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FAMILY BONNEMAISONIACEAE Schmitz in Engler 1892: 20

Phylum Rhodophyta – Class Florideophyceae – Order Bonnemaisoniales

Thallus (gametophyte, and tetrasporophyte in some taxa) erect, much branched radially or complanately and distichously, branches opposite or alternate, terete or compressed; attachment by a discoid or fibrous holdfast or by retrorse spinous branchlets if epiphytic. Tetrasporophyte isomorphic, or small and of tufted, branched, filaments, or prostrate, minute, of branched filaments. Structure uniaxial, axial filament conspicuous throughout, with the subapical cells each cutting off either two opposite periaxial cells which may diverge on a 1/4 spiral, or two pairs at right angles with the first formed of each pair forming a longer lateral periaxial filament which gives rise to the ramuli, and the shorter transverse filaments contributing to the cortex; lateral filaments remaining separate or coherent laterally in compressed thalli. Ramuli with three pericentral cells, some half the length of the axial cells, and in some taxa many cells of the ramuli and branch cortex cut off small globose gland (vesicular) cells, usually on their inner sides.

Reproduction: Gametangial thalli monoecious or dioecious. Carpogonial branches 3-celled, with (in Asparagopsis) or without lateral nutritive cells, borne on a supporting cell in the inner cortex or on an indeterminate branchlet. Fertilized carpogonium developing directly or after fusing with the hypogynous cell, forming a fusion cell with branched gonimoblast filaments producing swollen terminal carposporangia. Pericarp distinct, of small cells, either globular and stalked or sunken within the cortex of a branch. Spermatangia forming a surface layer on the ramuli or on distinct, ovoid, pedicellate structures.

Tetrasporangia in surface nemathecia, elongate-ovoid, cruciately divided (in Delisea spp. and Leptophyllis), or borne laterally on the filaments of prostrate or tufted tetrasporophytes (e.g. Falkenbergia stage of Asparagopsis).

Life history triphasic, with isomorphic or heteromorphic gametophytes and tetrasporophytes.

Taxonomic notes: A family of 5 genera, all present on southern Australian coasts; plus Pleuroblepharidella Wynne (1980) provisionally referred to the family.

References:

ENGLER, A. (1892). Syllabus der Vorlesungen über specielle und medicinisch-pharmaceutische Botanik ... Grosse Ausgabe. (Borntraeger: Berlin.)

WYNNE, M.J. (1980). Pleuroblepharidella nom. nov. (Bonnemaisoniaceae, Rhodophyceae) proposed for Pleuroblepharis Wynne. Taxon. 29, 325–326.

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

Author: H.B.S. Womersley

Publication: Womersley, H.B.S. (28 June, 1996)
The Marine Benthic Flora of Southern Australia
Rhodophyta. Part IIIB. Gracilarialse, Rhodymeniales, Corallinales and Bonnemaisoniales
Reproduced with permission from The Marine Benthic Flora of Southern Australia Part IIIB 1996, by H.B.S. Womersley. Australian Biological Resources Study, Canberra. Copyright Commonwealth of Australia.

KEY TO GENERA OF BONNEMAISONIACEAE

1. Branch axes terete or slightly compressed, radially or distichously branched; lateral periaxial filaments separate from each other	2
1. Branch axes compressed to flat, 0.5–4 mm broad, marginally branched; lateral periaxial filaments adherent to form the flat branch	4
2. Axes slightly compressed, lateral periaxial filaments forming marginal, distichous (at least at first) often spinous ramuli; cystocarps sessile on the axes between the ramuli; nutritive filaments present; where known, gametophytes and tetrasporophytes isomorphic	DELISEA
2. Axes terete, lateral periaxial filaments discrete, slender, not spinous; cystocarps pedicellate; nutritive filaments absent; gametophytes and tetrasporophytes heteromorphic (except Leptophyllis)	3
3. Branching radial, with opposite periaxial filaments spirally arranged on a VI divergence; cystocarps on a 9–11-celled stalk; tetrasporophyte tufted, of discrete, erect branches	ASPARAGOPSIS
3. Branching bilateral and distichous; cystocarps on a 5–8-celled stalk; tetrasporophyte a prostrate crust	BONNEMAISONIA
4. Thallus delicate, branches 4–5 cells thick, axial filament without a sheath of small cells; axial cells with two lateral periaxial cells only; gametophytes and tetrasporophytes isomorphic	LEPTOPHYLLIS
4. Thallus relatively robust, branches 10–15 cells thick in mid thallus, axial filament with a sheath of small cells; axial cells each with two pairs of lateral and transverse periaxial cells; only sexual thalli known	PTILONIA

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