Holotype selection criteria

[Fabio Moretzsohn]

Dear all

I am studying some material (mollusks) that may or may not belong to an undescribed species. I have a good number of specimens (perhaps a few dozens) on hand, and maybe more are available, including freshly caught and preserved specimens (in alcohol). Hypothetically, let's assume it is indeed a new species and merits description as such. 

What are (the best) criteria for holotype selection, or how do you rank the criteria below (or others) in decreasing order of importance?
1) Specimen with the diagnostic characters most pronounced;
2) Specimen with preserved soft parts;
3) Specimen with most intact (complete) body (or shell in this case);
4) Most mature specimen;
5) Largest (or smallest, or most [something]) specimen;
6) Average specimen in size, coloration, etc;
7) Specimen with the best collection data;
etc.

All of the conspecific specimens studied constitute the type series. I am wondering if the non-conspecific specimens used in the original description for comparison have any special label (other than vouchers)? It seems to me that a later worker might be interested in finding them, but other than a list of specimens studied, I don't recall any particular label applied to non-conspecific material in the literature I am familiar with.

Cheers,
Fabio

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Fabio Moretzsohn, Ph.D.
Post Doctoral Research Associate
Center for Coastal Studies
Texas A&M University-Corpus Christi
6300 Ocean Drive, NRC 3208
Corpus Christi, TX 78412-5866
Phone: (361) 825-3230
Fax: (361) 825-2770
fabio at falcon.tamucc.edu