Bysmatrum austrafrum sp. nov. (Dinophyceae), a novel tidal pool dinoflagellate from South Africa

Abstract

:A new species of the dinoflagellate genus Bysmatrum was isolated from tidal pool samples originating from Cape Peninsula, South Africa. This new species was investigated by light, scanning and transmission electron microscopy, and its phylogenetic affinities were analyzed using molecular data. Cells were pentagonal in ventral view, 25–45 μm long and 20–42.5 μm wide and only slightly flattened in a dorsiventral plane. The epitheca, in apical view, was almost circular, with a slight ventral depression. Plate tabulation (PO, X, 4′, 3a, 7″, 6c, 4s, 5′′′, 2′′′′) was typical for the genus Bysmatrum. Apical plate 1′ was heptagonal and broadly asymmetric, with an elongated, fingerlike extension at the base. The intercalary plates 2a and 3a were separated by a direct connection between plates 3′ and 4″. The thecal plates were perforated by pores of different sizes and ornamented with linearly arranged reticulations. Intercalary bands were smooth, and antapical plates were not indented. This new species differs from the five other known species of the genus Bysmatrum in morphology (e.g. the shape of apical plate 1′) and it occupies an isolated position in phylogenetic trees inferred by analyses of small-subunit ribosomal DNA (SSU-rDNA) sequence data. This also represents the first report of the SSU rDNA sequence for Bysmatrum arenicola.