Electronic Flora of South Australia Genus Fact Sheet

Genus CALLITHAMNION Lyngbye 1819: 123

Phylum Rhodophyta – Order Ceramiales – Family Ceramiaceae – Tribe Callithamnieae

Thallus erect, 1–8 (–12) cm high, much branched spirally or alternate distichously, with indeterminate axes and main branches bearing determinate lateral branchlets, with single branchlets from each cell, apex of branches overtopped or not; lower axes corticated or not, cortication by loose rhizoids or appressed filaments; holdfast rhizoidal. Cells uninucleate or multinucleate.

Reproduction: Gametophytes usually dioecious, some monoecious. Procarps on intercalary cells below apices of branches, with a pair of opposite periaxial cells, one bearing a 4-celled carpogonial branch; sterile cells absent. Fertilized carpogonium usually dividing vertically and fusing via two connecting cells with each auxiliary cell cut off from both periaxial cells, each then producing a foot cell and upper cells giving rise to twinned carposporophytes which may be rounded or furcate-lobed and tapering. Involucral branchlets absent or present and arising from cell(s) below the procarp. Spermatangial clusters borne on cells of determinate branches, usually 1 or 2 adaxial clusters per cell.

Tetrasporangia sessile or pedicellate, usually one per cell, adaxial on cells of determinate branchlets, tetrahedrally divided.

Lectotype species: C. corymbosum (Smith) Lyngbye 1819: 125.

Taxonomic notes: Aglaothamnion was distinguished from Callithamnion by Feldmann-Mazoyer (1941, p. 451) by being uninucleate, whereas the latter is multinucleate. Other features used by Feldmann-Mazoyer, such as the form of the carposporophyte, have been found in both genera, and they are separated by some authors, but only on the number of nuclei per cell. Most southern Australian species are uninucleate, except C. caulescens which is very similar to C. shepherdii, and until other features can be correlated with the nuclear situation and molecular comparisons are done, it seems preferable not to separate the species in 2 genera.

Recognition of species of Callithamnion requires presence in each collection of all fertile stages. Collections of female material can be placed as the genus, but male or tetrasporangial specimens only are difficult to identify unless distinctive vegetatively; numerous such collections in AD have been omitted from this account and further species certainly occur on southern Australian coasts.

Identification of the species of Callithamnion on southern Australian coasts is restricted by lack of knowledge of the several species of this genus from Rottnest I. named by Harvey (1855a). These include C. flabelligerum, C. multifidum, C. crispulum, C. pusillum, C. scopula and C. debile. Until these can be recollected, with female specimens, some names in current use must remain doubtful. Two other little known species are C. longinode Harvey (1863, synop.: liii); Sonder (1881, p. 10); De Toni (1903, p. 1340); Lucas (1909, p. 49), from Warrnambool, Vic., and C. ovuligerum Askenasy (1894, p. 16, p1. IV figs 19, 23, 24); De Toni (1903, p. 1340) and Lucas (1909, p. 49) from "Adelaide", S. Australia. Until these are recollected it is not possible to place them, but both are clearly not species of Callithamnion.

References:

ASKENASY, E. (1894). Über einige australische Meeresalgen. Flora 78, 1–18, Plates 1–4.

DE TONI, G.B. (1903). Sylloge Algarum omnium hucusque Cognitarum. Vol. 4. Florideae. Sect. 3, pp. 775–1521 + 1523–1525. (Padua.)

FELDMANN-MAZOYER, G. (1941). Recherches sur les Céramiacées de la Méditerranée occidentale. (Algiers.)

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.)

LUCAS, A.H.S. (1909). Revised list of the Fucoideae and Florideae of Australia. Proc. Linn. Soc. N.S.W. 34, 9–60.

LYNGBYE, H.CH. (1819). Tentamen Hydrophytologiae Danicae. (Copenhagen.)

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.

Author: H.B.S. Womersley & E.M. Wollaston

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 CALLITHAMNION

1. Branching essentially alternately distichous, at least on lesser branches	2
1. Branching radial, not distichous	4
2. Axes and often branch bases with a closely adherent rhizoidal cortex	C. pinnatum
2. Axes without cortication or with loose, corticating rhizoids over the lower cells	3
3. Axial cells 70–120 µm in diameter, lower cells of branchlets 30–55 µm in diameter, about half that of the axial cells	C. violaceum
3. Axial cells 160–250 µm in diameter, lower cells of branchlets 40–55 µm in diameter, about 1/4 that of the axial cells	C. obstipum
4. Most lower and/or mid axial cells long (L/D 4–15)	5
4. Most lower and mid axial cells relatively short [L/D 1–4 (–6)]	V
5. Lateral branchlets tapering over 4–8 cells. Lower axes 90–130 µm in diameter, cells L/D 8–15; carposporophytes involucrate with branches from lower cells	C. circinnatum
5. Lateral branchlets tapering gradually over many cells. Lower axes 45–75 µm or 150–500 µm in diameter, cells L/D 3–12; carposporophytes with or without involucral branchlets	6
6. Lower axes 45–75 µm in diameter, ecorticate, cells L/D (3–) 4–8 (–10); carposporophytes rounded and with irregular involucral branchlets from lower cells	C. pseudobyssoides
6. Lower axes 150–500 µm in diameter, corticate by descending rhizoids within the cell wall, mid cells L/D 8–12; carposporophytes rounded, without involucral branchlets	7
7. Terminal branchlet cells 5–8 µm in diameter and L/D 1.5–2.5; cells multinucleate	C. caulescens
7. Terminal branchlet cells 2.5–5 (–6.5) µm in diameter and L/D (3–) 4–10 (–12); cells uninucleate	C shepherdii
8. Lateral branchlets 40–65 µm in diameter basally, tapering to 20–30 µm at 3–4 cells below apices; carposporophytes rounded	C. confertum
8. Lateral branchlets 20–30 (–35) µm in diameter basally, tapering to 8–12 µm at 2–3 cells below apices; carposporophytes branched with tapering lobes	9
9. Determinate branchlets not well defined, apical cells 3–6 µm in diameter and L/D 2–5, mid axial cells 30–40 µm in diameter and L/D 3–5	C. byssoides
9. Determinate branchlets well defined, 200–400 µm and 5–10 cells long, apical cells 7–10 µm in diameter and L/D 1–2, mid axial cells 40–60 µm in diameter and L/D 2–3	C. propebyssoides

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