The adductor mandibulae muscle complex in lower teleostean fishes (Osteichthyes: Actinopterygii): comparative anatomy,synonymy, and phylogenetic implications

Bony fishes of the morphologically diverse infraclass Teleostei include more than 31 000 species, encompassing almost one‐half of all extant vertebrates. A remarkable anatomical complex in teleosts is the adductor mandibulae, the primary muscle in mouth closure and whose subdivisions vary in number and complexity. Difficulties in recognizing homologies amongst adductor mandibulae subdivisions across the Teleostei have hampered the understanding of the evolution of this system and consequently its application in phylogenetic analyses. The adductor mandibulae in representatives of all lower teleost orders is described, illustrated, and compared based on broad taxonomic sampling complemented by extensive literature information. Muscle division homologies are clarified via the application of a standardized homology‐driven anatomical terminology with synonymies provided to the myological terminologies of previous studies. Phylogenetic implications of the observed variations in the adductor mandibulae are discussed and new possible synapomorphies are proposed for the Notacanthiformes, Ostariophysi, Cypriniformes, Siluriphysi, Gymnotiformes, and Alepocephaloidei. New characters corroborate the putative monophyly of the clades Albuliformes plus Notacanthiformes (Elopomorpha), Argentinoidei plus Esocoidei plus Salmonoidei (Protacanthopterygii) and Hemiodontidae plus Parodontidae (Characiformes). We further confirm the validity of characters from the adductor mandibulae previously proposed to support the monophyly of the Esocoidei and the gonorynchiform clade Gonorynchoidei plus Knerioidei. © 2014 The Linnean Society of London     

Morphological specializations in heterocongrinae (Anguilliformes: Congridae) related to burrowing and feeding

The remarkable lifestyle of heterocongrines has drawn the attention of many authors in the past, though no or little attention has been paid to the morphology of the tail and the head of these species. In order to examine the true nature of possible morphological specializations of the head and tail and their relation to their tail-first burrowing habit and/or feeding mode, a detailed myological and osteological study of Heteroconger hassi and Heteroconger longissimus was performed. The osteological similarities of the cranial skeleton between H. hassi and H. longissimus are striking. Most of the cranial muscles show no variation in presence, insertion or origin between these two species except for the adductor mandibulae complex, the adductor hyomandibulae and the intermandibularis. The adductor mandibulae complex is small, compared to that of other anguilliform species, and is probably related to their suction-dominated feeding mode and a diet, comprising mainly small, soft prey items. Heterocongrinae have undergone several morphological specializations in the tail for their tail-first burrowing lifestyle. The skeleton and musculature of the tail of H. hassi and H. longissimus are similar. In both species the caudal skeleton is highly reduced and fortified, forming a firm, pointed burrowing tool. Intrinsic caudal musculature is reduced and some muscles (interradials, supracarinalis) are even absent.     

Morphology,molecules and the phylogeny of Characidae (Teleostei,Characiformes)

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.     

Comparative myology of the mandibular and hyoid arches of sharks of the order hexanchiformes and their bearing on its monophyly and phylogenetic relationships (Chondrichthyes: Elasmobranchii)

The order Hexanchiformes currently comprises two families, Chlamydoselachidae (frilled sharks) and Hexanchidae (six‐ and seven‐gill sharks), but its monophyly and relationships with other elasmobranchs are still discussed. Previous studies of hexanchiforms addressing these issues were based mainly on external morphology, teeth, skeletal features, and molecular data, whereas the employment of characters derived from variations in muscles has not been significantly explored. Dissections of four species of Hexanchiformes (including Chlamydoselachus anguineus) are reported here describing the mandibular (musculus adductor mandibulae dorsalis, m. adductor mandibulae ventralis, m. levator labii superioris, m. intermandibularis, and m. constrictor dorsalis) and hyoidean (m. constrictor hyoideus dorsalis and ventralis) arch muscles. Our results provide new data concerning the relationships of hexanchiforms to other elasmobranchs. The m. adductor mandibulae superficialis is described and illustrated in C. anguineus, contradicting previous accounts in which is was considered absent. The anteroposterior orientation of the m. adductor mandibulae superficialis in Chlamydoselachus is similar to the pattern found in hexanchids, squaloids, and hypnosqualeans (including batoids), suggesting it was secondarily lost in Echinorhinus. This muscle therefore provides further support for the inclusion of the Chlamydoselachidae and Hexanchidae in the Squalomorphi, and not basal to all other elasmobranchs or nested within an all‐shark collective, as has been previously proposed. However, the m. adductor mandibulae superficialis originating at the jaw joint and with an aponeurotic insertion in hexanchids, squaliforms, and hypnosqualeans, may be a separate derived feature uniting these taxa. The insertion of the m. constrictor dorsalis is restricted to the postorbital articulation in hexanchids, whereas it extends farther anteriorly in C. anguineus. The insertion of the m. constrictor hyoideus dorsalis solely on the palatoquadrate is found exclusively in the Hexanchidae. We conclude that no specific pattern of mandibular or hyoid arch muscles support the monophyly of hexanchiforms (i.e., including Chlamydoselachus). J. Morphol., 2013. © 2012 Wiley Periodicals, Inc.     

Relationships among characiform fishes inferred from analysis of nuclear and mitochondrial gene sequences

Suprafamilial relationships among characiform fishes and implications for the taxonomy and biogeographic history of the Characiformes were investigated by parsimony analysis of four nuclear and two mitochondrial genes across 124 ingroup and 11 outgroup taxa. Simultaneous analysis of 3660 aligned base pairs from the mitochondrial 16S and cytochrome b genes and the nuclear recombination activating gene (RAG2), seven in absentia (sia), forkhead (fkh), and alpha-tropomyosin (trop) gene loci confirmed the non-monophyly of the African and Neotropical assemblages and corroborated many suprafamilial groups proposed previously on the basis of morphological features. The African distichodontids plus citharinids were strongly supported as a monophyletic Citharinoidei that is the sistergroup to all other characiforms, which form a monophyletic Characoidei composed of two large clades. The first represents an assemblage of both African and Neotropical taxa, wherein a monophyletic African Alestidae is sister to a smaller clade comprised of the Neotropical families Ctenolucidae, Lebiasinidae, and the African Hepsetidae, with that assemblage sister to a strictly Neotropical clade comprised of the Crenuchidae and Erythrinidae. The second clade within the Characoidei is strictly Neotropical and includes all other Characiformes grouped into two well supported major clades. The first, corresponding to a traditional definition of the Characidae, is congruent with some groupings previously supported by morphological evidence. The second clade comprises a monophyletic Anostomoidea that is sister to a clade formed by the families Hemiodontidae, Parodontidae, and Serrasalmidae, with that assemblage, in turn, the sistergroup of the Cynodontidae. Serrasalmidae, traditionally regarded as a subfamily of Characidae, was recovered as the sistergroup of (Anostomoidea (Parodontidae+Hemiodontidae)) and the family Cynodontidae was recovered with strong support as the sistergroup to this assemblage. Our results reveal three instances of trans-continental sistergroup relationships and, in light of the fossil evidence, suggest that marine dispersal cannot be ruled out a priori and that a simple model of vicariance does not readily explain the biogeographic history of the characiform fishes.     

Same but different: ontogeny and evolution of the Musculus adductor mandibulae in the Tetraodontiformes

The morphological diversity of fishes provides a rich source to address questions regarding the evolution of complex and novel forms. The Tetraodontiformes represent an order of highly derived teleosts including fishes, such as the pelagic ocean sunfishes, triggerfishes, and pufferfishes. This makes the order attractive for comparative analyses to understand the role of development in generating new forms during evolution. The adductor mandibulae complex, the main muscle associated with jaw closure, represents an ideal model system within the Tetraodontiformes. The adductor mandibulae differs in terms of partitions and their attachment sites between members of the different tetraodontiform families. In order to understand the evolution of the jaws among the Tetraodontiformes, we investigate the development of the adductor mandibulae in pufferfishes and triggerfishes as representatives of two different suborders (Balistoidei and Tetraodontoidei) that follows two different adaptations to a durophagous feeding mode. We show that the varied patterns of the adductor mandibulae derive from similar developmental sequence of subdivision of the partitions. We propose a conserved developmental program for partitioning of the adductor mandibulae as a foundation for the evolution of different patterns of subdivisions in Tetraodontiformes. Furthermore, we argue that derived conditions in the higher taxa are realized by supplementary subdivisions and altered attachment sites. These findings support a reinterpretation of homology of different muscle partitions among the Tetraodontiformes, as muscle partitions previously thought to be disparate, are now clearly related.     

Evolutionary trend in feeding habits of <Emphasis Type="Italic">Girella</Emphasis> (Perciformes: Girellidae)

Although some Girella species are herbivorous, having basically tricuspid teeth, some are omnivorous. To determine the evolutionary trends in feeding habits of Girella, the phylogenetic relationships of several species of Girella were estimated by partially sequencing the mitochondrially encoded NADH dehydrogenase subunit 2 gene, and the dentition and adductor mandibulae complex of each species were examined. The cladogram determined from the mitochondrial DNA analysis indicated that multiple tooth-rows containing incisor-like teeth existed in adults of the ancestral species of Girella, species with a single tooth-row of tricuspid teeth in the adult stage having diverged subsequently on several occasions. The tendinous connections between each section of the adductor mandibulae complex are believed to have been simple in the ancestral species, more complicated connections also having diverged later on several occasions. Multiple tooth-rows containing incisor-like teeth and the simple adductor mandibulae complex are deduced as adaptations to herbivory; on the other hand, a single tooth-row of tricuspid teeth and the complicated adductor mandibulae complex are deduced as adaptations to omnivory. Therefore, the ancestral species of Girella is suggested as having been adapted to herbivory, with species adapted to omnivory having diverged on several subsequent occasions.     

Phylogenetic relationships within the speciose family Characidae (Teleostei: Ostariophysi: Characiformes) based on multilocus analysis and extensive ingroup sampling

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.     

Homologies among different adductor mandibulae sections of teleostean fishes, with special regard to catfishes (Teleostei: siluriformes)

The adductor mandibulae complex has been a subject of discussion and uncertainties due to a wide range of differentiations and fusions that have occurred during teleost evolution. The adductor mandibulae of numerous catfishes was studied in detail and compared with that of several other teleosts described in the literature. Our observations and comparisons demonstrate that: 1) the adductors mandibulae Aomega, A2, and A3 of acanthopterygians correspond, respectively, to the Aomega, A2, and A3 of ostariophysines; 2) the antero-dorso-lateral (A1) and the antero-ventro-lateral (A1-OST) sections of the adductor mandibulae present, respectively, in acanthopterygians and in basal ostariophysines are the result of two different patterns of differentiation of this muscle; 3) some derived ostariophysines present a lateral section of the adductor mandibulae attached to the upper jaw (A0) that is not homologous with any other section of this muscle present in any other ostariophysine or acanthopterygian fish; 4) the configuration of the adductor mandibulae present in Diplomystes seems to be the plesiomorphic condition for catfishes; and 5) the muscle retractor tentaculi, present in a large number of catfishes, is derived from the inner section of the adductor mandibulae (A3) and, thus, is not homologous with the lateral bundle of this muscle (A0) that inserts on the upper jaw in some derived ostariophysine fishes.     

Cranial muscles of the anurans leiopelma hochstetteri and ascaphus truei and the homologies of the mandibular adductors in lissamphibia and other gnathostomes

The frogs Ascaphus truei and Leiopelma hochstetteri are members of the most basal lineages of extant anurans. Their cranial muscles have not been previously described in full and are investigated here by dissection. Comparison of these taxa is used to review a controversy regarding the homologies of the jaw adductor muscles in Lissamphibia, to place these homologies in a wider gnathostome context, and to define features that may be useful for cladistic analysis of Anura. A new muscle is defined in Ascaphus and is designated m. levator anguli oris. The differences noted between Ascaphus and Leiopelma are in the penetration of the jaw adductor muscles by the mandibular nerve (V³). In the traditional view of this anatomy, the paths of the trigeminal nerve branches define homologous muscles. This scheme results in major differences among frogs, salamanders, and caecilians. The alternative view is that the topology of origins, insertions, and fiber directions are defining features, and the nerves penetrate the muscle mass in a variable way. The results given here support the latter view. A new model is proposed for Lissamphibia, whereby the adductor posterior (levator articularis) is a separate entity, and the rest of the adductor mass is configured around it as a folded sheet. This hypothesis is examined in other gnathostomes, including coelacanth and lungfish, and a possible sequence for the evolution of the jaw muscles is demonstrated. In this system, the main jaw adductor in teleost fish is not considered homologous with that of tetrapods. This hypothesis is consistent with available data on the domain of expression of the homeobox gene engrailed 2, which has previously not been considered indicative of homology. Terminology is discussed, and “adductor mandibulae” is preferred to “levator mandibulae” to align with usage in other gnathostomes. J. Morphol., 2011. © 2011 Wiley‐Liss, Inc.     

Comments on the evolution of the jaw adductor musculature of snakes

The aim of this study is to provide a general view of the adductor musculature of the alethinophidian snakes. The aponeurotic system present in anilioid snakes is here described as being also present in colubroid and booid snakes. Although modified in various groups, this aponeurotic system retains the same topographical pattern in the anilioids, booids and colubroids, and is thus hypothesized to be homologous. An analysis of the aponeurotic system and related muscular bundles within the alethinophidian snakes is given. A new terminology is proposed for the jaw adductor muscles where the muscles levator anguli oris and adductor mandibulae externus superficialis (proper) of snakes (sensu Lakjer, 1926; Haas, 1962) retain these names even if this fails to reflect the presumed homologies with the bundles of the same name in lizards (see Rieppel, 1988b); the fibres originating from the temporal tendon in the Anilioidea, and presumed to form a bundle of composite nature (Rieppel, 1980b), are named the M. adductor mandibulae externus temporalis (lost by the Macrostomata); the M. adductor mandibulae externus medialis is a composite muscle in the Anilioidea (Rieppel, 1980b) which give rise to two different muscles in the ‘booids’, the M. adductor mandibulae externus medialis, pars anterior and the M. adductor mandibulae externus profundus, the former being secondarily lost by the Caenophidia which retains only fibres homologues of the 3b and 3c heads of the profundus layer of lizards; the so-called M. adductor mandibular externus profundus of snakes (sensu Lackjer, 1926; Haas, 1962) is also a composite muscle in the Anilioidea (Rieppel, 1980b), in the alethinophidians it is essentially made of fibres homologous with the posterior pinnate part of the medialis layer of lizards, and is here named the M. adductor mandibulae externus medialis, pars posterior. As a result from this analysis it follows that: (1) the Macrostomata are characterized by the downward extension of the fibres forming the M. adductor mandibulae externus medialis, pars anterior and the loss of the M. adductor mandibulae externus temporalis: (2) the Xenopeltidae are set apart from the remaining macrostomatan snakes by the retention of the M. levator anguli oris and of a well developed lateral sheet of the quadrate aponeurosis; (3) the ‘booids’ form a monophyletic group comprising only the Boidae and Bolyeriidae (with the exclusion of the Xenopeltidae and Tropidophiidae) which is characterized by a differentiated M. adductor mandibulae externus medialis, pars anterior inserting on the lateral surface of the compound bone via its own aponeurosis; (4) the Tropidophiidae are set apart from all other snakes by the peculiar course of their lateral head vein; however, they belong to the Caenophidia as they show a facial carotid artery which passes dorsally to the mandibular and maxillary branches of the trigeminus; (5) a possible additional character in favour of an Acrochordoidea + Colubroidea monophyletic unit may be given by the pattern of innervation of the jaw adductor muscles in these two taxa; (6) a new interpretation of the compressor glandulae muscular complex of Atractaspis resulted in a morphologically similar pattern to that of the viperids; the phylogenetic implications of such similarity are discussed in detail.     

Ontogeny of the jaw and maxillary barbel musculature in the armoured catfish families Loricariidae and Callichthyidae (Loricarioidea,Siluriformes), with a discussion on muscle homologies

The neotropical loricarioid catfishes include six families, the most species‐rich of which are the Callichthyidae and the Loricariidae. Loricariidae (suckermouth armoured catfishes) have a highly specialized head morphology, including an exceptionally large number of muscles derived from the adductor mandibulae complex and the adductor arcus palatini. Terminology of these muscles varies among the literature, and no data exist on their ontogenetic origin. A detailed examination of the ontogeny of both a callichthyid and a loricariid representative now reveals the identity of the jaw and maxillary barbel musculature, and supports new hypotheses concerning homologies. The adductor mandibulae muscle itself is homologous to the A1‐OST and A3′ of basal catfishes, and the A3′ has given rise to the newly evolved loricariid retractor veli as well. The A2 and A3″ have resulted in the retractor tentaculi of Callichthyidae and the retractor premaxillae of Loricariidae. Thus, these two muscles are shown to be homologous. In Loricariidae, the extensor tentaculi consists of two separate muscles inserting on the autopalatine, and evidence is given on the evolutionary origin of the loricariid levator tentaculi (previously and erroneously known as retractor tentaculi) from the extensor tentaculi, and not the adductor mandibulae complex. © 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2009, 155 , 76–96.     

Comparative anatomy of the cheek muscles within the Centromochlinae subfamily (Ostariophysi, Siluriformes, Auchenipteridae)

Glanidium melanopterum Miranda Ribeiro, a typical representative of the subfamily Centromochlinae (Siluriformes: Auchenipteridae), is herein described myologically and compared to other representative species within the group, Glanidium ribeiroi, G. leopardum, Tatia neivai, T. intermedia, T. creutzbergi, Centromochlus heckelii, and C. existimatus. The structure of seven pairs of striated cephalic muscles was compared anatomically: adductor mandibulae, levator arcus palatini, dilatator operculi, adductor arcus palatini, extensor tentaculi, retractor tentaculi, and levator operculi. We observed broad adductor mandibulae muscles in both Glanidium and Tatia, catfishes with depressed heads and smaller eyes. Similarities between muscles were observed: the presence of a large aponeurotic insertion for the levator arcus palatini muscle; an adductor arcus palatini muscle whose origin spread over the orbitosphenoid, pterosphenoid, and parasphenoid; and the extensor tentaculi muscle broadly attached to the autopalatine. There is no retractor tentaculi muscle in either the Glanidium or Tatia species. On the other hand, in Centromochlus, with forms having large eyes and the tallest head, the adductor mandibulae muscles are slim; there is a thin aponeurotic or muscular insertion for the levator arcus palatini muscle; the adductor arcus palatini muscle originates from a single osseous process, forming a keel on the parasphenoid; the extensor tentaculi muscle is loosely attached to the autopalatine, permitting exclusive rotating and sliding movements between this bone and the maxillary. The retractor tentaculi muscle is connected to the maxilla through a single tendon, so that both extensor and retractor tentaculi muscles contribute to a wide array of movements of the maxillary barbels. A discussion on the differences in autopalatine-maxillary movements among the analyzed groups is given.     

The cephalic vascular anatomy of three species of sea snakes

The primary and secondary elements of the cephalic vascular system in some sea snakes are similar to those of the generalized ophidian pattern. The three species examined in this study revealed only minor variations in vascular morphology; these variations appear to be correlated with myological differences among the three species. For example, in Hydrophis melanocephalus it appears that the depressor mandibulae artery is displaced by the cranially expanded insertion of the semi-spinalis and spinalis muscles. A preliminary hypothesis is put forth that explains the apparent constancy of the cephalic vascular system of ophidians in terms of possible constraints due to cranial kinesis.     

Phylogenetic relationships of the tilefish family Branchiostegidae (Pereiformes) based on comparative myology

The adductor mandibulae complex of the tilefish family Branchiostegidae contains five major subdivisions (A1α, A1β, A2, A3α and A3β). No other group of fishes among those examined exhibited the degree of complexity found among the branchiostegids. The closely related sand tilefishes (Malacanthidae) have a less complex adductor mandibulae musculature, lacking an A3β muscle. The proposed phylogeny of the branchiostegids is based upon: (1) the A3β', A3β" and A1β subdivisions, (2) overall degree of development of the adductor mandibulae (distinctness, origins, insertions, and degree of aponeurotic development). The phylogenetic implications of the adductor mandibulae complex are discussed.     

The phylogenetic placement of Hollandichthys Eigenmann 1909 (Teleostei: Characidae) and related genera

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.     

Two patterns of differentiation in the jaw musculature of teleostean fishes

In its most generalized configuration among modern teleosts the M. adductor mandibulae comprises a single, almost continuous mass of musculature extending from the cheek to the inner surface of the mandible. In more advanced teleosts this muscle is usually divided into sections. Two basically different pathways of differentiation in the cheek part of the adductor mandibulae are dealt with here. One is that in the ostariophysine fishes. The other is represented in at least the great majority of acanthopterygians. Only certain of the differentiated sections are homologous in these two large groups of fishes.     

Weighted parsimony phylogeny of the family Characidae (Teleostei: Characiformes)

The family Characidae, including more than 1000 species, lacks a phylogenetic diagnosis, with many of its genera currently considered as incertae sedis . The aims of the present study are to propose a phylogenetic diagnosis and to assess higher-level relationships of and within Characidae. In this regard, 360 morphological characters are studied for 160 species of Characidae and related families. Phylogenetic analyses under implied weighting and self-weighted optimization are presented, exploring a broad range of parameters. The analysis under self-weighted optimization is innovative for this size of matrices. Familial status of Serrasalmidae is supported, and Acestrorhynchidae and Cynodontidae are included in a monophyletic Characidae. Engraulisoma taeniatum is transferred from Characidae to Gasteropelecidae. Thus constituted, the monophyly of Characidae is supported by seven synapomorphies. A new subfamily, Heterocharacinae, is proposed, and the subfamilies Aphyocharacinae, Aphyoditeinae, Characinae, Gymnocharacinae, and Stevardiinae are redefined. The Glandulocaudinae are included in Stevardiinae together with remaining members of "clade A" ( sensu Malabarba and Weitzman, 2003 . Comun. Mus. Ciênc. Tecnol. PUCRS, Sér. Zool. 16, 67–151.) and the genera Aulixidens and Nantis . Most incertae sedis genera are assigned, at least tentatively, to a phylogenetically diagnosed clade.     

Phylogenetic interrelationships of living and extinct Tinamidae,volant palaeognathous birds from the New World

Tinamous, one of the earliest diverging living avian lineages, consists of a Neotropical clade of palaeognathous birds with a fossil record limited to the early Miocene–Quaternary of southern South America. Here, we conduct a comprehensive, morphology‐based phylogenetic study of the interrelationships among extinct and living species of tinamous. Morphological data of fossil species are included in a matrix of 157 osteological and myological characters of 56 terminal taxa. The monophyly of most recognized genera is supported by the results of the analysis. The cladistic analysis also recovers the traditional subdivision between those tinamous specialized for open areas (Nothurinae) and those inhabiting forested environments (Tinaminae). Temporal calibration of the resultant phylogeny indicates that such a basal divergence had already taken place in the early Miocene, some 17 million years ago. The placement of the fossil species within the open‐area (Nothurinae) and the forest‐dwelling (Tinaminae) tinamous is also consistent with the palaeoenvironmental conditions inferred from the associated fauna. © 2014 The Linnean Society of London