New additions to the shallow-water hydroids (Cnidaria: Hydrozoa) of the French Lesser Antilles: Martinique Author Galea, Horia R. text Zootaxa 2013 3686 1 1 50 journal article 10.11646/zootaxa.3686.1.1 b5a2eb3f-2555-41ba-a303-9fac9d2618c3 1175-5326 284148 17A93C58-F09C-484A-A26A-F4F27BC91A6C ? Gastroblasta sp. ( Fig. 3 E) Material examined . Stn. 7 , 23.i.2012 , 6 m, M019 : four fragments on Amphimedon compressa (Porifera) bearing numerous hydrothecae, but no gonothecae (MHNG-INVE-82920). Description . Hydrothecal pedicels arising irregularly from within the inhalant pores of the sponge host; hydrorhiza deeply embedded in host's tissues. Pedicels annulated basally and distally, sometimes in between, protruding at 365–1700 µm above surface of sponge, diameter 80–105 µm; each carrying a hydrotheca distally. Hydrotheca campanulate with slightly diverging walls from base to rim, 505–620 µm high, 310–380 µm wide at aperture; subhydrothecal chamber rather tall, 90–120 µm high; diaphragm well marked, a ring of desmocytes above; margin with 9–10 wide, triangular, moderately high cusps with rounded tips. Hydranths with ca . 20 tentacles. Gonothecae absent. Remarks . Clytia -like polyps of the genus Gastroblasta Keller, 1883 , living in symbiotic associations with sponges, are only known for G. r a f f a e l e i Lang, 1886 ( Gravili et al. 2007 ). The two remaining congeners, G. t i m i d a Keller, 1883 from the Red Sea, and G. o v a l i s ( Mayer, 1900 ) from Florida, are only known from their medusa stage. The present hydroid may represent the polyp of G. o v a l i s , though rearing experiments or genetic data are necessary to test this assertion. Geographical distribution . The sole known record of this hydroid is from Martinique , while the medusa of G. ovalis occur from Florida ( Mayer 1900 ) to Brazil ( Vannucci 1949 ).