Electronic Flora of South Australia Species Fact Sheet
Phylum Rhodophyta – Class Florideophyceae – Order Gigartinales – Family Halymeniaceae
Halymenia digitata J. Agardh 1892: 54. Wilson 1892: 184.
Dactylymenia digitata (J. Agardh)J. Agardh 1899: 52. Parkinson 1980a: 10.
Callymenia digitata (J. Agardh) Kylin 1956: 233. Womersley & Norris 1971: 41, fig. 107 (as Kallymenia.)
Thallus (Fig. 52D) medium to dark red, membranous to cartilaginous, 10–25 cm high, complanately and subdichotomously branched at intervals of usually 1–5 cm, often with marginal proliferations 2–30 mm long, branches elongate with linear margins and rounded apices, basally not or slightly constricted, 5–10 (–15) mm broad below, 3–4 mm broad near apices, (75–) 100–250 (–350) µm thick. Holdfast discoid, 1–3 mm across; probably epilithic. Structure (Fig. 52F) of a cortex 3–5 (–6) cells and 10–45 (–60) µm thick, outer cells isodiametric to slightly elongate and 2–4 (–7) µm across, inner cells subspherical to ovoid, becoming slightly stellate and 6–10 (–12) µm across with a medulla 50–200 (–250) µm thick and usually 0.6–0.8 of the branch thickness, of entwined filaments (2–) 4–6 µm in diameter and a network of connected refractive ganglionic cells (Fig. 52E) with long, slender arms. Rhodoplasts discoid, few to several per cell.
Reproduction: Sexual thalli dioecious. Carpogonial branch ampullae (Fig. 51G) lying in the inner cortex and outer medulla, with a 2-celled carpogonial branch and 6–8 simple, 5–6-celled, secondary filaments, converging above. Auxiliary cell ampullae very similar to carpogonial branch ampullae, also with about 6 simple, 5–6-celled, secondary filaments and tertiary filaments. Carposporophytes (Fig. 52G) lying in the outer medulla, 100–150 µm across, with subspherical to angular carposporangia 8–12 µm in diameter and a slight involucre of ampullary and medullary filaments. Spermatangia cut off from outer cortical cells in groups, forming small clusters of fertile cells, spermatia isodiametric, 2–3 µm across.
Tetrasporangia (Fig. 51H) scattered in the outer cortex, ovoid, 12–18 µm in diameter, cruciately divided.
Type from Port Phillip Heads, Vic. (Wilson 30, 31.xii.1886); lectotype in Herb. Agardh, LD, 22327, with two isolectotypes (LD, 22324, 22326).
Selected specimens: Port Elliot, S. Aust., drift (Womersley, 10.viii.1957; AD, A21151). Robe, S. Aust., drift (Womersley, 24.viii.1960; AD, A24434). Port Phillip Heads, Vic. (Wilson, 22.xii.1887; MEL, 502379 and 30.i.1888; MEL, 502411, slide in AD, A50831).
Taxonomic notes: Distribution: Port Elliot, S. Aust., to Port Phillip Heads, Vic.
Considerable confusion has surrounded the circumscription of the genus Dactylymenia. J. Agardh (1892, p. 54) first described Dactylymenia as a subgenus of Halymenia with H. digitata the only species, based on sterile specimens from Port Phillip, Vic. He had initially considered the taxon to be a species of Blastophye, but subsequently published it as a subgenus of Halymenia because of differences in both habit and structure. Subsequently, in 1899, J. Agardh (p. 52) described Dactylymenia as a "genere novo", relating it to Kallymenia, and adding two New Zealand species, D. berggrenii (formerly Kallymenia berggrenii J. Agardh) and D. laingii. In this account, D. digitata was also credited to New Zealand but, as no New Zealand specimens appear to exist in the Agardh Herbarium in LD, this reference seems erroneous. J. Agardh's descriptions of reproductive stages for the genus appear to be based on observations of the two New Zealand species.
Kylin (1956, p. 233) returned D. digitata to Kallymenia and seemingly included D. laingii as a synonym. However, it appears likely that a printing error in this publication resulted in the omission of one line of text which should have included the basionym D. berggrenii J. Agardh for Callymenia berggrenii, and the new combination Callymenia laingii (J. Agardh) Kylin for D. laingii. Chapman & Parkinson (1974, p. 210) retained D. berggrenii in Kallymenia, but (p. 233) referred D. laingii to Cirrulicarpus.
J. Agardh (1899) described zonate tetraspores for this genus, but the source of this observation is unclear. Womersley & Norris (1971, p. 41) considered that it must be based on the New Zealand material, but this is denied by Chapman & Parkinson (1974, p. 232) who claim that D. laingii has never been found with tetraspores, and that those of D. berggrenii are cruciate to irregular but not zonate.
Numerous specimens of D. digitata were collected by J. Bracebridge Wilson toward the end of the last century in the vicinity of Port Phillip Heads in Victoria, but the plant has only rarely been collected since. The lack of recently-collected fertile material has prevented the detailed investigation of reproductive stages necessary to clarify the affinities of this taxon and it seems best to place it in Cryptonemia for the present.
AGARDH, J.G. (1892). Analecta Algologica. Acta Univ. lund. 28, 1–182, Plates 1–3.
AGARDH, J.G. (1899). Analecta Algologica. Cont. V. Acta Univ. lund. 35, 1–160, Plates 1–3.
CHAPMAN, V.J. & PARKINSON, P.G. (1974). The marine algae of New Zealand. Part DI: Rhodophyceae. Issue 3: Cryptonemiales. (Cramer: Germany.)
KYLIN, H. (1956). Die Gattungen der Rhodophyceen. (Gleerups: Lund.)
PARKINSON, P.G. (1980a). Halymenia. (Pettifogging Press: Auckland.)
WILSON, J.B. (1892). Catalogue of algae collected at or near Port Phillip Heads and Western Port. Proc. R. Soc. Vict. 4, 157–190.
WOMERSLEY, H.B.S. & NORRIS, R.E. (1971). The morphology and taxonomy of Australian Kallymeniaceae (Rhodophyta). Aust. J. Bot. Suppl. 2, pp. 1–62.
The Marine Benthic Flora of Southern Australia Part IIIA complete list of references.
Womersley, H.B.S. (14 January, 1994)
The Marine Benthic Flora of Southern Australia
Rhodophyta. Part IIIA, Bangiophyceae and Florideophyceae (to Gigartinales)
Reproduced with permission from The Marine Benthic Flora of Southern Australia Part IIIA 1994, by H.B.S. Womersley. Australian Biological Resources Study, Canberra. Copyright Commonwealth of Australia.
Illustrations in Womersley Part IIIA, 1994: FIGS 51G, H, 52 D–G.
Figure 51 enlarge
Fig. 51. A–C. Polyopes constrictus (A, B, AD, A61531; C, AD, A41752). A. Carpogonial branch ampulla. B. Auxiliary cell ampulla. C. Section of cortex with tetrasporangia. D–F. Polyopes tenuis (D, E, AD, A35901, type; F, MELU, A39818). D. Carpogonial branch ampulla. E. Auxiliary cell ampulla. F. Section of cortex with tetrasporangia. G, H. Cryptonemia digitata (G, AD, A50831; H, AD, A21151). G. Carpogonial branch ampulla. H. Section of cortex with tetrasporangia.
Figure 52 enlarge
Fig. 52. A. Polyopes tenuis (AD, A35901). Longitudinal section with auxiliary cell ampullae and carposporophyte chambers. B, C. Cryptonemia wilsonii (AD, A28026). B. Habit. C. Transverse section of thallus and cystocarp (Photo: J.A. Lewis). D–G. Cryptonemia digitata (D, E, AD, A24434; F, AD, A21151; G, MEL, 502411). D. Habit. E. Refractive ganglionic cells in surface (squash) view. F. Transverse section of thallus. G. Section of thallus with young carposporophyte and lax involucral filaments (Photo: J.A. Lewis).
State Herbarium of South Australia