Morphology and molecular relationships of Leptofauchea leptophylla comb. nov. (Rhodymeniales, Rhodophyta) from Japan.

Detailed morphological studies and molecular analyses based on nuclear-encoded large subunit ribosomal RNA (LSU rRNA) gene sequences were undertaken on Gloiocladia leptophylla, a poorly known species from Japan. Both newly collected samples and the holotype were examined. Herein we describe for the first time the structure of tetrasporangial nemathecia, decussately dividing tetrasporangia and male gametophytes. We show that this species has a thin cortex, decussately divided tetrasporangia formed in nemathecia and a tela arachnoidea (network of inner pericarp filaments surrounding mature carposporophytes), as in the genus Leptofauchea. LSU rRNA analyses resolved G. leptophylla in the Faucheaceae (in which it was robustly separated from Gloiocladia), forming a well-supported clade with five other species of Leptofauchea and two species of Webervanbossea. We therefore propose the new combination Leptofauchea leptophylla comb. nov. Iridescence in water, a distinct short stipe and a medulla composed of three to four cell layers are conspicuous diagnostic characters of L. leptophylla within the genus. [ABSTRACT FROM AUTHOR]