[Taxacom] Very bad paraphyly

Joshua A. Ludtke joshualudtke at gmail.com
Mon Apr 6 12:15:22 CDT 2009

Ken and taxacom,

I haven't read the Mares et al. 2000 paper or ...to be honest, heard
of this taxonomic situation until your email a few hours ago. So this
is me talking from ignorance, and from stuff I read on wikipedia. My
understanding thus might be reaaaaal low, and, for all I know, your
inclination that they are all the same species might be accurate.

Wikipedia says that Tympanoctomys (102 chromosomes) and Pipanacoctomys
(92 chromosomes) are tetraploid organisms, possibly descended from
Octomys mimax (56 chromosomes). The different chromosomal counts of
the descendant taxa from the parental species obviously mean, at the
least, that they are reproductively isolated and should be recognized
as different species. But what level of taxa is the one that
taxonomists can agree on as being sufficient to distinguish these
organisms from Octomys? Obviously monotypic genera are intellectually
annoying, but what is the better solution?

The potential solutions my brain comes up with are:
1) dump all three of these species into one genus (which is what
Walker's mammals of the world 5th ed did for Tympanoctomys)
2) demote the new taxa into subgenera of Octomys

Neither of which sounds satisfactory to me but I'm interested in
hearing what the listserv thinks.

Joshua Ludtke
PhD student
University of Calgary
Department of Biological Sciences
2500 University Drive NW
Calgary, AB T2N 1N4

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