A new freshwater species Conticribra sinica (Thalassiosirales, Bacillariophyta) from the lower reaches of the Yangtze River, China

Abstract

A new freshwater diatom species Conticribra sinica sp. nov. Yu, You et Wang from three lakes in the lower reaches of the Yangtze River, China, is described here using a combination of morphological and molecular data from ribosomal DNA genes. The primary distinguishing characteristic of C. sinica was the presence of a non-plicate or slightly-plicate valve face and a single ring marginal fultoportulae that was located at the junction between the valve face and the mantle. There were 4-11 valve face fultoportulae that were located at the subcenter of the valve face. In addition, a single rimoportula replaced a marginal fultoportulae. Areolae loculate were open to the outside by irregularly circular foramina or slit foramina that are radially arranged. Internally, cribra were continuously arranged long a radial arrangement of areolae. Characteristics of the new species with other similar species of Conticribra. Phylogenetic analysis of the nuclear small subunit (SSU) rDNA sequences and nuclear large subunit (LSU) rDNA gene sequences revealed that C. sinica in a single clade at a considerable sequence distance from the other Conticribra species.