Electronic Flora of South Australia Species Fact Sheet

Sporochnus apodus Harvey 1859a: pl. 92; 1859b: 287.

Phylum Phaeophyta – Order Sporochnales

Selected citations: Womersley 1967: 239.

Thallus (Fig. 99C) medium to dark brown, (5–) 20–50 cm long, with one (to a few) axes bearing radially long primary laterals 1–10 (–20) mm apart, with numerous short, determinate, radial branchlets (Fig. 101C), each with an apical tuft of assimilatory filaments; attachment by a rhizoidal holdfast 1–3 mm across and long; epilithic. Growth apical, with a convex branch meristem surmounted by the tuft of slender, trichothallic filaments 1.5–5 (–8) mm long, each with a meristem 3–6 cells above their base, (12–) 15–25 µm in diameter above with cells L/B (2–) 4–6 (–8). Fronds (Fig. 101C) slender, terete, 0.5–1.5 mm in diameter in lower axes, decreasing to 200–300 µm in diameter near apices, with the short determinate branchlets 0.2–1 mm apart, (0.3–) 0.5–2 (–4) mm long and 200–300 µm in diameter when sterile (soon becoming fertile). Structure haplostichous and pseudoparenchymatous, with a medulla of elongate cells and a single-layered smooth-surfaced cortex of cells (5–) 7–12 µm across and L/B (1–) 2–3, with numerous discoid phaeoplasts.

Reproduction: Sporangial receptacles (Fig. 101C,D) slightly clavate to ovoid, covering the whole of the short branchlets with sporangial paraphyses extending slightly from the base of the branchlet, 0.3–2 (–4) mm long and 200–500 µm in diameter. Paraphyses (Fig. 101E) clavate, (80–) 100–150 µm and 4–6 cells long, simple or once branched, with the terminal cell larger, pyriform to subspherical, (10–) 12–18 µm in diameter, bearing lateral, clavate, unilocular sporangia 20–30 µ long and 8–10 µ in diameter.

Gametophyte unknown.

Type from George Town, Tas.; in Herb. Harvey, TCD.

Selected specimens: Venus Bay, S. Aust., drift (Womersley, 12.ii.1954; ADU, A19487). Investigator Str., S. Aust., 31 m deep, 35°21'S, 137°17'E (Watson, 24.i.1971; ADU, A38389). Grange, S. Aust., 20 m deep on tyre reef (Branden, 7.iii.1985; ADU, A56424). Marino, S. Aust., drift ( Womersley, 22.ix.1945; ADU, A16396). Muston, American R. inlet, Kangaroo I., S. Aust., 2–3 m deep (Womersley, 21.xi.1968; ADU, A32938). Sorrento, Vic., 11 m deep in bay ( Womersley, 7.iv.1959; ADU, A22769). Pittwater, S.E. Tas., dredged (Olsen, 15.xi.1950; ADU, A16077).

Distribution map based
on current data relating to
specimens held in the
State Herbarium of SA

Distribution: From Venus Bay, S. Aust. to Sorrento, Vic. and around Tasmania.

Taxonomic notes: S. apodus is distinguished by the short, completely fertile, lateral sporangial receptacles, but is similar to S. comosus in habit.

References:

HARVEY, W.H. (1859a). Phycologia Australica. Vol. 2, Plates 61–120. (Reeve: London.)

HARVEY, W.H. (1859b). Algae. In Hooker, J.D., The Botany of the Antarctic Voyage. Part III. Flora Tasmaniae. Vol. 2, pp. 282–343, Plates 185–196.

WOMERSLEY, H.B.S. (1967). A critical survey of the marine algae of southern Australia. II. Phaeophyta. Aust. J. Bot. 15, 189–270.

The Marine Benthic Flora of Southern Australia Part II complete list of references.

Author: H.B.S. Womersley

Publication: Womersley, H.B.S. (14 December, 1987)
The Marine Benthic Flora of Southern Australia
Part II
©Board of the Botanic Gardens and State Herbarium, Government of South Australia

Illustrations in Womersley Part II, 1997: FIGS 99C, 101 C–E.

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 101   enlarge

Fig. 101. A,B. Sporochnus stylosus (ADU, A56265). A. Branch with fertile laterals with sterile regions between sporangial receptacles and apical tufts. B. Paraphyses with unilocular sporangia. C–E. Sporochnus apodus (ADU, A16396). C. A long lateral branch with short, completely fertile, branchlets. D. Sporangial receptacles extending from assimilatory tufts to parent branch. E. Paraphyses with unilocular sporangia. F–H. Sporochnus comosus, typical form (ADU, A16397). F. Branches with shortly-pedicellate sporangial receptacles. G. Sporangial receptacles with apical tufts and short, sterile pedicels. H. Paraphyses and unilocular sporangia. I,J. Sporochnus comosus, with elongate sporangial receptacles (ADU, A42542). I. Branches with shortly-pedicellate sporangial receptacles. J. Sporangial receptacles with apical tufts and short, sterile, pedicels.

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