A Description of Biremis panamae sp. nov., a New Diatom Species from the Marine Littoral, with an Account of the Phylogenetic Position of Biremis D.G. Mann et E.J. Cox (Bacillariophyceae)

Here we present a formal description of Biremis panamae Barka, Witkowski et Weisenborn sp. nov., which was isolated from the marine littoral environment of the Pacific Ocean coast of Panama. The description is based on morphology (light and electron microscopy) and the rbcL, psbC and SSU sequences of one clone of this species. The new species is included in Biremis due to its morphological features; i.e. two marginal rows of foramina, chambered striae, and girdle composed of numerous punctate copulae. The new species also possesses a striated valve face which is not seen in most known representatives of marine littoral Biremis species. In this study we also present the relationship of Biremis to other taxa using morphology, DNA sequence data and observations of auxosporulation. Our results based on these three sources point to an evolutionary relationship between Biremis, Neidium and Scoliopleura. The unusual silicified incunabular caps present in them are known otherwise only in Muelleria, which is probably related to the Neidiaceae and Scoliotropidaceae. We also discuss the relationship between Biremis and the recently described Labellicula and Olifantiella.

本研究正式描述了巴拿马双肋藻（Biremis panamae Barka, Witkowski et Weisenborn, sp. nov.）这一新种，该菌株分离自巴拿马太平洋沿岸的海洋潮间带生境。本描述基于光学显微镜与透射电子显微镜的形态学观察结果，以及该物种单克隆株的rbcL、psbC及SSU序列数据。该新种因具备以下形态特征被归入双肋藻属（Biremis）：两列边缘孔纹、具室纹结构，以及由大量具点纹带片构成的壳环带。此外，该新种还拥有具纹壳面，这一特征在多数已报道的海洋潮间带双肋藻属物种中尚未见记录。本研究同时结合形态学观察、DNA序列数据与复大孢子形成过程的观测，探讨了双肋藻属与其他类群的亲缘关系。基于上述三类研究手段得到的结果显示，双肋藻属、新舟形藻属（Neidium）与鞘柄藻属（Scoliopleura）之间存在演化关联。此类群所特有的硅质化初生硅质帽，目前仅在Muelleria属中有所报道，而Muelleria属大概率与新舟形藻科（Neidiaceae）及鞘柄藻科（Scoliotropidaceae）亲缘关系相近。本研究还讨论了双肋藻属与近年发表的Labellicula属及Olifantiella属之间的亲缘关系。