The unheeded existence of the tubular greens: molecular analyses reveal the distribution of a new Ulva species (Ulvophyceae, Chlorophyta), Ulva capillata sp. nov. in the Atlantic-Baltic Sea transect

The ubiquitous and species rich genusUlvacomprises entities of green macroalgae with variable morphologies.Ulvaspecies are important from ecological and economic perspectives, but their identification is often problematic. Current knowledge onUlvadiversity has focused mainly on foliose individuals of temperate regions, but genetic and morphological data on tubular species are often insufficient and the species richness is ambiguous due to the lack of molecularly identified type vouchers. Together with a previous study, our study demonstrates that due to the crypticity of tubular entities of the genusUlvapresent in the Atlantic-Baltic Sea transect, certain species remained undetected until recently whereas molecular evidence of other historically identified species is missing. An entity which appears to be a relatively frequent species in the Atlantic-Baltic Sea transect and which was probably mis-identified with other species in the past is here described asUlva capillatasp. nov.. The description is based on molecular identification usingtufA andrbcLsequences, and by comparing the species´ phylogenetic relationships, distribution and range margins in the Atlantic-Baltic Sea transect, as well as on morpho-anatomical characters, and early ontogenetic development. By comparisons with closely related and potentially morphologically overlapping species concepts we were able to identify the uniqueness ofU. capillata. Therefore, the description ofU. capillataas a new species within the genusUlvais supported by a combination of molecular, morphological, and ontogentic evidence which confirm their uniqueness in comparison to other species concepts. Furthermore, our results strongly emphasize the importance and necessity to molecularly investigate especially tubular historic type vouchers within the genusUlvato facilitate a clear species identification to omit continuing with taxonomic confusion and ongoing misapplication of names of e.g. cryptic species concepts within this important green algal genus.