Taxonomic
Relationships of the Cormorants
modified after Johnsgard P. A.
- 1993
Cormorants, Darters and
Pelicans of the World.
Smithsonian Institution Press, Washington and London.
In his taxonomic treatment of the
cormorants, Ogilvie-Grant (1898) recognized only a single genus Phalacrocorax,
and his linear sequence of the 36 species was seemingly one of
convenience, based on the construction of his identification key.
Thus, little value is gained by discussing it in detail, and
instead one may pass on to the widely adopted classification by Peters (1931). In addition to Phalacrocorax,
Peters accepted Nannopterumas a
monotypic genus for the flightIess cormorant, and generically
separated four species of very small, short-bilIed cormorants as Halietor.
Although accepting a considerable number of now-discarded
subspecies, he admitted a total of only 30 species in the entire
family.
Van Tets (1976a) provided what might well be
regarded as the first biologically meaningful classification of
the cormorants as part of a zoogeographic analysis of the
family's probable origins. Van Tets subdivided the family into
two approximately equal genera, Phalacrocorax("cormorants") and Leucocarbo("shags"), with a total of 34 extant species
exclusive of the extinct Pallas' cormorant, which he didn't take
into account. Van Tets offered a number of morphological and
biological criteria for his generic separation. He furthermore
divided each of these two genera into a total of five subgenera,
the shags consisting of two subgenera (Leucocarbo
and Stictocarbo), and
the cormorants consisting of three (Phalacrocorax,
Hypoleucus, and Microcarbo,
with the last-named subgenus corresponding to Peters's genus Halietor.
The most recent and by far the most fully
documented of the available classifications of the
Phalacrocoracidae is that of Siegel-Causey(1988), which is based on a cladistic
analysis using quantitative osteological characters. His
resulting proposed classìfication accepts 37 species and bears a
considerable number of similaritìes to that of van Tets.
However, instead of dividing the family into two genera, he
accepts two subfamilies, the overall composìtions of which are
very similar, and also recognízes a total of nine genera. In
several cases these genera correspond to the subgenera of van
Tets, but the large subgenus Leucocarbo as
proposed by van Tets was subdivided by Siegel-Causey into five
genera.
The revision of the Phalacrocoracidae by Dorst and Mougin (1979) may be thought of as a compressed
variation on that proposed by van Tets. These authors reduced van
Tets's proposed genus Leucocarboto
a subgenus and accepted only 29 species, all within Phalacrocorax.
Sibley and Monroe's recent (1990) taxononomy of the
cormorants accepted 38 species, all of which they likewise
included within the single genus Phalacrocorax.
Sibley and Monroe further reported that Sibley's DNA
hybridization results do not support a "diversity of
relationships" such as the two subfamilies and nine genera
proposed by Siegel-Causey, although they did adopt his suggested
sequence of species.
Note:
(1) Subgeneric allocation uncertain; possibly part of Stictocarbo. (2) Identified as component members of superspecies groups.
(3) Considered as possibly conspecific with pygmaeus. (4) Exclusive of perspicillatus, which was not
considered by van Tets. Comments in a recent handbook (Marchant
& Higgins, 1990) indicate that van Tets now admits five
genera in two subfamilies (Phalacrocorax and Microcarbo
in the Phalacrocoracinae, plus Nannopterum, Stictocarbo, and
Leucocarbo in the Leucocarboninae). His genus Phalacrocorax
thus encompasses Siegel-Causey's Hypoleucus, and his
genus Nannopterum includes most of the forms separated by
Siegel-Causey as Compsohalieus,Notocarbo, Nesocarbo, and Euleucocarbo.
The remaining three genera correspond to van Tetss prior
subgenera as listed above. Sibley and Monroe (1990) accepted 38
species, all included in Phalacrocorax. (5) This list does not include P. kenyoni a new
species described by Siegel-Causey in 1991.
References:
Dorst J. & Mougin J. L . 1979. Order
Pelecaniformes. Pp. 155-93, in: E. Mayr and G. W. Cottrell
(eds.), Check List of Birds of the World, vol. L 2d ed. Museum of
Comp. Zool., Cambridge, Mass.
Marchant S. & Higgins P. H. (eds.).
1990. Handbook of Australian, New Zealand and Antarctic birds.
Vol. l. Oxford Univ. Press, Melbourne.
Ogilvie-Grant W.R. 1898. Steganopodes. pp.
329-484, in: Catalogue f the birds in the british Museum, vol.
26. British Museum (Nat. Hist.), London.
Peters J. P. 1931. Check-list of the birds
of the world. Vol. I. Harvard Univ. Press, Cambridge.
Sibley C. G. & Monroe B. L. Jr. 1990.
Distribution and taxonomy of birds of the world. Yale Univ.
Press, New Flaven.
Siegel-Causey D. 1988. Phylogeny of the
Phalacrocoracidae. Condor, 90(4): 885-905.
Siegel-Causey D. 1991. Systematics and biogeography
of north Pacific shags, with a description of a new species.
Occasional papers of the Museum of Natural History (Lawrence,
Kansas: The University of Kansas), 140 : 1-17.
van Tets C. F. 1976. Australasia and the
origin of shags and cormorants, Phalacrocoracidae. Pp. 121-124,
in: Proc. 16th Inter. Ornith. Congr., Canberra, Australia, 1974.
In his taxonomic treatment of the
cormorants, Ogilvie-Grant (1898) recognized only a single genus Phalacrocorax,
and his linear sequence of the 36 species was seemingly one of
convenience, based on the construction of his identification key.
Thus, little value is gained by discussing it in detail, and
instead one may pass on to the widely adopted classification by Peters (1931). In addition to Phalacrocorax,
Peters accepted Nannopterum as a
monotypic genus for the flightIess cormorant, and generically
separated four species of very small, short-bilIed cormorants as Halietor.
Although accepting a considerable number of now-discarded
subspecies, he admitted a total of only 30 species in the entire
family.