Dear Richard,

I have a couple of comments/questions:

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The taxon concept is considered the use of a species concept in literature, so that equals your definition, however, the issue of taxon concepts is very much a botanic subject.

I'm not sure I understand the difference between a "species concept" and a "taxon concept", in your quote above.

If I understand your prior remark: "but in general we understand as species concept the species name plus the associated subjective synonyms" -- I think this is the same as the "taxon concept", but taken to a resolution involving only name-bearing type specimens. I do not see any difference between a zoologist's "species concept" and a botanist's "taxon concept" -- they are all taxon concepts. In all cases, a "concept" is a set of multiple individual organisms, representing a subjective scope of biodiversity to which a scientific name is applied. How that scope is communicated (e.g., via synonym names as surrogates of their respective name-bearing types; or by a broader spectrum of non-type specimen material; or by character descriptions; or whatever) is necessarily variable, but they are just different ways of defining the boundaries of a circumsctiption of organisms. Same for botany and zoology. Also, the connection with literature is not so much (in my mind) a definitive attribute of a taxon concept. Rather, it is the easiest way to *refer* to an implied taxon concept. So the literature is not part of the concept -- just part of a convenient way of representing a concept in short-hand notation (and also representing a cross-reference to documentation that will in most cases further describe the boundaries of the concept).

From a zoological perspective I fully agree with your comment that species concept and taxon concept are equivalent; in zoology there is indeed no difference how the scope of a concept is communicated (therefore I said that in zoology the taxon concept is more implicit and often merged to the species concept). From a botanical perspective I am not so sure if species concept and taxon concept can be understand as fully equivalent because from the work of Mark Geoffroy I remember that in botany every observation counts, meaning that even when the taxonomy (synonymy) in two publications is similar, but both publications include dissimilar observations both publication can be understood to cover different taxon concepts.

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• However, an unique species name id can be easily artificially

created by merging both generic and epithet id's (a trick we also use for Species2000).

By this, do you mean that combinations *other* than the original combination are stored in Fauna Europaea? If so, then are they simply indicated as a direct link between two naked names; or is the link qualified in some way with a "source" (e.g., some publication or expert's assertion that the genus name and species epithet are linked)?

The 'other' combinations stored in Fauna Europaea aside the original combinations are the currently accepted species names.

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For practical reasons I think the starting point for assigning GUIDs should be basically nomenclatural.

I completely agree -- but again, what gets a "Name" GUID? (as opposed to a "usage" GUID or a "concept" GUID) Only basionyms? (I hope!) Or also different combinations? (I hope not!) Or also spelling variants? (I *really* hope not!!) There is also a problem of how to deal with autonyms (=nominotypical names in zoology). One GUID, or two? Logically, only one -- but most people don't do it that way.

These are some of the most fundamental questions that need to be addressed before any universal GUID system can be implemented.

I think zoologists would like to focus on basionyms (and for them a basionym is already a concept proceeding from the name elements), botanist would like to focus on concepts (and for them basionym are already the really minimal name units).

Kind regards,

Yde