Phylogenetic position of Zygogonium ericetorum (Zygnematophyceae, Charophyta) from a high alpine habitat and ultrastructural characterization of unusual aplanospores. Issue 5 (18th September 2014)

• Record Type: Journal Article
• Authors: Stancheva, Rosalina; Hall, John D.; Herburger, Klaus; Lewis, Louise A.; McCourt, Richard M.; Sheath, Robert G.; Holzinger, Andreas; Graham, L.
• Is Part Of: Journal of phycology. Volume 50:Issue 5(2014:Oct.)
• Page Start: 790
• Page End: 803
• Publication Date: 2014-09-18
• Subjects: Algae -- Periodicals; 579.8
• DOI: 10.1111/jpy.12229
• Languages: English
• ISSNs: 0022-3646

Abstract

<abstract abstract-type="main" id="jpy12229-abs-0001"> <title> <x xml:space="preserve">Abstract</x> </title> <p> <italic>Zygogonium ericetorum</italic>, the type species of the genus, was studied from a natural population collected in Mt. Schönwieskopf, Tyrol, Austria. Generic concepts of <italic>Zygogonium</italic> and <italic>Zygnema</italic> were tested with <italic>atpB</italic>, <italic> psbC</italic>, and <italic>rbcL</italic> gene sequence analysis, which showed a sister relationship between <italic>Z. ericetorum</italic> and <italic>Mesotaenium</italic>, in an early branching clade sister to a grouping of <italic>Zygnema</italic> and several other filamentous and unicellular zygnematalean taxa. A variety of light, confocal, transmission electron microscopy, and cytochemical techniques provided new data on the variable chloroplast shape of <italic>Z. ericetorum</italic>, and its aplanospore structure and development, which has been previously considered taxonomically important but has been ambiguously interpreted. <italic>Zygogonium</italic> can be distinguished from other zygnematophytes (particularly <italic>Zygnema</italic>), based on the combination of two characters: (i) irregular, compressed plate‐like chloroplasts and (ii) residual cytoplasmic content left in sporangia outside of the fully developed aplanospores or zygospores. The presence of a sporangial wall that separates the spores from the parent cell should be excluded from the definition of <italic>Zygogonium</italic>, because it is also observed in <italic>Zygnema</italic>. Similarly, the ecological characterization of <italic>Zygogonium</italic> as acidophilic is not unique to the genus. The names of 18 species currently belonging to <italic>Zygogonium</italic> are here changed to <italic>Zygnema</italic>, because of incompatibility with this new proposed <italic>Zygogonium</italic> concept. In the species transferred to <italic>Zygnema</italic>, chloroplasts are typically stellate in three‐dimensions, and the entire content of fertile cells is transformed into the spore, so there is no cytoplasmic residue.</p> </abstract>