Whalefishes
Phylogenetic investigations of the Stephanoberyciformes and Beryciformes, particularly whalefishes (Euteleostei: Cetomimidae)
Whalefish are a family of fish found principally in deep waters. Here we investigated the relationship between different genera of whalefish by comparing the DNA sequences from two genes.
IThe deepsea whalefishes (Family Cetomimidae) have about 35 species in nine genera (Paxton, 1989). The family is found principally in very deep waters (more than 1500m), with a few smaller individuals more shallow waters. Whalefishes have a cosmopolitan distribution ranging from 52oN to 72oS. It may be the most abundant family of fish below about 1800m (Paxton, 1989). Some 500 specimens are now held in zoological collections. The fishes are generally small although one species of Gyrinomimus attains a length of 408 mm. No larvae from the family have been identified and only a few small males have been found (Paxton, 1990).
The data for the present project (12S and 16S rDNA sequences) (Download
) were collected to investigate intergeneric relationships within the deepsea whalefishes, family Cetomimidae, and to test statistically alternative hypotheses of the family's wider phylogenetic relationships, principally in regard to its placement within the stephanoberyciform and beryciform lineages.
Maximum parsimony trees without imposed constraints are notably shorter than trees constrained to show ordinal groupings or either of the two main current hypotheses of Stephanoberyciformes/Beryciformes relationships. Beryciformes in particular is unlikely to be a monophyletic group, with the Berycidae (possibly) and Holocentridae (probably) being more closely related to other lineages.
The Stephanoberyciformes is also unlikely to be a monophyletic group as our samples of one of its supposed families, the Melamphaidae is sister to the Berycidae in the 16S and combined analyses, but dispersed in the 12S analyses.
The data are generally concordant with intra-familial relationships of the Cetomimidae determined from morphological analyses (Paxton, 1989). Suitable specimens from the more primitive subfamily (Procetichthyinae) and of some genera (Cetichthys, Notocetichthys and Danacetichthys) in the Cetomiminae were not obtainable. Within Cetomimidae, species of Gyrinomimus and Cetomimus are grouped, but the former is paraphyletic with respect to the latter. Cetostoma is sister to Ditropichthys rather than to Gyrinomimus and Cetomimus as suggested by morphological analyses.
Acknowledgements
Financial support was provided by "Readers' Digest Australia", the Ken Myer bequest to the Evolutionary Biology Unit and the Australian Museum.
Participants
Don Colgan
Zhang Chunguang Institute of Zoology, Chinese Academy of Sciences, Beijing, China
John Paxton
Anne Buckman
Selected references
- Johnson, G. D., and Patterson, C. (1993). Percomorph phylogeny: a survey of acanthomorphs and a new proposal. Bull. Mar. Sci. 52: 554 -626.
- Moore, J. A. (1993). The phylogeny of the Trachichthyiformes (Teleostei: Percomorpha). Bull. Mar. Sci. 52: 284 - 326
- Paxton, J. R. (1989). Synopsis of the whalefishes (family Cetomimidae) with descriptions of four new genera. Rec. Aust. Mus. 41: 135 - 206.
- Paxton, J. R. (1990). Whalefishes: little fish with big mouths. Aust. Nat. Hist. 23: 379-385.
- Wiley, E. O., Johnson, G. D., and Dimmick, W. W. (1998). The phylogenetic relationships of lampridiform fishes (Teleostei: Acanthomorpha), based on a total-evidence analysis of morphological and molecular data. Mol. Phylogenet. Evol. 10: 417-425.
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