Tetras, piranhas, hatchetfishes, headstanders, pencilfishes, and their relativesGuillermo Ortí and Richard P. Vari
This tree diagram shows the relationships between several groups of organisms.
The root of the current tree connects the organisms featured in this tree to their containing group and the rest of the Tree of Life. The basal branching point in the tree represents the ancestor of the other groups in the tree. This ancestor diversified over time into several descendent subgroups, which are represented as internal nodes and terminal taxa to the right.
You can click on the root to travel down the Tree of Life all the way to the root of all Life, and you can click on the names of descendent subgroups to travel up the Tree of Life all the way to individual species.close box
The family Characidae, whose members live in Africa and from Texas in North America through Central and South America, is probably non-monophyletic.
The order Characiformes includes a vast array of fishes that live in rivers and lakes of Africa and the New World (from Texas in North America through Central and South America). They are divided into 14 or 16 families (Géry, 1977, and Greenwood et al., 1966, respectively), four of which are African (over 200 species), and the rest live mostly in the Neotropics (more than 1,200 species). They include well-known forms like piranhas, tetras (e.g. neon tetras, silver dollars), hatchetfishes, and pencilfishes, popular in the aquarium trade. Other characiforms also have commercial importance as a food resource for human communities living along the banks of broad tropical rivers. These include the African citharinids and the Neotropical prochilodontids, which are very abundant, large-bodied species, typically forming massive schools that migrate up and down the main river channels. Other characid groups (family Characidae) include important sport-fishing species, like the african tiger fish (genus Hydrocynus, subfamily Alestiinae), and the Neotropical dorados (genus Salminus, subfamily Bryconinae). These are voracious predators that may reach a size of 100-130 cm in length and a weight of up to 50 Kg. In contrast, the smallest characiform species, known as miniature forms (Weitzman and Vari, 1988), have adults that do not exceed 26 mm in length (some tetras, glandulocaudines, and lebiasinids). The only comprehensive account of the order Characiformes as a whole published to date is that of Géry (1977).
The variety of ecological specializations found among characiforms is remarkable. The range of feeding modes varies from detritivory (mud-eating prochilodontids and curimatids), herbivory (plant-eating citharinids and anostomids), and planktivory (plankton-filtering, e.g. Anodus and Clupeocharax), to predation (Hepsetus, Hoplias, Hydrocynus and Salminus), fin-eating and scale-eating (some distichodontids and characids), and to the notorious and voracious group-predation of some piranhas.
Peculiar morphological and physiological adaptations permit the survival of some groups in extreme conditions of low oxygen concentration, typical of flood-plain environments (e.g., erythrinids are capable of air-breathing, and some pacus, ctenolucids, and leporins have swollen lips that allow them to exchange gases in the uppermost film of water). Figure 1 shows a picture of Ctenolucius doing this. Some characiform groups exhibit nesting behaviors and parental care (erythrinids, Hepsetus, piranhas, and lebiasinids). The Characiformes are all primary freshwater fishes, unable to survive in saline environments.
Origin of the major characiform lineages has been dated to more than 100 million years ago, when Africa and South America still formed part of a single continental mass called Gondwana (Lundberg 1993; Ortí and Meyer 1997). Given the paucity of direct fossil evidence, this inference has been based on indirect evidence such as the phylogenetic and geographic distribution of extant characiform families and the genetic distances separating them. The alternative view, suggesting that most lineages had originated from a few ancestral forms independently in each continent after the separation of Africa and South America (some 80-100 million years ago), is not consistent with the available evidence. Under this view, all African and all Neotropical families should form reciprocally monophyletic groups. But as shown above in the characiform tree, the African families (Citharinidae, Distichodontidae, Hepsetidae, and part of Characidae) are dispersed among the Neotropical families rather than forming a single monophyletic unit. Also, genetic distances among African characiforms and their closest Neotropical relatives are not significantly larger than genetic distances among families within each continent. The primary diversification of charciform fishes is thus placed in the Gondwanan continent, more than 100 million years ago.
Characiforms usually have an adipose fin (Figure 2) and almost always, well developed scales (the only naked characin is Gymnocharacinus bergi from Argentina, also the most southerly distributed species). Teeth are also usually present since most are carnivores or omnivores. Pelvic fins are present (with 5-12 rays) and the anal fin is short to moderately long (fewer than 45 rays). The lateral line is often decurved and sometimes incomplete. Barbels are always absent. Characiformes share with other otophysan fishes a strucuture called the Weberian apparatus, which is a distinctive modification of the anterior-most four or five vertebrae. It contains a series of movable bony parts (ossicles) and ligaments that connect the swim bladder to the inner ear, presumably for effcient sound transmission.
Characiformes are exclusively freshwater fishes that live in streams, rivers, and lakes (marked red). Distribution in Africa taken from Daget et al. (1984).
The division of the order Characiformes into families is a controversial matter, in part because not all of the proposed groups have been shown to be monophyletic. Many well-characterized lineages are currently lumped into the family Characidae, which may not form a natural group (Weitzman and Fink, 1983, but see our discussion of Lucena, 1993). For the present discussion, we will use a family-group classification that follows Greenwood et al. (1966), with a few exceptions: the family Cynodontidae is included in the family Characidae, as suggested by Howes (1976); the ichthyborids are included within the family Distichodontidae, following Vari (1979); and the characid subfamilies Characidiinae and Crenuchinae are grouped into the new family Crenuchidae (following Buckup, 1991). Provisionally, we recognize 15 characiform families.
The establishment of higher-order phylogenetic relationships among characiform families has been difficult and controversial. Following a conservative approach, we present a mostly unresolved phylogeny rather than any of the alternative hypotheses published to date. The groupings shown are supported by or consistent with both morpological and molecular evidence.
The only comprehensive phylogenetic study to date to include all putative characiform families (and several lineages from the family Characidae) was based on mitochondrial DNA sequence data (Ortí and Meyer, 1997). The molecular data, however, fell short of providing a robust hypothesis of relationsips among characiform families, except for a few clades also suggested by previous morphological evidence (some of the DNA sequence-based phylogenetic trees published are shown here). Several pylogenetic studies based on morphology have targeted lower-level relationships within families (e.g., Vari, 1988; Weitzman et al., 1988; Buckup, 1993; Langeani, 1996) or a subset of closely-related lineages (Vari, 1979, 1983, 1995). More inclusive studies were presented by Buckup (1991) and Uj (1990). A summary of the most relevant hypotheses based on morphological data sets is shown in Figure 3.
The African families Citharinidae and Distichodontidae were shown to be monophyletic and to form a well-supported monophyletic unit by Vari (1979). Their basal position in the Characiformes, originally suggested by Fink and Fink (1981), was corrobarated by Buckup (1991) and by molecular evidence.
Monophyly of the families Curimatidae, Prochilodontidae, Anostomidae, and Chilodontidae was proposed by Vari (1983). He also hypothesised a monophyletic unit composed by these four families, later corroborated by Buckup (1991; see figure 3C). The molecular evidence strongly supports a sister-group relationship between prochilodontids and curimatids, and is also consistent with a sister-group relationship between Anostomids and Chilododontids. Relationships between these latter two units remains poorly resolved by the mtDNA data.
The assemblage formed by the families Hepsetidae, Erythrinidae, Ctenoluciidae, and Lebiasinidae was suggested by Buckup (1991), and later corroborated by Vari (1995). Although a critical appraisal of the question of the monophyly of the families Lebiasinidae, Erythinidae, and Hepsetidae is lacking, Vari (1995) listed some putative synapomorphic characters for each of these units in his analysis of the Ctenoluciidae. Monophyly of the Ctenoluciidae was well supported by 22 synapomorphies (Vari 1995). Hypotheses of relationships among these four familes differ between studies (compare Figure 3C and D). The molecular data supports a sister-group relationship between Hepsetidae and Erythrinidae.
Buckup (1991, 1993) proposed a monophyletic family Crenuchidae, which includes the Characidiinae and Crenuchinae. These units were previosuly part of the family Characidae. Langeani (1996) reported 17 synapomorphies that support the hypothesis of monophyly of the family Hemiodontidae. No detailed phylogenetic analysis of the family Parodontidae has been published, but information provided by Roberts (1974) and Starnes and Schindler (1993) support the monophyly of Parodontidae (see Starnes and Schindler, 1993:755). Finally, Weitzman (1954) provided a detailed description of the osteology of the family Gasteropelecidae. Although that study long predated the advent of cladistic methodology, a number of features of this distinctive family noted by Weitzman are undoubtedly synapomorphies for this group.
- Tetras, piranhas, hatchetfishes, headstanders, pencilfishes, and their relatives
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Correspondence regarding this page should be directed to Guillermo Ortí at
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- First online 27 January 1997
Citing this page:
Ortí, Guillermo and Richard P. Vari. 1997. Characiformes. Tetras, piranhas, hatchetfishes, headstanders, pencilfishes, and their relatives. Version 27 January 1997 (under construction). http://tolweb.org/Characiformes/15062/1997.01.27 in The Tree of Life Web Project, http://tolweb.org/