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 Caliphylla mediterranea A. Costa, 1867 ( Figure 5 (g)) Material examined Cala d’Aiguafreda , Begur ( Spain ), 41°57 ʹ 49”N , 3°13 ʹ 41”E , 5 September 2017 , 0.8 m depth , 2 spcs, adults, L = 17 mm ; CalaVentosa, Sant Feliu de Guíxols ( Spain ), 41°47 ʹ 5”N , 3°2 ʹ 52”E , 13 September 2017 , 1.5 m depth , 1 spc., adult, L = 20 mm ; Cala Maset caves, Sant Feliu de Guíxols ( Spain ), 41°47 ʹ 10”N , 3°2 ʹ 44”E , 5 December 2017 , 0.7 m depth , 9 spcs, adults and egg masses, L = 5–40 mm ; Fòrum pools, Barcelona ( Spain ), 41°24 ʹ 34.5”N , 2°13 ʹ 36.8”E , 5 December 2017 , 0.7 m depth , 8 spcs, juveniles, adults and egg masses, L = 5–40 mm ; Cova de l’infern ( Spain ), 42°19 ʹ 2.75”N , 3°19 ʹ 12.74”E , 18 September 2018 , 1.3 m depth , 1 spc., adult and egg masses, L = 40 mm ; Punta de la Mona , Andalucía ( Spain ), 36°43 ʹ 12.9”N 3°43 ʹ 43.1”W , 20 September 2020 , 1–5 m depth ,>40 spcs, juveniles, adults and egg masses, L = 4–30 mm . External morphology Body elongate, thick, background colour light green with small brown and white dots along body, and a white pigmented area between eyes. Cerata numerous, flat; transparent with green lines running towards apex. Rhinophores long, folded, divided in ‘Y’ shape, tips divided into two unequal parts. Ecology Specimens found at night and during the day on the green algae Bryopsis duplex (De Notaris, 1844) and Cladophora prolifera laying egg masses. At night slugs actively crawled and laid egg masses, while by day they hid among the algae. Distribution Gulf of Mexico (BioGoMx 2021); Brazil (GBIF.org 2021); Gibraltar ( García-Gómez 2002 ); Atlantic Spanish coast: Canary Islands ( Ortea and Bacallado 1981 ; Ortea et al. 1999 , 2001 ; Moro et al. 2003 ); Mediterranean Spanish coast, Andalucía ( Luque 1983 ; García Raso et al. 1992 ; Ocaña et al. 2000 ), Levantine coast ( Templado et al. 1987 , 2002 ), Balearic Islands (GROC 2009–2021), Catalonia (this study). Remarks This species is distinguished from similar ones like C. viridis ( Deshayes, 1857 ) (formerly Polybranchia viridis ) by the presence of a ramified digestive gland in the cerata (see Poybranchia viridis in Rudman 2021 ). Genus Cyerce Bergh, 1870