Girne, Turkish Republic of Northern Cyprus Author LaFollette, Patrick I. Malacology Section, Natural History Museum of Los Angeles County, 900 Exposition Blvd., Los Angeles, CA 90007, USA Author Lubinevsky, Hadas National Institute of Oceanography, Israel Oceanographic and Limnological Research (IOLR), Haifa 3108001, Israel Author Mulas, Martina https://orcid.org/0000-0001-9228-786X National Institute of Oceanography, Israel Oceanographic and Limnological Research (IOLR), Haifa 3108001, Israel & The Leon H. Charney School of Marine Sciences, University of Haifa, 199 Aba Khoushy Ave., Mt. Carmel, Haifa 3498838, Israel Author Stockinger, Martina Department of Palaeontology, University of Vienna, Althanstrasse 14, 1090, Vienna, Austria Author Azzarone, Michele Department of Palaeontology, University of Vienna, Althanstrasse 14, 1090, Vienna, Austria Author Sabelli, Bruno Museo di Zoologia dell'Universita di Bologna, via Selmi 3, 40126, Bologna, Italy text ZooKeys 2021 2021-01-13 1010 1 95 http://dx.doi.org/10.3897/zookeys.1010.58759 journal article http://dx.doi.org/10.3897/zookeys.1010.58759 1313-2970-1010-1 45DF30C9AEB448AAAC32BBE77CB7191D D317557D854C577289AA424187C079D2 Elachisina sp. Figure 12A-E New records. Israel • 1 spcm; north of Atlit; 32.7417°N , 34.9177°E ; depth 31 m; 25 Apr. 2017; sand; grab; HELM project (sample NG30_8M) • 14 spcms, 1 sh; west of Rosh HaNikra Islands; 33.0725°N , 35.0923°E ; depth 20 m; 1 May 2018; rocky substrate; suction sampler; HELM project (samples S13_1F, S13_1M, S13_2F, S13_3L); size of largest specimen: H 1.6 mm, W 1.3 mm • 9 spcms; same collecting data as for preceding; depth 19 m; 29 Oct. 2018; HELM project (samples S53_1F, S53_2F, S53_3F). Additional material examined. Elachisina robertsoni Kay, 1979: United States • 1 sh; Hawaii, Oahu, Maunalua Bay; BPBM 9754 (holotype). Remarks. The morphology of this species is unique among the native mollusks of the Mediterranean, which does not host any shallow water Elachisinidae . Therefore, we consider it a new non-indigenous species in the basin. The only Indo-Pacific Elachisina we are aware of is E. robertsoni Kay, 1979, which indeed shares the general characters of our species. However, it can be readily distinguished by the thicker and fewer spiral cords, less rounded whorls and sigmoid, rather than strongly prosocline, aperture profile. Elachisina sp. is more similar to the West-African E. tenuisculpta ( Rolan and Gofas 2003 ), but the Israeli shells have more rounded whorls, a greater height/width ratio and smaller ratio between aperture and shell height. Figure 12. Comparison between Elachisina sp. and Elachisina robertsoni Kay, 1979 A-E Elachisina sp., west of Rosh HaNikra Islands, Israel, HELM project (sample S13_3L): front ( A, B ), side ( C ) and back ( D, E ) views F-H Elachisina robertsoni , BPBM 9754 (holotype), Maunalua Bay, Oahu, Hawaii: front ( F ), side ( G ) and back ( H ) views (photograph courtesy N. Young). Scale bars: 0.5 mm.