Interpreting the Code

In the October 2014 issue of Taxon there’s a nomenclatural article by John McNeill on holotype specimens and type citations.  It is definitely aimed at those in the thick of taxonomic nomenclature and herbarium work.  He attempts to clarify when the term “holotype” is to be used, and this is a case where timing seems to be everything, or at least crucial.  The problem McNeill addresses is that only since 1990 has there been a requirement that a single herbarium must be designated as holding the type specimen.  Before that time, type specimens, that is, material that had been used in the original work on naming and describing plant could be sent to several institutions.  After 1990 only one institution could hold a holotype, considered the specimen used in the description; all others are isotypes.  This is because, if there were several specimens in different places, how could one be sure of the specimen used in the description?  Well, usually one can’t be sure, which is the major point of McNeill’s article.  He gives very specific guidelines for when the term holotype can and cannot be used for older material.  This is just one example of the clarifications of the International Code of Nomenclature (ICN) that appear in almost every issue of Taxon.

Also in the October Taxon, is a Point-of-View piece by Erin Tripp and James Lendemer on naming taxa just on the basic of DNA sequences.  In the past, new species were described based on taxonomic information, along with genetic and ecological data, but recently a number of bryophytes and fungi have been named solely on the basis of DNA sequences.  In this brief paper, the authors suggest a set of guidelines that they hope will spur further work on this area in updating the ICN.  They begin by arguing that basing diagnoses and descriptions of taxa solely on molecular characters should only be done as a last resort, that is, when the investigation of nonmolecular characters are either not available or not informative.  And even though the morphological description is not diagnostic, it should still be included.  Also, data from two or more independent loci should be included.  These two items are followed by eight more, providing extensive details on the issue, just as McNeill did in his article.  That is why I’ve cited the two of them here.  To me, they are both good examples of how carefully botany is done so that only the best data gets published and so that names are as unambiguous as possible.

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