''Chroicocephalus'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of medium to relatively small

gull Gulls, or colloquially seagulls, are seabirds of the subfamily Larinae. They are most closely related to terns and skimmers, distantly related to auks, and even more distantly related to waders. Until the 21st century, most gulls were placed ...

s which were included in the genus ''

Larus ''Larus'' is a large genus of gulls with worldwide distribution (by far the greatest species diversity is in the Northern Hemisphere). Many of its species are abundant and well-known birds in their ranges. Until about 2005–2007, most gulls ...

'' until genetic evidence published in 2005 showed that ''Larus'' as then constituted was

paraphyletic Paraphyly is a taxonomic term describing a grouping that consists of the grouping's last common ancestor and some but not all of its descendant lineages. The grouping is said to be paraphyletic ''with respect to'' the excluded subgroups. In co ...

. Ten species are currently accepted. The genus name ''Chroicocephalus'' is from

Ancient Greek Ancient Greek (, ; ) includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Greek ...

''khroizo'', "to colour", and ''kephale'', "head".

Taxonomy

The species now placed in this genus were formerly assigned to the genus ''

''. A

molecular phylogenetic Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...

study published in 2005 found that ''Larus'', as then constituted, was

. In the resulting rearrangement to create

monophyletic In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent co ...

genera, the genus ''Chroicocephalus'' with resurrected to contain a clade of species, all of which have black heads. The genus ''Chroicocephalus'' had been introduced in 1836 by the English naturalist Thomas Campbell Eyton. Although he listed two species in the new genus, he did not specify a

type Type may refer to: Science and technology Computing * Typing, producing text via a keyboard, typewriter, etc. * Data type, collection of values used for computations. * File type * TYPE (DOS command), a command to display contents of a file. * ...

. In 1840 George Gray designated the type as ''Larus capistratus'' which had been described by

Coenraad Jacob Temminck Coenraad Jacob Temminck (; 31 March 1778 – 30 January 1858) was a Dutch people, Dutch patrician, Zoology, zoologist and museum director. Biography Coenraad Jacob Temminck was born on 31 March 1778 in Amsterdam in the Dutch Republic. Fro ...

in 1820. This taxa is now considered to be a

junior synonym In taxonomy, the scientific classification of living organisms, a synonym is an alternative scientific name for the accepted scientific name of a taxon. The botanical and zoological codes of nomenclature treat the concept of synonymy differently. ...

of ''Larus ridibundus'', the

black-headed gull The black-headed gull (''Chroicocephalus ridibundus'') is a small gull that breeds in much of the Palearctic in Europe and Asia, and also locally in smaller numbers in coastal eastern Canada. Most of the population is migratory and winters fu ...

, that had been named in 1766 by

Carl Linnaeus Carl Linnaeus (23 May 1707 – 10 January 1778), also known after ennoblement in 1761 as Carl von Linné,#Blunt, Blunt (2004), p. 171. was a Swedish biologist and physician who formalised binomial nomenclature, the modern system of naming o ...

. The genus name ''Chroicocephalus'' combines the

χρωικος/''khrōikos'' meaning "coloured" with -κεφαλος /''-kephalos'' meaning "-headed". Saunders's gull was formerly included in this genus until a 2022 study demonstrated that although it occupied a basal position in the genus, it was not closely related to the other members. It is now placed in its own genus ''Saundersilarus''.

Description

The species range from 28 cm up to 48 cm long, with Bonaparte's gull being the smallest, and

Andean gull The Andean gull (''Chroicocephalus serranus'') is a species in subfamily Larinae of the family Laridae, the gulls, terns, and skimmers. It is found in Argentina, Bolivia, Chile, Colombia, Ecuador, and Peru.Remsen, J. V., Jr., J. I. Areta, E. ...

the largest. In all species, the body and tail are white, and the upperwing pale grey; the wingtips have distinct grey, white, and black patterns important for identification. Several have distinctively brown, pale grey, or blackish-grey coloured heads in the breeding season, but some also have the head pure white like the rest of the body. The eyes are dark in some species, or with a distinctive white iris in others; the legs and bills are bright to very dark red. Representatives of this genus are found in regions/subregions all over the world, except for Antarctica; the species are often parapatric, but with two species together in New Zealand, the Mediterranean region, parts of southern Africa, and parts of South America. Exceptionally, three species (black-headed, brown-headed, and slender-billed gulls) can occur together in parts of southwest Asia.

Species

The genus contains ten species.

Fossils

* Huahine gull †''Chroicocephalus utunui'' -French Polynesia.

References

{{Authority control Bird genera Taxa named by Thomas Campbell Eyton