Electronic Flora of South Australia Species Fact Sheet

Apjohnia laetevirens Harvey 1855a: 335; 1858: pl. 5.

Phylum Chlorophyta – Order Cladophorales – Family Cladophoraceae

Selected citations: Dawes 1969: 77. Lucas 1936: 30, fig. 12. Papenfuss & Chihara 1975: 311–315, figs 4–11. Womersley 1956: 376.

Thallus (Fig. 58A) to 25 cm high, dendroid, with a single (or often clustered) stipitate basal segment 1–6 cm long and 1–4 mm in diameter attached by branched, sparsely septate rhizoids, and producing at its apex a row of 2–5 branches often lying in one plane (Fig. 59A) or an irregular cluster or whorl of 3–9 elongate, linear or slightly expanded upwards, segments 0.5–2 cm long and 0.5–1.5 (–2) mm in diameter. This pattern is repeated two to several times with the subterminal segments producing usually three and later five segments, the central one being produced first, followed by more or less equally developed lateral branches. Segments with prominent annular constrictions (Fig. 59A) confined to the lower quarter to half on upper segments but sometimes extending over the lower half to three quarters (or even more) of lower segments; segments with complete end walls, vacuolar acicular calcium oxalate crystals present; bases of older segments often cutting off 2–8 small hapteroid cells (Fig. 59B) which come to lie between the segments and extend rhizoidal processes downward and largely within the wall of the lower segment; cell wall lamellate, tough, 10–20 µm thick in younger segments, up to 50 µm thick below; chloroplasts discoid, closely packed, each with a prominent pyrenoid.

Reproduction: Reproduction by biflagellate zooids, liberated through lateral pores following reticulation of the protoplasm, has been observed.

Type from Phillip I., Victoria; in TCD.

Selected specimens: Robe, S. Aust., upper sublittoral pools (Wornersley, 18.i.1967; ADU, A27299). Flinders, Vic., upper sublittoral (Womersley, 18.i.1967; ADU, A31802). East Cove, Deal I., Bass Strait (Shepherd & Lewis, 5.v.1974; ADU, A45246).


Distribution map based
on current data relating to
specimens held in the
State Herbarium of SA

Distribution: From Green Head (30°04'S) in W. Aust., around southern Australia to Collaroy, N.S.W. Deal I. and King I., Bass Str. Often common in deep, shaded pools on rock platforms, and recorded to 16 m deep.

Taxonomic notes: A. laetevirens is a most distinctive alga, with much larger coenocytic segments than other algae of the Cladophorales. Its dimensions and branching pattern separate it satisfactorily from Cladophora. The other species, A. scoparia from New Caledonia, differs in habit, branching and the frequent presence of more than one cell between laterals.

Young plants of A. laetevirens, comprising a tuft of elongate, clavate basal segments only, are not uncommon.

References:

DAWES, C.J. (1969). A study of the ultrastructure of a green alga, Apjohnia laetevirens Harvey with emphasis on cell wall structure. Phycololgia 8, 77–84.

HARVEY, W.H. (1855a). Short characters of some new genera and species of algae discovered on the coast of the Colony of Victoria, Australia. Ann. Mag. nat. Hist. 15, 332–336.

HARVEY, W.H. (1858). Phycologia Australica. Vol. 1, Plates 1–60. (Reeve: London.)

LUCAS, A.H.S. (1936). The Seaweeds of South Australia. Pt. I. Introduction and the Green and Brown Seaweeds. (Govt Printer: Adelaide.)

PAPENFUSS, G.F. & CHIHARA, M. (1975). The morphology and systematic position of the green algae Ernodesmis and Apjohnia. Phycologia 14, 309–316.

WOMERSLEY, H.B.S. (1956). A critical survey of the marine algae of southern Australia. I. Chlorophyta. Aust. J. mar. freshw. Res. 7, 343–383.

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

Author: H.B.S. Womersley

Publication: Womersley, H.B.S. (31 May, 1984)
The Marine Benthic Flora of Southern Australia
Part I
©Board of the Botanic Gardens and State Herbarium, Government of South Australia


Illustrations in Womersley Part I, 1984: FIGS 58A, 59A,B.

Figure 58 image

Figure 58   enlarge

Fig. 58. A. Apjohnia laetevirens (ADU, A27299). B. Cladophoropsis herpestica (ADU, A13612). C. Cladophoropsis magna (Type).

Figure 59 image

Figure 59   enlarge

Fig. 59. A,B. Apjohnia laetevirens (ADU, A27299). A. A branch with series of basally annulate segments. B. Lower cells with annular constrictions and hapteroid cells. C. Cladophoropsis herpestica (ADU, A13612). Filaments with descending rhizoids and open connection to lateral branches. D. Cladophoropsis magna (Type). A cluster of filaments showing branches in open connection to lower cells. E–G. Cladophora rhizoclonioidea (Holotype). E. Habit. F. A group of entangled filaments. G. An old regenerating filament with young lateral branches.


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