Phylogenetic relationships among atheriniform fishes (Teleostei: Atherinomorpha)

We present evidence from adult and larval morphology for the monophyly and relationships of Atheriniformes, using other atherinomorphs, mugilids and acanthomorph fishes as outgroups. Atheriniformes is diagnosed by ten characters (larval: short preanal length, single mid-dorsal row of melanophores; adult: vomerine ventral face concave, long Al muscle tendon to lacrimal, two anterior infraorbital bones, pelvic-rib ligament, pelvic medial plate not extended to anterior end, and second dorsal-fin spine flexible). We recognize six families within the order, the hierarchical relationships among which are: (Atherinopsidae (Notocheiridae (Melanotaeniidae (Atherionidae (Phallostethidae, Atherinidae))))). Other major conclusions include: (1) Atherinopsidae (Menidiinae, Atherinopsinae) is diagnosed by 20 characters (e.g. ethmomaxillary ligament attached to palatine dorsal process, ventral postcleithrum with two dorsal rami); (2) Melanotaeniidae (Bedotiinae (Melanotaeniinae (Telmatherinini, Pseudomugilini))) is diagnosed by six characters (e.g. absence of second dorsal-fin spine, sexual dimorphism in body colour and median-fin development, greater body depth); (3) Dentatherina is in Phallostethidae; (4) Atherinidae (Atherinomorinae (Craterocephalinae, Atherininae)) is diagnosed by three characters (lacrimal notch, ventral postcleithrum between first and second pleural ribs, pelvic ventral spine); (5) Atherinidae and Phallostethidae form the Atherinoidea clade diagnosed by seven characters (e.g. interopercle dorsal process absent, dorsal wings of urohyal absent, ventral postcleithrum laminar, pelvic medial plate extended to anterior end, presence of anal plate). Bedotia, Rhodes , and melanotaeniines are shown to be derived within atheriniforms rather than the plesiomorphic sister groups to a paraphyletic 'atherinoid' group. We also demonstrate that groups traditionally placed in Atherinidae (Menidiinae, Atherininae, Atherioninae, etc.) comprise a paraphyletic assemblage.     

Effects of jaw adductor hypertrophy on buccal expansions during feeding of air breathing catfishes (Teleostei,Clariidae)

Some species of Clariidae (air breathing catfishes) have extremely well developed (hypertrophied) jaw closing muscles that increase the maximal biting force of these species. As these enlarged jaw muscles tightly cover the suspensoria, which are firmly connected to the neurocranium, we expect diminished lateral expansions during suction for species with hypertrophied jaw muscles. In turn, this could imply a reduced suction performance for these species. Compared to Clarias gariepinus, which has relatively small jaw closers, Clariallabes longicauda shows a clear hypertrophy of the jaw adductors. A kinematic analysis of prey capture in these two species is presented here. As predicted, Clariallabes longicauda shows less lateral expansion (average abduction of the hyoids of 19.0°) than Clarias gariepinus (abduction of 31.1°). However, our data indicate that the decrease in lateral expansion capacity in the species with excessive adductor development is compensated for by a larger and faster ventral expansion of the buccal cavity by depression of the hyoid.     

Karyotypes of the most primitive catfishes (Teleostei: Siluriformas: Diplomystidae)

Karyotypes of Diplomystes composensis and Diplomystes nahuelbutaensis were the same diploid number (n= 56).The chromosome formula for D. composensis was 16 metacentric + 24 submetacentric + 8 subtelocentric + 8 telocentric chromosomes and for D. nahuelbutaensis was 14 metacentric + 26 submetacentric + 8 subtelocentric +8 telocentric chromosomes. In contrast, the differences in the chromosomal C-banding patterns between these species was large. For instance, chromosome pairs 5,6, and 7 of D. nahuelbutaensis showed heterochromatic centromeres and pairs 23, 24, 27, and 28 were entirely heterochromotic. Diplomystes composensis showed conspicuous C-banded blocks in pairs 7, 24, and 25 (chromosome pair 7 had one heterochromatic arm, chromosome pair 24 was entirely heterochromatic, and chromosome pair 25 had heterochromatin close to centromere). Comparison with other ostariophysan karyotypes (e.g. gymnotiforms, characiforms, and cypriniforms), does not allow any conclusions about the ploesiomorphic catfish condition, because the karyotypes of the outgroups are too variable. A synapomorphy shared by characiforms, gymnotiforms, and diplomystid catfishes is the presence of more metacentric to submetacentric than substelocentric to telocentric chromosomes. Cypriniforms are more primitive because they have more subtelocentric to telocentric than metacentric to submetacentric chromosomes.     

Systematics of Tanganyikan cichlid fishes (Teleostei: Perciformes)

The relationships among 53 genera of Tanganyikan cichlid fishes were analyzed based on internal and external morphological features. Comparison of the morphological cladistic tree with a previously proposed classification showed 5 of 12 tribes to be nonmonophyletic. Sixteen tribes were recognized, the changes in classification being that Trematocarini was treated as a junior synonym of Bathybatini; 5 new tribes were established for each of the following genera, Benthochromis, Boulengerochromis, Ctenochromis benthicola, Cyphotilapia, and Greenwoodochromis; Ctenochromis horei was transferred from Haplochromini to Tropheini; and Gnathochromis pfefferi was transferred from Limnochromini to Tropheini. The revised classification was supported by previously proposed molecular trees.     

Molecular phylogeny of the fishes traditionally referred to Cyprinini sensu stricto (Teleostei: Cypriniformes)

Yang, L., Mayden, R. L., Sado, T., He, S., Saitoh, K. & Miya, M. (2010). Molecular phylogeny of the fishes traditionally referred to Cyprinini sensu stricto (Teleostei: Cypriniformes). —Zoologica Scripta, 39, 527–550. Carps (e.g. Koi) of the genus Cyprinus and Crucian carps (e.g. Goldfish) of the genus Carassius are among the most popular freshwater fishes around the world. However, their phylogenetic positions within the subfamily Cyprininae, relationships with their allies (e.g. Procypris, Carassioides), and the monophyly of the group formed by them and their allies, which is referred as the tribe Cyprinini sensu stricto, are far from clear. Historically, the Cyprinini was defined by different people according to whether a cyprinine fish possessed a spinous anal‐fin ray (or anal spine), the spine was serrated or not, and occasionally, the number of branched dorsal‐fin rays. Some definitions were established without providing any diagnostic characters. In this study, we investigated the monophyly of the tribe Cyprinini sensu stricto, based on four different historical definitions, and explored the phylogenetic relationships of these members in the subfamily Cyprininae. Using five mitochondrial genes as markers, both maximum‐likelihood and Bayesian trees were constructed using the optimal partitioning strategy. Both analyses successfully resolved a monophyletic Cyprininae and recovered seven major clades from this subfamily. The diagnosis limiting the tribe Cyprinini sensu stricto to four genera, Cyprinus, Carassius, Carassioides and Procypris, received most support. We propose that only those cyprinines that possess a serrated anal spine and have no <10 branched dorsal‐fin rays should be considered members of this tribe. Cyprinini is sister to the Sinocyclocheilus clade, a group traditionally considered a barbin, and together they form the ‘Cyprinini‐Sinocyclocheilus’ clade. Procypris forms the basal clade of the Cyprinini, whereas species of Carassius and Carassioides locate at the top.     

Internal fertilization,testis and sperm morphology in glandulocaudinae fishes (Teleostei: Characidae: Glandulocaudinae)

In this report, the gonads of 32 glandulocaudine species, representing 18 genera, are compared with 11 outgroup characiform species. Through the presence of spermatozoa within the ovarian cavity, internal fertilization of the female is confirmed for the 16 genera for which mature ovaries were available. No outgroup ovary studied contains spermatozoa. All mature glandulocaudine testes have a large portion of the posterior testis, which is devoid of developing germ cells and spermatocysts (aspermatogenic), devoted to sperm storage, with the degree of partitioning in that region varying greatly within the group. All outgroup species examined have spermatozoa with spherical nuclei. With the exception of the species of the genus Planaltina, which also have spherical nuclei, all glandulocaudines have elongated nuclei, which vary among the species from 3.6 μm to 31.6 μm in length. Distinct sperm packets (spermatozeugmata) are formed in five genera by two different methods. In the genera Xenurobrycon, Tyttocharax, and Scopaeocharax, all of the tribe Xenurobryconini, the spermatozeugmata are formed within the spermatocysts and released fully formed. In all genera of the tribe Glandulocaudini, which includes Glandulocauda and Mimagoniates, loose spermatozoa are released which cluster into spermatozeugmata within the posterior storage areas. These morphological specializations are discussed within a phylogenetic framework as adaptations for internal fertilization and are hypothesized to be independently derived. © 1995 Wiley-Liss, Inc.     

Relationships among four genera of mojarras (Teleostei: Perciformes: Gerreidae) from the western Atlantic and their tentative placement among percomorph fishes

A phylogenetic study of the percoid family Gerreidae at both lower and higher taxonomic levels is presented based on DNA sequence data of four genes: mitochondrial 12S and 16S, and nuclear genes rhodopsin and recombination activating gene 1 (RAG1). The taxonomic sampling includes four genera of Gerreidae from the western Atlantic, 39 additional percomorph representatives and two outgroups. Phylogenetic results confirm the monophyly of the Gerreidae and suggest that the family is divided into two sub-groups ( Diapterus auratus plus Eugerres plumieri and Eucinostomus gula plus Gerres cinereus ), which correspond to two previously defined taxonomic assemblages characterized by the shape of the preoperculum. Gerreids are placed at an intermediate position in the percomorph tree between two basal clades (L and Q) and a terminal clade N (grouping tetraodontiforms, acanthuroids, lophiiforms, caproids and several percoids). In addition, topology tests indicate that two traditional assemblages, Labroidei (seven representatives sampled) and Percoidei (22 representatives sampled) are not natural groups. Labrids and scarids appear to be more closely related to gerreids and to the members of clade N than to any other basal percomorphs, including their labroid 'allies' sampled in this study, Embiotocidae, Pomacentridae and Cichlidae, which are all nested within clade Q that also includes atherinomorphs, mugiliforms and Chandidae. The percoid taxa included in this study are widely distributed among various percomorph lineages. The percomorph phylogeny obtained is highly congruent with results from recent molecular studies.     

The monophyly of the Characidiinae, a Neotropical group of characiform fishes (Teleostei: Ostariophysi)

Although virtually no phylogenetic evidence (in the sense advocated by Hennig, 1966) had been previously presented to support the monophyly of the Characidiinae, and most 'diagnostic' characters used by previous authors were found to be unacceptable in a cladistic classification, i t is still possible to diagnose the Characidiinae in a phylogenetic sense. This study revealed the existence of 13 synapomorphies supporting the monophyly of the group. Several of these synapomorphies, such as the modifications associated with the mesethmoid, the jaw bones, and the ribs of the fifth vertebra, are unique to the Characidiinae, thus providing a solid basis for recognizing the group as a monophyletic unit of characiform fishes. Demonstration of characidiin monophyly provides a solid foundation for further phylogenetic analysis of characidiin interrelationships, and higher level relationships among characiform fishes.     

The caudal skeleton of ostariophysan fishes (Teleostei): Intraspecific variation in trichomycteridae (Siluriformes)

The different elements of the caudal skeleton of the South American catfish genera Nematogenys (Nematogenyinae) and Trichomycterus, Hatcheria, and Bullockia (Pygidiinae) (Siluriformes, Trichomycteridae) show Ontogenetic transformation of the second ural centrum in Trichomycteridae separates the subfamilies Nematogenyinae and Pygidiinae. In the former, the second ural centrum is aligned with the first ural centrum in early stages of ontogeny; it is not fused with the bases of hypurals 3 and 4 in any stage of development. In the Pygidiinae, in contrast, the second ural centrum is connected with the base of hypural 3 from an early stage of development on. One of the most noteworthy features of the Pygidiinae is the epural, a polymorphic element with three or four morphotypes that are species specific. The primitive catfish Nematogenys shows intraspecific variation in the ural centra, segmentation of procurrent caudal rays, and principal caudal ray formulae. Species of Trichomycterus, Hatcheria, and Bullockia are characterized by great intraspecific variability that involves ural centra, the epural, hypurapophyses, and the neural arches of the compound centrum. There is intraspecific variation in the fusion of the hypurals in some species of Trichomycterus. Intraspecific variation of the caudal skeleton of fishes of the family Trichomycteridae involves the presence and frequency of different morphotypes of the epural, neural arch of the compound centrum, fusion of hypurals, and principal caudal ray formulae. Ontogenetic changes of the first and second ural centra, hypurapophyses (with the exception of Nematogenys), and segmentation of procurrent caudal rays (in Nematogenys) are involved also.     

Molecular phylogeny of basal gobioid fishes: Rhyacichthyidae, Odontobutidae, Xenisthmidae, Eleotridae (Teleostei: Perciformes: Gobioidei)

Morphological character analyses indicate that Rhyacichthyidae, Odontobutidae, Eleotridae, and Xenisthmidae are the basal families within the perciform suborder Gobioidei. This study uses DNA sequence data to infer the relationships of genera within these families, as well as determine the placement of more derived gobioids (family Gobiidae) and the identity of the outgroup to Gobioidei. Complete sequences of the mitochondrial ND1, ND2, COI, and cyt b genes (4397 base pairs) are analyzed for representatives of 27 gobioid genera and a variety of perciform and scorpaeniform outgroup candidates; the phylogeny is rooted with a beryciform as a distal outgroup. The single most parsimonious tree that results indicates that, of the outgroups sampled, the perciform family Apogonidae is most closely related to Gobioidei. Gobioidei is monophyletic, and Rhyacichthys aspro is the most basal taxon. The remainder of Gobioidei is resolved into clades corresponding to the families Odontobutidae (plus Milyeringa) and Eleotridae+Xenisthmidae+Gobiidae. Within Eleotridae, the subfamily Butinae (minus Milyeringa) is paraphyletic with respect to Gobiidae, and Eleotrinae is paraphyletic with respect to Xenisthmidae. Other than these groupings, the primary disagreement with the current morphology-based classification is that the molecular data indicate that the troglodytic Milyeringa should be placed in Odontobutidae, not Butinae, although support for this placement is weak. The most basal lineage of Gobioidei is known from the freshwaters of the Indo-Pacific, with marine-dwelling lineages arising several times independently in the group. The phylogeny also indicates that different gobioid lineages are distributed in Asia, Africa, Madagascar and the Neotropics. Five sister pairs of basal gobioid species inhabit Atlantic and Pacific drainages of Panama, with widely varying divergences.     

Feeding patterns in eastern tropical Pacific blennioid fishes (Teleostei: Tripterygiidae,Labrisomidae, Chaenopsidae,Blenniidae)

Summary In terms of species number (47) and numerical abundance, blennioids are the most important primary resident rocky reef fishes in the Gulf of California, Mexico. We present the feeding patterns of the 34 most abundant species of blennioid fishes, 8 of which are Gulf endemics. A total of 2,144 specimens were sampled at 51 anaesthetic stations in 9 areas throughout the Gulf. Four feeding guilds were distinguished: 1) The majority (29 of 34 species) are microcarnivores exhibiting a number of different feeding strategies (ambush and stalking predators, active foragers, pickers, etc.). The more important prey categories were mobile invertebrates, and to some extent also sedentary fauna. Algae were of no importance for most of the latter species. 2) Hypsoblennius brevipinnis and H. gentilis are two omnivorous species, browsing mainly on sessile items including 52% and 13% (Vol.) algae in their diets. 3) Entomacrodus chiostictus and Ophioblennius steindachneri are herbivores, grazing on fine algae. 4) Plagiotremus azaleus specializes in cropping mucus and scales from the body surface of other fishes.Crustaceans account for 58.6% of the total volume of prey items in the 34 species investigated. Benthic amphipods were most important and made up 26% of the total volume of all prey items.Cluster analysis of percentage volumetric data using Squared Euclidian Distance and Horn's Index of Overlap produced distinct subgroups which coarsely reflected taxonomic grouping.The species are separated either by their geographic ranges, habitat and microhabitat preferences, feeding, or a combination thereof. Only rarely do sympatric species significantly overlap in diet.Trophic diversity as measured by the Shannon-index provides a tool for distinguishing: 1) specialists (6 species) from 2) low diversity feeders (18 species) and 3) high diversity generalists (10 species). Two different types of specialists can be distinguished: those which feed on the same items as the generalists but utilize only a very restricted prey spectrum (Stathmonotus sinuscalifornici and the chaenopsids Chaenopsis alepidota and Emblemaria hypacanthus). A second group of specialists (Entomacrodus chiostictus and Ophioblennius steindachneri as well as Plagiotremus azaleus) feed on items not utilized by any of the generalists.There is some evidence that high diversity generalists are numerically more abundant than the other trophic groups.In the labrisomids and blenniids a phylogenetic trend from microcarnivory towards feeding on sessile items appears to be expressed.     

Illustrated key for the Chilean fishes of the family Serranidae (Teleostei: Perciformes)

A taxonomic key for identification of fish species of the family Serranidae of Chile, grouped in the subfamilies Epinephelinae, Serraninae and Anthiinae is presented. Basic data about the taxonomic of the group to facilitate the identification is given. In each specific case, the geographical distribution is showed. Reduced illustrations for the currently 13 serranid species considered in the Chilean ichthyofauna are included.     

A rod-dominated visual system in leptocephalus larvae of elopomorph fishes (Elopomorpha: Teleostei)

The nature and distributions of photoreceptor cell types were investigated in the retinas of 12 species (5 families) of elopomorph anguilliform leptocephalus larvae. Anti-opsin immunofluorescence, light microscopy and transmission electron microscopy (TEM) were used to assess opsin distribution across the retinas and to associate photoreceptor morphology and opsin content. Retinas of all species were immunoreactive with anti-rhodopsin throughout, while anti-cone opsin immunoreactivity was restricted only to the ventral region of the retina in all specimens. Rod and cone photoreceptors were morphologically indistinguishable at low magnifications; TEM revealed that nearly all photoreceptors had rod-like ultrastructure, with only rare examples of cone-like cells identified in the ventral retina. These results indicate a rhodopsin/rod-dominated retina in leptocephalus larvae of anguilliform eels in the teleost subdivision Elopomorpha, contrasting with the cone-dominated retinas of nearly all other species of teleost larvae. This distinctive developmental pattern shared among elopomorph larvae has important evolutionary and ecological implications, indicating a shared ancestor and/or ecological characteristics that are very different from most other teleost larvae.     

Relationships among major lineages of characid fishes (Teleostei: Ostariophysi: Characiformes), based on molecular sequence data

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.     

Anatomy and evolution of the mandibular, hyopalatine, and opercular muscles in characiform fishes (Teleostei: Ostariophysi)

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.     

Phylogenetics of notothenioid fishes (Teleostei: Acanthomorpha): inferences from mitochondrial and nuclear gene sequences

Notothenioids represent an adaptive radiation of teleost fishes in the frigid and ice-laden waters of the Southern Ocean surrounding Antarctica. Phylogenetic hypotheses for this clade have resulted primarily from analyses of mtDNA gene sequences, and studies utilizing nuclear gene DNA sequence data have focused on particular sub-clades of notothenioid fishes. In this study, we provide the first phylogenetic analysis of notothenioids using both mtDNA and nuclear gene sequences for a comprehensive sampling of all major lineages in the clade. Maximum parsimony and Bayesian analyses of aligned mtDNA genes, an aligned nuclear gene (S7 ribosomal protein intron 1), and combined dataset containing the mtDNA and nuclear genes resulted in phylogenies that contained the previously identified Antarctic and High Antarctic Clades. There were areas of agreement and disagreement between different datasets and methods of phylogenetic analysis, and the phylogenies resulting from the nuclear encoded S7 ribosomal protein intron 1 sequences were considerably less resolved than those inferred from mtDNA gene sequences. However, we anticipate increased resolution of the notothenioid phylogeny from future analyses that sample DNA sequences from several nuclear genes.     

Transmission of force and velocity in the feeding mechanisms of labrid fishes (Teleostei,Perciformes)

Summary The feeding mechanisms of four species of the teleostean family Labridae (Cheilinus fasciatus, C. trilobatus, Oxycheilinus bimaculatus, and O. unifasciatus) were modeled using four-bar linkage theory from mechanical engineering. The predictions of four-bar linkage models regarding the kinematics of feeding were compared to the movements observed with high speed cinematography (200 frames/s). A four-bar linkage was an accurate model of the mechanism by which upper jaw protrusion, maxillary rotation, and gape increase occur in each species. A four-bar mechanism of hyoid depression was an accurate predictor of hyoid depression when simultaneous cranial elevation and sternohyoideus contraction were simulated. Morphometrics of the linkage systems of the jaws and hyoid were collected for 12 labrid species. These data were used to calculate the transmission of force and motion through the musculoskeletal linkages. Several measures of mechanical advantage and displacement advantage were compared, including both traditional lever ratios and transmission coefficients of four-bar linkages. Alternative designs of the feeding mechanisms maximize force or velocity for the capture of different prey types. High velocity transmission of both the jaw and hyoid systems is characteristic of those species that feed on evasive prey, whereas species that feed on benthic invertebrates favor increased force transmission in both systems. Quantitative models of biomechanical systems supply criteria for functionally relevant morphometrics, and aid in calculating the capacity for transmission of force and velocity in musculoskeletal systems.