Abstract
The caudal fin skeleton has been regarded as a major source of characters used in the evaluation of teleostean interrelationships. Despite the increasing number of papers drawing attention to the variability observed within species when large samples are considered, intraspecific variation of this complex remains poorly known for many teleostean groups, and comparative anatomical studies still often rely on a small number of specimens. Within the Osteoglossomorpha, there are few studies concerning instraspecific variation patterns, and many aspects of both the anatomy and homology of the caudal fin skeleton elements are controversial (e.g. epurals versus uroneurals; number of hypurals compounding the “hypural fan”). Given this perspective, we examined the caudal skeleton of 84 specimens of the neotropical osteoglossid fish Osteoglossum bicirrhosum, and described and quantified its morphological variation. We determined that the number of neural spines on the preural centra and hypural fusion patterns showed the greatest variation. Despite the widespread distribution of this taxon, the observed variation appears to be geographically independent, and occurs randomly within populations.
References
Arratia, G. (1997) Basal teleosts and teleostean phylogeny. Palaeoichthyologica, 7, 1–168.
Cuvier, G. (1829) Le Règne Animal, distribué d'après son organisation, pour servir de base à l'histoire naturelle des animaux et d'introduction à l'anatomie comparée. Gallica Bibliotheque Numérique [Document électronique] Edition 2. i–xv + 1–406
Cuvier, G. & Valenciennes, A. (1847) Histoire naturelle des poissons. Tome dix-neuvième. Suite du livre dix-neuvième. Brochets ou Lucioides. Livre vingtième. De quelques familles de Malacoptérygiens, intermédiaires entre les Brochets et les Clupes. i-xix + 1-544 + 6 pp., Pls. 554-590.
Dingerkus, G & L.D.Uhler (1977) Enzyme clearing of alcian blue stained whole small vertebrates for demonstration of cartilage. .Stain Technology, 52, 229–232.
Fujita, K. (1990) The caudal skeleton of teleostean fishes. Tokyo University Press, 897 p.
Gosline, W.A. (1960) Contributions toward a classification of modern isospondylous fishes. Bulletin of the British Museum (Natural History) Zoology, 6, 327–365.
Grande, L. & Bemis, W. (1998) A comprehensive phylogenetic study of amiid fishes (Amiidae) based on comparative skeletal anatomy. An empirical search for interconnected patterns of natural history. Journal of Vertebrate Paleontology Memoirs, 4: 1–690. (supplement to Journal of Vertebrate Paleontology, 18[1]).
Grande, L. (2004) Categorizing various classes of morphological variation, and the importance of this to vertebrate paleontology. In: Arratia, G. & Tintori, A. (eds). Mesozoic Fishes 3 – Systematics, Paleoenvironments and Biodiversity. Verlag Dr Friedrich Pfeil, München, Germany, 123–136.
Greenwood, P.H. (1967) The caudal fin skeleton in osteoglossoid fishes. Annals and Magazine of Natural History, 9(13), 581–597.
Hilton, E.J. (2002) Osteology of the extant North American fishes of the genus Hiodon Lesuer, 1818 (Teleostei: Osteoglossomorpha: Hiodontiformes). Fieldiana (Zoology) New Series, 100, 1–142.
Hilton, E. J. (2003) Comparative osteology and phylogenetic systematics of fossil and living bony-tongue fishes (Actinopterygii, Teleostei, Osteoglossomorpha). Zoological Journal of the Linnean Society, 137(1), 1–100.
Hoedeman, J.J. (1961) Contributions to the Osteology of Teleostean Fishes. 1. The caudal skeleton and the hypural complex. Bulletin of Aquatic Biology, v. 3 (25), 17–52.
Kanazawa, R. H. (1966) The fishes of the genus Osteoglossum with a description of a new species from the Rio Negro. Ichthyological Aquarium Journal, 37(4), 161–172.
Kirschbaum, F. & Meunier, F.J. (1981) Experimental regeneration of the caudal skeleton of the glass-knife fish, Eigenmannia virescens (Rhamphichthyidae, Gymnotoidei). Journal of Morphology, 168, 121–135.
Kirschbaum, F. & Meunier, F.J. (1988) South American Gymnotiform fishes as model animals for regeneration experiments. Monographs in Developmental Biology, 21, 112–123.
Li, G-Q, & Wilson, M.V.H. (1994) An Eocene species of Hiodon from Montana, its phylogenetic relationships, and the evolution of the postcranial skeleton in the Hiodontidae (Teleostei). Journal of Vertebrate Paleontology, 14, 153– 167.
Li, G-Q, & Wilson, M.V.H. (1996) Phylogeny of Osteoglossomorpha. In: Stiassny, M.L.J., Parenti, L.R. & Johnson, G.D. (eds). Interrelationships of fishes. Academic Press, San Diego, 163–174.
Li, G-Q, & Wilson, M.V.H. (1999) Early divergence of Hiodontiformes sensu stricto in East Asia and phylogeny of some Late Mesozoic teleosts from China. In: Arratia, G. & Schultze, H-P. (eds). Mesozoic Fishes 2 –systematics and fossil record. Verlag Dr Friedrich Pfeil, München, Germany, 369–384.
Meunier, F.J., & François, Y. (1992) La croissance du squelette chez lês téléostéens. II. La croissance du squelette. L’Année Biologique, 4e Série, 31(4), 185–219.
Meunier, F.J. & Kirschbaum, F. (1979) Étude anatomique et histologique du squelette axial de la région caudale de Gymnarchus niloticus (Cuvier 1829) (Gymnarchidae). Archives de Zoologie Experimental et Generale, 120, 415–429.
McDowall, R.M. (2001) The principal caudal fin ray count – a fundamental character in the galaxioid fishes. New Zealand Journal of Zoology, 28, 395–405.
Monod, T. (1968) Le complex urophore des poisons téléostéens. Mémoires de l’Institut Fondamental d’Afrique Noire, 81, 1–705.
Nelson, G.J. (1969) Infraorbital bones and their bearing on the phylogeny and geography of osteoglossomorph fishes. American Museum Novitates, 2394, 1–37.
Nybelin, O. (1963) Zur Morphologie und Terminologie des Schwanzskelettes der Actinopterygier. Arkiv för Zoologi, 15, 485–516.
Patterson, C. (1968) The caudal skeleton in Lower Liassic pholidophorid fishes. Bulletin of the British Museum (Natural History) Geology, 16, 201–239.
Patterson, C. (1977) Cartilage bones, dermal bones and membrane bones, or the exoskeleton versus the endoskeleton. In Andrews, S.M., Miles, R.S., & Walker, A.D. (eds). Problems in Vertebrate Evolution. Academic Pres, London, 77– 121.
Patterson, C. & Rosen, D.E. (1977) Review of the ichthyodectiform and other Mesozoic fishes and the theory and practice of classifying fossils. Bulletin of the American Museum of Natural History, 158, 81–172.
Potthoff, T. (1984) Clearing and staining techniques. In H.G. Moser (ed). Ontogeny and Systematics of Fishes. Special Publication—American Society of Ichthyology and Herpetology. Allen Press, Lawrence, Kansas, 35–37.
Schepper, N., Adriaens, D., Teugels, G.G., Devaere, S., & Verraes, W. (2004) Instraspecific variation in the postcranial skeleton morphology in African clariids: a case study of extreme phenotypic plasticity. Zoological Journal of the Linnean Society, 140, 437–446.
Schultze, H-P & Arratia, G. (1988) Reevaluation of the caudal skeleton of some actinopterygian fishes. II. Hiodon, Elops and Albula. Journal of Morphology, 195, 257–303.
Schultze, H-P & Arratia, G. (1989) The composition of the caudal skeleton of teleosts (Actinopterygii: Osteichthyes). Zoological Journal of the Linnean Society, 97, 189–231.
Statsoft Patch Ink. (2001) STATISTICA (data analysis software sistem), version 6. Available from: www.statsoft.com (05/12/2005).
Taverne, L. (1972) Ostéologie des genres Mormyrus Linné, Mormyrops Muller, Hyperopisus Gill, Myomyrus Boulenger, Stomatorhinus Boulenger et Gymnarchus Cuvier. Considérations générales sur la systématique des poissons de l’order des Mormyriformes. Annales Musée Royal de l’Afrique Centrale, Série in-8o, Sciences Zoologiques, 200, 1– 194.
Taverne, L. (1977) Ostéologie, phylogénèse et systématique des Téléostéens fossiles et actuels du super-ordre des Ostéoglossomorphes. Première partie. Ostéologie des genres Hiodon, Eohiodon, Lycoptera, Osteoglossum, Scleropages, Heterotis et Arapaima. Académie Royale de Belgique, Mémoires de la Classe des Sciences, 42: 1–235.
Taverne, L. (1978) Ostéologie, phylogénèse et systématique des Téléostéens fossiles et actuels du super-ordre des Ostéoglossomorphes. Première partie. Ostéologie des genres Phareodus, Phareoides, Brychaetus, Musperia, Pantodon, Singida, Notopterus, Xenomystus et Papyrocranus. Académie Royale de Belgique, Mémoires de la Classe des Sciences, 42: 1–212.
Wallace, A.R. (2002) Peixes do Rio Negro – Alfred Russell Wallace (1850–1852). Ragazzo, M.T-P (org). Uspiana Brasil 500 anos, Edusp, São Paulo, 520 pp.
Wiens, J.J. (1995) Polymorphic characters in phylogenetic systematics. Systematic Biology, 44, 482–500.
Wiens, J.J. (2000) Coding morphological variation within species and higher taxa for phylogenetic analysis. In Wiens, J.J. (ed). Phylogenetic analysis of morphological data. Smithsonian Institution Press, Washington, pp. 115–145.
Wiens, J.J. & Servedio, M.R. (2000) Species delimitation in systematics: inferring diagnostic differences between species. Proceedings of the Royal Society of London, 267: 631–636.