Systematics of green algae resembling Ulva conglobata, with a description of Ulva adhaerens sp. nov. (Ulvales, Ulvophyceae)

Figures & data

Fig. 1. ML tree of Ulva based on rbcL sequences. Bootstrap values are indicated at branches (ML/MP/NJ). A bootstrap value of 100% is represented by *, while that below 50% is represented by -. Samples sequenced in this study are shown in bold. ¹Blomster et al. (1999). ²Tan et al. (1999). ³Hayden et al. (2003). ⁴Shimada et al. (2003). ⁵Hiraoka et al. (2004a). ⁶Hayden & Waaland (2004). ⁷Loughnane et al. (2008). ⁸Heesch et al. (2009). ⁹Ichihara et al. (2009). ¹⁰O’Kelly et al. (2010). ¹¹Kraft et al. (2010). ¹²Mareš et al. (2011).¹³Horimoto et al. (2011). ¹⁴Ichihara et al. (2013).

Fig. 2. ML tree of Ulva based on ITS1 and ITS2 sequences. Bootstrap values are indicated at branches (ML/MP/NJ). A bootstrap value of 100% is represented by *, while that below 50% is represented by -. Samples sequenced in this study are shown in bold. ¹Coat et al. (1998). ²Blomster et al. (1999). ³Tan et al. (1999). ⁴Hayden et al. (2003). ⁵Shimada et al. (2003). ⁶Hiraoka et al. (2004a). ⁷Hayden & Waaland (2004). ⁸Kraft et al. (2010). ⁹Mareš et al. (2011).

Figs 3–7. Representative fresh materials of green algae resembling Ulva conglobata. Fig. 3. U. fasciata. Fig. 4. U. pertusa. Fig. 5. U. tanneri. Fig. 6. Ulva sp. 1. Fig. 7. Ulva sp. 2 (U. adhaerens; fresh condition of the specimen designated for the holotype). Scale bars: 1 cm.

Figs 8–12. Morphology of Ulva sp. 1. Fig. 8. Marginal denticulations. Fig. 9. Surface view of the middle region. Fig. 10. Section near the base. Fig. 11. Section of the middle region. Fig. 12. Section near the margin. Scale bars: 50 μm.

Table 1. Summary of morphological characters of the specimens resembling U. conglobata, and of the original material of U. conglobata.

Species	Marginal denticulation	Plastid orientation in surface view	Number of pyrenoids	Thallus thickness (μm)	Thickness ratio of layers	Length/width ratio of cells in section
U. fasciata	present	ranging from lateral to covering the cells	1–2	50–120	1.0–1.4	0.8–3.4
U. pertusa	absent	usually lateral	1–2, rarely 3	50–150	1.0–1.3	1.4–4.3
U. tanneri	absent	usually covering the cells	1–2	40–90	1.0–1.7	0.9–3.2
Ulva sp. 1	present	usually covering the cells	1–3	40–80	1.0–1.5	0.9–2.5
Ulva sp. 2 (= U. adhaerens)	absent	ranging from lateral to covering the cells	1–2	50–110	1.1–2.1(–2.7^†)	0.8–4.3(–5.0^†)
U. conglobata	present (this study)	usually covering the cells (Kjellman, 1897 tafl. 3. fig. 14; this study)	at least 1–2 (this study)	50– more than 75 (Kjellman, 1897)	n/a	1–2 (Kjellman, 1897)

^†at regions with the rhizoidal extensions.

Figs 13–19. Morphology of Ulva sp. 2 (U. adhaerens). Fig. 13. Close-up of thallus, showing rhizoids in a distromatic region (arrowheads). Fig. 14. Surface view of the middle region. Fig. 15. Section near the rhizoid. Fig. 16. Section of the middle region. Fig. 17. Section near the margin. Fig. 18. Section of the lobes adhering with the rhizoids. Fig. 19. Close-up of the rhizoid. Scale bars: Fig. 13, 1 mm; Figs 14–19, 50 μm.

Figs 20–31. Ulva sp. 1. Swarmers and cultures grown at 20°C with a 14: 10 h light/dark cycle. Fig. 20. Swarmers. Fig. 21. Settled swarmer. Figs 22–26. Germling. Fig. 22. 4 days. Fig. 23. 6 days. Fig. 24. 10 days. Fig. 25. Two weeks. Fig. 26. Five weeks. Fig. 27. Thalli, 52 days. Fig. 28. Margin with an overlapped portion (arrowhead), 58 days. Fig. 29. Section of the overlapped marginal portion of the thallus shown in Fig. 28. Figs 30, 31. Thallus with holes due to releasing swarmers, 44 and 45 days. Scale bars: Figs 20–24, 10 μm; Figs 25, 26, 30, 31, 5 mm; Fig. 27, 1 cm; Fig. 28, 1 mm; Fig. 29, 50 μm.

Figs 32–48. Ulva sp. 2 (U. adhaerens). Swarmers and cultures grown at 15°C with a 12: 12 h light/dark cycle. Fig. 32. Swarmers. Fig. 33. Settled swarmer. Figs 34–38. Germling. Fig. 34. 5 days. Fig. 35. 6 days. Fig. 36. 9 days. Fig. 37. 20 days. Fig. 38. Five weeks. Fig 39. Thalli, 53 days. Fig. 40. Thalli, 62 days. Fig. 41. Margin with an overlapped portion (arrowhead), 49 days. Fig. 42. Section of the overlapped marginal portion of the thallus shown in Fig. 41. Fig. 43. Thallus having released swarmers from marginal portion, 62 days. The adhered regions with rhizoids look paler; arrowheads. Fig. 44. Thalli adhering near the bases (arrowheads), between the different surfaces (upper) or the same surfaces (lower). Fig. 45. Basal portion with the basipetal rhizoidal extensions, 31 days. Fig. 46. Longitudinal section of the connecting region of the distromatic lobes, 47 days. Fig. 47. Close-up of Fig. 46, showing rhizoidal extensions. Fig. 48. Section of the adhering region of the thallus shown in Fig. 44 (upper), showing secondary rhizoids. Scale bars: Figs 32–36, 10 μm; Figs 37, 38, 5 mm; Figs 39, 40, 43, 44, 1cm; Fig. 41, 1 mm; Figs 42, 45, 47, 48, 50 μm; Fig. 46, 200 μm.

Figs 49–59. Morphology of the original material of U. conglobata. Fig. 49. Specimens of U. conglobata f. typica (1–7) and U. conglobata f. densa (8–11). Figs 50–52. Specimen no. 1. Fig. 50. Marginal denticulations. Fig. 51. Surface view. Fig. 52. Section. Figs 53, 54. Specimen no. 2. Fig. 53. Surface view. Fig. 54. Section. Figs 55, 56. Specimen no. 3. Fig. 55. Surface view. Fig. 56. Section. Figs 57–59. Specimen no. 4. Fig. 57. Marginal denticulation. Fig. 58. Surface view. Fig. 59. Section. Scale bars: Fig. 49, 1 cm; Figs 50–59, 50 μm.

Fig. 60. Ulva adhaerens. Photograph of the holotype herbarium specimen, TNS-AL 183435. Scale bar: 1 cm.

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