Electronic Flora of South Australia Genus Fact Sheet

Genus GRIFFITHSIA C. Agardh 1817: xxviii

Phylum Rhodophyta – Order Ceramiales – Family Ceramiaceae – Tribe Griffithsieae

Thallus erect, tufted or flabellate; indeterminate branches subdi- (tri-) chotomous, ecorticate or clothed at the thallus base with decurrent anastomosing rhizoids; cells large, 0.14–4 mm in diameter and L/D 1–9, cylindrical to ovoid-globose; filaments often constricted at the nodes or moniliform; synchronic hair-like laterals usually in pairs, flanking female fertile axes, caducous. Cells multinucleate, rhodoplasts discoid, scattered or in chains; cytoplasm containing large crystalline inclusions.

Reproduction: Gametophytes dioecious. Female axis lateral, adaxial, of 3 small, discoid cells, confined to the constriction between vegetative cells, bearing a subapical procarp system consisting of a lateral, abaxial, sterile cell and adaxially a supporting cell bearing apically a sterile cell and laterally 1 (–2) recurved, 4-celled carpogonial branch(es); hypogenous cell remaining small, becoming semi-circular when viewed from above as a result of producing 5–13 two-celled synchronic involucral branches in an abaxial arc, the lower cell of each branch small, the upper cell elongate and incurved, forming a hemi-cupulate involucre. Spermatangia on masses of minute whorled fascicles in the constrictions between vegetative cells near the thallus apex, fascicles naked or associated with an involucre of inflated cells borne on the fascicles peripheral to clusters, or developed as a whorl of reniform, 1-celled synchronic branches from the vegetative cells bearing the fascicles, and forming a palisade-like involucre.

Tetrasporangia without prominent hyaline sheaths, borne in groups of 2-several on masses of minute whorled fascicles in similar positions and involucral patterns to the spermatangia, tetrahedrally divided.

Type species: G. corallina C. Agardh 1817: XXVIII.

Taxonomic notes: A genus of some 27 species, worldwide in distribution, divided into subgeneric groups by Baldock (1976, pp. 545–6) on the basis of tetrasporangial features.

References:

AGARDH, C.A. (1817). Synopsis Algarum Scandinaviae. (Berling: Lund.)

BALDOCK, R.N. (1976). The Griffithsieae group of the Ceramiaceae (Rhodophyta) and its southern Australian representatives. Aust. J. Bot. 24, 509–593.

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

Author: R. N. Baldock

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

KEY TO SPECIES OF GRIFFITHSIA

1. Tetrasporangial and spermatangial clusters without an involucre	G. teges
1. Tetrasporangial clusters with an involucre	2
2. Cells in mid thallus ovoid-globose to pyriform, 0.8–4 mm in diameter and L/D 1–3, filaments moniliform or much constricted between cells, ecorticate. Tetrasporangial, and in some species spermatangial, fascicles peripheral to clusters bearing inflated involucral cells (inconspicuous and equal in size to a mature tetrasporangium in G. pulvinata), vegetative cells adjacent to the reproductive structures normal in size, persistent (G. corallina group)	3
2. Cells in mid thallus cylindrical to doliform, 0.3–0.9 mm in diameter and L/D 2.5–4.5, filaments rarely constricted between the cells, often clothed near the thallus base with rhizoids. Spermatangial and tetrasporangial fascicles enclosed by palisade-like involucres each produced as a synchronic whorl of 1-celled branches from the vegetative axial cell; vegetative cells adjacent to reproductive structures conspicuously swollen; axial filaments above spermatangial and tetrasporangial clusters often caducous leaving the involucre as an apparently terminal cupulate structure (G. antarctica group)	8
3. Cells clavate-obovoid, thallus forming small, dense, pulvinate masses of crowded, erect filaments on rocks. Carposporophytes restricted to upper parts of the thallus, appearing terminal, flanked by 1–3 swollen vegetative cells; spermatangial involucre absent. Tetrasporangial involucral cells of similar size to mature tetrasporangia	G. pulvinata
3. Cells ovoid-globose, branching loose or spreading, thallus moniliform. Carposporophytes lateral in the constriction between vegetative cells, or axillary in branch dichotomies; spermatangial involucre present or absent. Tetrasporangial involucral cells larger than mature tetrasporangia	4
4. Thallus complanately and flabellately branched, regularly subdichotomous. Carposporophytes axillary in branch dichotomies	G. pilalyea
4. Thallus subdichotomous, radially branched, of irregularly branched laterals. Carposporophytes lateral in constrictions between vegetative cells or in terminal branch dichotomies	5
5. Thallus 9–26 cm high, spreading, branched many times; cells in mid thallus allantoid or cylindrical with slightly swollen ends, cylindrical only near the thallus base	G. crassiuscula
5. Thallus 1–14 cm high, branched 3–5 times; cells in mid thallus globose or ovoid	6
6. Thallus light red, spreading, epiphytic on seagrasses. Cells near the mid thallus ovoid, clavate in lower thallus parts. Tetrasporangia large, 80–108 (–130) µm in diameter, with an involucre of narrow-clavate cells, inflated involucral cells only in fascicles peripheral to each sporangial cluster	G. ovalis
6. Thallus medium dark red, loosely branched, epilithic or epiphytic. Cells in mid thallus globose-ovoid. Tetrasporangia 50–80 µm in diameter, with an involucre of ovoid or inflated cells, irregularly furcate or lobed	7
7. Thallus 8–14 cm high, branching lax; often growing in deeper water; cells in mid thallus globose-ovoid, 3–4 mm in diameter, and L/D 1.5–2. Spermatangial fascicles naked. Tetrasporangial fascicles involucrate, bearing either ovoid sterile cells about the same size as tetrasporangia or clavate involucral cells 50–60 µm in diameter and L/D 2–3	G. grandis
7. Thallus 1.5–4.5 (–8) cm high, branching spreading, several times subdichotomous; growing in the lower eulittoral to 5 m depth; cells globose, often with a short proximal neck (ampulliform), in mid thallus 1.6–2.5 mm in diameter. Spermatangial fascicles involucrate or naked. Tetrasporangial fascicles bearing large, swollen, reniform involucral cells often apically furcate, 210–490 µm in diameter and L/D 2–3	G. monilis
7a. Plants usually epilithic from the lower eulittoral to 2m depth. Each supporting cell bearing a single carpogonial branch; carposporophyte involucre of 4–6 branches; spermatangial fascicles naked	a. G. monilis var. monilis
7b. Plants invariably epiphytic in the upper sublittoral to 5 m depth. Each supporting cell bearing a pair of carpogonial branches; carposporophyte involucre of 9–13 branches; spermatangial fascicles bearing large, clavate, apically furcate, involucral cells	b. G. monilis var. cincta
8. Thallus irregularly branched with long axes bearing whorled laterals of limited growth	G. balara
8. Thallus irregularly subdichotomous or distichous, without whorled laterals of limited growth	9
9. Thallus light red; branching distichous, largely complanate, axes bearing regularly alternate, flabellate branch systems, sparsely clothed below with rhizoids; cells in mid thallus 0.4–0.9 mm in diameter and L/D 2.5–3.5	G. elegans
9. Thallus dark red; branching essentially radial, irregularly subdichotomous; axes bearing irregular, dense, lateral tufts, in lower parts twisted together and entwined with rhizoids, rope-like; laterals sparse in the lower thallus, consisting of a few spreading, virgate, sub-dichotomies; cells in mid thallus 0.5–0.8 mm in diameter and L/D 3–4	G. gunniana

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