Morphology and phylogeny of three planktonic Radiococcaceae sensu lato species (Sphaeropleales, Chlorophyceae) from China, including the description of a new species Planktosphaeria hubeiensis sp. nov.

Abstract

Abstract:The family Radiococcaceae sensu lato, defined as colonial autospore-producing mucilaginous coccoid green algae, is widespread in terrestrial and freshwater habitats. Three species of Radiococcaceae sensu lato, including two Radiococcus species and one Planktosphaeria species, were described from China by light and electron microscopy. A new species of Planktosphaeria, Planktosphaeria hubeiensis sp. nov. was erected based on morphological comparisons and genetic analyses. Our phylogenetic analyses indicated that Radiococcaceae sensu lato is polyphyletic, and separated into three lineages. The Radiococcus species did not cluster into a monophyletic group in phylogenetic analyses; therefore the taxonomy of the genus Radiococcus should be revised in the future.

<p><strong><em>Dispora speciosa</em></strong><strong>, a new addition to the genus <em>Parallela</em> and the first coccoid member of the family Microsporaceae</strong></p>

“…One clear conclusion from our analyses is that the strain ACOI 1508, from here on referred to as Parallela speciosa (unless historical context dictates otherwise), is phylogenetically distant from all previously analyzed lineages of the former, morphologically-defined Radiococcaceae. This is not surprising, considering the previously demonstrated polyphyly of Radiococcaceae (Pažoutová 2008, Pažoutová et al 2010, Fučíková 2014a, Zhang et al 2018. In light of the phylogeny, Dispora's mucilage could possibly be referred to as ´gelatinous matrix´ as it is called in Parallela in one case (Novis et al 2010) rather than mucilage envelopes/covers of Radiococcaceae, to reinforce the taxonomic distinction.…”

“…Nevertheless, the latest complex morphological studies (Komárek 1979, Komárek & Fott 1983, Ettl & Gärtner 1988, Kostikov et al 2002 all placed Dispora in the family Radiococcaceae, highlighting especially the presence of mucilage covers. The few available insights to the phylogeny of Radicococcaceae all uncovered that the family is considerably polyphyletic (Wolf et al 2003, Pažoutová 2008, Pažoutová et al 2010, Fučíková 2014a, Zhang et al 2018. Former Radicococcaceae members appeared scattered in the class Trebouxiophyceae (Hanagata & Chihara 1999, Wolf et al 2003, Pažoutová 2008, Pažoutová et al 2010 and in the class Chlorophyceae (Wolf et al 2003, Pažoutová 2008, Fučíková 2014a, Zhang et al 2018 in various lineages, which proves that extracellular mucilage is a rather common and circumstantial trait and thus offers limited taxonomic information.…”

Algal affinity and possible life cycle of the early Cambrian acritarch Yurtusia uniformis from South China

“…2017; Zhang et al . 2018). For example, the multiple daughter cells (autospores) of Dictyochloropsis splendida (Trebouxiophyceae) are formed within the young autosporangium and finally released from the opened mature autosporangium (Fig.…”