[Taxacom] 75% rule for subspecies recognition

[Kenneth Kinman]

      I would second what Robin and others wrote.  It depends on the
group involved and a invoking a 75% (or any other percentage) rule on
any specific taxon is totally arbitrary and will probably cause big
problems in most cases.  I have studied spiders for decades (like Robin)
and monomorphic females are a big problem (as well as their males with
two or even three separate polymorphisms within single species).  
      My other major area of interest (mammals) is less ambiguous, but I
still would not invoke a general 75% rule on their subspecies either.
Such rules are generally so poorly conceived that they have very limited
applicability, and are more likely to cause more problems than they
solve.  Perhaps as Robin suggested, genetic data might be somewhat less
problematic than morphological, but even there trying to pin something
like a 75% rule might prove to be  problematic if you appy it too
rigidly.  "Rules are made to be broken".  Best to be flexible on such
things, depending on the taxon involved.     
         --------Ken Kinman       
    
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Robin Leech wrote:
Try many of the species of Embioptera.  Males are distinct, but females
are often identifiable to genus only.  The only sure way to determine
the species for the female is to find 
her in association with a male. 

We have similar problems in many spider species - males are distinct,
whereas a female, without the male association, often is not. 
Don't worry about rules - that's just the way it is. 
Perhaps you need to go beyond the usual morphological features and start
some genetic work. 
Robin