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1.
The phylogenetic relationships among characids are complex with many genera remaining of uncertain systematic position inside the family. The genus Hollandichthys is one of these problematic genera. It has been considered as incertae sedis inside this family until two recently published phylogenies, one morphological and one molecular, arrived at alternative hypothesizes as to the relationships of Hollandichthys with Pseudochalceus or Rachoviscus, respectively. In this paper, we infer the phylogenetic relations of these taxa based on five genes (three mitochondrial - COI, ND2 and 16S; and two nuclear - Sia and Trop), totaling up to 2719 bp. The 41 analyzed species in the Characidae include four incertae sedis characid taxa once hypothesized as related to Hollandichthys, but never analyzed in a single phylogeny (Rachoviscus, Pseudochalceus, Nematocharax and Hyphessobrycon uruguayensis). Here we propose Rachoviscus as the sister-group of Hollandichthys, grouped in the large clade C previously defined, along with the remaining incertae sedis taxa studied here. In addition, we support the evidence that insemination evolved independently at least three times in the Characidae.  相似文献   

2.
This is the most comprehensive phylogenetic analysis of the Characidae to date and the first large-scale hypothesis of the family, combining myriad morphological data with molecular information. A total of 520 morphological characters were analysed herein, of which 98 are newly defined. Among the analysed taxa, 259 species were coded by examining specimens, three fossil species were coded from the literature, one species was coded almost completely from published figures, 122 were partially coded from the literature, and 88 were analysed exclusively from molecular data. The total number of species in the analysed dataset is 473. Analyses were made by parsimony under equal and extended implied weighting with a broad range of parameters. The final hypothesis was selected using a stability criterion that chooses among the most parsimonious trees of all searches. It was found by weighting molecular characters with the average homoplasy of entire partitions (markers). The resulting hypothesis is congruent with previous molecular-based phylogenies of the family. The Characidae are monophyletic, with four main clades: the Spintherobolinae new subfamily; an expanded Stethaprioninae including the Grundulini, Gymnocharacini, Rhoadsiini and Stethaprionini; the Stevardiinae; and a clade composed of the Aphyocharacinae, Characinae, Cheirodontinae, Exodontinae and Tetragonopterinae. Also, a stem Characidae was found, as formed by the Eocene–Oligocene genera †Bryconetes and †Paleotetra as successive sister groups of extant members of the family. A subfamilial classification is proposed, but deep changes in the systematics that are beyond the scope of this study are still needed to classify the Characidae into monophyletic genera.  相似文献   

3.

Background

With nearly 1,100 species, the fish family Characidae represents more than half of the species of Characiformes, and is a key component of Neotropical freshwater ecosystems. The composition, phylogeny, and classification of Characidae is currently uncertain, despite significant efforts based on analysis of morphological and molecular data. No consensus about the monophyly of this group or its position within the order Characiformes has been reached, challenged by the fact that many key studies to date have non-overlapping taxonomic representation and focus only on subsets of this diversity.

Results

In the present study we propose a new definition of the family Characidae and a hypothesis of relationships for the Characiformes based on phylogenetic analysis of DNA sequences of two mitochondrial and three nuclear genes (4,680 base pairs). The sequences were obtained from 211 samples representing 166 genera distributed among all 18 recognized families in the order Characiformes, all 14 recognized subfamilies in the Characidae, plus 56 of the genera so far considered incertae sedis in the Characidae. The phylogeny obtained is robust, with most lineages significantly supported by posterior probabilities in Bayesian analysis, and high bootstrap values from maximum likelihood and parsimony analyses.

Conclusion

A monophyletic assemblage strongly supported in all our phylogenetic analysis is herein defined as the Characidae and includes the characiform species lacking a supraorbital bone and with a derived position of the emergence of the hyoid artery from the anterior ceratohyal. To recognize this and several other monophyletic groups within characiforms we propose changes in the limits of several families to facilitate future studies in the Characiformes and particularly the Characidae. This work presents a new phylogenetic framework for a speciose and morphologically diverse group of freshwater fishes of significant ecological and evolutionary importance across the Neotropics and portions of Africa.  相似文献   

4.
The Characiformes are distributed throughout large portions of the freshwaters of Africa and America. About 90% of the almost 2000 characiform species inhabit the American rivers, with their greatest diversity occurring in the Neotropical region. As in most other groups of fishes, the current knowledge about characiform myology is extremely poor. This study presents the results of a survey of the mandibular, hyopalatine, and opercular musculature of 65 species representing all the 18 traditionally recognized characiform families, including the 14 subfamilies and several genera incertae sedis of the Characidae, the most speciose family of the order. The morphological variation of these muscles across the order is documented in detail and the homologies of the characiform adductor mandibulae divisions are clarified. Accordingly, the mistaken nomenclature previously applied to these divisions in some characiform taxa is herein corrected. Contradicting some previous studies, we found that none of the examined characiforms lacks an A3 section of the adductor mandibulae, but instead some taxa have an A3 continuous with A2. Derived myological features are identified as new putative synapomorphies for: the Characoidei; the clade composed of the Alestidae, Characidae, Gasteropelecidae, Cynodontoidea, and Erythrinoidea; the clade Cynodontoidea plus Erythrinoidea; the clade formed by Ctenoluciidae and Erythrinidae; the Serrasalminae; and the Triportheinae. Additionally, new myological data seems to indicate that the Agoniatinae might be more closely related to cynodontoids and erythrinoids than to other characids.  相似文献   

5.
The Sordariomycetes is one of the largest classes in the Ascomycota, and the majority of its species are characterized by perithecial ascomata and inoperculate unitunicate asci. It includes more than 600 genera with over 3000 species and represents a wide range of ecologies including pathogens and endophytes of plants, animal pathogens and mycoparasites. To test and refine the classification of the Sordariomycetes sensu Eriksson (2006), the phylogenetic relationship among 106 taxa from 12 orders out of 16 in the Sordariomycetes was investigated based on four nuclear loci (nSSU and nLSU rDNA, TEF and RPB2), using three species of the Leotiomycetes as outgroups. Three subclasses (i.e. Hypocreomycetidae, Sordariomycetidae and Xylariomycetidae) currently recognized in the classification are well supported with the placement of the Lulworthiales in either a basal group of the Sordariomycetes or a sister group of the Hypocreomycetidae. Except for the Microascales, our results recognize most of the orders as monophyletic groups. Melanospora species form a clade outside of the Hypocreales and are recognized as a distinct order in the Hypocreomycetidae. Glomerellaceae is excluded from the Phyllachorales and placed in Hypocreomycetidae incertae sedis. In the Sordariomycetidae, the Sordariales is a strongly supported clade and occurs within a well supported clade containing the Boliniales and Chaetosphaeriales. Aspects of morphology, ecology and evolution are discussed.  相似文献   

6.
A fish from the early Oligocene (Rupelian) of Canton Glarus, Switzerland,Cryptobalistes brevis (Rath 1859), until now placed incertae sedis among triacanthoid tetraodontiforms, is shown to be a triacanthid. It is redescribed and compared with the only other known fossil triacanthids, these being the two species ofAcanthopleurus, also from Canton Glarus, and with the seven Recent species of four genera. All of these triacanthids share five derived features. The four Recent genera are in a clade defined by five synapomorphies, andCryptobalistes andAcanthopleurus form an unresolved trichotomy with that clade. Reconstructions of the three fossil species are provided.  相似文献   

7.
Synopsis A total of 121 actinistian species belonging to 47 genera and 17 undetermined actinistians is reported from the literature. There are 69 valid species with fair assessment of their phylogenetic position; 21 valid species with poor assessment of their phylogenetic position; 31 actinistian incertae sedis; and 18 taxa that had been identified incorrectly as actinistians or are nomen nuda. The fossil record of the actinistians covers a history of approximately 380 million years. The greatest diversity occurred during the Scythian (Early Triassic).  相似文献   

8.
Scuticociliates are a rich assemblage of species with mostly unresolved phylogenetic relationships, especially in the order Philasterida. In the present work, 48 new sequences for three linked genes are characterized and phylogenetic trees are constructed to assess the inter- and intra-generic relationships of philasterids. Results reveal the following: (1) the combined three-gene tree provides more resolution in nodes than in the SSU-rDNA topologies; (2) the family Orchitophryidae is non-monophyletic as it is split into two parts and Paranophrys magna, Metanophrys sp. and Metanophrys sinensis are designated incertae sedis at the familial level; (3) Uronematidae is non-monophyletic and Homalogastra setosa is designated incertae sedis; (4) Parauronematidae becomes a junior synonym of Uronematidae and the clade containing A. haemophila, Miamiensis avidus, and Glauconema trihymene might stand for a new family; (5) Parauronema being a junior synonym of Uronema is supported and P. longum should be removed from the genus Parauronema; (6) Uronema is not monophyletic and molecular analyses reveal that Uronema sp. QD shares a more recent common ancestor with Uronemella species than with other Uronema species; (7) Metanophrys is polyphyletic; (8) multiple samples of two highly controversial species, viz., Mesanophrys pugettensis and M. chesapeakensis have identical ITS1-5.8S-ITS2 region sequence and we propose they should be synonymous with M. carcini, and (9) there may be cryptic species in M. carcini and M. avidus.  相似文献   

9.
The Aclopinae is a small subfamily within the family Scarabaeidae. It currently comprises five extant genera with 28 species, and eight fossil genera with 25 species. The systematic position of Aclopinae within the family Scarabaeidae is uncertain, particularly because representative species of Aclopinae have been absent in previous phylogenetic studies. Here we performed phylogenetic analyses using morphological and molecular data to investigate the phylogenetic position of fossil and extant Aclopinae. For this objective, we expanded and revised a former morphological data matrix (composed of 68 characters) including all extant genera of Aclopinae. We complemented our morphological investigations with a molecular phylogenetic analysis based on four genes of several extant taxa of Aclopinae and a wide sample of diverse Scarabaeoidea. Our phylogenetic analyses show that all the type species of the fossil genera formerly included within Aclopinae do not belong within the extant Aclopinae clade and support both the exclusion of those fossil taxa and the monophyly of the extant genera of Aclopinae: Aclopus Erichson, Desertaclopus Ocampo & Mondaca, Gracilaclopus Ocampo & Mondaca, Neophanaeognatha Allsopp and Phanaeognatha Hope. Our results also show that the fossil taxa Prophaenognatha robusta Bai et al. and Ceafornotensis archratiras Woolley are closely related to Ochodaeidae, while the remaining type species of fossils formerly included in Aclopinae (Cretaclopus longipes (Ponomarenko), Holcorobeus vittatus Nikritin, Juraclopus rodhendorfi Nikolajev, Mesaclopus mongolicus (Nikolajev), and Mongolrobeus zherikhini Nikolajev) belong to a distinct lineage closely related to Diphyllostomatidae. Based on these results, the subfamily Aclopinae appears monophyletic and sister to the ‘pleurostict’ lineage. Consequently, we propose the following changes to the current classification of the fossil taxa: Holcorobeus monreali (Gómez‐Pallerola) belongs to Carabidae (incertae sedis) as proposed by the original author, and we place Ceafornotensis Woolley, Cretaclopus Nikolajev, Holcorobeus Nikritin, Juraclopus Nikolajev, Mesaclopus Nikolajev, Mongolrobeus Nikolajev and Prophaenognatha Bai et al. in Scarabaeoidea (incertae sedis). Furthermore, we provide an identification key to, and diagnoses of, the genera, illustrations of diagnostic characters and checklists of their included species. The evolutionary perspective presented provides new insights into the evolution of the pleurostict condition in Scarabaeoidea and the biogeography of this group, which is now regarded as Gondwanan, probably evolving during the Cretaceous and not from the upper Jurassic as previously assumed.  相似文献   

10.
Hoppenrath M  Leander BS 《Protist》2006,157(3):279-290
Ebria tripartita is a phagotrophic flagellate present in marine coastal plankton communities worldwide. This is one of two (possibly four) described extant species in the Ebridea, an enigmatic group of eukaryotes with an unclear phylogenetic position. Ebriids have never been cultured, are usually encountered in low abundance and have a peculiar combination of ultrastructural characters including a large nucleus with permanently condensed chromosomes and an internal skeleton composed of siliceous rods. Consequently, the taxonomic history of the group has been tumultuous and has included a variety of affiliations, such as silicoflagellates, dinoflagellates, 'radiolarians' and 'neomonads'. Today, the Ebridea is treated as a eukaryotic taxon incertae sedis because no morphological or molecular features have been recognized that definitively relate ebriids with any other eukaryotic lineage. We conducted phylogenetic analyses of small subunit rDNA sequences from two multi-specimen isolations of Ebria tripartita. The closest relatives to the sequences from Ebria tripartita are environmental sequences from a submarine caldera floor. This newly recognized Ebria clade was most closely related to sequences from described species of Cryothecomonas and Protaspis. These molecular phylogenetic relationships were consistent with current ultrastructural data from all three genera, leading to a robust placement of ebriids within the Cercozoa.  相似文献   

11.
We present a phylogenetic hypothesis of the anuran clade Terrarana based on partial sequences of nuclear (Tyr and RAG1) and mitochondrial (12S, tRNA-Val, and 16S) genes, testing the monophyly of Ischnocnema and its species series. We performed maximum parsimony, maximum likelihood, and Bayesian inference analyses on 364 terminals: 11 outgroup terminals and 353 ingroup Terrarana terminals, including 139 Ischnocnema terminals (accounting for 29 of the 35 named Ischnocnema species) and 214 other Terrarana terminals within the families Brachycephalidae, Ceuthomantidae, Craugastoridae, and Eleutherodactylidae. Different optimality criteria produced similar results and mostly recovered the currently accepted families and genera. According to these topologies, Ischnocnema is not a monophyletic group. We propose new combinations for three species, relocating them to Pristimantis, and render Eleutherodactylus bilineatus Bokermann, 1975 incertae sedis status within Holoadeninae. The rearrangements in Ischnocnema place it outside the northernmost Brazilian Atlantic rainforest, where the fauna of Terrarana comprises typical Amazonian genera.  相似文献   

12.
Panicum L. is a cosmopolitan genus with approximately 450 species. Although the genus has been considerably reduced in species number with the segregation of many taxa to independent genera in the last two centuries, Panicum remains a heterogeneous assemblage, as has been demonstrated in recent years. The genus is remarkably uniform in its floral characters but exhibits considerable variation in anatomical, physiological, and cytological features. As a result, several classifications, and criteria of what the genus should really include, have been postulated in modern literature. The purpose of this research, based on molecular data of the chloroplast ndhF gene, is to test the monophyly of Panicum, to evaluate infrageneric classifications, and to propose a robust phylogenetic hypothesis. Based on the present results, previous morphological and molecular phylogenetic studies, and inferred diagnostic morphological characters, we restrict Panicum sensu stricto (s.s.) to the former subgenus Panicum and support recognition of Dichanthelium, Phanopyrum, and Steinchisma as distinct genera. We have transfered other species of Panicum to other genera of the Paniceae. Most of the necessary combinations have been made previously, so few nomenclatural changes have been required. The remaining species of Panicum sensu lato (s.l.) are included within Panicum incertae sedis representing isolated species or species grouped within monophyletic clades. Additionally, we explore the performance of the three codon position characters in producing the supported phylogeny.  相似文献   

13.
The family Characidae is a group of freshwater bony fishes that exhibits high species-level diversity and whose members inhabit parts of Texas, Mexico, and Central and South America. Thus far, morphological data have been of limited use in discerning relationships among subfamilies and incertae sedis genera of the family Characidae. In this study, DNA sequence data from GenBank were combined with new sequences for analyses under Bayesian and parsimony schemes. Sequences fell into four gene partitions, with three genes in the mitochondrial subset (12S, 16S, COI genes) and one gene in the nuclear subset (RAG2 gene). Inferred Bayesian and parsimony-based phylogenies reject the monophyly of certain groups (e.g., Astyanax, Hyphessobrycon, and Bryconamericus), do not reject the monophyly of others (e.g., Cheirodontinae and “clade A” of previous authors), and present new sister-group hypotheses (e.g., Brittanichthys sister to Paracheirodon). Sister to clade A is a lineage referred to herein as “clade B” which includes Exodon and exemplars from Cheirodontinae (the most basal lineage within clade B), Aphyocharacinae, Tetragonopterinae, and Characinae (excluding Gnathocharax). “Clade C” is sister to A + B and contains representatives of large incertae sedis genera (e.g., Hyphessobrycon, Hemigrammus), as well as members of Stethaprioninae. Unless certain other subfamilial names are to be disregarded, the use of Tetragonopterinae should continue to be restricted to species of Tetragonopterus because other genera previously referred to this subfamily grouped in clades A or C, quite distant from Tetragonopterus.  相似文献   

14.
The Characinae is a subunit of the Characidae of special significance in including Charax, the type genus of the family and the order Characiformes. Twelve genera and 79 species have been traditionally assigned to the Characinae, but the subfamily still lacks a phylogenetic diagnosis. Herein, a data matrix including 150 morphological characters and 64 taxa (35 species representing all genera of the Characinae and 29 included in other lineages within the Characiformes) was submitted to two cladistic analyses that differ in the inclusion/exclusion of Priocharax due to the difficulty of coding most of the character states in the miniature species of this genus. Both analyses resulted in a non‐monophyletic Characinae and this subfamily is herein restricted to only seven of the original 12 genera forming the clade (Phenacogaster((Charax Roeboides)(Acanthocharax(Cynopotamus(Acestrocephalus Galeocharax))))), which is supported by ten non‐ambiguous synapomorphies and is more closely related to other genera of the Characidae than those traditionally placed in the subfamily. A second clade includes the members of the tribe Heterocharacini (Lonchogenys(Heterocharax Hoplocharax)) as the sister‐group of Gnathocharax, supported by seven non‐ambiguous synapomorphies. This clade is more closely related to a taxon formed by Roestes and Gilbertolus based on seven non‐ambiguous synapomorphies. Results do not corroborate a close relationship between RoestesGilbertolus and the Cynodontinae. Inclusion of the genus Priocharax suggests that it is related more closely to the Heterocharacini, but the profound modifications in its anatomy possibly related to ontogenetic truncations obscure a better understanding of its relationships. A new classification of the Characinae and the Heterocharacinae is proposed. © 2012 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 165 , 809–915.  相似文献   

15.
A recent phylogenetic study based on morphological, biochemical and early life history characters resurrected the genus Scartomyzon (jumprock suckers, c . eight−10 species) from Moxostoma (redhorse suckers, c . 10–11 species) and advanced the understanding of relationships among species in these two genera, and the genealogical affinities of these genera with other evolutionary lineages within the tribe Moxostomatini in the subfamily Catostominae. To further examine phylogenetic relationships among moxostomatin suckers, the complete mitochondrial (mt) cytochrome b gene was sequenced from all species within this tribe and representative outgroup taxa from the Catostomini and other catostomid subfamilies. Phylogenetic analysis of gene sequences yielded two monophyletic clades within Catostominae: Catostomus + Deltistes + Xyrauchen + Erimyzon + Minytrema and Moxostoma + Scartomyzon + Hypentelium + Thoburnia . Within the Moxostomatini, Thoburnia was either unresolved or polyphyletic; Thoburnia atripinnis was sister to a monophyletic Hypentelium . In turn, this clade was sister to a monophyletic clade containing Scartomyzon and Moxostoma . Scartomyzon was never resolved as monophyletic, but was always recovered as a polyphyletic group embedded within Moxostoma , rendering the latter genus paraphyletic if ' Scartomyzon ' continues to be recognized. Relationships among lineages within the Moxostoma and' Scartomyzon 'clade were resolved as a polytomy. To better reflect phylogenetic relationships resolved in this analysis, the following changes to the classification of the tribe Moxostomatini are proposed: subsumption of' Scartomyzon 'into Moxostoma ; restriction of the tribe Moxostomatini to Moxostoma ; resurrect the tribe Erimyzonini, containing Erimyzon and Minytrema , classified as incertae sedis within Catostominae; retain the tribe Thoburniini.  相似文献   

16.
Moenkhausia is one of the most speciose genera in Characidae, currently composed of 75 nominal species of small fishes distributed across South American hydrographic basins, primarily the Amazon and Guyanas. Despite the large number of described species, studies involving a substantial number of its species designed to better understand their relationships and putative monophyly are still lacking. In this study, we analysed a large number of species of Moenkhausia to test the monophyly of the genus based on the phylogenetic analysis of DNA sequences of two mitochondrial and three nuclear genes. The in‐group included 29 species of Moenkhausia, and the out‐group was composed of representatives of Characidae and other members of Characiformes. All species of Moenkhausia belong to the same clade (Clade C); however, they appear distributed in five monophyletic groups along with other different genera, which means that Moenkhausia is polyphyletic and indicates the necessity of an extensive revision of the group.  相似文献   

17.
The possession of wings and ability to fly are a unifying character of higher insects, but secondary loss of wings is widespread. Within the bushcrickets, the subfamily Phaneropterinae (Orthoptera: Tettigonioidea) comprises more than 2000 predominantly long-winged species in the tropics. However, the roughly 300 European representatives are mainly short-winged. The systematics of these radiations have been unclear, leading to their unreliable formal treatment, which has hindered analysis of the evolutionary patterns of flight loss. A molecular phylogeny is presented for 42 short-winged species and members of all European long-winged genera based on the combined data from three nuclear gene sequences (18S, H3, ITS2). We found four phylogenetic lineages: (i) the first included the short-wing species of the genus Odontura; (ii) a further branch is represented by the South-American short-winged Cohnia andeana; (iii) an assemblage of long-wing taxa with a deep branching pattern includes the members of the tribes Acrometopini, Ducetiini, Phaneropterini, and Tylopsidini; (iv) a large group contained all short-winged taxa of the tribe Barbitistini. Phaneropterinae flightlessness originated twice in the Western Palaearctic, with a number of mainly allo- and parapatrically distributed species of the Barbistini in Southeastern Europe, and the Middle East and a limited number of Odontura species in Northern Africa and Southwestern Europe. Both short-winged lineages are well separated, which makes it necessary to restrict the tribe Odonturini to the West-Palaearctic genus Odontura. Other flightless genera previously included in the Odonturini are placed as incertae sedis until their phylogenetic position can be established.  相似文献   

18.
Three of the subgenera in the sipunculan genus Phascolosoma are reviewed, based on examination of type material. The presumed difference between the subgenera Antillesoma and Rueppellisoma (number of retractor muscles) is shown to be invalid and the taxa are therefore synonymous. The 15 species are either considered junior synonyms of P. antillarum (eight), transferred to other species or genera (six), or considered incertae sedis (one). Phascolosoma antillarum is redescribed. Of the eight species in the subgenus Satonus, only P. pectinatum remains valid: the others are considered either to belong to other taxa (four) or to be incertae sedis (three).  相似文献   

19.
The taxonomic placement of freshwater and marine Savoryella species has been widely debated, and the genus has been tentatively assigned to various orders in the Sordariomycetes. The genus is characterized as possessing paraphyses that deliquesce early, elongate, clavate to cylindrical asci with a poorly developed apical ring and versicolored, three-septate ascospores. We performed two combined phylogenetic analyses of different genes: (i) partial small subunit rRNA (SSU), large subunit rRNA (LSU), DNA-dependent RNA polymerase II largest subunit (rpb2) dataset and (ii) SSU rDNA, LSU rDNA, DNA-dependent RNA polymerase II largest subunit (rpb1 and rpb2), translation elongation factor 1-alpha (tef1), the 5.8S ribosomal DNA (5.8S rDNA) dataset. Our results indicate that Savoryella species formed a monophyletic group within the Sordariomycetes but showed no affinity to the Hypocreales, Halosphaeriales (now Microascales), Sordariales and Xylariales, despite earlier assignments to these orders. Savoryella, Ascotaiwania and Ascothailandia (and its anamorph, Canalisporium) formed a new lineage that has invaded both marine and freshwater habitats, indicating that these genera share a common ancestor and are closely related. Because they show no clear relationship with any named order we erect a new order Savoryellales in the subclass Hypocreomycetidae, Sordariomycetes. The genera Savoryella and Ascothailandia are monophyletic, while the position of Ascotaiwania is unresolved. All three genera are phylogenetically related and form a distinct clade similar to the unclassified group of marine ascomycetes comprising the genera Swampomyces, Torpedospora and Juncigera (TBM clade: Torpedospora/Bertia/Melanospora) in the Hypocreomycetidae incertae sedis.  相似文献   

20.
Suckers (Family Catostomidae) are holarctic in distribution and include 76 recent species in 14 genera, with 13 genera and 75 species occurring in North and Central America and Siberia. Although this group constitutes a significant component of many aquatic ecosystems, most historic systematic effort has been either alpha- or limited beta-level studies focusing on the two largest tribes within the family, the Catostomini and the Moxostomatini. A recent phylogenetic study based on morphological, biochemical, and early life history characters has advanced current understanding of relationships among catostomid fishes. To further examine phylogenetic relationships among basal lineages of catostomids, we sequenced the entire mitochondrial (mt) SSU and LSU rRNA genes from genera representing all subfamilies and tribes within Catostomidae. Phylogenetic analysis of gene sequences yielded monophyletic Catostomidae, Ictiobinae, and Catostominae and para- or polyphyletic Cycleptinae, with Myxocyprinus as the basal-most taxon and Cycleptus as either the next most-basal taxon or the taxon basal to the Catostominae. Relationships within the Catostominae were generally consistent with those proposed in the above-noted recent phylogenetic study although Thoburnia and Hypentelium were either a clade sister to or a grade group relative to Moxostoma and Scartomyzon. In all trees, Scartomyzon was paraphyletic and embedded within Moxostoma. Phylogenetic affinities of Erimyzon and Minytrema varied depending on data set and character weighting scheme employed. To better reflect phylogenetic relationships resolved in this extensive analysis, we propose the following changes to the classification of catostomids: formation of the new subfamily Myxocyprininae, containing Myxocyprinus from China; restriction of the Cycleptinae to the two species of Cycleptus from North America; restriction of the tribe Moxostomatini to Moxostoma and Scartomyzon; Erimyzon and Minytrema are incertae sedis within Catostominae; and resurrection of the tribe Thoburniini, containing Thoburnia and expanded to include Hypentelium.  相似文献   

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