The Biological Soil Crusts of the San Nicolas Island: Enigmatic Algae from a Geographically Isolated Ecosystem

Composite soil samples front 7 sites on San Nieolas Island were evaluated quantitatively and qualitatively for the presence of cyanobacteria and enkaryotic microalgae. Combined data demonstrated a rich algal flora with 19 cyanobacterial and 19 eukaryotic microalgal genera being identified, for a total of 56 species. Nine new species were identified and described among the cyanobacteria and the enkaryotic microalgae that were isolated: Leibleinia edaphica, Aphanothece maritima, Chroococcidiopsis edaphica, Cyanosarcina atroceneta, Hassallia californica, Hassallia pseudo-ramosissima, Microchaete terrestre, Palmellopsis californicus, and Pseudotetracystis compactis. Distinct distributional patterns of algal taxa existed among sites on the island and among soil algal floras of western North America. Sense algal taxi appeared to he widely distributed across many desert regions, including Microcoleus caginatus, Nostoc pnnctiforme, Nastoc paludosum, and Tolypothrix distorta, Chlorella vulgaris, Diplosphaera ef. chodatii, Myrmecia astigmatica, Myrmecia biatorellae, Hantzschia amphioxys, and Luticola mutica. Some taxa share a distinctly southern distribution with soil algae from southern Arizona, southern California, and Baja California (e.g., Scenedesmus deserticola and Eustigmatos magnus). The delta presented herein support the view that the cyanobacterial and microalgal floras of soil crusts possess significant biodiversity, much of it previously undescribed