MORPHOLOGICAL CHARACTERISTICS OF THREE CRYPTIC SPECIES RELATED TO PORPHYRA TENERA KJELLMAN ELUCIDATED BY MOLECULAR DATA

Abstract

In the previous study, three cryptic species were elucidated by the analysis of molecular data (nuclear SSU rDNA, plastid rbcL and mitochondrial cox1 gene sequences) to find out the phylogenetic relationship of Porphyra tenera Kjellman and its related species from Korea and Japan: P. kinositae (Yamada et Tanaka) Fukuhara, P. koreana Hwang et Lee, P. kuniedae Kurogi, P. yezoensis Ueda. The morphological characters discriminating the species other than the cryptic ones are thickness of gametophytic thalli, shape of spermatangial sori, division pattern of spermatangia and zygotosporangia, and so on. However, the characters show the variation according to the environmental conditions so that the species discrimination has been problematic even to Porphyra taxonomists. The cryptic species are hardly distinguished from P. yezoensis by those characters, and only minute differences were observed in the length of trychogynes on carpogonia of gametophytic thalli and some characters of sporophytic thalli such as the length of vegetative cells of conchocelis filaments, the branching pattern of conchosporangial branches. Morphological characteristics of gametophytic and sporophytic thalli of each cryptic species will be presented and the incongruity of divergence degree between morphological and molecular characters in a group including P. tenera and its related species will be discussed.