Loren L. Bahls

SMALL-CELLED NUPELA SPECIES FROM NORTH AMERICA

Three small-celled Nupela species were found in streams and moist habitats of the United States, with a concentration of locations in the eastern part of the country. Two new species are described here: N. neglecta Ponader, Lowe & Potapova and N. Carolina Potapova & Clason. These two species and Nupela wellneri (Lange-Bertalot) Lange-Bertalot have external hymenate occlusions of their areolae, which apparently are diagnostic for this genus. These often erode during sample preparation, and hence have not been previously recognized as a generic character. All three species were recorded primarily from epilithon and epiphyton of small, heavily shaded streams with low to moderate conductivity, and relatively high concentrations of dissolved silica, total nitrogen, and dissolved organic matter.

Nupela potapovae sp. nov. (Bacillariophyta), a lentic alpine species from North America

Nupela potapovae sp. nov., a distinctive new species from ponds and small lakes in the Rocky Mountains of western North America, is described and compared with similar species. In the central area under light microscopy, the new species displays four refractive spots that correspond to shallow internal depressions adjacent to the proximal raphe endings. Nupela potapovae shares this feature with N. rhetica (Wuthrich) Lange-Bertalot, a lentic alpine species from Switzerland.

A Toxic Bloom of Anabaena Flos-Aquae in Hebgen Reservoir Montana in 1977

Because of the volcanic nature of the Yellowstone Park area, waters draining it are highly mineralized. Consequently, Hebgen Lake is also mineralized, with a high concentration of nutrients. While the main lake is not highly productive, the Grayling Arm commonly produces algal blooms both early and late in the season. Predominating species in the early blooms are usually Anabaena spiroides and Aphanizomenon flos-aquae. In June of 1977 a heavy bloom of Anabaena flos-aquae occurred which developed toxic characteristics. A number of cattle and dogs died as a result, and it was necessary to close the beaches and camp sites on the Grayling Arm. Stomach contents of the dead animals were toxic to mice, and anatoxin-a was isolated from algae samples by Wayne Carmichael, Wright State University, Dayton, Ohio. The bloom declined during July and was non-toxic by the end of the month.

MORPHOLOGICAL STUDIES OF DISTRIONELLA INCOGNITA (REICHARDT) WILLIAMS (BACILLARIOPHYCEAE) FROM NORTH AMERICA WITH COMMENTS ON THE TAXONOMY OF DISTRIONELLA WILLIAMS

Detailed morphological observations at the light microscopy (LM) and scanning electron microscopy (SEM) levels were made on North American populations of Distrionella incognita (Reichardt) Williams (=Fragilaria incognita Reichardt). Results are used to show the distinctiveness of this taxon from closely related species and to justify its separation from Fragilaria Lyngbye as suggested by Williams (1990a). The protologue of Distrionella Williams is herein emended to include features newly discovered under SEM. Likewise, two recently described species and a form, Fragilaria germainii Reichardt and Lange-Bertalot, Fragilaria husvikensis Van de Vijver, Denys et Beyens, and Fragilaria germainii fo. acostata Lange-Bertalot are here transferred to Distrionella based on LM and SEM data presented by their original authors. Relationships among these taxa and other morphologically related species are discussed in this work. Ecological attributes are provided for habitats that support Distrionella incognita in North America.

Three New Araphid Diatoms (Bacillariophyta) from Rivers in North America

ABSTRACT. Three new diatoms from North American rivers are described: Staurosira reimeri, Staurosirella elegantula and Staurosirella magna. The features of these diatoms are distinctive, and although they are reported here for the first time, misidentifications and lumping with other taxa in the past are likely. The finding of these three new taxa has two main implications: 1) knowledge of the diversity of araphid diatoms in the Fragilariaceae in North America is still incomplete, and 2) the full set of characters for araphid genera such as Staurosira and Staurosirella is still unknown since the three species described here have novel characters that were unknown or uncommon until the present study. The morphology of the new taxa is shown using light microscopy (LM) and scanning electron microscopy (SEM) and compared with the available literature on this group. S. reimeri is unique within Staurosira because it includes rhomboid, isopolar valves with a narrow linear axial area, rudimentary spines, and apical pore fields reduced to two slits located perpendicularly on the valve mantle edge at the valve apices. S. elegantula and S. magna are unique within Staurosirella due to their large and heavily silicified valves. Both taxa are also shown here to have thick spines with less densely silicified cores, a first report of this feature for Staurosirella. Additionally, S. magna has copulae possessing well developed ligulae that can be folded outwards, a feature that has not been seen in any other published taxa within Staurosirella. Finally, two varieties are transferred to the genus Staurosirella at the species level: S. dubia and S. rhomboides, based on a previous study of these diatoms in North American material done at the LM and SEM levels. New taxa: Staurosira reimeri Morales, Manoylov et Bahls, Staurosirella elegantula Morales et Manoylov, Staurosirella magna Morales et Manoylov. New combinations: Staurosirella dubia (A. Grunow) Morales et Manoylov, Staurosirella rhomboides (A. Grunow) Morales et Manoylov.

Neidiopsis hamiltonii sp. nov., N. weilandii sp. nov., N. levanderi and N. wulffii from western North America

Neidiopsis hamiltonii sp. nov. and Neidiopsis weilandii sp. nov. are described from a stream, lakes and ponds in western North America. The new species are readily distinguished from the three other published species of Neidiopsis by valve size, valve shape and the nature of the proximal raphe ends. In both new species, loculi along the valve margins are continuous and form hollow longitudinal canals, as in Neidium. Diagnostic features common to all five Neidiopsis species include: (1) a mix of uniseriate and biseriate striae; (2) striae arranged in two offset ranks; (3) distal raphe fissures simple (not bifurcate); (4) habitat restricted to cold oligotrophic streams, lakes and ponds with low conductivity; and (5) distribution limited to the Arctic, sub-Arctic and alpine zones of temperate regions in the northern hemisphere. Considerable variation in valve shape, including apical shape, is demonstrated in Rocky Mountain populations of N. hamiltonii, N. levanderi (Hustedt) Lange-Bertalot & Metzeltin and N. wulffii (Petersen) Lange-Bertalot. A comparison of morphometric data for various populations of N. levanderi and N. wulffii indicates that valves from the Rocky Mountains tend to be larger than valves from European and more northerly North American populations.

Cymbopleura laszlorum spec. nov. (Cymbellaceae, Bacillariophyceae), a glacial relic from a calcium-rich floodplain fen in southwestern Montana, USA

Cymbopleura laszlorum is described using LM and SEM microscopy from a recently rehabilitated floodplain fen in southwestern Montana, USA. The new species is most similar to C. mongolica and C. stauroneiformis and shares features with several other northern/alpine species. Cymbopleura laszlorum lives in cold, calcareous, spring-fed pools where it is associated with Mastogloia lacustris , Cymbopleura florentina and Epithemia argus . The fen also supports three rare vascular plants that have northern/alpine affinities. These diatom and vascular plant associates and the close morphological resemblance of C. laszlorum to C. mongolica and C. stauroneiformis suggest that the new species is a glacial relic and survives at the type locality because it has retained the muskeg-like conditions that were more widespread during the last glacial period. Wetland habitats that support rare species of vascular plants are also likely to support new and rare species of diatoms.

Potential loss of cold-water stenothermal diatoms (Bacillariophyta) from their southern refugia in the western United States

A large number of cold-water stenothermal diatom taxa live between 39 and 49°N latitude at the southern limits of their respective ranges in the mountainous northwest sector of the United States. These taxa are either endemics, alpine taxa with disjunct populations in Europe and Asia, or boreal taxa that are more common at higher latitudes. The southern populations are vulnerable to extirpation from the effects of climate change and other stressors. A simple model was created to assess relative risk of extirpation from the northwest United States for a subset of 35 cold-water stenothermal taxa. The model has five input variables: number of populations south of 49°N latitude, mean population size, distance of the southernmost population from 49°N, mean water temperature at the time of sampling, and lowest elevation of a refugium population. Nine taxa, including three local endemics, were found to be at a high risk of extirpation or extinction resulting from climate change. Eight taxa were rated at a low risk of extirpation and risk to the remaining 18 taxa was rated as moderate. Type localities, images of voucher specimens, and latitudinal spectra are provided for each of the 35 selected taxa. The fate of rare and sensitive diatoms will depend on how the global community addresses (or does not address) climate change and how the lands and habitats that support these species are managed (or not managed) to protect larger and more charismatic species.

The role of amateurs in modern diatom research

Amateurs or hobbyists have made significant contributions to diatom research since the inception of our discipline in the late eighteenth century. Many of these contributions were made early in our history when there was little distinction between professionals and amateurs, and both could participate equally. But statistical methods and analytical tools used in diatom research have become increasingly sophisticated and expensive. Today, citizen scientists who have a passion for diatoms may feel excluded from research because they lack the requisite training, resources and connections. But even today, despite some obstacles, there remain many opportunities for the serious self-taught novice to make meaningful contributions to diatom science.