MESOPHYLLUM SPHAERICUM SP. NOV. (CORALLINALES, RHODOPHYTA):A NEW MAERL-FORMING SPECIES FROM THE NORTHEAST ATLANTIC

Abstract

Mesophyllum rhodoliforme Pe？a, B？rbara, Adey, Riosmena-Rodr？guez et Choi is described based on spherical ma？rl individuals (up to 10 cm) collected in a subtidal ma？rl bed in Galicia (NW Spain). The thalli of these specimens are radially-organized, composed of arching tiers of compact medullary filaments. Epithallial cells have flattened to rounded outermost walls and they occur in a single layer. Subepithallial initials are as long, or longer, than the daughter cells that subtend them. Cell fusions are abundant. Multiporate asexual conceptacles are protruding, mound-like with a flattened pore plate, lacking a peripheral raised rim. Filaments lining the pore canal and the conceptacle roof are composed of 5-6 cells with straight elongate and narrow cells at their base. Carposporangial conceptacles are uniporate, protruding, conical. Spermatangial conceptacles were not observed. Molecular results placed M. rhodoliforme near to M. erubescens, but M. rhodoliforme is anatomically close to M. canariense.of these specimens are radially-organized, composed of arching tiers of compact medullary filaments. Epithallial cells have flattened to rounded outermost walls and they occur in a single layer. Subepithallial initials are as long, or longer, than the daughter cells that subtend them. Cell fusions are abundant. Multiporate asexual conceptacles are protruding, mound-like with a flattened pore plate, lacking a peripheral raised rim. Filaments lining the pore canal and the conceptacle roof are composed of 5-6 cells with straight elongate and narrow cells at their base. Carposporangial conceptacles are uniporate, protruding, conical. Spermatangial conceptacles were not observed. Molecular results placed M. rhodoliforme near to M. erubescens, but M. rhodoliforme is anatomically close to M. canariense.