taxonID	type	description	language	source
03E087B2FFF7FFAE15E3FED3FEC0FE57.taxon	materials_examined	Material examined: — SINGAPORE. Changi: Changi Beach Carpark 1, 16 July 2022, NYF 220701, NYF 220702, NYF 220703, NYF 220704, NYF 220705, NYF 220707 (SING); Changi: Changi Point Ferry Terminal, 16 July 2022, N YF 220708, NYF 220711, NYF 220712, NYF 220713 (SING); Pulau Ubin: Chek Jawa, 17 July 2022, NYF 220724, NYF 220726, NYF 220731, NYF 220732 (SING); Pulau Ubin: Sensory Trail, 17 July 2022, NYF 220735 (SING); East Coast: East Coast Park Carpark G, 18 July 2022, NYF 220738, NYF 220739, NYF 220740, NYF 220741, NYF 220743, NYF 220745, NYF 220746, NYF 220755 (SING); Changi: Changi Beach Carpark 7, 12 August 2022, NYF 220811, NYF 220812, NYF 220813, NYF 220814, NYF 220815, NYF 220816, NYF 220821 (SING); Pulau Hantu, 14 August 2022, NYF 220829, NYF 220834, NYF 220840 (SING); Sentosa: Tanjong Rimau, 23 December 2022, NYF 221209 (SING); Changi: Changi Beach Carpark 6, 24 December 2022, NYF 221211 (SING).	en	Ng, Yu Fei, Huang, Danwei (2024): Species diversity and phylogeny of the green macroalga Ulva (Ulvophyceae, Chlorophyta) in Singapore. Phytotaxa 662 (1): 67-79, DOI: 10.11646/phytotaxa.662.1.5, URL: https://doi.org/10.11646/phytotaxa.662.1.5
03E087B2FFF7FFAE15E3FED3FEC0FE57.taxon	description	Description: — U. ohnoi comprises five morphotypes: reticulate, expanded, expanded with some reticulations, lobe-shaped, and filamentous thalli. The reticulate morphotype has reticulated ribbon-shaped thallus without perforations, 5 – 50 cm in length and 0.2 – 2.5 cm in width (Figs. 3 A, 3 F). The morphotype with expanded thalli shows foliose, irregularly expanded thallus with no reticulations, but sometimes with perforations and / or tears, 5 – 30 cm in length and 5 – 30 cm in width (Fig. 3 C). The morphotype with expanded thalli possessing some reticulations shows foliose thalli expanding irregularly at the base along with some reticulations and perforations; sometimes with ribbonlike structures with reticulations towards the tips, 8 – 20 cm in length and 20 – 50 cm in width (Fig. 3 G). The small lobe-shaped morphotype has foliose thallus forming small tufts, without reticulations or perforations, 0.5 – 1.5 cm in length and 1.2 – 3 cm in width (Fig. 3 H). The filamentous morphotype has long, filamentous, non-tubular thallus with wrinkles and some reticulations, sometimes with secondary branches, 17 – 53.5 cm in length and 0.3 – 0.9 cm in width (Figs. 3 D – E). Surface cells are irregular, polygonal, or rectangular, 7 – 19 μm in length, 7 – 12 μm in width (n = 20). Chloroplast with 1 to 2 pyrenoids (Fig. 3 I). Various microscopic teeth present at margin (Figs. 3 J – M), but lacking teeth in filamentous morphotype (Fig. 3 N). The transverse width of the thallus is 58 – 59 μm (n = 5) and transverse cell shape is rectangular, 21 – 24 μm in length, 13 – 18 μm in width (n = 6), and contains parietal chloroplast with pyrenoids (Fig. 3 O).	en	Ng, Yu Fei, Huang, Danwei (2024): Species diversity and phylogeny of the green macroalga Ulva (Ulvophyceae, Chlorophyta) in Singapore. Phytotaxa 662 (1): 67-79, DOI: 10.11646/phytotaxa.662.1.5, URL: https://doi.org/10.11646/phytotaxa.662.1.5
03E087B2FFF7FFAE15E3FED3FEC0FE57.taxon	distribution	Distribution in Singapore: — Chek Jawa, Sensory Trail, East Coast Park Carpark G, Changi Point Ferry Terminal, Changi Beach Carpark 1, 6, and 7.	en	Ng, Yu Fei, Huang, Danwei (2024): Species diversity and phylogeny of the green macroalga Ulva (Ulvophyceae, Chlorophyta) in Singapore. Phytotaxa 662 (1): 67-79, DOI: 10.11646/phytotaxa.662.1.5, URL: https://doi.org/10.11646/phytotaxa.662.1.5
03E087B2FFF7FFAE15E3FED3FEC0FE57.taxon	biology_ecology	Habitat: — Mostly found in seagrass meadows and occasionally on sandy beaches. Morphotypes reticulate, expanded and expanded with some reticulates are either free-floating or attached to sandy substrate (Fig. 3 A). Lobe-shaped thallus morphotype found attached to hard substrates like rocks or logs (Fig. 3 B) while filamentous thallus morphotype attaches to sandy substrate (Fig. 3 D).	en	Ng, Yu Fei, Huang, Danwei (2024): Species diversity and phylogeny of the green macroalga Ulva (Ulvophyceae, Chlorophyta) in Singapore. Phytotaxa 662 (1): 67-79, DOI: 10.11646/phytotaxa.662.1.5, URL: https://doi.org/10.11646/phytotaxa.662.1.5
03E087B2FFF7FFAE15E3FED3FEC0FE57.taxon	discussion	Remarks: — New species record for Singapore. In the tuf A tree, Ulva ohnoi DNA sequences from Singapore formed a well-supported clade with five other species: Ulva pseudo-ohnoi, U. lactuca, U. spinulosa, U. reticulata and U. taeniata (ML bootstrap / BI posterior probability: 97 / 1) (Fig. 2). There was also strong support for the same clade in the ITS and rbc L trees (Supplementary Files 3, 4). Based on morphological data, we excluded U. taeniata, U. reticulata, and U. spinulosa from our sampled collections. Ulva taeniata thalli have wrinkles (Setchell & Gaedner 1920), U. spinulosa has either smooth or heavily denticulate margins, and U. reticulata has smooth microscopic margins (Tran et al. 2023). These morphological characteristics are not found in the Ulva samples collected in this study. Ulva ohnoi cell sizes measured at surface view and transverse section in our specimens were within the range reported for the U. ohnoi holotype (Hiraoka et al. 2004). U. ohnoi intraspecific DNA sequence divergences observed in this study were 0.0 – 0.79 % and 0.0 – 0.36 % for tuf A and rbc L, respectively. When comparing our sequences with that of the U. ohnoi holotype (Hiraoka et al. 2004), the genetic distances were 0.0 – 0.53 % based on rbc L, supporting conspecificity. There appear to be no phylogenetic patterns associated with the five U. ohnoi thallus morphotypes, indicating that all non-tubular Ulva samples collected in this study are of the same species. Three of five U. ohnoi morphotypes reported here have similar gross morphology to U. ohnoi reported in other studies (Hiraoka et al. 2004, O’Kelly et al. 2010, Tran et al. 2023). Two new morphotypes have been uncovered, one with lobe-shaped thallus that attaches to hard objects and the other with filamentous thallus found on sandy substrate. However, the lobe-shaped thallus is smaller in length and width when compared to other morphotypes suggesting that these could be young U. ohnoi. There are gross and microscopic variations within the U. ohnoi species (Hiraoko et al. 2004, O’Kelly et al. 2010, Lee et al. 2019) that may be driven by various environmental factors. For example, pollution from wastewater discharge and surface runoffs could affect Ulva morphology as Zeroual et al. (2020) reported that U. intestinalis and U. rigida thickened their cell wall and had a reduction of thalli size in the presence of heavy metals. Such environmental variations could result in morphological variation among U. ohnoi specimens. Hiraoka et al. (2004) recommended distinguishing U. ohnoi from other Ulva species by examining the life history and morphology such as the number of perforations in the middle of the thallus. As U. ohnoi has not been recorded in Singapore until this study, the newly discovered morphotypes in this study expand upon the morphological range described for the species thus far (Hiraoka et al. 2004). We note that the filamentous morphotype is represented by a single specimen (NYF 221211), so its identity requires further validation. Ulva ohnoi has similar gross morphology to some Ulva species which were previously recorded in Singapore, including U. beytensis, U. reticulata, U. lactuca, U. australis, and U. rigida.	en	Ng, Yu Fei, Huang, Danwei (2024): Species diversity and phylogeny of the green macroalga Ulva (Ulvophyceae, Chlorophyta) in Singapore. Phytotaxa 662 (1): 67-79, DOI: 10.11646/phytotaxa.662.1.5, URL: https://doi.org/10.11646/phytotaxa.662.1.5
03E087B2FFF6FFAE15E3FC0DFAAEFB5A.taxon	materials_examined	Material examined: — SINGAPORE. Pulau Ubin: Chek Jawa, 17 July 2022, NYF 220716, NYF 220717, NYF 220718, NYF 220719, NYF 229720, NYF 220722, NYF 220725 (SING); East Coast: East Coast Park Carpark G, 18 July 2022, NYF 220742 (SING); Sentosa: Tanjong Rimau, 23 August 2022, NYF 220805, NYF 220807 (SING); Pulau Hantu, 14 August 2022, NYF 220832 (SING).	en	Ng, Yu Fei, Huang, Danwei (2024): Species diversity and phylogeny of the green macroalga Ulva (Ulvophyceae, Chlorophyta) in Singapore. Phytotaxa 662 (1): 67-79, DOI: 10.11646/phytotaxa.662.1.5, URL: https://doi.org/10.11646/phytotaxa.662.1.5
03E087B2FFF6FFAE15E3FC0DFAAEFB5A.taxon	description	Description: — Thallus in the shape of tubular filaments, smooth or wrinkled (Figs. 4 C – F, 4 H). Thallus width decreases towards the base (Fig. 4 G). Second-order branching restricted to the thallus base. Some thalli have one to multiple transverse constrictions (Fig. 4 I). Thallus filaments are 0.6 – 19.5 cm in length; apex / median of filament are 3 – 100 mm in width (n = 6); base of filament are 60 – 472 μm in width (n = 6). Surface cells are mostly cuboidal, polygonal, or irregular. Cells in surface view are 6 – 15 μm in length and 5 – 11 μm in width (n = 20). In surface view, chloroplast covers the periphery of cell with 1 to 3 pyrenoids (Fig. 4 J). In transverse sections, thallus 28 – 33 μm in width (n = 5), cell shape is rectangular, 20 – 23 μm in length and 13 – 17 μm in width (n = 6), with parietal chloroplast (Fig. 4 L).	en	Ng, Yu Fei, Huang, Danwei (2024): Species diversity and phylogeny of the green macroalga Ulva (Ulvophyceae, Chlorophyta) in Singapore. Phytotaxa 662 (1): 67-79, DOI: 10.11646/phytotaxa.662.1.5, URL: https://doi.org/10.11646/phytotaxa.662.1.5
03E087B2FFF6FFAE15E3FC0DFAAEFB5A.taxon	distribution	Distribution in Singapore: — Chek Jawa, East Coast Park Carpark G, Tanjong Rimau, and Pulau Hantu.	en	Ng, Yu Fei, Huang, Danwei (2024): Species diversity and phylogeny of the green macroalga Ulva (Ulvophyceae, Chlorophyta) in Singapore. Phytotaxa 662 (1): 67-79, DOI: 10.11646/phytotaxa.662.1.5, URL: https://doi.org/10.11646/phytotaxa.662.1.5
03E087B2FFF6FFAE15E3FC0DFAAEFB5A.taxon	biology_ecology	Habitat: — Anchors onto sand, in between pebbles, or on rocks (Figs. 4 A – B).	en	Ng, Yu Fei, Huang, Danwei (2024): Species diversity and phylogeny of the green macroalga Ulva (Ulvophyceae, Chlorophyta) in Singapore. Phytotaxa 662 (1): 67-79, DOI: 10.11646/phytotaxa.662.1.5, URL: https://doi.org/10.11646/phytotaxa.662.1.5
03E087B2FFF6FFAE15E3FC0DFAAEFB5A.taxon	discussion	Remarks: — New species record for Singapore. Ulva meridionalis has similar gross morphology to the previously recorded U. compressa, U. flexuosa and U. intestinalis due to its filamentous thalli. There was generally strong support for the Ulva meridionalis clade in the tuf A, ITS and rbc L trees (Fig. 2; Supplementary Files 3, 4). The Vietnamese Ulva spp. 3 and 4 (Tran et al. 2023) are closely related to U. meridionalis. However, they can be distinguished from U. meridionalis because there are no pyrenoids in Ulva sp. 3 and 3 – 6 pyrenoids in Ulva sp. 4 (Tran et al. 2023).	en	Ng, Yu Fei, Huang, Danwei (2024): Species diversity and phylogeny of the green macroalga Ulva (Ulvophyceae, Chlorophyta) in Singapore. Phytotaxa 662 (1): 67-79, DOI: 10.11646/phytotaxa.662.1.5, URL: https://doi.org/10.11646/phytotaxa.662.1.5
03E087B2FFF6FFAE15E3FB39FEF5F86A.taxon	materials_examined	Material examined: — SINGAPORE. Changi: Changi Beach Carpark 1, 16 July 2022, NYF 220710 (SING); East Coast: East Coast Park Carpark G, 18 July 2022, NYF 220747, NYF 220754 (SING).	en	Ng, Yu Fei, Huang, Danwei (2024): Species diversity and phylogeny of the green macroalga Ulva (Ulvophyceae, Chlorophyta) in Singapore. Phytotaxa 662 (1): 67-79, DOI: 10.11646/phytotaxa.662.1.5, URL: https://doi.org/10.11646/phytotaxa.662.1.5
03E087B2FFF6FFAE15E3FB39FEF5F86A.taxon	description	Description: — Thallus monostromatic, in the shape of tubular filaments, smooth with the width decreasing towards the base (Fig. 5 B). Thallus base with second-order branching (Fig. 5 C). Filaments 1 – 14 mm in length, filament apices 0.2 – 0.9 mm in width (n = 6), filament bases 8 – 72 μm in width (n = 6). Surface cells are rectangular or irregularly shaped, 7 – 19 μm in length and 4 – 11 μm in width (n = 20) (Figs. 5 D – E). Chloroplast occupies most of the cell periphery, with 0 – 2 pyrenoids. In transverse section, thallus 16 – 18 μm in width (n = 5), cell shape is rectangular, 12 – 14 μm in length and 8 – 11 μm in width (n = 6), with parietal chloroplasts (Fig. 5 F).	en	Ng, Yu Fei, Huang, Danwei (2024): Species diversity and phylogeny of the green macroalga Ulva (Ulvophyceae, Chlorophyta) in Singapore. Phytotaxa 662 (1): 67-79, DOI: 10.11646/phytotaxa.662.1.5, URL: https://doi.org/10.11646/phytotaxa.662.1.5
03E087B2FFF6FFAE15E3FB39FEF5F86A.taxon	distribution	Distribution in Singapore: Changi Point Ferry Terminal and East Coast Park Carpark G.	en	Ng, Yu Fei, Huang, Danwei (2024): Species diversity and phylogeny of the green macroalga Ulva (Ulvophyceae, Chlorophyta) in Singapore. Phytotaxa 662 (1): 67-79, DOI: 10.11646/phytotaxa.662.1.5, URL: https://doi.org/10.11646/phytotaxa.662.1.5
03E087B2FFF6FFAE15E3FB39FEF5F86A.taxon	biology_ecology	Habitat: — Attached to upper intertidal rocks (Fig. 5 A).	en	Ng, Yu Fei, Huang, Danwei (2024): Species diversity and phylogeny of the green macroalga Ulva (Ulvophyceae, Chlorophyta) in Singapore. Phytotaxa 662 (1): 67-79, DOI: 10.11646/phytotaxa.662.1.5, URL: https://doi.org/10.11646/phytotaxa.662.1.5
03E087B2FFF6FFAE15E3FB39FEF5F86A.taxon	discussion	Remarks: — New species record for Singapore. Because U. tepida is smaller than most other Ulva species, it is likely that this species had been missed during previous surveys and collections. Ulva tepida has similar gross morphology to the previously recorded U. compressa, U. flexuosa and U. intestinalis due to its filamentous thalli. The tuf A phylogeny showed moderate ML and full BI support for the U. tepida / Ulva sp. 5 (Vietnam) clade (85 / 1) (Fig. 2), while the U. tepida clade was weakly supported in the ITS tree (67 / 0.67) (Supplementary File 3). There was no phylogenetic support for the U. tepida clade in the rbc L tree (Supplementary File 4). Even though Ulva sp. 5 from Vietnam is nested within the Ulva tepida clade, the former is distinguishable from U. tepida as it lacks pyrenoids (Tran et al. 2023).	en	Ng, Yu Fei, Huang, Danwei (2024): Species diversity and phylogeny of the green macroalga Ulva (Ulvophyceae, Chlorophyta) in Singapore. Phytotaxa 662 (1): 67-79, DOI: 10.11646/phytotaxa.662.1.5, URL: https://doi.org/10.11646/phytotaxa.662.1.5
