3
numerous researchers who sent kindly me copies of their paper(s). I also wish to express my
sincere gratitude to Petr Ráb, who plowed through the whole manuscript and gave me valuable
comments, and to T. Ryan Gregory for improving the English text.
Availability of Fish Karyotypes
Karyotypes have been reported for 3,425 species/subspecies of fishes (including jawless, cartilagifi
nous, ray-finned, and lobe-fi
fi
nned fi
fi
shes) (see Table 1). This total represents a coverage of about
fi
12.2% of extant fi sh diversity (62 orders, 515 families, and 27,977 species); however, these are not
fi
sampled evenly from among fi sh groups and instead are biased toward freshwater taxa such as the
fi
Cypriniformes, Characiformes, Siluriformes, Cyprinodontiformes, and Cichlidae in the Perciformes. Specifically, numbers of karyotyped species/subspecies are 747 (21.8%) in Cypriniformes,
fi
341 (10.0%) in Characiformes, 362 (10.6%) in Siluriformes, 345 (10.1%) in Cyprinodontiformes,
and 130 (3.8%) in Cichlidae (Perciformes). On the other hand, 4 orders (Orectolobiformes, Echinorhiniformes, Pristiophoriformes, and Pristiformes) and 30 families in cartilaginous fishes and
fi
5 orders (Albuliformes, Saccopharyngiformes, Ateleopodiformes, Lampriformes, and Polymixiiformes) and 216 families in actinopterygian fishes currently lack any karyotype data. Of course,
fi
relative coverage depends on the number of recognized taxa, which has been updated signifi cantly
fi
in recent times consequent to molecular analyses that may or may not reflect undue infl
fl
ation
fl
(Nelson 2006: N-68; Kottelat and Freyhof 2007: K-130).
Fish Vouchering and Identification
To verify the identification of fi
fi
shes included in karyotype studies, voucher specimens should be
fi
deposited in a museum, curated university collection, or another appropriate institute. Unfortunately, vouchered specimens are not available for most species for which karyotypes have been
reported, meaning that their initial identification cannot be confi
fi
rmed. Moreover, there are many
fi
papers in which the localities of material fishes purchased from fi
fi
sh dealers were not described,
fi
which further increases the prospect of taxonomic errors. This problem is especially relevant when
the classifi cation of a taxon in question has been revised, making it diffi
fi
cult to link old and new
fi
names. For example, two different karyotypes were reported in a labrid, Pseudolabrus japonicus
(Arai and Koike 1980: A-75; Ojima and Kashiwagi 1979: O-27). Thereafter, Pseudolabrus japonicus
was separated to two different species, P. eosthinus and P. sieboldi by revisional study of P. japonicus (Mabuchi and Nakabo 1997: M-1). By examination of P. japonicus material deposited at a
museum, it was known that the two karyotypes corresponded to these two different species
(Mabuchi et al. 2002: M-2).
Classification of Extant Fishes
Fish systematics has developed greatly during the past 10 years, mainly based on molecular phylogenetic studies. Although results in molecular phylogenetics are not always agreed upon by all
researchers, it is necessary that a consistent taxonomic system be used in a database such as this.
In this regard, the higher taxonomic classifi cation proposed by Nelson (2006: N-68) has been used
fi
with the following updates:
Orders Batrachoidiformes and Lophiiformes were changed from the superorder Paracanthopterygii to the superorder Acanthopterygii (Miya et al. 2003, 2005: M-138, 139).
Although polyphyly of the order Gasterosteiformes and the suborder Labroidei (order
Perciformes) has been reported (Kawahara et al. 2008: K-105; Mabuchi et al. 2007: M-17) and
numerous researchers who sent kindly me copies of their paper(s). I also wish to express my
sincere gratitude to Petr Ráb, who plowed through the whole manuscript and gave me valuable
comments, and to T. Ryan Gregory for improving the English text.
Availability of Fish Karyotypes
Karyotypes have been reported for 3,425 species/subspecies of fishes (including jawless, cartilagifi
nous, ray-finned, and lobe-fi
fi
nned fi
fi
shes) (see Table 1). This total represents a coverage of about
fi
12.2% of extant fi sh diversity (62 orders, 515 families, and 27,977 species); however, these are not
fi
sampled evenly from among fi sh groups and instead are biased toward freshwater taxa such as the
fi
Cypriniformes, Characiformes, Siluriformes, Cyprinodontiformes, and Cichlidae in the Perciformes. Specifically, numbers of karyotyped species/subspecies are 747 (21.8%) in Cypriniformes,
fi
341 (10.0%) in Characiformes, 362 (10.6%) in Siluriformes, 345 (10.1%) in Cyprinodontiformes,
and 130 (3.8%) in Cichlidae (Perciformes). On the other hand, 4 orders (Orectolobiformes, Echinorhiniformes, Pristiophoriformes, and Pristiformes) and 30 families in cartilaginous fishes and
fi
5 orders (Albuliformes, Saccopharyngiformes, Ateleopodiformes, Lampriformes, and Polymixiiformes) and 216 families in actinopterygian fishes currently lack any karyotype data. Of course,
fi
relative coverage depends on the number of recognized taxa, which has been updated signifi cantly
fi
in recent times consequent to molecular analyses that may or may not reflect undue infl
fl
ation
fl
(Nelson 2006: N-68; Kottelat and Freyhof 2007: K-130).
Fish Vouchering and Identification
To verify the identification of fi
fi
shes included in karyotype studies, voucher specimens should be
fi
deposited in a museum, curated university collection, or another appropriate institute. Unfortunately, vouchered specimens are not available for most species for which karyotypes have been
reported, meaning that their initial identification cannot be confi
fi
rmed. Moreover, there are many
fi
papers in which the localities of material fishes purchased from fi
fi
sh dealers were not described,
fi
which further increases the prospect of taxonomic errors. This problem is especially relevant when
the classifi cation of a taxon in question has been revised, making it diffi
fi
cult to link old and new
fi
names. For example, two different karyotypes were reported in a labrid, Pseudolabrus japonicus
(Arai and Koike 1980: A-75; Ojima and Kashiwagi 1979: O-27). Thereafter, Pseudolabrus japonicus
was separated to two different species, P. eosthinus and P. sieboldi by revisional study of P. japonicus (Mabuchi and Nakabo 1997: M-1). By examination of P. japonicus material deposited at a
museum, it was known that the two karyotypes corresponded to these two different species
(Mabuchi et al. 2002: M-2).
Classification of Extant Fishes
Fish systematics has developed greatly during the past 10 years, mainly based on molecular phylogenetic studies. Although results in molecular phylogenetics are not always agreed upon by all
researchers, it is necessary that a consistent taxonomic system be used in a database such as this.
In this regard, the higher taxonomic classifi cation proposed by Nelson (2006: N-68) has been used
fi
with the following updates:
Orders Batrachoidiformes and Lophiiformes were changed from the superorder Paracanthopterygii to the superorder Acanthopterygii (Miya et al. 2003, 2005: M-138, 139).
Although polyphyly of the order Gasterosteiformes and the suborder Labroidei (order
Perciformes) has been reported (Kawahara et al. 2008: K-105; Mabuchi et al. 2007: M-17) and