Acanthomorpha

Introduction

Acanthomorpha is the crown group of teleost fishes. It includes some 14,000+ species including the more familiar cods, tunas, flounders, basses, and perches as well as the exotic oarfishes, stonefishes, and puffers (Nelson, 1993; Paxton and Eschmeyer, 1994). Acanthomorphs are found in most aquatic habitats available to fishes, from the abyssal plains of the ocean basins to mountain streams, desert springs, and caves. Size ranges from some of the longest (17 meters, the lampridiform, Regalecus glesne) and most massive (>3000 kilograms, the tetraodontiform, Mola mola) bony fishes to the smallest of all vertebrates (7-8mm, the gobiod, Schindleria).

Characteristics

Synapomorphies of Acanthomorpha include the following:

1. True dorsal and anal fin spines present (Johnson and Patterson, 1993); there are notable exceptions, e.g., gadiforms, most lampridiforms, various perciforms).
2. Median rostral cartilage present and strongly bound to premaxillary ascending process via well-developed rostro-premaxillary ligament (Hartel and Stiassny, 1986; Stiassny, 1986; Johnson and Patterson, 1993).
3. Median caudal cartilages absent (Fujita, 1990; Johnson and Patterson, 1993).
4. Anterior and medial infracarinales separate (Stiassny, 1993; Johnson and Patterson, 1993).
5. Dorsal limb of posttemporal firmly bound to exoccipital (Stiassny, 1986; Johnson and Patterson, 1993)
6. Medial pelvic processes ossified distally (Johnson and Patterson, 1993).
7. First centrum with anterior surface bearing distinct facets that articulate with the exoccipital condyles (Rosen, 1985).

Discussion of Phylogenetic Relationships

Rosen (1973) proposed Acanthomorpha to comprise two putatively monophyletic clades, Acanthopterygii and Paracanthopterygii. Subsequently, the monophyly of the group has been corroborated with morphological characters by Stiassny (1986), Hartel and Stiassny (1986), and Johnson and Patterson (1993), whereas the monophyly of the two subgroups has been refuted. Rosen (1985) and Stiassny (1986) removed the Polymixiiformes from Acanthopterygii to the base below Paracanthopterygii, and Stiassny and Moore (1992) suggested that lampridiform fishes might also be basal. Johnson and Patterson (1993) corroborated both of these hypotheses, and they have subsequently been supported in DNA studies (Wiley et al., 2000; Miya et al., 2001). Johnson and Patterson (1993) used only Percopsiformes to represent Paracanthopterygii, assuming the monophyly of the group following Patterson and Rosen (1989). Gill (1997) suggested that the morphological evidence for monophyly of Paracanthopterygii is weak. DNA studies (Le et al., 1993; Wiley et al. 2000; Miya et al., 2001, 2005) suggest that Paracanthopterygii is polyphyletic, with Gadiformes and Percopsiformes being basal at the level now shown for Paracanthopterygii and Lophiiformes and Batrachoidiformes embedded within Acanthopterygii.

References

Fujita, K. 1990, The caudal skeleton of teleostean fishes: Tokyo: Tokai University Press, xiii + 897 pp.

Gill, A. C. 1996. Comments on an intercalar path for the glossopharyngeal (Cranial IX) nerve as a synapomorphy of the Paracanthopterygii and on the phylogenetic position of the Gobiesocidae (Teleostei: Acanthomorpha) Copeia 1996(4), 1022-1029.

Hartel, K. E., and M. L. J. Stiassny. 1986. The identification of larval Parasudis (Teleostei: Chloropthalmidae); with notes on the anatomy and relationships of aulopiform fishes. Breviora 487:1-23.

Johnson, G. D. and C. Patterson. 1993. Percomorph phylogeny: A survey of acanthomorph characters and a new proposal. Bull. Mar. Sci. 52, 554-626.

Le, H. L. V., G. Lecointre, and R. Perasso. 1993. A 28S rRNA-based phylogeny of the gnathostomes: first steps in the analysis of conflict and congruence with morphologically based cladograms. Mol. Phylogenet. Evol. 2(1):31-51.

Miya, M. A, A. Kawaguchi, and M. Nishida. 2001. Mitogenomic exploration of higher teleostean phylogenies: a case study of moderate-scale evolutionary genomics with 38 newly determined complete mitochondrial DNA sequences. Mol. Biol. Evol. 18(11)1993-2009.

Miya, M., Satoh, T.P., and Nishida. 2005. The phylogenetic position of toadfishes (Order Batrachoidiformes)in the higher ray-finned fishes as inferred from partitioned Bayesian analysis of 102 whole mitochondrial sequences. Biol. Jour. Linn. Soc. 85:289-306

Nelson, J. S. 1994. Fishes of the World, 3rd Edition. Wiley-Interscience, NY.

Patterson, C, and D. E. Rosen. 1989. The Paracanthopterygii revisited: Order and disorder. In Papers on the Systematics of Gadiform Fishes. (Cohen, D. M. ed), pp. 5-36. Natural History Museum of Los Angeles County, Los Angeles, California.

Paxton, J. R., and W. N. Eschmeyer (eds.). 1994. Encyclopedia of Fishes, Second Edition. Weldon, Owen, Pty, Sydney. 240pp.

Rosen, D. E. 1973. Interrelationships of higher euteleostean fishes. In Interrelationships of Fishes. (Greenwood, P. H., Miles, S., Patterson, C. eds), pp 397-513. J. Linn. Soc. (London) 53 Supplement 1. Academic Press, New York, New York.

Rosen, D. E. 1985. An essay on euteleostean classification. Amer. Mus. Novit. 2827:1-57.

Stiassny, M. L. J. 1986. The limits and relationships of the acanthomorph fishes. J. Zool. London (B) 1:411-460.

Stiassny, M. L. J., and J. A. Moore. 1992. A review of the pelvic girdle of acanthomorph fishes, with comments on hypotheses of acanthomorph interrelationships. Zool J. Linnean Soc. London 104, 209-242.

Wiley, E. O., G. D. Johnson, and W. W. Dimmick. 2000. The interrelationships of acanthomorph fishes: a total evidence approach using morphological and molecular data. Biochem. Syst. Evol. 28(2000):319-350.