Reproductive and genetic distinction between broad and narrow entities of Caloglossa continua (Delesseriaceae, Rhodophyta)

The relationship of Caloglossa continua ssp. postiae to closely related tax a was assessed through an analysis of morphological characters, life histor y and culture studies, and molecular sequencing. Reproductive morphology pr ovided no features by which subspecies postiae might be characterized. Howe ver, the distinctive narrow blades on which the taxon was originally descri bed proved to be stable in a wide range of culture conditions. Crosses betw een isolates of subspecies postiae from Australia and Japan resulted in pse udocystocarps, but neither group of isolates was interfertile with C. conti nua ssp. continua or with C. monosticha. DNA sequence data from the RUBISCO spacer and the flanking regions of the rbcL and rbcS genes showed that sub species postiae does not form a sister group with subspecies continua but i s basal to the clade of taxa that exhibit endogenous branching. On the basi s of these observations, subspecies postiae is described as a distinct spec ies, Caloglossa postiae Kamiya et R.J. King.