The Apogonoidei is a

suborder Order () is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and recognized ...

of gobiiform fish consisting of two families: the

Indo-Pacific The Indo-Pacific is a vast biogeographic region of Earth. In a narrow sense, sometimes known as the Indo-West Pacific or Indo-Pacific Asia, it comprises the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the ...

Kurtidae ''Kurtus'' is a genus of percomorph fishes, called the nurseryfishes, forehead brooders, or incubator fish, native to fresh, brackish and coastal marine waters ranging from India, through southeast Asia, to New Guinea and northern Australia. ''K ...

(consisting solely of two species in the genus ''

Kurtus ''Kurtus'' is a genus of Percomorpha, percomorph fishes, called the nurseryfishes, forehead brooders, or incubator fish, native to fresh, brackish and coastal marine waters ranging from India, through southeast Asia, to New Guinea and northern Au ...

'') and the much more diverse and widespread

Apogonidae Cardinalfishes are a family, Apogonidae, of ray-finned fishes found in the Atlantic, Indian, and Pacific Oceans; they are chiefly marine, but some species are found in brackish water and a few (notably '' Glossamia'') are found in fresh water. ...

(the cardinalfishes). The order is part of the

Percomorpha Percomorpha () is an extremely large and diverse clade of ray-finned fish. With more than 17,000 known species (including Scombroidei, tuna, Syngnathiformes, seahorses, gobies, Cichlidae, cichlids, flatfish, Labridae, wrasse, Perciformes, perches ...

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

and, based on phylogenetic evidence, is considered a sister taxon to the

gobies Gobiidae or gobies is a family of bony fish in the order Gobiiformes, one of the largest fish families comprising over 2,000 species in more than 200 genera. Most of gobiid fish are relatively small, typically less than in length, and the fam ...

and sand divers. In some older treatments, it is instead treated as its own order, Kurtiformes ().

Relationships and defining characteristics

A close relationship between the Kurtidae and Apogonidae was postulated based on the similarity of constituent parts of their dorsal

gill arch Branchial arches or gill arches are a series of paired bony/ cartilaginous "loops" behind the throat ( pharyngeal cavity) of fish, which support the fish gills. As chordates, all vertebrate embryos develop pharyngeal arches, though the event ...

es and that in both groups the eggs have filaments on the micropyle, which enable the eggs to form a mass. This mass is brooded in the mouth in the Apogonidae and borne on the supraoccipital hook of at least one of the two nursery fishes in the Kurtidae. They also have horizontal and vertical rows of sensory papillae on their heads and bodies, which are often arranged in a pattern resembling a grid (similar patterns of sensory papillae can be observed in some species in the Gobiiformes). The two families comprising the Kurtiformes are recovered as sister groups in some molecular

phylogenies A phylogenetic tree or phylogeny is a graphical representation which shows the evolutionary history between a set of species or taxa during a specific time.Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, MA. In o ...

, but others instead recover them as successive sisters to the Gobiiformes.

Families

Two extant families are classified under the suborder Apogonoidei: *

( Bleeker, 1859) - nurseryfish *

Günther, 1859 - cardinalfish The suborder was also treated as containing the Pempheridae, but this is now known to be inaccurate, with the pempherids actually belonging to the Acropomatiformes. The earliest fossil evidence of the group is apogonid otoliths from the

Maastrichtian The Maastrichtian ( ) is, in the International Commission on Stratigraphy (ICS) geologic timescale, the latest age (geology), age (uppermost stage (stratigraphy), stage) of the Late Cretaceous epoch (geology), Epoch or Upper Cretaceous series (s ...

References

Gobiiformes {{Kurtiformes-stub