Nerillidae (Annelida) from the Corona lava tube, Lanzarote, with description of Meganerilla cesari n. sp.

Five species of Nerillidae are previously known from Atlantic cave systems. Another four species of Nerillidae are reported here from the Corona lava tube (Lanzarote, Canary Islands) presenting the first records of Mesonerilla and Meganerilla from anchialine environments. We here describe Meganerilla cesari n. sp. which resembles Meganerilla swedmarki by the leaf-shaped interramal cirri and lack of median antenna, but differs by the smaller size, shorter chaetae, dense ciliation and presence of ventral lobes on the parapodia. One identified and two unidentified species of Mesonerilla are also reported. Updated diagnoses are presented for Mesonerilla armoricana, reported here for the first time from the Canary Islands, and Leptonerilla diatomeophaga, the only nerillid previously known from the Corona lava tube. The Corona lava tube holds a large variety of benthic habitats, which may explain the high diversity of Nerillidae in this cave system.