Electronic Flora of South Australia Species Fact Sheet
Phylum Rhodophyta – Class Florideophyceae – Order Gigartinales – Family Nemastomataceae
Nemastoma comosum Harvey 1859a: pl. 109. J. Agardh 1899: 76. De Toni 1905: 1664. Kylin 1932: 7.
Thallus (Fig. 87E) medium to dark red-brown, fading to grey-red, mucilaginous, 20–80 cm high, with the main axes 4–15 times furcate, compressed, 4–15 mm broad, bearing mainly from the margins (a few from the surface) crowded, slightly compressed, laterals, simple or several times furcate, mostly 1–6 (–15) cm long and 1–4 mm broad; main axes denuded near their base and bare within 5–10 cm of their apices. Holdfast discoid, 4–8 (–10) mm across; epilithic. Structure of a cortex (Fig. 88E) 150–250 µm thick, of discrete branch systems with an inner cortex of ovoid cells (12–) 15–30 µm in diameter, with 3–4 subdichotomies, decreasing in size to the outer cortex of elongate cells, the inner 8–10 µm in diameter and Up 2–3, the outer with unbranched rows of cells 4–6 µm in diameter and UD 1–2; gland cells absent; rhizoids produced by innermost cortical cells; medulla of entangled filaments of long cells 6–10 µm in diameter. Rhodoplasts few per cell, discoid to elongate.
Reproduction: Carpogonial branches (Fig. 88E) 3-celled, borne on inner cortical cells, with a coiled trichogyne; auxiliary cells also inner cortical cells, producing a subspherical to ovoid carposporophyte 60–120 µm in diameter with each cell becoming a carposporangium 12–16 µm in diameter; carposporophyte (Fig. 88F) lying within the cortex, scarcely separating the cortical branch systems. Spermatangia unknown.
Tetrasporangia (Fig. 88G) scattered, borne on mid cortical cells, ovoid, 35–70 µm long and 15–30 µm in diameter, cruciately (slightly obliquely) divided.
Type from Phillip I., Western Port, Vic. (Harvey); lectotype in Herb. Harvey, TCD.
Selected specimens: Elliston, S. Aust., 4–8 m deep outside bar (Shepherd, 25.x.1971; AD, A42581). Cable Hut Bay, Yorke Pen., S. Aust., drift (Womersley, 15.x.1988; AD, A59157). Seal Bay, Kangaroo I., S. Aust., outer reef pool, shaded (Womersley, 29.x.1966; AD, A311 14). Victor Harbor, S. Aust., drift (Womersley, 14.xi.1965; AD, A29677). 2 km NW of Blackfellows Caves, SE S. Aust., drift (Womersley, 24.xi.1992; AD, A61774). Port MacDonnell, S. Aust., drift (G. & L. Kraft 7671, 30.x.1986; MELU, 37182, mixed phase).
Distribution: Elliston, S. Aust., to Phillip I., Vic.
Taxonomic notes: T. comosa is a distinctive species in habit, confined to deeper water or shaded situations on rough-water coasts. Young plants, however, can appear very similar to T. feredayae prior to development of the marginal laterals, but mature plants are usually distinct; a few plants appear to be intergrades.
AGARDH, J.G. (1899). Analecta Algologica. Cont. V. Acta Univ. lund. 35, 1–160, Plates 1–3.
DE TONI, G.B. (1905). Sylloge Algarum omnium hucusque Cognitarum. Vol. 4. Florideae. Sect. 4, pp. 1523–1973. (Padua.)
HARVEY, W.H. (1859a). Phycologia Australica. Vol. 2, Plates 61–120. (Reeve: London.)
KYLIN, H. (1932). Die Florideenordnung Gigartinales. Lunds Univ. Årsskr. N.F. Avd. 2, 28 (8), 1–88, Plates 1–28.
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: PLATE 4 fig. 1; FIGS 87E, 88 E–G.
Plate 4 enlarge
PLATE 4 fig. 1. Tsengia comosa (AD, A61774). fig. 2. Sarcothalia radula (AD, A62995). fig. 3. Gigartina muelleriana at Evans Cave, Cape Lannes, S. Aust. (AD, A62993). fig. 4. Plocamium mertensii at Breaksea I., Albany, W. Aust. (in Murdoch). Photo: J.M. Huisman.
Figure 87 enlarge
Fig. 87. A–C. Predaea huismanii (AD, A53054). A. Habit of the southern Australian record. B. Fascicles of cortical filaments with two carposporophytes. C. Auxiliary cell with attached bulbous end of connecting filament producing a carposporophyte, with chains of small nutritive cellules on cells adjacent to auxiliary cell. D. Tsengia feredayae (AD, A19622). Habit. E. Tsengia comosa (AD, A29677). Habit. F. Tsengia laingii (AD, A35160). Habit.
Figure 88 enlarge
Fig. 88. A–D. Tsengia feredayae (A, AD, A43955; B, C, AD, A19833; D, AD, A31774). A. Transverse section of cortex with two carpogonial branches. B. Young carposporophyte arising from the auxiliary cell, with end of a connecting filament. C. A carposporophyte. D. Transverse section of cortex with tetrasporangia. E–G. Tsengia comosa (E, F, AD, A59157; G, AD, A29677). E. Transverse section of cortex with carpogonial branches. F. Carposporophyte. G. Transverse section of cortex with a tetrasporangium (with an irregularly divided one on right). H–K. Tsengia laingii (AD, A35160). H. Carpogonial branch on an inner cortical cell. I. Auxiliary cell producing a young gonimoblast, with a connecting filament on the right. J. Cortex with a mature carposporophyte. K. Cortex with a tetrasporangium (two irregularly divided ones on right).
State Herbarium of South Australia