Maximum Taxon names within a single Parent

Richard Pyle deepreef at BISHOPMUSEUM.ORG
Fri May 24 02:45:49 CDT 2002

> There certainly is! The genus Hieracium contains far more than
> 5000 species, it is routinely devided into subgenera and sections
> but some of the latter are still very large, e.g. H. sect.
> Hieracium contains more than 570 species in Sweden alone.

Thanks to Torbjörn, and to the many people who responded off-list!  I've
never participated in a Taxacom thread in which I didn't learn something
new, and this was certainly no exception.

I know my original question was a bit out of left-field, but I'd like to
follow up a little more, with some elaboration of why I'm asking.

Specifically, I need to know what the maximum number of "valid" child-level
taxon names included within a single, most proximal parent-level taxon name
that have ever been, or likely ever will be, cited within a single
reference. The number of taxon names regarded as junior synonyms within the
Reference don't matter, and it also doesn't matter if a reference included
e.g. 5,000 species within a genus, as long as those species are subdivided
into intermediate groupings (i.e., subgenera, sections, etc.). The number
I'm looking for is the maximum number of child-taxa (at any rank) within the
most proximal, direct parent-taxon (at any rank), as cited in a Reference.

Now, here's more elaboration on why I'm asking:

Throughout much of the history of taxonomic nomenclature, many authors of
References have attempted to convey/assert their interpretations of
phylogenetic placement of same-rank taxon names by listing those names in a
non-alphabetical sequence within their respective parent taxon names. For
instance, in many published fish checklists, the families are arranged in
some sort of "phylogenetic" sequence, rather than simple alphabetical order.
I would like to provide a means in my database of capturing this
sorting-within-parent information, as asserted by authors of said
references.  In the vast majority of cases, this practice of conveying
phylogeny through name seqencing is limited to the rank of family and
higher.  However, there are some taxonomic references that have extended the
practice to lower-level ranks as well.

I want to ensure that the database design does not ever limit the ability
for storing this sort of information, so I want to err on the side of
increased capability.  However, for very technical reasons that I won't
elaborate on here (but would be happy to discuss off-list with anyone who is
interested), the smaller the number I allow, the better the database
performance and storage efficiency will be. Again, for technical reasons,
there are several "threshold" values for this number, the first of which was
256 (clearly not sufficient).  The complete set of threshold values are:


According to the off-list responses I've received, the current front-runner
for "species-within-genus-without-intermediate-groupings" is in the range of
about 1,500 -- so this means I'd probably go with the option that provides
me with 4,096 values (unless, of course, some author has previously or will
someday list all 5,000 species of Hieracium non-alphabetically and without
reference to subgeneric groupings...).

However, because the phylogenetic sorting pracice usually involves taxa at
the rank of family and above, I'm also entertaining the idea of designing
the system with smaller/simpler threshold values for ranks of family (or
perhaps genus) and higher; and a larger threshold for species and perhaps
Genus as well. follow-up questions to this list are:

1. What threshold value is "safe" for ranks of family and higher?  Would 256
cover me for for all these ranks, or should I opt for 1,296?
2. Same question, but for Genus-level ranks (incl. subgenus, section, etc.).
Would 1,296 safely cover me, or should I go with 4,096?
3. Same question, but for species-level ranks. Is 4,096 enough, or should I
bump it up to 32K?

Many thanks again to those who have expressed an interest in this question,
and my apologies to those who see it as inbox clutter...


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