Semicryptic Diversity around Chaetoceros elegans (Bacillariophyta, Mediophyceae), and the Description of Two New Species

The globally distributed Chaetoceros elegans belongs to the lorenzianus (C. lorenzianus) complex and is characterized by having tear-shaped setae poroids. Several strains of C. were established from Chinese coastal waters. vegetative cells resting spores observed using light electron microscopy. Phylogenetic analyses two nuclear ribosomal RNA genes (SSU D1–D3 region LSU) internal transcribed spacer (ITS) revealed that clustered into three clades, corresponding different morphotypes. Based on type material, delineation was amended, new taxa, (Chaetoceros macroelegans) macroelegans sp. nov. densoelegans) C.densoelegans nov., described. taxa are featured presence types poroids, round-oval whereas only poroids seen in elegans. base distinct elegans, but absent or short taxa. In macroelegans, intercalary larger less densely spaced than other species. more although they have same size. Resting characterize unknown amended When comparing ITS2 secondary structure, four compensatory changes (CBCs) distinguish C.densoelegans, respectively. Between no CBC five hemi-CBCs (HCBCs) present. shape, size density as well morphology spores, important characteristics for species identification among presently nine known within complex.