Electronic Flora of South Australia Species Fact Sheet

Myriodesma tuberosum J. Agardh 1894b: 93.

Phylum Phaeophyta – Order Fucales – Family Cystoseiraceae

Selected citations: Nizamuddin & Womersley 1967: 378, pls 71B, 73 fig. 6. Yabu 1972: 2, pl. I figs 1,2,11,111.

Thallus (Fig. 153B) light to medium brown, 10–25 cm long, with usually two complanately branched fronds from the branched stipe. Holdfast discoid-conical, 4–8 mm across; epilithic. Stipe 2–10 cm long, with di- (or tri-)chotomies at intervals of 1–3 cm, each 1.5–2 (–3) mm in diameter. Fronds 10–15 cm long, irregularly pinnate, with alternate branches 1–4 cm apart, 6–12 mm broad in mid parts, 3–6 mm broad in laterals, upper parts prominently serrate (Fig. 156C), less so below with slightly undulate margins, laterals not or slightly basally constricted; midrib present throughout, prominent below. Structure of fronds 300–500 µm and 8–10 cells thick, with a slight central medulla and an inactive meristoderm.

Reproduction: Thalli monoecious. Conceptacles scattered over terminal branches, prominent, bisexual, with a slight basal tuft of phaeophycean hairs; oogonia sessile, ovoid, 80–110 µm long and 35–50 µm in diameter; antheridia sessile or on branched paraphyses, elongate-ovoid, 16–24 µm long and 8–12 µm in diameter.

Type from Eucla, W. Aust.; holotype in Herb. Agardh, LD, 2411; possible isotype in MEL, 18847.

Selected specimens: Israelite Bay, W. Aust., 6 m deep (Kirkman, 8.xii.1981; ADU, A56679). Off Eyre, W. Aust., 33°01'S, 126°29'E (Yabu, 23.xii.1965; ADU, A30635). Investigator Str.,

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

Distribution: From Israelite Bay, W. Aust. to Port Elliot, S. Aust.

Taxonomic notes: M. tuberosum is a deep water species, apparently rare, characterised by its dimensions, midrib reaching the apices, serrate upper parts, and scattered conceptacles.

References:

AGARDH, J.G. (1894b). Analecta Algologica. Cont. II. Ada Univ. lund. 30, 1–98, Plate 1.

NIZAMUDDIN, M. & WOMERSLEY, H.B.S. (1967) The morphology and taxonomy of Myriodesma (Fucales). Nova Hedwigia 12, 373–383, Plates 69–73.

YABU, H. (1972). Cytological observations on two species of Myriodesma (Fucales: Phaeophyta). Bull. Fac. Fish. Hokkaido Univ. 23, 1–7, Plates 1–6.

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 153B, 156C.

Figure 153   enlarge

Fig. 153. A. Myriodesma harveyanum (ADU, A10576, holotype). B. Myriodesma tuberosum (ADU, A25427).

Figure 156   enlarge

Fig. 156. A,B. Myriodesma harveyanum (A, ADU, A57375; B, ADU, A3311). A. Upper branches with conceptacles. B. Transverse section of thallus with bisexual conceptacles each with a central columella bearing phaeophycean hairs. C. Myriodesma tuberosum (ADU, A51679). Upper branches with conceptacles. D,E. Myriodesma quercifolium (D, ADU, A33718; E, ADU, A13435). D. Mid and apical parts of a branch. E. Transverse section of thallus with a bisexual conceptacle and central group of phaeophycean hairs. F. Myriodesma calophyllum. Mid and apical parts of a branch with conceptacles.

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