Chaetodon

Chaetodon is a tropical fish genus in the family Chaetodontidae. Like their relatives, they are known as "butterflyfish". This genus is by far the largest among the Chaetodontidae, with about 90 living species included here, though most might warrant recognition as distinct genera.

Species
There are currently 87 recognized species in this genus:

Chaetodon sensu stricto

 * Chaetodon capistratus Linnaeus, 1758 (Foureye butterflyfish)
 * Chaetodon ocellatus Bloch, 1787 (Spotfin butterflyfish)
 * Chaetodon striatus Linnaeus, 1758 (Banded butterflyfish)

C. robustus group

 * Chaetodon hoefleri Steindachner, 1881 (Four-banded butterflyfish)
 * Chaetodon robustus Günther, 1860 (Three-banded butterflyfish)

Lepidochaetodon group
Subgenus Exornator (including Burgessius, Heterochaetodon and possibly Rhombochaetodon; tentatively placed here)
 * Chaetodon citrinellus G. Cuvier, 1831 (Speckled butterflyfish, Citron butterflyfish)
 * Chaetodon dolosus C. G. E. Ahl, 1923 (African butterflyfish)
 * Chaetodon guentheri C. G. E. Ahl, 1923 (Crochet butterflyfish)
 * Chaetodon guttatissimus E. T. Bennett, 1833 (Peppered butterflyfish)
 * Chaetodon miliaris Quoy & Gaimard, 1825 (Millet butterflyfish)
 * Chaetodon multicinctus A. Garrett, 1863 (Pebbled butterflyfish)
 * Chaetodon pelewensis Kner, 1868 (Sunset butterflyfish)
 * Chaetodon punctatofasciatus G. Cuvier, 1831 (Spotband butterflyfish)
 * Chaetodon quadrimaculatus J. E. Gray, 1831 (Fourspot butterflyfish)
 * Chaetodon sedentarius Poey, 1860 (Reef butterflyfish)

Subgenus Lepidochaetodon (including Tifia)
 * Chaetodon daedalma D. S. Jordan & Fowler, 1902 (Wrought-iron butterflyfish) (tentatively placed here)
 * Chaetodon interruptus C. G. E. Ahl, 1923 (Yellow teardrop butterflyfish)
 * Chaetodon kleinii Bloch, 1790 (Sunburst butterflyfish, black-lipped butterflyfish, Klein's butterflyfish)
 * Chaetodon litus J. E. Randall & D. K. Caldwell, 1973 (Easter Island butterflyfish) (tentatively placed here)
 * Chaetodon nippon Steindachner & Döderlein (de), 1883 (Japanese butterflyfish) (tentatively placed here)
 * Chaetodon smithi J. E. Randall, 1975 (Smith's butterflyfish) (tentatively placed here)
 * Chaetodon trichrous Günther, 1874 (Tahiti butterflyfish)
 * Chaetodon unimaculatus Bloch, 1787 (Teardrop butterflyfish)

Subgenus Rhombochaetodon (including Roaops, might belong in Exornator; tentatively placed here)
 * Chaetodon argentatus H. M. Smith & Radcliffe, 1911 (Asian butterflyfish)
 * Chaetodon blackburnii Desjardins, 1836 (Brownburnie) (tentatively placed here)
 * Chaetodon burgessi G. R. Allen & Starck, 1973 (Burgess' butterflyfish)
 * Chaetodon declivis J. E. Randall, 1975 (Marquesas butterflyfish) (tentatively placed here)
 * Chaetodon flavocoronatus R. F. Myers, 1980 (Yellow-crowned butterflyfish) (tentatively placed here)
 * Chaetodon fremblii E. T. Bennett, 1828 (Blue-striped butterflyfish)
 * Chaetodon madagaskariensis C. G. E. Ahl, 1923 (Seychelles butterflyfish)
 * Chaetodon mertensii G. Cuvier, 1831 (Atoll butterflyfish)
 * Chaetodon mitratus Günther, 1860 (Indian butterflyfish) (tentatively placed here)
 * Chaetodon paucifasciatus C. G. E. Ahl, 1923 (Eritrean butterflyfish, Crown butterflyfish)
 * Chaetodon tinkeri L. P. Schultz, 1951 (Hawaiian butterflyfish) (tentatively placed here)
 * Chaetodon xanthurus Bleeker, 1857 (Pearlscale butterflyfish, Philippines chevron butterflyfish, yellow-tailed butterflyfish)

Megaprotodon group
Subgenus "Citharoedus" (tentatively placed here)
 * Chaetodon meyeri Bloch & J. G. Schneider, 1801 (Scrawled butterflyfish)
 * Chaetodon ornatissimus G. Cuvier, 1831 (Ornate butterflyfish)
 * Chaetodon reticulatus G. Cuvier, 1831 (Mailed butterflyfish)

Subgenus Corallochaetodon (tentatively placed here)
 * Chaetodon austriacus Rüppell, 1836 (Blacktail butterflyfish, exquisite butterflyfish)
 * Chaetodon lunulatus Quoy & Gaimard, 1825 (Oval butterflyfish, red-finned butterflyfish)
 * Chaetodon melapterus Guichenot, 1863 (Arabian butterflyfish) (tentatively placed here)
 * Chaetodon trifasciatus M. Park, 1797 (Melon butterflyfish)

Subgenus Discochaetodon
 * Chaetodon aureofasciatus W. J. Macleay, 1878 (Golden butterflyfish)
 * Chaetodon octofasciatus Bloch, 1787 (Eightband butterflyfish)
 * Chaetodon rainfordi McCulloch, 1923 (Rainford's butterflyfish)
 * Chaetodon tricinctus Waite, 1901 (Three-striped butterflyfish) (tentatively placed here)

Subgenus Gonochaetodon (tentatively placed here)
 * Chaetodon baronessa G. Cuvier, 1829 (Eastern triangular butterflyfish)
 * Chaetodon larvatus G. Cuvier, 1831 (Hooded butterflyfish)
 * Chaetodon triangulum G. Cuvier, 1831 (Triangle butterflyfish)

Subgenus Megaprotodon
 * Chaetodon trifascialis Quoy & Gaimard, 1825 (Chevron Butterflyfish, Triangulate butterflyfish, V-lined butterflyfish)

Subgenus Tetrachaetodon
 * Chaetodon andamanensis Kuiter & Debelius (de), 1999 (Andaman butterflyfish) (tentatively placed here)
 * Chaetodon bennetti G. Cuvier, 1831 (Bluelashed butterflyfish)
 * Chaetodon plebeius G. Cuvier, 1831 (Blue-blotched butterflyfish)
 * Chaetodon speculum G. Cuvier, 1831 (Mirror butterflyfish)
 * Chaetodon zanzibarensis Playfair (fr), 1867 (Zanzibar butterflyfish)

Rabdophorus group
Including Aspilurochaetodon, Chaetodontops


 * Chaetodon adiergastos Seale, 1910 (Philippine butterflyfish)
 * Chaetodon auriga Forsskål, 1775 (Threadfin butterflyfish)
 * Chaetodon auripes D. S. Jordan & Snyder, 1901 (Oriental butterflyfish) (tentatively placed here)
 * Chaetodon collare Bloch, 1787 (Redtail butterflyfish, Pakistani butterflyfish)
 * Chaetodon decussatus G. Cuvier, 1829 (Indian vagabond butterflyfish)
 * Chaetodon ephippium G. Cuvier, 1831 (Saddle butterflyfish)
 * Chaetodon falcula Bloch, 1795 (Blackwedged butterflyfish)
 * Chaetodon fasciatus Forsskål, 1775 (Diagonal butterflyfish, Red Sea raccoon butterflyfish)
 * Chaetodon flavirostris Günther, 1874 (Black butterflyfish)
 * Chaetodon gardineri Norman, 1939 (Gardner's butterflyfish) (tentatively placed here)
 * Chaetodon leucopleura Playfair, 1867 (Somali butterflyfish) (tentatively placed here)
 * Chaetodon lineolatus G. Cuvier, 1831 (Lined butterflyfish)
 * Chaetodon lunula (Lacépède, 1802) (Raccoon butterflyfish, Crescent-masked butterflyfish, lunule butterflyfish)
 * Chaetodon melannotus Bloch & J. G. Schneider, 1801 (Blackback butterflyfish)
 * Chaetodon mesoleucos Forsskål, 1775 (White-faced butterflyfish)
 * Chaetodon nigropunctatus Sauvage, 1880 (Black-spotted butterflyfish) (tentatively placed here)
 * Chaetodon ocellicaudus G. Cuvier, 1831 (Spot-tail butterflyfish)
 * Chaetodon oxycephalus Bleeker, 1853 (Spot-naped butterflyfish)
 * Chaetodon pictus Forsskål, 1775 (Horseshoe butterflyfish)
 * Chaetodon rafflesii Anonymous [Bennett], 1830 (Latticed butterflyfish)
 * Chaetodon selene Bleeker, 1853 (Yellow-dotted butterflyfish)
 * Chaetodon semeion Bleeker, 1855 (Dotted butterflyfish)
 * Chaetodon semilarvatus G. Cuvier, 1831 (Bluecheek butterflyfish)
 * Chaetodon ulietensis G. Cuvier, 1831 (Pacific double-saddle butterflyfish, false falcula butterflyfish)
 * Chaetodon vagabundus Linnaeus, 1758 (Vagabond butterflyfish)
 * Chaetodon wiebeli Kaup, 1863 (Hong Kong butterflyfish)
 * Chaetodon xanthocephalus E. T. Bennett, 1833 (Yellowhead butterflyfish) (tentatively placed here)

Incertae sedis
Most are probably either Chaetodon sensu stricto or C. robustus group.
 * Chaetodon assarius Waite, 1905 (West Australian butterflyfish)
 * Chaetodon dialeucos Salm & Mee, 1989 (Oman butterflyfish)
 * Chaetodon humeralis Günther, 1860
 * Chaetodon marleyi Regan, 1921 (Doublesash butterflyfish)
 * Chaetodon sanctaehelenae Günther, 1868 (Saint Helena butterflyfish)

Proposed subgenera
Several subgenera have been proposed for splitting out of this group. It is becoming clear how the genus might be split up, with a range of DNA sequence data in large parts agreeing with S.D. Blum's landmark 1988 phylogenetic assessment of osteology.

Basically, a core group around the type species Chaetodon capistratus would remain in Chaetodon, while maybe four clades would be split off. These could use the names Lepidochaetodon, Megaprotodon and Rabdophorus, and there is one unnamed group containing the three-banded butterflyfish (C. robustus) and its relatives. But the monophyly of the Lepidochaetodon group is not fully established; it is both unclear whether Rhombochaetodon is a lineage distinct from Exornator, and whether Lepidochaetodon is indeed closer to these than to any other Chaetodon, particularly to some lineages otherwise placed in Megaprotodon.

Prognathodes, for some time contained in Chaetodon, is worthy of recognition as full genus, as is Roa.

Historically, more distantly related fish were placed in Chaetodon too, for resembling them in details – e.g. the common scat Scatophagus argus, which has a similar shape and size, as well as armored larvae like the Chaetodontidae – or simply because they are colorful, smallish, and unusual-looking – e.g. the quite unrelated paradise fish, as C. chinensis.

The classification proposed in Fessler and Westneat is based on the species of Chaetodon they sampled and these sorted into the following clades:


 * Clade 1
 * Chaetodon robustus
 * Chaetodon hoefleri
 * Clade 2
 * Chaetodon kleini
 * Chaetodon unimaculatus
 * Chaetodon fremblii
 * Chaetodon burgessi
 * Chaetodon xanthurus
 * Chaetodon paucifasciatus
 * Chaetodon mertensi
 * Chaetodon quadrimaculatus
 * Chaetodon citrinellus
 * Chaetodon multicinctus
 * Chaetodon punctatofasciatus
 * Chaetodon pelewensis
 * Chaetodon sedentarius
 * Chaetodon dolosus
 * Chaetodon miliaris
 * Chaetodon guentheri
 * Clade 3
 * Chaetodon austriacus
 * Chaetodon trifasciatus
 * Chaetodon ornatissimus
 * Chaetodon reticularis
 * Chaetodon meyeri
 * Chaetodon larvatus
 * Chaetodon baronessa
 * Chaetodon trifascialis
 * Chaetodon rainfordi
 * Chaetodon octofasciatus
 * Chaetodon bennetti
 * Chaetodon plebius
 * Chaetodon speculum
 * Chaetodon zanzibarensis
 * Clade 4
 * Chaetodon ocellatus
 * Chaetodon capistratus
 * Chaetodon striatus
 * Chaetodon semeion
 * Chaetodon ephippium
 * Chaetodon selene
 * Chaetodon melannotus
 * Chaetodon ocellicaudus
 * Chaetodon rafflesi
 * Chaetodon auriga
 * Chaetodon vagabundus
 * Chaetodon collare
 * Chaetodon adiergastos
 * Chaetodon fasciatus
 * Chaetodon lunula
 * Chaetodon semilarvatus
 * Chaetodon lineolatus
 * Chaetodon oxycephalus
 * Chaetodon falcula
 * Chaetodon ulietensis

Fossil record
The oldest fossils that are usually assigned to Chaetodon date from the late Oligocene, about 25 million years ago. But since it is not easy to distinguish this genus from close relatives, it may be that the Oligocene fossils are actually of other Chaetodontidae. The fossil record of this family is scant indeed, only Chelmon (or some similar genus like Chelmonops or Coradion) being known from Miocene remains. As even crude molecular clocks suggest that the ancestors of the Chaetodon and the Chelmops lineage diverged in the Late Eocene already, nothing more can be said without new fossils being discovered.