Stancheva Rosalina, Lewis Louise A, Hall John, Šoljaková Tereza, Permann Charlotte, Holzinger Andreas
Department of Environmental Science and Policy, George Mason University, Fairfax, Virginia, USA.
Department of Ecology and Environmental Biology, University of Connecticut, Storrs, Connecticut, USA.
J Phycol. 2025 Jun;61(3):587-606. doi: 10.1111/jpy.70012. Epub 2025 Apr 9.
The globally distributed genus Zygogonium exhibits a narrow environmental range, with 19 morphologically described species. Its molecular characterization is poor, based on a single accession of the type species Z. ericetorum from Austria. We examined the genetic variability, morphology, and ultrastructure of field-collected Zygogonium material from different sampling sites in Austria, Norway, Ireland, Scotland, and the United States. Phylogenetic analysis based on partial sequences of the psbC gene distinguished three well-supported groups and one subgroup. AtpB gene sequences collected from a subset of samples also support this result, while rbcL gene data provided lower support. Group 1A contained the type species Z. ericetorum from Obergurgl/Austria and samples from Kühtai/Austria, Norway, and Scotland. The morphology was characterized by wide vegetative filaments (15-31 μm) and the occurrence of aplanospores with purple residue. Group 1B contained Z. cf. ericetorum from Ireland and Ellmau/Austria. Filaments were in a similar size range (12-30 μm) as in group 1A. This group had round unusual akinetes with green or purple content, had one or two chloroplasts, and was surrounded by a thick cell wall; no aplanospores were observed. Group 2 collected from Ireland had narrower filaments (8-12 μm), cells up to six times longer than wide, and contained elongated aplanospores. Therefore, we have described a new species Z. angustum sp. nov. Group 3 contained Z. cf. ericetorum from Norway and the United States, represented by vegetative filaments with an intermediate width (13-20 μm), but no other distinct morphological features. The morphological and genetic variability observed in Zygogonium is possibly related to habitat and ecology.
全球分布的双星藻属环境范围狭窄，有19个形态学描述的物种。其分子特征描述不足，仅基于来自奥地利的模式种埃里克双星藻（Z. ericetorum）的一个序列。我们研究了从奥地利、挪威、爱尔兰、苏格兰和美国不同采样点采集的野外双星藻材料的遗传变异性、形态和超微结构。基于psbC基因部分序列的系统发育分析区分出三个得到充分支持的类群和一个亚类群。从部分样本中收集的atpB基因序列也支持这一结果，而rbcL基因数据的支持度较低。1A类群包含来自奥地利奥贝古格尔的模式种埃里克双星藻以及来自奥地利屈泰伊、挪威和苏格兰的样本。其形态特征为宽的营养丝（15 - 31μm）以及带有紫色残留物的不动孢子的出现。1B类群包含来自爱尔兰和奥地利埃尔毛的疑似埃里克双星藻。丝状体大小范围与1A类群相似（12 - 30μm）。该类群有圆形的异常厚壁孢子，内含绿色或紫色物质，有一或两个叶绿体，被厚细胞壁包围；未观察到不动孢子。从爱尔兰采集的2类群有较窄的丝状体（8 - 12μm），细胞长度可达宽度的六倍，且包含细长的不动孢子。因此，我们描述了一个新物种——窄形双星藻（Z. angustum sp. nov.）。3类群包含来自挪威和美国的疑似埃里克双星藻，以中等宽度（13 - 20μm）的营养丝为代表，但无其他明显形态特征。在双星藻中观察到的形态和遗传变异性可能与栖息地和生态有关。
