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Chapter 9 Hiodontidae: Mooneyes
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and the specific epithet for the Mooneye (tergisus) means “polished.” DIVERSITY AND DISTRIBUTION Extant Mooneyes occur only in North America and are represented by one genus with two species: Hiodon tergisus , the Mooneye, and H. alosoides, the Goldeye (Table 9.1). The two species have broadly overlapping ranges throughout much of the central and eastern parts of North America (Fig. 9.1). Their ranges are remarkably broad latitudinally , extending from the southernmost portion of the Mississippi River drainage to the far northwestern drainages of the Northwest Territories. The range of the Goldeye extends farther north than that of Mooneye, following the Mackenzie River to its entrance into the Beaufort Sea. An isolated population of Goldeyes also occurs in the southern tributaries of James Bay, Quebec and Ontario. Species of Hiodon were present west of the North American Continental Divide until the Miocene (25–5mya; G. R. Smith 1981; Cavender 1986). In contrast to many other widely distributed fishes, phylogeographic variation is unstudied within the Goldeye and Mooneye. Non-Native Distribution Both species of the genus have been introduced outside of their native ranges but only to a limited extent. In Nebraska, the Goldeye was stocked in the White River in 1896 and Lake Minatare in 1952; Mooneyes were introduced in a canal in Washington County, Maryland, in the late 1800s. All these stockings apparently were unsuccessful, and the The family Hiodontidae, the Mooneyes (subdivision Osteoglossomorpha , order Hiodontiformes), contains two species that are considered living fossils and are similar to other basal groups of fishes (e.g., Gars, Lepisosteidae; Bowfins, Amiidae) in having a long fossil record from the fresh waters of North America and being species-poor relative to the extant fauna. The sister-order to the Mooneyes , the Osteoglossiformes (Bonytongues), are also freshwater and found in South America, Africa, Southeast Asia, and northern Australia (the fossil record of the osteoglossomorphs includes several marine taxa, and the group is found on all continents except Antarctica). In contrast to Hiodontiformes, the Osteoglossiformes are quite diverse (4 families, 28 genera, 218 species) and include one of the world’s largest freshwater fishes (to 2.5m TL), the Pirarucú (Arapaima gigas) of South America . Most of the diversity of the Osteoglossiformes is found in a single family, the Elephantfishes of Africa (Mormyridae; 18 genera and >200 species), which can transmit and detect weak electric currents, have a large brain comparable in relative size to the human brain, and appear to have considerable learning capability (e.g., Cain & Malwal 2002; Nelson 2006; Walton & Moller 2010). Mooneyes superficially resemble shad of the family Clupeidae, the Herrings, but can be distinguished by the absence of abdominal scutes and the presence of strongly developed dentition on the basibranchial and basihyal toothplates. The name Hiodon means “toothed hyoid” and refers to particularly well-developed teeth on the basihyal toothplate. This gross morphological similarity to Herrings is reflected in the species epithet for the Goldeye (alosoides), which denotes similarity to the shad genus Alosa. Mooneyes are generally silvery fish, Chapter 9 Hiodontidae: Mooneyes Eric J. Hilton, William E. Bemis, and Lance Grande 300 FRESHWATER FISHES OF NORTH AMERICA sidered by many as the most basal group of teleosts with living representatives (e.g., Patterson & Rosen 1977; but see Arratia 1997, 1999, 2004, in which Elopomorpha— Ladyfishes, Elopidae; Tarpons, Megalopidae; Bonefishes, Albuliformes; Eels, Anguilliformes, and their relatives— takes this position). Two monotypic genera (†Pleisolycoptera and †Yanbiania) included in the family Hiodontidae (Fig. 9.2) are known from Late Cretaceous deposits of China (89–65mya; Li & Wilson 1999). Several other putative members of Hiodontidae described from Asia and Eastern Europe are in need of re-examination to verify their taxonomic placement. Within Osteoglossomorpha, Hiodontidae was once considered the sister-group to Notopteridae + Mormyridae, the Featherfin or Old World Knifefishes and Elephant- fishes, respectively (e.g., G. J. Nelson 1968, 1969b; Lauder & Liem 1983). Now, morphological and molecular character data firmly establish that Hiodontidae is the living sister-group to the group containing all other living osteoglossomorphs (e.g., Taverne 1979; Li & Wilson 1996, 1999; Hilton 2003; Lavoué & Sullivan 2004; Zhang 2006; Wilson & Murray 2008). Within Osteoglossomorpha, Hiodonimpacts of their attempted introductions are unknown (Fuller et al. 1999). PHYLOGENETIC RELATIONSHIPS Phylogenetic relationships of living and fossil species within Hiodon (including species previously classified in the genus †Eohiodon) are unclear and need further study (Hilton & Grande 2008). Hiodontidae is part of the group Osteoglossomorpha, the bony-tongue fishes, which is conGenus Hiodon Figure 9.1...