A new melobesioid alga Synarthrophyton chejuensis sp nov (Corallinales, Rhodophyta), including comparison with Mesophyllum cystocarpideum

Abstract

Synarthrophyton chejuensis (Corallinales, Rhodophyta) is newly described from Korea and represents the first northern hemisphere species of that genus. It differs from other known species of Synarthrophyton in having the following combination of features: it has thalli that are thin, foliose, discoid, more or less proliferously lobate, and lamellate with numerous horizontally to vertically oriented layers of branches. The thalli are partially attached to the substrate. Mature tetra- or bisporangial conceptacles have flat or moundlike pore plates, and usually two or more conceptacles are joined. The pore plates are composed of filaments of four or five cells along with an epithallial cell. The pore canal is lined by filaments with cells similar in size and shape to the cells of other filaments making up the pore plate. Korean plants belonging to S. chejuensis previously had been misidentified as Lithothamnion cystocarpideum or Mesophyllum cystocarpideum, but a reexamination of the type of M. cystocarpideum has shown that it is specifically distinct from S. chejuensis. A detailed morphological and anatomical account of S. chejuensis is provided, and the value of several characters used to distinguish species within Synarthrophyton is discussed.