In an important paper in Notornis 40(1993):145-162, David Medway considered
the identity of the "Chocolate Albatross" of Latham,1785, which is the
basis of J.F.Gmelin's Diomedea spadicea 1789, and concluded that it can be
identified with Diomedea dabbenena Mathews,1929. Gmelin's spadicea would
presumably be a nomen oblitum, since no-one has used it since
G.R.Gray,1849. He also considers the type of Linnaeus's Diomedia exulans
1758.
On page 156, Medway states:"The Diomedea exulans of Linnaeus would be
completely worthless as an acceptable name for a specific albatross taxon
had he not included the "Albatross" of Edwards,1743-51 among his literature
references for the species he was attempting to describe." Medway goes on
to compare the measurements given by Edwards with those of various
Albatross taxa and concludes:"It so happens, therefore, that rather than
being or dabbenena, or the recently described antipodensis or gibsoni, or
being indeterminable as to population (Bourne 1989:113),the albatrosses
described by Edwards can be safely identified on the basis of the only
available and acceptable evidence as being of the larger souther
populations of the Wandering Albatross."
This is fine as long as the "larger souther populations of the Wandering
Albatross" are assigned to one species or subspecies. But in the paper by
Robertson and Nunn,1998, in Albatross Biology and Conservation, p.17, they
present a phylogenetic tree derived from the complete cytochrome-b gene
sequence of 24 taxa. Not only does this split the larger southern
populations into two distinct species, exulans Linnaeus,1758 and
chionoptera Salvin, 1896, but the tree places chionoptera as a sister
species of amsterdamensis. The node combining both these taxa is closest
to a node containing gibsoni and antipodensis. Finally, the node which
includes all the four preceding taxa forms a sister species with exulans.
Gale,1998, in the same book, incidentally, does not recognise chionoptera
as distinct from exulans.
If chionoptera is split from exulans, then Edwards's bird appears to be
indeterminable between these two taxa. And that, in turn, following
Medway's reasoning, would make exulans Linnaeus 1758 indeterminable.
It is a pity that Robertson and Nunn do not give us more of their data. It
would have been good if they had included the matrix of percentage
differences between taxa. It would also have been good if they had used
Neighbourhood Joining to compute Bootstrapping values, which would tell us
how much confidence to have in the proposed tree.But if their tree can be
validated, it appears that exulans Linnaeus 1758 IS indeterminable.
Any thoughts????
John Penhallurick
Associate Professor John M. Penhallurick<>
Canberra, Australia
Phone BH( 61 2) 6201 2346 AH (61 2) 62585428
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