Molecular phylogeny and taxonomic revision of the genus Wittrockiella (Pithophoraceae, Cladophorales), including the descriptions of W. australis sp. nov. and W. zosterae sp. nov.

Abstract

Wittrockiella is a small genus of filamentous green algae that occurs in habitats with reduced or fluctuating salinities. Many aspects of the basic biology of these algae are still unknown and the phylogenetic relationships within the genus have not been fully explored. We provide a phylogeny based on three ribosomal markers (ITS, LSU, and SSU rDNA) of the genus, including broad intraspecific sampling for W. lyallii and W. salina, recommendations for the use of existing names are made, and highlight aspects of their physiology and life cycle. Molecular data indicate that there are five species of Wittrockiella. Two new species, W. australis and W. zosterae, are described, both are endophytes. Although W. lyallii and W. salina can be identified morphologically, there are no diagnostic morphological characters to distinguish between W. amphibia, W. australis, and W. zosterae. A range of low molecular weight carbohydrates were analyzed but proved to not be taxonomically informative. The distribution range of W. salina is extended to the Northern Hemisphere as this species has been found in brackish lakes in Japan. Furthermore, it is shown that there are no grounds to recognize W. salina var. kraftii, which was described as an endemic variety from a freshwater habitat on Lord Howe Island, Australia. Culture experiments indicate that W. australis has a preference for growth in lower salinities over full seawater. For W. amphibia and W. zosterae, sexual reproduction is documented, and the split of these species is possibly attributable to polyploidization.

The endemic Cladophorales (Ulvophyceae) of ancient Lake Baikal represent a monophyletic group of very closely related but morphologically diverse species

“…2.8%), which typically have a strong phylogenetic signal at the interspecific level in the Cladophorales with, for example, sister species originating from polyploid speciation differing by 14% in Wittrockiella (Boedeker et al. ) and 7%–29% between species divergence in Boodlea and Phyllodictyon (Leliaert et al. , ).…”

“…This lack of resolution stems from the small amount of divergence in the data set even in ITS sequences (max. 2.8%), which typically have a strong phylogenetic signal at the interspecific level in the Cladophorales with, for example, sister species originating from polyploid speciation differing by 14% in Wittrockiella (Boedeker et al 2017) and 7%-29% between species divergence in Boodlea and Phyllodictyon (Leliaert et al 2008(Leliaert et al , 2009b. While most of the morphospecies are well defined and easily identified, there is also a problem with identifying some of the morphospecies due to ambiguities in morphological character states (namely, C. compacta, C. globulus, and C. pulvinata; see Table S1), therefore the names used in Table S2 and in Figure 4 must be treated with some caution.…”

Hidden diversity in high‐latitude Southern Hemisphere environments: Reinstatement of the genus Rama and description of Vandenhoekia gen. nov. (Cladophoraceae, Ulvophyceae, Chlorophyta), two highly variable genera

“…The genetic diversity within Rama suggests that the four lineages represent four distinct species, as the interspecific divergence ranges from 5% to 10% in the ITS rDNA region sequences. In other studies of the Cladophorales, ITS rDNA region sequences between species had differed by 7% to 29% in Boodlea and Phyllodictyon Leliaert et al, 2008) and by 14% between sister species of Wittrockiella originating from polyploid speciation (Boedeker et al, 2017). When it comes to the taxonomy and nomenclature of Rama, the main problem lies in applying existing names.…”