[Taxacom] Response to Dallwitz - part 1

Bob Mesibov mesibov at southcom.com.au
Tue Sep 8 19:16:16 CDT 2009

Hi, Mike.

It's easy for me to say we're talking at cross purposes here, but I don't think we are; we genuinely disagree. Part of that disagreement has to do with how complicated the subject is, and yes, I do think that's one of the reasons it isn't dragged through the wash like so many other Taxacom topics. Another point of disagreement is that you seem to be taking a particularly hardline approach. Please correct me if I'm misinterpreting, but your position seems to be

- unless a character can be explicitly defined as one that can be observed in mutually exclusive states, it isn't a proper character
- unless a description consists entirely of reports on characters of this kind, it isn't a proper description
- unless taxonomists produce descriptions of this kind, they aren't doing proper taxonomy.

You go on to criticise people who go down this route but fail, in your view ("... they generally don't succeed very well..."), and you regard identifying a specimen by comparing it with a description as an untrustworthy procedure ("...it's too easy to agree with the description (like a leading question)." More reliable, in the Dallwitz view, is to follow a structured key which has had non-reproducibility 'nipped in the bud' by being constructed a la http://mailman.nhm.ku.edu/pipermail/taxacom/2009-August/030098.html

Minor points first. Yes, of course, characters aren't apomorphic or plesiomorphic. I meant character states, and my point was that when an apparently apomorphic *state* is later recognised as a plesiomorphic *state*, then the *character* may get dropped from the description.

Second, I didn't get the impression that Watson was talking only about contemporary taxonomic publications. I don't see how he could have been, since *comparative* character data in a publication are only *comparative* when tested against other works, every one of which will have appeared before that new publication.

Third, your easy acceptance of images and their importance is interesting. You're happy to have images incorporated holus-bolus into descriptions and keys, but you want text to be treated differently: restricted to explicitly defined strings tested in particular ways. (I disagree because I'm happy to see less structured text in descriptions.)

Dr Robert Mesibov
Honorary Research Associate
Queen Victoria Museum and Art Gallery, and
School of Zoology, University of Tasmania
Home contact: PO Box 101, Penguin, Tasmania, Australia 7316
(03) 64371195; 61 3 64371195
Website: http://www.qvmag.tas.gov.au/mesibov.html

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