Sea slug night fever: 39 new records of elusive heterobranchs in the western Mediterranean (Mollusca: Gastropoda) Author Salvador, Xavier 0000-0003-3039-7566 Author Fernández-Vilert, Robert 0000-0002-2812-4414 Author Moles, Juan 0000-0003-4511-4055 text Journal of Natural History 2022 2022-05-18 56 5 - 8 265 310 http://dx.doi.org/10.1080/00222933.2022.2040630 journal article 83506 10.1080/00222933.2022.2040630 38f6df24-838f-409a-90df-b56087e6a9bc 1464-5262 6758438 Runcina ornata ( Quatrefages, 1844 ) ( Figure 5 (e)) Material examined Cala d’Aiguafreda , Begur ( Spain ), 41°57 ʹ 49”N , 3°13 ʹ 41”E , 13 October 2017 , 0.1 m depth , 7 spcs, adults, L = 2–3 mm ; 21 November 2017 , 0.1 m depth , 1 spc., adult, L = 2 mm ; 31 January 2018 , 0.1 m depth , 9 spcs, adults, L = 2–3 mm ; 23 April 2018 , 0.1 m depth , 2 spcs, adults, L = 3 mm ; 25 May 2018 , 0.1 m depth , 2 spcs, adults, L = 3 mm ; Punta del Romaní , L’Escala ( Spain ), 42°6 ʹ 54”N . 3°10 ʹ 9”E , 10 January 2018 , 0.2 m depth , 4 spcs, adults, L = 2–3 mm ; 24 April 2018 , 0.2 m depth , 3 spcs, adults, L = 2–3 mm ; 7 December 2018 , 0.2 m depth , 7 spcs, adults, L = 2–3 mm ; Punta d’en Bosch, Sant Feliu de Guíxols ( Spain ), 41°45 ʹ 54”N , 3°0 ʹ 11”E , 17 April 2018 , 0.1 m depth , 5 spcs, adults, L = 1–3 mm . External morphology Body elongate, narrow, black or brown in colour, rear tail darker. Foot large. Ecology Specimens found grazing on biofouling at night over calcarean red algae or boulders, in very superficial waters. Distribution Atlantic Spanish coast: Canary Islands and Strait of Gibraltar ( Cervera et al. 2004 ) and Mediterranean Spanish coast: Catalonia (this study). Remarks This species is rarely observed and very small. Easily distinguishable from other Runcina species by its absence of spots and white marks and its uniform black colour ( Quatrefages 1844 ). Superorder SACOGLOSSA Ihering, 1876 Family HERMAEIDAE H. Adams and A. Adams, 1854 Genus Aplysiopsis Deshayes, 1853