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Gracilaria corallicola and G. multipartita (Gracilariales, Rhodophyta), two related flattened European species

2016; Taylor & Francis; Volume: 51; Issue: 4 Linguagem: Inglês

10.1080/09670262.2016.1201867

1469-4433

Conxi Rodríguez‐Prieto, D. Wilson Freshwater, Max H. Hommersand,

Coral and Marine Ecosystems Studies

Two European species of Gracilaria possess flattened blades borne on cylindrical axes, namely, G. multipartita, known primarily from the Atlantic coast, and G. corallicola from the Mediterranean Sea. They are sister species that cluster with G. armata, G. bursa-pastoris and G. longa in rbcL analyses with strong bootstrap support. Blades of G. multipartita taper towards the tips, whereas those of G. corallicolla have broadly rounded tips. Spermatangia of G. corallicola are borne in shallow conceptacles (textorii-type) and data from the literature indicate that the same is true of G. multipartita. Cystocarp morphology is similar, with the gonimoblast filaments initially elongated, narrow and densely filled with cytoplasm, and with tubular nutritive cells issuing initially from lower gonimoblast cells and fusing with cells in the lowermost regions of the outer pericarp. Tetrasporangia are initiated terminally and displaced laterally with the production of side branches from the subterminal cell. The diagnostic characters of the Gracilariaceae are reviewed from a developmental perspective.