Morphology, reproduction and taxonomy of the Mediterranean species of Gracilaria (Gracilariales, Rhodophyta)

Abstract

Species of the marine algal genus Gracilaria (Gracilariaceae, Rhodophyta) reported from the Mediterranean are critically reassessed. Nine species are recognized: Gracilaria armata (C. Agardh) J. Agardh, G. bursapastoris (S.G. Gmelin) Silva, G. conferta (Schousboe ex Montagne) J. Feldmann et G. Feldmann, G. corallicola Zanardini, G. dendroides Gargiulo, De Masi et Tripodi, G. dura (C. Agardh) J. Agardh, G. heteroclada (Montagne) J. Feldmann et G. Feldmann, G. longa Gargiulo, De Masi et Tripodi, and G. verrucosa (Hudson) Papenfuss. Descriptions and distributional data are provided for these species, and a synoptic key to their features is presented. An examination of the reproductive morphology of these species suggests that the currently accepted criteria for distinguishing between the genera Gracilaria, Hydropuntia (Polycavernosa) and Gracilariopsis are not sustainable, particularly with regard to the development and nutrition of the developing carposporophyte and the formation of sperrnatangia.