Rarity in the native range of the Lessepsian migrant Plocamopherus ocellatus (Nudibranchia): Fact or artifact?

The opening of the Suez Canal in 1869 enabled a large number of Indo-Pacific marine species to expand their ranges into the Mediterranean Sea (Galil et al. 2017), entering the Gulf of Suez from the Red Sea and migrating northwards towards the easternmost basin of the Mediterranean. These species have been called 'Lessepsian migrants' (Yonow 2015), 'Lessepsian immigrants' (Kleitou et al. 2019), or 'Lessepsian invaders' (Ivkic et al. 2019), named after Ferdinand de Lesseps who planned the Suez Canal's construction, or 'Erythraean non-indigenous species' (Galil et al. 2017), after the Erythraean Sea, an earlier maritime designation including both the Red Sea and the Gulf of Aden.