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 Hemiliostraca clandestina (Mifsud & Ovalis, 2019) comb. nov. Figure 16A-C New records. Israel • 1 spcm; Ashqelon; 31.6868°N , 34.5516°E ; depth 12 m; 30 Apr. 2018; offshore rocky reef; suction sampler; HELM project (sample S12_1F) • 38 spcms; Ashqelon; 31.6891°N , 34.5257°E ; depth 25 m; 2 May 2018; offshore rocky reef; suction sampler; HELM project (samples S16_1F, S16_2F, S16_2M); size: H 2.7 mm, L 0.9 mm (illustrated shell) • 16 spcms; same collecting data as for preceding; depth 28 m; 31 Oct. 2018; HELM project (samples S59_1F, S59_2F, S59_3F) • 1 spcm; west of Rosh HaNikra Islands; 33.0725°N , 35.0923°E ; depth 20 m; 1 May 2018; rocky substrate; suction sampler; HELM project (sample S13_3F). Remarks. Sticteulima clandestina and S. athenamariae , both Mifsud & Ovalis, 2019, were described on specimens collected in Turkey ( Mifsud and Ovalis 2019 ). However, both belong to species present in the Red Sea and were illustrated by Blatterer (2019) for the Gulf of Aqaba on plate 131, fig. 8a-d and plate 131, fig. 9a-h, respectively. Sticteulima clandestina appears rather variable but our specimens clearly match Mifsud and Ovalis (2019 : fig. 1B). Both S. clandestina and S. athenamariae look closely related to Hemiliostraca and thus we propose the new combinations Hemiliostraca clandestina and Hemiliostraca athenamariae . This is the first record of H. clandestina in Israel, but the species has been recorded for Lebanon based on empty shells collected in 1999 ( Crocetta et al. 2020 ). Consequently, it is likely present here since at least 1999, with a ~ 20 year time-lag in first detection as quantified also for other non-indigenous species in the Mediterranean Sea ( Crooks 2005 ; Albano et al. 2018 ). This is also the first record of living individuals from the Mediterranean Sea. Despite the relatively large number of living individuals, we did not find any attached to an echinoderm host; this is consistent with the fact that some eulimids actively leave the host if disturbed ( Waren 1984 ). Figure 16. Hemiliostraca clandestina (Mifsud & Ovalis, 2019), and comparison between Vitreolina philippi (de Rayneval & Ponzi, 1854) and Vitreolina sp. A-C Hemiliostraca clandestina , Ashqelon, Israel, HELM project (sample S16_1F): front ( A ), side ( B ) and back ( C ) views. D Vitreolina philippi (de Rayneval & Ponzi, 1854), Plakias, Crete, Greece (sample Rh.05_5M): front view. E, F Vitreolina cf. philippi , Ashqelon, Israel, HELM project (S16_2F): front ( E ) and side ( F ) views. Scale bars: 0.5 mm.