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Electronic Flora of South Australia Species Fact Sheet
Phylum Rhodophyta – Order Ceramiales – Family Dasyaceae
Synonym
Dasya mollis sensu Harvey 1855a: 543; 1863, synop.: xxii. J. Agardh 1863: 1216, in part; 1890a: 104, in part. De Toni 1903: 1204, in part; 1924: 443, in part. Kützing 1865: I, pl. la, b. Lucas 1912: 158. Sonder 1881: 36. NON Dasya mollis Harvey 1853: 62.
Thallus (Fig. 197A) light to dark red-brown, soft and mucilaginous, 3–20 (–45) cm high, with 1–2 corticated axes 1–2 mm in diameter. Main axes profusely and irregularly branched throughout, with lower laterals often as long as the main axes, moderately to heavily covered by basally branched, pigmented, attenuate, monosiphonous filaments. Holdfast small, discoid; epiphytic or on solid substrates. Structure. Pericentral cells 5, formed in circular order, not obvious in transverse sections of older axes (Fig. 197B), heavily corticated by rhizoidal filaments which occur both internally and externally to the pericentral cells. Pseudolaterals from every segment, 1–2 mm long, basally subdichotomous every 1–2 cells with 3–5 subdichotomies on any filament giving 10–20 ultimate branches, distinctly attenuate from their base to beyond the last subdichotomy and then scarcely attenuate in the ultimate unbranched filament. Adventitious monosiphonous filaments similar to young pseudolaterals, frequent, arising from the upper portion of pericentral cells 1, 3, and 4 (not the smaller 2 and 5), beginning about 12 segments from the apex, and also from later formed cortical cells. Basal cells of pseudolaterals and adventitious filaments 45–65 µm in diameter, L/D 0.7–1; cells after the last subdichotomy 22–23 µm in diameter, L/D 1–2 (–3); cells of ultimate filaments 12–22 µm in diameter, L/D (1–) 2–9. Intercalary cell divisions occasional in the ultimate branches. Lateral axes usually adventitious, arising from the basal cell of the first branch of a monosiphonous filament. Rhodoplasts discoid to elongate, reticulate in older cells.
Reproduction: Gametophytes dioecious. Procarps borne spirally on a polysiphonous, usually adventitious, axis. Carposporophytes with a moderate basal fusion cell and ovoid to clavate, apical and lateral carposporangia. Cystocarps (Fig. 197C) sessile on lateral axes, urecolate, 400–700 µm in diameter, with a neck (0.2–) 0.3–0.5 the diameter of the cystocarp in length; pericarp 3–4 cells thick, outer cells irregularly ovoid. Spermatangial branches (Fig. 197D) sessile or on a 1–2-celled monosiphonous stalk, on the lower branches of both pseudolaterals and adventitious monosiphonous filaments, prominent, ovoid to ellipsoid, 120–250 µm long and 75–100 µm in diameter, with 7–11 fertile segments and a 6–16-celled attenuate apical filament.
Stichidia (Fig. 197E) on a 1–2 (–3)-celled monosiphonous stalk, on the lower branches of both pseudolateral and adventitious monosiphonous filaments, cylindrical, 100–650 µm long and 100–150 µm in diameter, with 8–15 fertile segments of (4–) 5 pericentral cells (Fig. 197F) all of which become fertile. Each tetrasporangium with (2–) 3 cover cells (Fig. 197G) which are at first small, rather narrow and irregular in shape, scarcely covering the sporangium, later becoming elongate irregularly upwards and often dividing once.
Holotype: Third Beach, Esperance, W. Aust., on fucoids at reef edge (Parsons, 21.xi.1968; AD, A33349; isotype CHR, 315367).
Selected specimens: Point Clune, Rottnest I., W. Aust., 13 m deep on sand covered rocks (Millar, 6.xii.1984; AD, A56297). Hopetoun, W. Aust., lower eulittoral on reef (Parsons, 20.xi.1968; AD, A33363;
Distribution: Rottnest I., W. Aust., to Cape Thomas, S. Aust. and Montagu, NW Tasmania.
Taxonomic notes: CHR, 315365), Point Sinclair, S. Aust., shallow pools on reefs (Womersley, 8.ii.1954; AD, A19624). Arno Bay, Eyre Pen., S. Aust., on Posidonia sp., drift (Kraft 4212, 12.xi.1971; AD, A42252). Vivonne Bay, Kangaroo 1., S.Aust., 3–4 m deep on jetty piles (Lutz, 22.xi.1968; AD, A33027) and 0–5 m deep on jetty piles (Kraft & Min Theirs, 4.xii.1971; AD, A41415). American R. inlet, Kangaroo I., S. Aust., drift (Womersley, 25.viii.1963; AD, A26741). N of Cape Thomas, S. Aust., drift (Womersley, 24. viii.1960; AD, A24381). Montagu, NW Tas. (Perrin, 24.iii. 1950; AD, A16412).
Etymology: named for Dr Gerald T. Kraft, University of Melbourne, for the contributions he has made to phycology, particularly the collection of uncommon species of Dasya.
Dasya kraftii has been often found with D. baldockii, and their general habit is very similar. They are however easily distinguished by the shape of their spermatangial branches and the occasional intercalary cell divisions in the monosiphonous filaments of the former. D. kraftii occurs on fucoids in the sublittoral fringe and in pools, or sublittoral on Osmundaria prolifera Lamouroux, on Posidonia sp. to 10 m deep and on wooden jetty piles 1–2 m deep; records of D. kraftii are from early spring to late summer, when plants are fertile.
References:
AGARDH, J.G. (1863). Species Genera et Ordines Algarum. Vol. 2, Part 3, pp. 787–1291. (Gleerup: Lund.)
AGARDH, J.G. (1890a). Till algernes systematik. Acta Univ. lund. 26(3), 1–125, Plates 1–3.
DE TONI, G.B. (1903). Sylloge Algarum omnium hucusque Cognitarum. Vol. 4. Florideae. Sect. 3, pp. 775–1521 + 1523–1525. (Padua.)
DE TONI, G.B. (1924). Sylloge Algarum omnium hucusque Cognitarum. Vol. 6. Florideae. (Padua.)
HARVEY, W.H. (1853). Nereis Boreali-Americana. Part II. - Rhodospermae. (Smithsonian Inst.: Washington.)
HARVEY, W.H. (1855a). Some account of the marine botany of the colony of Western Australia. Trans. R. Jr. Acad. 22, 525–566.
HARVEY, W.H. (1863). Phycologia Australica. Vol. 5, Plates 241–300, synop., pp. i-lxxiii. (Reeve: London.)
KÜTZING, F.T. (1865). Tabulae Phycologicae. Vol. 15. (Nordhausen.)
LUCAS, A.H.S. (1912). Supplementary list of the marine algae of Australia. Proc. Linn. Soc. N.S.W. 37, 157–171.
SONDER, O.W. (1881). In Mueller, F., Fragmenta Phytographiae Australiae. Supplementum ad volumen undecinum: Algae Australianae hactenus cognitae, pp. 1–42, 105–107. (Melbourne.)
The Marine Benthic Flora of Southern Australia Part IIIC complete list of references.
Publication:
Womersley, H.B.S. (24 December, 1998)
The Marine Benthic Flora of Southern Australia
Rhodophyta. Part IIIC. Ceramiales – Ceramiaceae, Dasyaceae
©State Herbarium of South Australia, Government of South Australia
Illustration in Womersley Part IIIA, 1998: FIG. 197.
Figure 197 enlarge
Fig. 197. Dasya kraltii (AD, A33349). A. Habit. B. Transverse sections of young and older branches. C. Cystocarp. D. Spermatangial branches. E. A stichidium. F. Longitudinal sectional view of a stichidium. G. Stichidial cover cells.
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