Mew / Short-billed Gull     Larus brachyrhynchus
Richardson  1831
U.S.A.: Alaska; Canada: Yukon, nw,s Mackenzie s to e British Columbia, n Alberta, c Saskatchewan and ne Manitoba
split from: Larus canus
insert after: Larus canus
Robert M. Zink, Sievert Rohwer, Alexander V. Andreev & Donna L. Dittmann,
Trans-Beringia comparisons of mitochondrial DNA differentiation in birds
The Condor 97 (1995): 639-649
 

Thayer's Gull     Larus thayeri
Brooks-WS   1915
Arctic archipelago; w Canada (winter); w U.S.A. (winter)
split from: Larus glaucoides
insert after: Larus glaucoides
American Ornithologists' Union,
Check-list of North American Birds. Sixth edition (1983)
 

American Herring Gull     Larus smithsonianus
Coues   1862
Canada; USA: Alaska, ne states; winters s to Panama
split from: Larus argentatus
insert after: Larus glaucoides
Pierre-André Crochet, Jean-Dominique Lebreton & François Bonhomme,
Systematics of large white-headed gulls: Patterns of mitochondrial DNA variation in western European taxa
Auk 119, 3 (2002): 603-620
 

Baraba Gull     Larus barabensis
Johansen   1960
Russia: sw Siberia; n Kazakhstan
split from: Larus cachinnans
insert after: Larus cachinnans
D. Liebers, Andreas J. Helbig & Peter de Knijff,
Genetic differentiation and phylogeography of gulls in the Larus argentatus-cachinnans-fuscus group
Molecular Ecology 10, 10 (2001): 2447-2462
 

Heuglin's Gull     Larus heuglini
Bree   1876
n Russia: nw Siberia, Kanin peninsula e to w Taimyr peninsula
split from: Larus argentatus
insert after: Larus argentatus
Pierre-André Crochet, Jean-Dominique Lebreton & François Bonhomme,
Systematics of large white-headed gulls: Patterns of mitochondrial DNA variation in western European taxa
Auk 119, 3 (2002): 603-620
 

East-Siberian Gull     Larus vegae
Palmén   1887
n Russia: n Siberia, from e Taimyr peninsula e to Chukotski peninsula, Anadyrland and Koryakland (nominate); cs Russia: se Altay Mts; n Mongolia; n China (mongolicus)
split from: Larus argentatus
insert after: Larus argentatus
Pierre Yésou,
Systematics of Larus argentatus-cachinnans-fuscus complex revisited
Dutch Birding 24, 5 (2002): 271-298
 

I am not very confident about a proper treatment of the larger gulls in these pages, and therefore try to deal with them cautiously.  It seems for decades now that breakthrough papers are in press, yet they never seem to materialize.

The interest in the larger gulls is big amongst amateur ornithologists, and seems to be on the rise even.  Needless to state that there is some pressure from the gullers amongst us for adding more taxa here.
Give me real references!

Yellow-legged Gull     Larus michahellis
Naumann   1840
France; Iberian Peninsula; Mediterranean basin
split from: Larus cachinnans
insert after: Larus cachinnans
R. Klein & A. Buchheim,
Die westlichen Schwarzmeerküste als Kontaktgebiet zweier Grossmöwenformen der Larus cachinnans-Gruppe
Vogelwelt 118 (1997): 61-70
 

Long-billed Murrelet     Brachyramphus perdix
(Pallas)  1811
Japan; through Sea of Okhotsk and Kamchatka Peninsula
split from: Brachyramphus marmoratus
insert after: Brachyramphus marmoratus
V.L. Friesen, J.F. Piatt & A.J. Baker,
Evidence from cytochrome-b sequences and allozymes for a ‘new' species of alcid: The Long-billed Murrelet (Brachyramphus perdix)
The Condor 98 (1996): 681-690