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

Abstract

The relationship of Caloglossa continua ssp. postiae to closely related taxa was assessed through an analysis of morphological characters, life history and culture studies, and molecular sequencing. Reproductive morphology provided no features by which subspecies postiae might be characterized. However, the distinctive narrow blades on which the taxon was originally described proved to be stable in a wide range of culture conditions. Crosses between isolates of subspecies postiae from Australia and Japan resulted in pseudocystocarps, but neither group of isolates was interfertile with C. continua 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 subspecies postiae does not form a sister group with subspecies continua but is basal to the clade of taxa that exhibit endogenous branching. On the basis of these observations, subspecies postiae is described as a distinct species, Caloglossa postiae Kamiya et R.J. King.