Phylogenetic analysis of ITS2 sequences suggests the taxonomic re‐structuring of D unaliella viridis( C hlorophyceae, D unaliellales)

Summary We analyzed theITS2primary and secondary structure (includingCompensatoryBaseChanges (CBCs)) of 17 newDunaliellastrains (11D. viridis, twoD. tertiolecta, and fourDunaliellasp.), and compared these with otherDunaliellasequences available from theITS2database to circumscribe their taxonomic position. TheITS2primary and secondary structure analysis positioned the majority ofD. viridisstrains in four main clades, showing thatD. viridisis polyphyletic. The detection of at least oneCBCamong these clades strongly suggests that they could correspond to different biological species. Unexpectedly, whileD. viridisvar.euchlora(CCAP19/21) was positioned within the subgenusDunaliella,D. viridisvar.palmelloides(CCAP11/34) was positioned clearly outside this subgenus, suggesting that this taxon may not be properly placed inDunaliella. Furthermore, the detection of at least three compensatory base changes (CBCs) betweenD. viridisvar.palmelloides(CCAP11/34) and the other strains analyzed, confirm that this strain is a different species. For these reasons we propose re‐namingD. viridisvar.palmelloides(CCAP11/34) toincertae sedis, andD. viridisvar.euchlora(CCAP19/21) toDunaliellasp. Therefore, theITS2primary and secondary structure data suggest a taxonomic re‐structuring ofD. viridis.