Holotypes mark 2

Peggy made a statement that a lot of holotypes of CB. Adams are poor
quality specimens. Well this is true of a lot of the types of old
workers including C. Linnaeus, M.C.D. Lamarck, L. Reeve, A.A. Gould,
T.A. Conrad, I. Lea, G.B. Sowerby's I, II & III, J.E. Gray, E.A.
Smith, H. Crosse, C. Hedley, T. Iredale, H. Suter, F.W. Hutton, A. &
W.G. Binney, H.A. Pilsbry, G.W. Tryon, A. & H. Adams, R.A.
Philippi,  L. Pfeiffer, W.H. Dall among many others.

Type specimens also get broken, scratched, faded etc depending on a
great number of factors. Frequently the specimens the above authors
had at hand were the only ones known at the time, or were the only
specimens they or more often than not what friends, colleagues or
people otherwise interested in nature might have picked up on their
travels. When relying on other people to pick up things for you in
far off lands can be very rewarding but often you only get a glimpse
of what might be there. They may only have a brief period in between
what there doing to pick something up, or it basically fell on them
etc etc. For example one of the species of Tasmanian cave snail I
coauthored, is apparently quite common in the cave where it lives ( I
am yet to visit the cave) but the initial sample we received had 5
specimens because the person who picked them up thought that was more
than enough but he later learnt was not, eventually we got more
material which was used to formally name the species.

Colours can fade etc for example land snails in the genus Meridolum,
frequently have purple coloured lips, unfortunately this fades to
white over a period of time, regardless of whether the specimen is
kept in the dark or not. Also depending on how the specimen may have
been displayed over its life time is another consideration,
especially if the specimens are heading towards 200+ years old. For
example Helix jervisensis was named in 1832 by Quoy and Gaimard, but
they collected the actual specimen in 1826 from Jervis Bay, New South
Wales. They figured the specimen reasonably accurately except for the
colour of the actual snail was a little off, 181 years later the
shell is very faded and the bright red umbilical patch present in the
original illustration and present day specimens is virtually absent.

Art asked why can't we replace the poor/broken/faded/eroded holotypes
with a better specimen when it comes to hand. Well this simply is not
allowed. Because the idea of the type is to have a single specimen
that can represent the species concerned for time immemorial. If we
just replaced that specimen with a better specimen at some future
date we run the risk of another species being substituted, which
could lead to all sorts of problems from all sorts of angles
including taxonomic, conservation or legal issues. In addition it
would create an entire other set of potential problems including what
would be an acceptable number of times to replace such as specimen,
do you replace when a nicer coloured specimen is found, or one with
more or less ribs, smaller or larger than the original, is it
acceptable to replace specimen if the new one is merely 0.1 mm
larger. Do you replace the specimen in the collection where the
original is or can you simply say I now have the "holotype" specimen
because mind is better etc etc. So there is no way we want to go down
that path.

Choosing holotypes is something that should not be done lightly, eg
this specimen is the one that all future workers will use to make
sure that their specimens are the same as or different to when
identifying material if there is some problem. I have now chosen
roughly 200 holotypes so far and I have always tired to pick a
specimen that is typical of the material at hand, that is a nice
specimen and has most of the characters that can best distinguish the
species from other congers, it is virtually never the largest or the
smallest specimen. Often holotypes do not have the animal tissue
preserved, thus the specimen itself may not have all the characters
that completely distinguish it for example characters of the
reproductive system or the radula. For a couple of my new species of
land snail from my PhD I know the anatomy, radula, allozyme and DNA
data for that particular individual.

Stephanie



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Dr Stephanie A. Clark

Malacologist / Assistant Collections Manager
Chicago Academy of Sciences
4001 North Ravenswood Ave, Suite 201
Chicago, IL 60613-2576 USA
Phone: 1 (773) 477 4295 FAX: 1 (773) 755 5199
Mobile 1 (205) 310 9942
email [log in to unmask]

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