Electronic Flora of South Australia Species Fact Sheet
Phylum Phaeophyta – Order Sporochnales
Thallus (Fig. 99A) light to medium brown, 6–16 cm long, with one to a few percurrent axes with irregular, long and short, fastigiate laterals, all densely tomentose (Fig. 100A,B), attached by a rhizoidal holdfast 2–8 mm across and 1–5 mm long; epilithic. Growth apical, with a convex branch meristem (Fig. 100C) surmounted by a tuft of coarse, trichothallic, assimilatory filaments 2–5 mm long, each with a meristem 3–7 cells above their base, 30–50 µm in diameter above with cells L/B (1.5–) 2–3. Fronds terete, 0.4–0.8 mm in diameter below, tapering to 200–300 µm in diameter near the apices, with irregularly placed and developed short laterals with apical tufts, and also with numerous scattered, simple and single, trichothallic assimilatory filaments (Fig. 100A,B) 1–2 mm and 30–40 cells long, 30–50 µm in diameter with cells L/B 2–3 above, arising adventitiously from the cortical cells and becoming determinate as the basal meristem ceases activity, tapering near their apex, with the basal cell of the filament usually dividing in the direction of the filament, and giving the branches a tomentose appearance. Structure haplostichous and pseudoparenchymatous, with a medulla of elongate cells narrower nearer the cortex, and with the cortical layer increasing in width (Fig. 100D) by periclinal divisions; outer cortical cells elongate, (8–) 10–16 (–20) µm across and L/B 2–3 (–4), with numerous discoid phaeoplasts (Fig. 100D) per cell in the outer cortex and assimilatory filaments.
Type from Investigator Strait, S. Aust., 31 m deep, 35°37'S, 137°08'E (Watson, 25.i.1971; holotype in ADU, A38180).
Distribution: Only known from the type and from Waldegrave I., Eyre Pen., S. Aust., 22 m deep (Shepherd, 23.x.1970; ADU, A37374).
Taxonomic notes: S. tomentosum is a deep water species known from only two sterile collections.
References: The Marine Benthic Flora of Southern Australia Part II
Womersley, H.B.S. (14 December, 1987)
The Marine Benthic Flora of Southern Australia
©Board of the Botanic Gardens and State Herbarium, Government of South Australia
Illustrations in Womersley Part II, 1997: FIGS 99A, 100.
Figure 99 enlarge
Fig. 99. A. Sporochnema tomentosum (ADU, A38180, holotype). B. Sporochnus stylosus (ADU, A41446). C. Sporochnus apodus (ADU, A32938). D. Sporochnus comosus (ADU, A30831).
Figure 100 enlarge
Fig. 100. Sporochnema tomernosum (ADU, A38180, type). A. Branch apex with apical tuft and scattered adventitious filaments. B. Part of branch with four juvenile laterals and scattered adventitious filaments. C. Longitudinal section of branch apex showing branch meristem, trichothallic assimilatory filaments with meristematic zones, and adventitious filaments also with meristematic cells. D. Transverse section of branch with central medulla, cortex increasing by periclinal (and some anticlinal) divisions, and bases of two adventitious filaments.
State Herbarium of South Australia