Molecular and morphological evidence for Sheathia gen. nov. (Batrachospermales, Rhodophyta) and three new species

Abstract

The freshwater red algal genus Batrachospermum has been shown to be paraphyletic since the first molecular studies of the Batrachospermales. Previous research, along with this study, provides strong support for the clade Batrachospermum section Helminthoidea. This study has found that heterocortication, the presence of both cylindrical and bulbous cells on the main axis, is an underlying synapomorphy of this clade. Based on support from DNA sequences of the rbcL gene, the COI barcode region and the rDNA ITS 1 and 2, along with morphological studies, the new genus Sheathia is proposed. Seven heterocorticate species were recognized from the molecular clades. Sheathia boryana and S. exigua sp. nov. appear to be restricted to Europe, whereas S. confusa occurs in Europe and New Zealand. Sheathia involuta is widespread in the USA and reported for the first time from Europe. Sheathia americana sp. nov., has been collected in the USA and Canada, and S. heterocortica and S. grandis sp. nov. have been collected only in the USA. Sheathia confusa and S. grandis can be distinguished based on morphological characters, whereas DNA sequence data are required to conclusively distinguish the other species. Sheathia fluitans and S. carpoinvolucra also are placed within this genus based on the presence of heterocortication. These data also hint at greater diversity among non-heterocorticate Sheathia than is recognized by the single species name S. arcuata.

Distribution, morphology and ecological niche ofBatrachospermumandSheathiaspecies (Batrachospermales, Rhodophyta) in thefontaniliof the Po plain (northern Italy)

“…Therefore, B. gelatinosum may be more sensitive to pollution than S. arcuata in the investigated springs. However, the results of this study may not be applicable to all populations of S. arcuata, as recent molecular sequence data suggest that the binomial S. arcuata may hide more than one taxon (Salomaki et al, 2014). Comparable results were obtained for Batrachospermum atrum.…”

“…Nevertheless, an ecological survey of lowland freshwater springs, known as fontanili, located in northern Italy, revealed the presence of a relatively high number of taxa referable to the freshwater red algal genera Batrachospermum Roth and Sheathia Salomaki & M.L. Vis. Sheathia is a new genus recently proposed for all taxa of Batrachospermum with heterocortication, formerly classified as Helminthoidea, and for B. arcuatum, a species with only cylindrical filaments covering axial cells (Salomaki et al, 2014). Heterocortication has been recognized as a synapomorphy of the clade, which is lost in B. arcuatum.…”

First record of Nocturama (Batrachospermales, Rhodophyta) in South America, with the description of a new species N. novamundensis

“…It can be distinguished from both of those taxa by the presence of only one or two large carposporophytes per whorl (carposporophyte diameter-to-whorl-radius ratio ranging from 0.5 to 1.0). In contrast, members of Sheathia and section Batrachospermum typically have more numerous carposporophytes (two to six, exceptionally up to ten, per whorl) that are much smaller than whorls (carposporophyte diameter-to-whorl-radius ratio < 0.5) (Kumano 2002, Salomaki et al 2014. This discovery highlights yet again the richness and distinctiveness of the Batrachospermales in the Southern Hemisphere, and that there are important discoveries still to be made even among existing collections.…”

Red Algae

“…Analysis of recent literature reveals a flora with 66 species and 27 genera from North America ( Table 1). Currently, Batrachospermum is the most diverse genus in North America, but this genus is not monophyletic and recent studies (Entwisle et al, 2009;Salomaki et al, 2014), along with those in the near future, will continue to establish new monophyletic genera for each section of Batrachospermum. Currently, Batrachospermum is the most diverse genus in North America, but this genus is not monophyletic and recent studies (Entwisle et al, 2009;Salomaki et al, 2014), along with those in the near future, will continue to establish new monophyletic genera for each section of Batrachospermum.…”