Abstract:

Scanning electron microscopy (SEM) was used to conduct morphological observations on diatoms of the genera Falcula and Pseudofalcula distributed along the coasts of South China and Australia. Falcula media Voigt was reported as a newly recorded diatom species for China, while the ultrastructural morphology of F. semiundulata Voigt was studied for the first time. Morphological differences between Falcula and Pseudofalcula were further defined by comparing the former two species with P. hyalina (Takano) Gomez, Wang, & Lin. A key distinguishing feature between the two genera was the structure of the apical pore fields, comprising several slits in Falcula, and presenting as an ocellulimbus with a grid-like structure set into the valve mantle in Pseudofalcula. Falcula species were mainly epiphytic diatoms attached to seaweeds, while Pseudofalcula species were typically epizoic and attached to marine copepods. This study expands the geographic distribution of F. media, F. semiundulata, and P. hyalina and clarifies the basis of the morphological classification of the Falcula and Pseudofalcula genera.

摘要：

利用扫描电镜对华南沿海及澳大利亚分布的镰刀藻属（Falcula）和伪镰刀藻属（Pseudofalcula）硅藻进行了形态学观察。发现一中国新记录硅藻，即中间镰刀藻（F. media Voigt）；首次报道了半波镰刀藻（F. semiundulata Voigt）的超微形态结构；通过与透明伪镰刀藻（P. hyalina (Takano) Gómez, Wang & Lin）的比较进一步界定了两属的形态学差异。其中，二者顶纹区结构的差异最为显著：镰刀藻属的顶纹区由数条狭缝组成，而伪镰刀藻属的顶纹区为嵌入壳套的眼点且呈网格状结构。此外，明确了镰刀藻属物种多是大型海藻上的植表生硅藻，而伪镰刀藻属则为典型的动表生硅藻，其宿主为海洋桡足类。本文扩大了中间镰刀藻、半波镰刀藻和透明伪镰刀藻的地理分布区域，厘清了镰刀藻属和伪镰刀藻属的形态学划分依据。