Freshwater Cyanoprokaryota of north-eastern Australia 1: Oscillatoriales.

In a recent review (Komárek 2007) of a new flora of the nonfilamentous species of cyanoprokaryotes (Cyanobacteria, Cyanophyta, ‘blue-green algae’) of inland waters of the Netherlands (Joosten 2006), the reviewer noted the great importance of studies of natural populations of cyanoprokaryotes from particular regions. He remarked that research of similar excellence had not been published from other regions of the world. The present volume now contributes another high-quality study from a greatly contrasting region. This very attractively produced small volume describes those cyanoprokaryotes with simple, unbranched, uniseriate, undifferentiated chains of cells. It presents their morphological diversity as observed by light microscopy with some supplementary data from transmission electron microscopy for a few taxa. The wide-ranging survey visited 253 sites, the large majority of which were in tropical and subtropical regions of Queensland and Northern Territory between latitudes 10 and 30uS. The sites encompassed a wide range of lotic and lentic habitats but with most (224 sites) being listed as either streams or reservoirs. Samples were taken of plankton, benthos, epiphyton and metaphyton. The Introduction provides usefully detailed descriptions of the study area, range in climate, and habitats sampled. The Systematic Account is introduced by a brief justification of the phenotypic approach taken here for the recognition of species. The valid point is made that at present this is the only practical approach for a survey of this sort. However, it is admitted that this is a first step towards a more complete evaluation of cyanoprokaryote diversity which would also utilise molecular, ultrastructural and biochemical data in a so-called polyphasic approach. The author follows the families, genera and species recognised in the major revision of the Oscillatoriales by Komárek & Anagnostidis (2005). Descriptions are based on preserved and living field specimens supplemented with observations made on simple multispecies, nonaxenic enrichment cultures. A total of 122 taxa are described. Ninety-eight are assigned to known morphospecies. Five are compared with closely similar morphospecies, whilst 16 remain identified to only the generic level. Three new morphospecies are proposed. It is interesting to note that although most samples were of planktonic communities, the large majority of species were found in benthic habitats. I wonder how many of the latter extend their distribution into soils and what diversity of oscillatorialeans might be restricted to soil and other nonaquatic habitats. A full survey of this order would also have to encompass those habitats. Keys are provided to families, genera and species. Concise but detailed descriptions of diagnostic characteristics are provided at all taxonomic levels. The distribution of each species is outlined, both in this survey and in other regions of Australia. Brief ecological notes are provided for all species and taxonomic notes for a minority. In the latter respect, it would have been useful to have had some comparison with known species for those specimens identified to only the generic level and for the three proposed new species. Joosten (2006) is more thorough in this aspect, as well as in providing more detailed taxonomic notes for each genus and many of the species. Each species is illustrated with exemplary line drawings of either a single typical filament or a selection of filaments which shows its morphological variability. Most species are also shown in the 14 plates of generally excellent colour photomicrographs. At the end of each section on a particular genus, Phycologia (2007) Volume 46 (6), 738–739 Published 1 November 2007