Sheathia yedoensis, a New Species of the Freshwater Red Alga (Batrachospermaceae, Rhodophyta) from Kitanomaru Park, Adjacent to the Imperial Palace, Tokyo, Japan

Abstract

A putative “Chantransia” alga was collected from Kitanomaru Park, adjacent to the Imperial Palace, Tokyo, Japan. The “Chantransia” alga is a sporophyte-stage of batrachospermacean algae having prostrate, rhizoidal filaments and Audouinella-like erect, straight filaments with monosporangia. Because most of the “Chantransia” algae could not be morphologically identified due to the lack of diagnostic characteristics, we determined the rbcL and cox1 DNA sequences of the “Chantransia” alga. The rbcL and cox1 analyses suggested that the “Chantransia” alga belongs to the genus Sheathia (Batrachospermaceae, Rhodophyta) and is distinguished from other Sheathia species. We propose herein Sheathia yedoensis sp. nov. for this alga based on the DNA sequence data. This is the second batrachospermacean species recorded at the Tokyo Imperial Palace and its surrounding gardens. The existence of two batrachospermacean algae indicates that the water environment in the area adjacent to the Imperial Palace is protected against water pollution from the urban area of Tokyo.