Ratio of valid to invalid (REPORT)

[christian thompson]

Sorry to be slow, but another set of statistics from a megadiverse group.

We are building a BioSystematic Database of World Diptera. Our nomenclator
(=name checker) is online at www.diptera.org under the names section. We now
have about over 2/3 of the estimated 150,000 species group names in the
system; all family-group and genus-group names are in the system.

The synonymy rate for the species data in the BDWD is for 105,396 names,
87,191 are valid (or 17% are synonyms), for genera, out of 21,089 names,
only 11,289 are marked as valid (or 46% are synonyms).  The average number
of species per genus is about 13.  In part, this reflect a conservative
trend in some important groups, like mosquitoes, not to split.  Genera like
Culex (759 spp.), Anopheles (437), Aedes (957) contains hundreds of species
(the genus Tipula is believe to have over 2,000 species in it, but we have
finished that one yet!)

And finally, it should be noted the only scientist who ever proposed a
scientific, logical, consistent method of ranking taxa so that comparisons
could be made was Willi Hennig, a dipterist. Unfortunately his proposal has
never been accepted (rank = age of clade / group). Had his proposal been
accepted then one could tell from these statistics, etc., rate of evolution,
character divergence, etc.

Oh, well ...





F. Christian Thompson
Systematic Entomology Lab., ARS, USDA
Smithsonian Institution
Washington, D. C. 20560-0169
(202) 382-1800 voice
(202) 786-9422 FAX
cthompso at sel.barc.usda.gov
visit our Diptera site at www.diptera.org