Electronic Flora of South Australia Species Fact Sheet
Phylum Chlorophyta – Order Ulotrichales – Family Ulotrichaceae
Thallus of microscopic filaments (Fig. 41D,E) to 200 (–250) µm high, unbranched, straight to slightly curved, each arising from a basal, gelatinous, conical attachment on Chaetomorpha linum or Pterocladia lucida, forming a tomentum on the host. Filaments increasing in diameter from the base upwards, 4–6 µm in diameter and L/B 4–6 in the upper cells, not or slightly incised at the cross walls; apical cells (Fig. 41D1) terete with a rounded end, becoming reproductive and soon lost, leaving wall remnants (often with bacteria) on the then apical cell; chloroplast single, occupying most of the cell but usually with invaginations at one or both ends, with a single (rarely two) prominent pyrenoid (Fig. 41D,E); wall about 1 µm thick, cross walls 1–2 µm thick.
Reproduction: Reproduction by zooids (Fig. 41D) formed in the slightly swollen terminal cell (occasionally in the subterminal cell), with a lateral pore; terminal cell lost soon after discharge of zooids.
Type from Kellidie Bay, Coffin Bay, S. Aust., on Chaetomorpha linum, lower eulittoral to upper sublittoral (Womersley, 22.viii.1967; ADU, A31827).
Distribution: As well as the type, also known from Strickland Bay, Rottnest I., W. Aust., on Pterocladia lucida, 1–2 m deep (Clarke & Engler, 5.ix.1979; ADU, A51119).
Taxonomic notes: Propagatio ope zoosporarum in cellula terminali paulum tumida (ranter in cellula subterminali) poro laterali formatorum; cellula terminalis exuta est cum zoosporae liberantur.
This species is provisionally referred to Uronema, but needs to be investigated from living material.
References: The Marine Benthic Flora of Southern Australia Part I
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
Illustration in Womersley Part I, 1984: FIG. 41D,E.
Figure 41 enlarge
Fig. 41. A–C. Ulothrix subflaccida. A. Upper part of filament (ADU, A 15399). B. Base of filament with elongate rhizoidal cell (ADU, A15399). C. Reproductive cells with zooids (ADU, A53176). D,E. Uronema marina. D. Filament with upper cell containing zooids (ADU, A51119). Dl. Terminal cell of young filament (ADU, A31827). E. Filament (ADU, A31827). F. Entocladia viridis. Thallus epiphytic on Cladophora rhizoclonioidea (ADU, A52871). G,H. Pilinia novae-zelandiae. G. Thallus on Sargassum, with terminal sporangia on short erect filaments (ADU, A32003). H. Part of a long erect filament with lateral sporangia (ADU, A50870).
State Herbarium of South Australia