Fottea, Olomouc, 18(2): 243–255, 2018 243 DOI: 10.5507/fot.2018.009 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. Qi Zhang1, Lingling Zheng1, Tianli Li2, Guoxiang Liu2 & Lirong Song1* 1 State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, 430072 Wuhan, China; *Corresponding author e–mail:
[email protected] 2 Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, 430072 Wuhan, China 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. Key words: morphology, Planktosphaeria, phylogeny, Radiococcaceae, Radiococcus, taxonomy Introduction 1959). The Radiococcaceae was erected by Fott (1959), validated by Komárek (1979) and revised by Kostikov Coccoid green algae are found commonly in aquatic et al. (2002). The family comprised autospore–produc- and terrestrial habitats worldwide, including extreme ing and zoospore–producing species in early definition environments such as postmining dumps, polar arid (Fott 1959), then was restricted to autospore–producing soils, and deserts (e.g.