The morphology and cytology of Audouinella sp. (Rhodophyta, Acrochaetiaceae)

Audouinella sp. (Rhodophyta, Acrochaetiaceae) was collected seasonally between May 1978 and April 1980 from the North Alouette River, British Columbia and occasionally from other regions in British Columbia, Washington and Oregon states. The plants were attached to rocks, moss, or the freshwater red alga, Lemanea. In general, macroscopic specimens were collected in the winter and spring and germlings in the summer and fall. Audouinella is a uniseriate branched filament with erect and basal systems. The basal system persists most of the year. Each cell contains one parietal chloroplast which varies from spiral to irregularly band shaped; pyrenoids are absent. Large lipid bodies of unknown function are common in most cells of field and cultured material and tend to aggregate near the pit plugs. Hair cells and monosporangia are commonly found on the tips of short branches. Regeneration of the monosporangia, hair cells and filaments is common. Sexual reproduction was not observed. Growth and elongation, observed with the aid of calcofluor white ST, is limited to the apical cells of the main axes, branches and branchlets. Morphological plasticity is evident in the varying cell sizes obtained from field and cultured material at different light intensities. Four chromosomes represent the haploid condition; there are two larger (ca. 0.4 μm) and two smaller (ca. 0.3 μm) chromosomes. Audouinella sp. has typical red algal ultrastructural features. Unicellular hairs are described ultrastructurally in the red algae for the first time. They contain a prominent nucleus, several mitochondria, endoplasmic reticulum, golgi bodies and many vesicles. Chloroplasts or proplastid type of organelles are absent. Audouinella sp. was compared to 24 descriptions of other freshwater members of the Acrochaetiaceae and it was concluded that at present it is not possible to provide a species name for the plant observed in this study. The generic name Audouinella was chosen in agreement with current taxonomic studies.Science, Faculty ofBotany, Department ofGraduat