nomenclature precedence

[Colin Smith]

Hi 

Could someone help me with the following problem?  Please return e-mails to the list or blackstn at edgehill.ac.uk. 

In a recent paper author X states that author Y (published in 1821) failed to give a clear definition of a taxon (plant).  Author X therefore re-names this taxon using what he considers to be the first validly published name.  However, author Y refers to an earlier plate (published in 1820) which author X accepts as representing a pure specimen of this taxon (indeed author X even lectotypifies the taxon with this plate).  Was author Y required to give a full description in order for his name to be validly published given that the plate he refers to is accepted as an accurate representation of this taxon?  In other words should I use the modern name or the 1821 name in my work.

Cheers

Nigel Blackstock