In this study nearly 50 species of diatoms new to science, collected from lake sediments across the western USA, are presented for the first time. A total of thirty-eight raphid species are described (across eighteen genera), while one non-raphid pennate and nine non-pennate species are also described from these collections. Observations with light and scanning electron microscopy are offered for each taxon. Nomenclatural and morphological details for previously known species encountered in the author's examination of these sediments are provided and indicate their distribution across the western USA.
80 plates, a taxon index and a comprehensive reference list round up Bibliotheca Diatomologica, Volume 61: Diatoms of the United States, Volume 1 and make it a valuable source of information for biologists and palaeontologists working not only on American but also on diatoms worldwide.
Materials and methods 6
Results and discussion 9
General conclusions 53
Literature cited 55
Taxon index 185
"Since the 19th century several researchers including European and American diatomists have described new diatom species from the inland waters of the United States. However, the characterisation of diatom flora of these territories is still in the period of discovery. Becoming acquainted with the diatom taxa living in these waterbodies and understanding their ecological characteristics is important because diatoms can be applied in water quality monitoring for both running and standing waters.
In the National Lakes Assessment program a thousand lakes of the United States were evaluated based on benthic diatoms from sediment core samples. In this book the authors present the diatom taxa of sediments from more than 200 lakes across the Western United States (12 states from North Dakota to California) investigated in the NLA program. Sixty-two taxa are described including 50 species (in 23 genera, mainly raphid pennates) new to science. Two new combinations are offered and one species (Navicula caldwellii) is reported for the first time from the USA.
The distinction between newly described and previously established taxa may appear to be slight. The reason for the use of such fine-grained taxonomic approach is that the authors took notice of the cases of the so-called “pseudo cryptic species” in diatoms. This term means species discovered an originally single, morphology-defined species using other (e.g. molecular) methods and their distinctive morphological features were defined after that.
The authors described the most new taxa from Oregon State due to the ultra pristine environments of the Cascade Mountains holding relict flora. This result shows the speciality of the Pacific Northwest of the United States. However, the diversity in the neighbouring California was much lower because of the many perturbed habitats.
The descriptions of taxa are included in the framework of a regular research paper involving introduction, materials and methods, results and discussion as well as general conclusion sections. In the taxonomic part light and in almost all cases scanning electron microscopic description in English, information on distribution across the study area and/ or comparison with similar taxa are provided for each taxon. For new species description in Latin, holotype and type locality, for new combinations basionym are also given. One taxon (Amphora sp.) could be identified only to genus level.
The descriptions of taxa are illustrated with good quality light and scanning electron microscopic photographs arranged on eighty plates. Highlighting certain distinguishing features these illustrations can help the understanding of the delineations. Overall, this volume provides a good insight into the diatom flora of the United States. It can be useful for everyone interested in the diatoms."
– M. Duleba, Acta Botanica Hungarica 56 (3-4)