Sabellariidae from Lizard Island, Great Barrier Reef, including a new species of Lygdamis and notes on external morphology of the median organ Author Capa, María Author Faroni-Perez, Larisse Author Hutchings, Pat text Zootaxa 2015 4019 1 184 206 journal article 10.11646/zootaxa.4019.1.10 52ee815e-9e7e-40c3-b900-e0e03f07c8ae 1175-5326 245139 28811FA6-340B-42AE-9D3A-12BA3BFC7EF6 Genus Gesaia Kirtley, 1994 Gesaia Kirtley, 1994 : 166 . Type-species. Phalacrostemma elegans Hartman & Fauchald, 1971 : 152 (not Fauvel 1911 ). Remarks. This planktonic larva is provided with four parathoracic segments, simple (unbranched) feeding tentacles, nuchal hooks (with strongly bent sharp tips), and without limbations, operculum completely divided in two lobes, features that are characteristic for Gesaia species ( Kirtley 1994 ; Capa et al . 2012; Capa & Hutchings 2015 ). The paleae morphology, with straight and cylindrical outer and inner paleae, and paleae arrangement, with outer paleae forming a semicircle and the inner paleae in an almost straight line between opercular lobes, is also most similar to benthic stages of members of this genus. However, the thecal ornamentation of the paleae, indicated to be the most important morphological trait for Gesaia species discrimination ( Kirtley 1994: 166–167 ) observed in the larva described herein differs from other Gesaia species.