Gary E. Dillard:

Freshwater Algae of the Southeastern United States, Part 8

Chrysophyceae, Xanthophyceae, Raphidophyceae, Cryptophyceae and Dinophyceae

2007. 127 pages, 22 plates, 14x23cm, 360 g
Language: English

(Bibliotheca Phycologica, Band 112)

ISBN 978-3-443-60039-6, paperback, price: 48.00 €

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Content Description top ↑

This is the eighth and concluding volume in a planned series to present a compendium of the freshwater algae, excluding the Bacillariophyceae, Cyanophyceae, Rhodophyceae and Charophyceae, reported as occurring in the southeastern United States“. An originally planned volume on the Cyanophyceae and Rhodophyceae will not be forthcoming. Parts 1 and 2 were published in 1989, Part 3 in 1990, Parts 4 and 5 in 1991, Part 6 in 1993 and Part 7 in 2000.

It is important to reiterate that this series was never intended to be a revisionary work but, rather, a compendium of reported taxa to serve as a biodiversity data base for those interested in the occurrence and distribution of freshwater algae in the south-eastern United States. In that regard, caution must be taken as many of the reports included herein are represented in the literature as “floristic lists” and are unaccompanied by figures and/or descriptions and, as a result, are impossible to confirm in respect to the accuracy of the original identifications.

In most cases, keys, figures and descriptions for reported algal taxa have been included. Additionally, supportive literature citations (LIT) for each genus and distributional data (DIST), by State, for each subgeneric category are provided. Synonymy, as applicable to taxa reported from the southeastern United States, has been brought up-to- date in all cases where warranted corrections were known.

Accurate illustrations of algal taxa, based upon authoritative sources, are of critical importance to the usefulness of a work such as this.

Review: Journal of Phycology 44 (2008) top ↑

In 1989, Gary Dillard published the first book in his series of floristic treatments on selected groups of freshwater algae from the southeastern United States. This is the eighth, and probably the last, in the series and focuses on the chl c–containing microalgal classes, exclusive of the diatoms. Various freshwater green-algal groups are covered in parts 1–6, and the pigmented Euglenophyceae comprise part 7. As with the previous books, only the pigmented forms are included in part 8. Dillard explains that although volumes on the Cyanophyceae and Rhodophyceae were planned originally, they will not be forthcoming. The region covered encompasses those states from Virginia south to Florida and westward to the Mississippi River, including all of Louisiana. Keys, figures, and descriptions are provided for almost all taxa. Supportive literature citations are included for each genus, and distributional data by state for each species. An effort was made to update taxon synonymies. Most species are illustrated with line drawings made from well-known publications as sources of authoritative images. The book begins with the introduction and reiteration of purpose as well as a key to the algal classes, followed by taxonomic sections on the Chrysophyceae (subclasses Acontochrysophycidae, Heterochrysophycidae, Isochrysophycidae), Xanthophyceae, Raphidophyceae, Cryptophyceae, and Dinophyceae (subclass Dinophycidae). The book ends with an addendum, a bibliography and literature cited section, and an index. Plates of line drawings with the corresponding species names on the facing pages complete the volume. The main text occupies about 100 pages, and the bibliography 16 pages. There are 22 plates.

At first glance, this book appears to be an effort to update the algal flora for this region in the style of Prescott (1962) and Whitford and Schumacher (1984). Although the work does perform many of the same functions as these classic floras, it is clear that there is a different objective here. Dillard’s intention is not to revise the algal flora of the southeastern United States, but to initiate a biodiversity database on the occurrence and distribution of the freshwater algae in the region. The goal was to document the published flora for the region, not publish firsthand observations. He has succeeded wonderfully, and the index should be used as a starting point or checklist for the freshwater algal flora from the southeastern U.S. Dillard cautions, however, that many of the species reports utilized were ‘‘floristic lists’’ lacking documentary figures or descriptions and, therefore, were impossible to confirm.

Although the additional effort probably was prohibitive, the author’s goal of initiating a floristic biodiversity database would have been enhanced if he had described the physiographic provinces comprising the region and referred to them in the distributional reports, rather than reporting taxa only by state. Comments on habitats also would have been helpful. Additionally, floristic or taxonomic studies of many of these groups frequently contain both pigmented and unpigmented taxa, and some pigmented taxa (e.g., Dinobryon spp.) now are known to be among the most significant bacteriovores in the plankton. Thus, the omission of unpigmented genera from some groups appeared wanting (e.g., several genera of scaled and naked chrysophytes, cryptomonads, and dinoflagellates). However, the book truly pulls together a large body of published species-level accounts on the southeastern U.S. with keys, illustrations, descriptions, and distributional information in a very useful, informative framework.

A series of keys has been provided to every taxon covered in the book, including the major algal classes, orders or families, genera, and species. The only exception is that no keys to species are provided for the silica-scale-bearing chrysophytes, for which only a key to the genera is given (see below). I cannot say with certainty that these keys work well as I have not had the opportunity to use them. However, they appear to be well written, clearly organized, and succinct. There seems to be a strong effort to avoid ambiguous couplets. In places where there probably are unresolved issues in distinguishing taxa (e.g., overlapping size ranges in Cryptomonas and Tribonema species), the couplets clearly reflect the problem and do not try to gloss over them, effectively providing hints for further study. The dinoflagellate keys may be particularly useful. Even though there are a relatively large number of species in some genera, the author avoids a long, cumbersome key in favor of several smaller keys to sections or subgenera (e.g., Peridinium, Peridiniopsis) and then another key to the species therein. The keys never exceed a single page, only rarely exceed a half-dozen couplets, and instruct the user in the taxonomic concepts utilized. They are a strength of the book.

The book’s organization makes it easy to use. The taxonomic structure in combination with appropriate spacing, indentations, and so forth facilitate the user in quickly finding information in both the text and the index. The order of the plates reflects the order of coverage in the text. Each species explanation provides the plate and figure numbers of the taxon, while each plate’s facing page lists the page number for each species. Likewise, the font style and size are easy to read, even in the index and bibliography. I do have one complaint, however. A genus name was centered at the bottom of a page with the description following at the top of the next page an unexpectedly high number of times. It looked strange and felt cumbersome. The line drawings are excellent and are arranged in a pleasant visual presentation on plates occupying a full page. Mostly, the figures seemed to be of an appropriate size—not too large, so there were only a few per page, yet not so small as to make them difficult to see. Closely related taxa are arranged on the same plate to rapidly convey the range of morphological diversity and facilitate understanding of generic or species concepts. For example, three loricate, chrysophyte genera, Pseudokephyrion, Epipyxis, and Dinobryon, are represented by two, five, and four species, respectively, on plate 5; and all nine Ophiocytium species are on plate 13. Credit is given to the author as the source of a drawing, but not the year of the citation, making it difficult to find the original drawing. A few figures contained multiple images, perhaps leading to confusion if the reader is unfamiliar with the taxa. Specifically, figure legends only contained the taxon’s name and page number, and only a figure number was associated with each figure. When multiple images occurred with a figure number, the identity of a given image was unclear at times, even after reading the corresponding text (e.g., Bourrellia skujae, plate 1, fig. 3). However, lines linking different cell views for the same taxon were used when needed in the dinoflagellate figures, resolving this problem for this group (e.g., plate 18, figs. 9–11).

The author provides a brief overview of the rapidly evolving classification scheme for the Chrysophyceae but utilizes the ‘‘traditional’’ (Dillard’s term) system of Bourrelly (1981) in this presentation. About 25 pages plus six plates are dedicated to freshwater chrysophycean taxa. Many nonspecialists have a poor understanding of chrysophycean taxa because much of the taxonomic literature is not in English or many taxa are encountered only infrequently. The section on the Chrysophyceae will help these folks. Users of this book will find the commonly encountered taxa (e.g., Dinobryon, Uroglena, Ochromonas) well represented here. Many of the poorly understood taxa are clearly delineated, including the rhizopodial and loricate forms, unicellular flagellates, and those with cells in gelatinous envelopes. Additionally, because electron microscopy (EM) is required for species-level identification of the silica-scaled species, routine examination of species is inhibited, and taxonomic enigmas sometimes exist for species described before the availability of EM. All pigmented, silica-scaled species in the Chrysophyceae, including those often placed in the Synurophyceae in other classifications, are organized as a single family (Mallomonadaceae) following Bourrelly’s classification and occupy an additional 15 pages. Reports that did not use EM are considered suspect and are identified as such. Likewise, genera of questionable validity (e.g., Microglena, Chlorodesmus) are discussed briefly. For the silica-scaled chrysophytes, the author only provides keys to genera, explaining ‘‘reliable keys … of all known species are wanting’’ (p. 31) and lists the silica-scaled species alphabetically. This presents a rather daunting list for the 84 Mallomonas species and even the 19 Synura species reported from the southeastern U.S. However, the book by Kristiansen and Preisig (2007) published in the same year has answered this complaint for those taxa with bilaterally symmetrical scales (i.e., Synurophyceae). Line drawings of a few silica-scaled chrysophyte taxa are included in the text, the only place where this occurs in the book, while line drawings of only three enigmatic or infrequently encountered species are illustrated in the plates. The paucity of illustrations for the silica-scaled chrysophytes is understandable due to the necessity of EM for most species-level identifications. Those wishing to understand the silica-scaled chrysophytes in the southeastern U.S. will need to supplement this book with references like Kristiansen and Preisig (2007) or similar publications. The haptophyte taxa are located within the Chrysophyceae and are represented by two genera totaling three species.

The yellow-green algae, including the Eustigmatophyceae, are organized into the Xanthophyceae following Bourrelly (1981). They occupy 26 pages and nine plates. There is a brief discussion of several more recent classifications. Genera in the Eustigmatophyceae are indicated as such adjacent to the genus name. Again, the full range of morphologies in the group is presented, including loricate, amoeboid cells; and coccoid, filamentous, and coenocytic forms. Eighty-six species are recorded among 41 genera; 30 of the genera are represented by only one species. Characiopsis, Ophiocytium, Vaucheria, and Tribonema were reported with 12, nine, nine, and six species, respectively.

The final three classes typically are present as flagellated cells in the vegetative state. The raphidiophytes are represented by four species within three genera. Likewise, three cryptomonad genera with a total of 16 species are recorded. The dinoflagellate organization follows Popovsky and Pfiester (1990). Four nonmotile genera are listed, each with a single species. Eleven more motile genera are presented with Peridinium, Peridiniopsis, Gymnodinium, Ceratium, and Woloszynskia recording nine, eight, seven, four, and four species, respectively. In both Peridinium and Peridiniopsis, the species are organized into sections.

This book will be a useful addition to anyone interested in species-level identification for the algal groups contained therein or interested in the biogeography of the southeastern U.S. The distribution record for the groups covered in this book is poorly known, and what is known mostly is scattered throughout the published literature. Pulling these species reports together in one place is in itself a significant contribution. Given the high biological diversity in parts of the region (e.g., Great Smokey Mountain National Park) and resurgent interest in microbial biodiversity, the appearance of this work is timely. Finally, I particularly liked the size (23 · 14 cm) and facile organization of the book. It will be handy to pull off the shelf and use next to the microscope or to digest for a better understanding of the generic or species concepts.

James L. Wee, Department of Biological Sciences, Loyola University New Orleans, Louisiana, USA

Journal of Phycology 44 (2008), p. 1360-1362

Review: CASTANEA Vol. 74 No. 1 top ↑

This book, the final installment of the series on freshwater algae of the southeastern United States, covers many of the lesser known algal groups. Dillard demonstrates thorough knowledge of the algae of the southeast as gleaned from floristic lists of algae in this very large region. The descriptions are based primarily on the literature, and the illustrations are also mostly redrawn from existing illustrated works of other authors. The author clearly indicates that many of the records have not been confirmed by him, but the work is nonethe- less critical for those studying algae of this region. If the eight volumes of this series are put together, they will likely make up the regional counterpart to Prescott’s Algae of the Western Great Lakes Region. They are region-specific, and very important for beginning and advanced algal taxonomists studying the algal flora of the southeast.

As someone who has studied the algal flora of a small part of the southeast, I can attest that the books by Dr. Dillard are critical for this effort. Floras from other regions are not really appropriate for this part of the United States. This flora is especially useful to me (and possibly others) because it covers a group of difficult taxa with which I have little expertise, and brings them together in a single volume. Many of these algae are small, unicellular or flagellated, rare, and poorly known, including: Akanthochloris, Amphichrysis, Bitrichia, Derepyxis, Bourrellia, Chadefaudiothrix, Chalkopyxis, Chrysidiastrum, Cyclonexis, Eirmodesmus, and Leuvenia (to name just a few). These taxa are well described and illustrated, and are clearly delineated in the keys.

Coverage of better known genera is also excellent. I found the treatments on Cryptomonas, Rhodomonas, Gymnodinium, Peridiniopsis, and Peridinium especially informative. It is also very helpful to have good treatments of the xanthophyte taxa Ophiocytium, Tribonema, and Vaucheria. By knowing which species in these genera have been reported from the southeast, it is easier to know when an unusual algal specimen is at hand.

There are no ecological notes on any of the taxa (e.g. trophic preference, habitat preference). For many taxa, the states in which they occur are given. For all taxa, at least one reference is given for original reports of the taxon from the southeast. The literature is exhaustive, and would greatly help a beginning phycologist assemble the difficult to find, off-the-internet floras for southeastern freshwater algae in the five classes covered in this book. While the text is not meant to be a revision, it appears that many of the new generic epithets proposed in recent years are used for the species reported.

In summary, the eighth volume on the Freshwater Algae of the Southeastern United States is an important addition to the phycological literature. It is critical for researchers in the southeast. Because of its modern coverage of rare groups, I would recommend the volume to any phycologist attempting to study algal floristics in North America.

Jeffrey R. Johansen, Department of Biology, John Carroll University, University Heights, Ohio 44118.

Castanea Vol. 74 No. 1

Contents top ↑

Introduction and reiteration of purpose 1
Key to classes 2
Class chrysophyceae 4
Subclass acontochrysophycidae 5
Subclass heterochrysophycidae 10
Subclass isochrysophycidae (Haptophyceae) 46
Class Xanthophyceaae 47
Class raphidophyceae (Chlormonadophyceae) 76
Class cryptophyceae 78
Class dinophyceae 83
Subclass dinophycidae 83
Addenda 100
Bibliography and literature cited 102
Index 118
Plates 127