Paleonet: question about holotype specimens [SEC=UNCLASSIFIED]

[John.Laurie at ga.gov.au]

Dear Jere,

 

I believe your logic is at fault here. Let me give you an example: in the
1930s Whitehouse published a paper in which he described a new species of
agnostid, Phoidagnostus limbatus, and he designated a single cephalon as the
holotype. During the 1990s Peter Jell examined the specimen, did some
excavation and discovered a couple of thoracic segments and a pygidium. Using
your logic, those thoracic segments and pygidium could not be part of the
holotype, but must remain simply topotypes (a term of no formal status). If
you do, then you presumably also consider that if I designate a holotype of
say a ¾ cephalon and at some later stage excavate the remaining quarter which
is separated by, say, a crack, from the originally illustrated specimen, then
the portion subsequently excavated cannot be part of the holotype, despite
their adjoining edges matching perfectly and being adjacent to one another.

 

As you state, it all gets down to what constitutes a specimen. In this regard
it is perhaps pertinent to consider that we designate a holotype to avoid
ambiguity (as much as is possible) in the understanding of a species or
subspecies. The fact that one could consider part and counterpart of a single
sclerite of an individual organism (which must be of a single species) to be
both holotype, and not, is puzzling, to say the least, as they both must
belong to a single individual which must, by definition, belong to a single
species or subspecies. There is therefore no ambiguity in the definition of a
species or subspecies. If you would have part and counterpart of a single
individual sclerite as a holotype and not a holotype, you presumably would
also have the two halves of a sclerite broken during collection as holotype
and not a holotype also. If some later preparator comes along, recognises the
two go together and glues them together, then we have a specimen which at one
end is a holotype while at the other end it is a topotype.

 

John

 

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Dr John R. Laurie 

Petroleum and Marine Division 

GEOSCIENCE AUSTRALIA 
GPO Box 378         
Canberra ACT 2601       
Australia 
              
Tel: (02) 6249 9412; Fax: (02) 6249 9980 
E-mail: John.Laurie at ga.gov.au 

Street Address: 
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Symonston ACT 2609 

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