New Species of Coelastrella and Scenedesmus (Chlorophyceae, Chlorophyta)

Abstract

Two green algae were collected from tree bark and coastal water. One isolated from tree bark is solitary and unicellular, and has network ribs on the cell wall. This alga is morphologically similar to Coelastrella vacuolata (Shihira & Krauss) Hegewald & Hanagata, but differs from it in the shape of cells and visible ornamentation on the cell wall in light microscopy. The other isolated from coastal water is in colony, and has a meridional ribs on the cell wall. The gross morphology of the second alga resembles that of Coelastrella multistriata (Trenkwalder) var. corcontica Kalina & Puncocharova, but differs from it in habitat. The phylogenetic trees constructed with sequence data of 18S rRNA gene showed that the second alga is distant from Co. multistriata var. corcontica. This alga is placed in the subgenus Acutodesmus of the genus Scenedesmus, and forms monophyletic relationship together with Scenedesmus rubescens (Dangeard) Kessler & al. and S. dissociatus (Verses & Trainor) Hegewald & Hanagata. Therefore, these two algae are described as new species, Coelastrella saipanensis Hanagata and Scenedesmus littoralis Hanagata, respectively.