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Diatoms of the United States is now known as Diatoms of North America.
This site has been redesigned and updated, and will be closing soon.



You misidentified a species, will you correct it?

If a contributor has missed something, we would like to hear about it. Please contact us with the original literature citation with a written explanation of the error. We plan for the contributor of each taxon page to manage and be responsible for that page, and make corrections over time. When the contributor makes a taxonomic correction (or transfer, or other change), we will post an entry on the taxonomic update page to document changes to that taxon. That log will document all changes to the species name.

This site would be better if the taxa were arranged according to evolutionary relationships. Why did you use the awkward scheme of “morphological groups” rather than diatom lineages?

We agree that it would have been preferable to organize the navigation of the site based on biological relationships, rather than similar morphological features. In fact, early in the stages of the site development we worked to incorporate a consensus phylogenetic tree of diatoms. We found, however, that there is still so much uncertainty in understanding relationships of diatoms that our tree was rather useless for organizing a web site. As knowledge in the field of systematics advances, we would like to incorporate phylogeny.

When I compare the synonyms for one of your species with those in another reference, I see that more synonyms are listed in the other reference. How do you determine what synonyms to include?

We rely on our expert contributors to determine the relevant nomenclatural synonyms to include on each species page. We consider the relevant synonyms to be those that analysts might typically encounter. A more complete list of nomenclatural synonyms is available under the California Academy of Sciences link, under the CITATIONS tab. We also names that may be subjective synonyms next to the REPORTED AS field.

When I learned diatom taxonomy, I learned the name Achnanthes minutissima. There have been so many name transfers and changes that I can’t keep up. I don’t know what this diatom is called now, and furthermore, all taxonomists do is cause trouble for the rest of us. How is your site of use to me?

If you use the taxon search box (on the upper right of every page), you can search for a species by the old name (Achnanthes minutissma), the more recent name (Achnanthidium minutissimum), or any part of the name (minu).  We include also notes about the species groups that have been transferred in the text of the genus pages. We know that taxonomists sometimes get a bad rap, but we hope to make searching easier.

Some descriptions and images of genera are missing from your site. Why didn’t you include them?

Genera are missing because the site organizer did not know enough, or understand the features of the genus, or have adequate images. If you are working on one of these genera and would like to have it included, please contact us to discuss adding information to a particular genus page, with you listed as a contributor.

How did you choose the species to include on the site?

Our work plan for developing the content of the site is based on starting with the 350 most common species in the USGS NAWQA database, also called the ANSP NAWQA list. There are approximately 1700 names in the list and it includes species identified from flowing waters of the U.S. Our priority is to begin with the most common species and species that are easily confused with the common ones. During a workshop held in January 2010, we found that for every one common species that we include on the site, we need to include 5-6 other species so that analysts should consider in making an identification. Since that time, contributors have added hundreds of species found in U.S. freshwaters.

What are the species "observations" based on?

Contributors have been asked to document their observations based on U.S. specimens. Observations from other published works are not necessarily included. For example, contributors do not include size ranges reported in Patrick and Reimer (1966) for a taxon. We do expect that the observations section will change over time as the contributor keeps the information current. When a significant change (content or taxonomic transfer) to the text is made, those changes will be recorded in the taxon update page. Note that taxon update pages are not visible unless a change has been made.

Can I contribute a “species page”?

We welcome new contributors! We tested the process of working with several new contributors and the Editorial Review Board. Instructions for new contributors are now posted in the SPECIAL NEWS section of the ABOUT page. We hope to expand the number of contributors, including diatom analysts working in different regions of the country.

 I am working on a large regional study, and I would like to include species from my area on this site. How do I do that?

One of the requirements that the Editorial Review Board provided is that specimens that appear on the site (their image) must be available in public herbaria. We hope to assist ecologists and managers in depositing their collections in a herbarium (Academy of Natural Sciences of Drexel University, California Academy of Sciences, University of Montana Herbarium, etc.). Please contact us about the process getting your collection into a public herbarium and then posting taxon pages for the species in your region.

Do you plan to include diatom species from other parts of the world?

This site began as a regional site, to cover the western United States and then expanded to national coverage of the US. We do include a number of freshwater and fossil genera that do not occur in North America, and we would like to include a more complete treatment of the freshwater genera. In terms of species, however, we will only include those species (and images) from US specimens.

Who are the people on the Editorial Review Board, and how are the taxon pages reviewed?

Details on the members of the board and their activities are contained on the ABOUT page.

Because the site undergoes scientific review by the Editorial Review Board, can new species be validly published here?

Not yet. Although the body that oversees the publication of species, the International Code of Nomenclature for algae, fungi, and plants (ICN), accepted online publications as sites of valid publication in 2012, we do not yet have the structure in place for publication. If you are interested in seeing the Diatoms of the United States become more like an online journal, please contact an Editorial Review Board member and get involved.

Will you post species that have not yet been described?

Yes. Although the site is not appropriate for publication, we will post species that have not yet been described (i.e., Puncticulata sp. #52). We hope that analysts, particularly those working with federal programs, will contact us about posting species that they observe in their analyses and need to use in environmental assessment. Pending obtaining of funding, we would like to hold a workshop to familiarize analysts with the system and elements needed for becoming an expert contributor.

The diatom species identifications on your site do not agree with Krammer and Lange-Bertalot (1986-1991). Who is right?

A primary goal of this project is to provide up to date, accurate taxonomic information for species in the United States, using images from the US. The light micrograph images of US populations form the basis for documenting this US flora. We start with US specimens and move forward by adapting to reflect current names for the "entities" in this geographic region. A number of publications have shown the that the US contains a distinct flora. What would you rather use to identify trees in the US, “Trees of Central Europe” or “Trees of the Western US”? Rather than the static nature of a publication, this site has been designed to grow, expand, and change with new knowledge.

What about including Integrated Taxonomic Information System (ITIS) codes?

We hope to include the ITIS taxon code (TSN) in the future.


If you can't find an answer to your question on this page,
please Contact Us.



I would like to use some of the images from your site, is that okay?

Please see the copyright page.

I noticed some mistakes in the text in your site. Do you want to know about them?

YES! Even though the text has been reviewed by at least two people, we may not notice errors before posting on the site. Please contact us about errors. For minor errors (typographic and spelling) it would be helpful if you send the URL of the page, along with noting the error. For taxonomic errors (authorship, morphology, missing references) we also need to have a reference citation to document the correction and make an update to the website. We encourage notes about corrections and will respond in a timely manner.

Do you have an iPhone app for the site?

We do not have an app, but you can view and use the site through your browser on your iPhone or other smartphone.  A mobile-optimized version of the website is more realistic goal for us in the future than an iPhone app.  Such an optimized website would work better on the small screen of a mobile device, requiring less zooming.  If such a website would be helpful to you, please contact us and provide specifics.

Does the site work on the iPad?

Yes, it works pretty well in both portrait and landscape orientations.  The only tricky part is that some links were designed for mouse use and may not behave as expected on the iPad.  In particular, the main navigation tabs and many of the genera and species images were designed so that more information would appear automatically when your mouse rolled over them.  Clicking those tabs or images would then take you to another page.  To mimic that behavior on the iPad, there are two kinds of taps.  A "short" tap on the main navigation tabs or the images will bring up more information.  A "long" tap will bring up a dialog asking if you want to open the new page directly or as a new page.  BTW, these two kinds of taps work the same way on the iPhone.



Can I obtain your database structure and code to set up my own web site for my region of the world?

The current code is fairly customized and requires specialized knowledge.  Please contact us with inquiries. Freshwater Algae of the United States? Marine Diatoms of the World? Great works remain.