Holotype fragment (botany)

Guido at Guido at
Thu Jan 12 11:43:41 CST 2006

By definition the holotype is the specimen used by the author to describe the
taxon. When a part of that holotype is split of at that time (or later on) and
transferred to another herbarium, it still is material used to describe the
taxon and thus fits the definition. Art. 8.1 of the ICBN states that the
holotype is 'a single specimen conserved in one herbarium' and for that reason
the separated material might be called an isotype (though effectively used for
the first description and evidently deserving some other 'status' than isotypes
not seen by the author). The ICBN also states that 'a specimen is usually
mounted on a single herbarium sheet' (art. 8.2). As 'usually' is 'not always',
the exceptions are clarified as 'a specimen may be mounted as more than one
preparation, as long as the parts are clearly labeled as being part of that same
specimen (Art. 8.3). 'Clearly' may have different meanings depending on the
extend one is familiar with the concerning annotations but anyway the parts have
to be in 'one herbarium' as says art. 8.1.
There remains some dispute whether this separated holotype part should be called
a holotype fragment or an isotype. The term 'holotype fragment' (which is not
the same as 'holotype' and clearly indicates a segregation act) is not defined
by the ICBN.

Guido Mathieu
Peperomia Research Group
Department of Biology
Ghent University
K.L. Ledeganckstraat 35,
B-9000 Gent. Belgium

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