Electronic Flora of South Australia Species Fact Sheet
Phylum Chlorophyta – Order Ulvales – Family Ulvaceae
Letterstedtia petiolata J. Agardh 1883: 176. Chapman 1956: 384, fig. 27, pl. 24 in part. De Toni 1889: 139.
Ulva petiolata (J. Agardh) Womersley 1956: 354.
Thallus (Fig. 46A) medium green, epiphytic (on Amphibolis?) or epilithic, 5–10 cm high, divided into numerous fronds from just above a relatively massive holdfast 2–5 mm across; fronds with narrow (1–2 (–3) mm broad) and long (2–4 cm) lower parts, simple or branched, with expanded, often lobed, spathulate terminal parts 1–2 (–3) cm long and 0.5- l(–1.5) cm broad, intact margin entire, surface smooth. Cells in surface view of upper and mid parts (Fig. 47A) in rows in both directions (more irregular below), isodiametric to elongate, 10–20 across, each with 1–2 pyrenoids. Thallus 70–80 µm thick in upper spathulate parts (Fig. 47A) with cells in transection (Fig. 47A) L/B 1–1.5, rounded to angular, 15–20 high; "petiolar" part (110–) 150–300 µm thick in upper parts (Fig. 47C) with cells 10–20 µm across in surface view, L/B 2–3 and 30–50 µm high in transection; 300–500 µm thick near base, with an internal layer of rhizoids usually 200–350 µm thick below and which develops just below the spathulate terminal parts.
Reproduction: Reproduction unknown.
Lectotype from Port Phillip, Vic.; in Herb. Agardh, LD, 14551.
Selected specimens: Point Sinclair, S. Aust., reef surface (low eulittoral) (Womersley, 26.i.1951 and 8.ii.1954; ADU, A15224 and A19623 respectively). Ward I., Investigator Group, S. Aust., 25–30 m deep (Shepherd, 31.iii.1982; ADU, A53126).
Distribution: The type locality, and from Ward I. and Point Sinclair in S. Aust., and Port Jackson and Lake Illawarra in N.S.W. Papenfuss (1960, p. 309) examined specimens from Fremantle, W. Aust. and New Zealand which he referred to this species. Chapman recorded it from throughout New Zealand.
Taxonomic notes: The type sheet in LD bears 4 specimens of which the two lower ones agree well with J. Agardh's type description. The lower left specimen is designated as lectotype and the lower right (14550) is probably from the same plant. The large upper specimen (14549) is probably a different species (possibly U. rigida or U. australis) of different form, and is the only specimen which appears to be attached to the stem of Amphibolis.
U. spathulata appears to be distinctive in form, with the elongate petiolar part resulting from loss of the sides of the spathulate terminal part as this develops. However, some plants of U. australis tend to this form and the differences need further assessment. It is desirable that the development of the adult form should be followed in culture and the field.
Chapman's specimens from New Zealand need re-investigation.
AGARDH, J.G. (1883). Till algernes systematik. VI. Ulvaceae. Acta Univ. lund. 19(2), 1–182, Plates 1–4.
CHAPMAN, V.J. (1956). The marine algae of New Zealand. Part I. Myxophyceae and Chlorophyceae. J. Linn. Soc. Bot. 55 (360), 333–501, Plates 24–50.
DE TONI, G.B. (1889–1924). Sylloge Algarum omnium hucusque Cognitarium. Vols 1–6. (Padua.)
PAPENFUSS, G.F. (1960). On the genera of the Ulvales and the status of the order. J. Linn. Soc. Bot. 56, 303–318, Plates 1–6.
WOMERSLEY, H.B.S. (1956). A critical survey of the marine algae of southern Australia. I. Chlorophyta. Aust. J. mar. freshw. Res. 7, 343–383.
The Marine Benthic Flora of Southern Australia Part I complete list of references.
Womersley, H.B.S. (31 May, 1984)
The Marine Benthic Flora of Southern Australia
©Board of the Botanic Gardens and State Herbarium, Government of South Australia
Illustrations in Womersley Part I, 1984: FIGS 46A, 47 A–C.
Figure 46 enlarge
Fig. 46. A. Ulva spathulata (ADU, A15224). B. Ulva fasciata (ADU, A22338). C. Ulva taineata (ADU, A24416).
Figure 47 enlarge
Fig. 47. A–C. Ulva spathulata (ADU, A15224). A. Surface and cross section views of upper spathulate part. B. Surface view of petiolar region. C. Cross section of petiolar region. D–G. Ulva fasciata (ADU, A22437). D. Surface view of young part near tip. E. Cross section of mid part of thallus. F. Surface view of thallus just above rhizoidal region. G. Cross section of thallus in rhizoidal region. H–M. Ulva taeniata (ADU, A24416). H. Margin with spines. I. Cross section of thallus near margin. J. Surface of mid part of upper thallus. K. Cross section view in central part of upper thallus. L. Surface view of rhizoidal region. M. Cross section view of rhizoidal region.
State Herbarium of South Australia