A reappraisal of the order Corallinales (Rhodophyceae)

Abstract

Articulated and non-articulated coralline algae were brought together in the family Corallinaceae in essentially its present-day circumscription by Decaisne in 1842. Since that time, this family has been perceived as one of the most distinctive assemblages of Rhodophyceae. Alignment of families of red algae into orders based on criteria that today are considered to reflect natural relationships extends back only as far as 1892, when Schmitz presented a scheme founded largely on details of the female reproductive system and gonimoblast development. In that scheme, the Corallinaceae occupied an anomalous position in the Cryptonemiales. While attempts have been made to modify the definition of the Cryptonemiales to accommodate the Corallinaceae more comfortably, an ongoing accumulation of information supports the segregation of that family into its own order. At least three previous authors have adopted the taxonomic concept of the Corallinales, but the name has not yet been validated. In the present paper a Latin diagnosis is provided. Diagnostic characters of the Corallinales include the following: (1) walls of most vegetative cells are impregnated with calcite; (2) meristems are often intercalary and covered by a layer of cells; (3) plugs of primary pit-connections have two-layered, dome-shaped caps; (4) reproductive structures are produced in roofed conceptacles in all genera but one; (5) tetrasporocytes usually undergo simultaneous zonate division; (6) post-fertilization events involve a cluster of procarpial filament systems.