Ulva sp.

4.2 Ulva sp. NC 2 - Ulva prolifera

This species was confirmed as Ulva prolifera by one of the North Carolina ITS2 haplotypes being an exact match to the epitype designated by Cui et al. (2018). While the ITS2 sequence of the epitype specimen was not made publicly available, Cui et al. (2018) reported that it was identical to the ITS2 region of GenBank accession AJ012276 View Materials , a sequence of the entire ITS region. The other three ITS2 haplotypes present in North Carolina specimens of U. prolifera were only 2 – 4 nucleotides different from that of the epitype. BLAST results for North Carolina specimens in this species include various specimens in the Ulva linza-procera-prolifera (LPP) complex clade (e.g., Cui et al. 2018; Kang et al. 2019). This species has a wide global distribution, including specimens from the Yellow Sea, Baltic Sea, Mediterranean, and East Pacific. Regionally, this species has been identified by DNA sequencing in the Northeast Pacific ( Kuba et al. 2022) and Northwest Atlantic ( Melton and Lopez-Bautista 2021).

Ulva ‘ linza ’ is the oldest of the three names applied to the specimens in the LPP clade, but no sequence data is available from its type specimen, and specimens morphologically identified as U. ‘ linza ’ are parts of multiple clades resolved by phylogenetic analyses including those in this study ( Figures 3 View Figure 3

and 4 View Figure 4 ). It is possible that when sequence data is generated from the type of U. linza it will show that U. prolifera is a heterotypic synonym of U. linza , which will then be the correct name to apply to this clade.

The bladed specimens of this species are of interest because U. prolifera traditionally has been described as having a tubular branched morphology ( Burrows 1991; Kapraun 1969, 1984; Schneider and Searles 1991), but our results mirror that of Kuba et al. (2022), who found that specimens of U. prolifera from the San Juan Islands, Washington, USA had a ‘ linza-morphotype ’ of blades that tapered and became tubes near and through the stipe. When attempts to identify the North Carolina specimens of this species strictly based on morphology are made using Kapraun (1984), the following names can be applied: U. ‘ linza ’, U. ‘ flexuosa subsp. flexuosa ’, U. ‘ flexuosa subsp. paradoxa ’, U. prolifera , U. ‘ compressa ’, Ulva fasciata , and Ulva rotundata .