Karyotypic diversity and evolution of Loricariidae (Pisces, Siluriformes)

We present cytogenetic analyses of four fish species, belonging to four Loricariidae subfamilies: Neoplecostomus microps (Neoplecostominae) with 2n=54 chromosomes, Harttia loricariformis (Loricariinae) with 2n=56 chromosomes, Hypostomus affinis (Hypostominae) with 2n=66 chromosomes and Upsilodus sp. (Upsilodinae), with 2n=96 chromosomes. In addition to karyotypes, data on the location of 18s rDNA sites are presented, derived from indirect (silver nitrate impregnation) and direct (FISH) methods. There is only one pair of nucleolar organizing regions (NORs) per species, except in H. affinis. Diversity and NOR macrokaryotypic evolution in the species analyzed are discussed in relation to the evolution of the Loricariidae as a whole. In addition, a revision of the cytogenetic data available for this family is presented.     

Spermiogenesis and sperm ultrastructure in ten species of Loricariidae (Siluriformes, Teleostei)

The current study describes the ultrastructural characteristics of spermatogenesis, spermiogenesis, and spermatozoa in specimens of siluriform taxa Neoplecostominae, Hypoptopomatinae, Otothyrinae, Loricariinae, and Hypostominae. Our data show that the characteristics of spermatogenesis and spermiogenesis and spermatozoa ultrastructure of Neoplecostominae are more common to Hypoptopomatinae and Otothyrinae than to Loricariinae and Hypostominae. Furthermore, Loricariinae and Hypostominae have more characteristics in common than with any other group of Loricariidae. These data reinforce the phylogenetic hypotheses of relationships among the subfamilies of Loricariidae. Considering the available data in Loricarioidei, Loricariidae presents ultrastructural characteristics of spermatogenesis and spermiogenesis that are also observed in Astroblepidae, its sister group. However, the most of the characteristics of spermatozoa ultrastructure found in Astroblepidae are also observed in Scoloplacidae, the sister group of a clade composed of Astroblepidae and Loricariidae.     

Trends in the karyotype evolution of Loricariidae fish (Siluriformes)

Six species of Loricariidae belonging to the subfamilies Hypostominae (Hypostomus emarginatus, Rhinelepsis aspera, Pogonopoma wertheimeri), Ancistrinae (Panaque cf. nigrolineatus, Hemiancistrus sp.) and Loricariinae (Sturisoma cf. nigrirostrum) were studied cytogenetically. The results show that 2n = 54 represents the basal diploid number for this fish family. Different trends in the karyotypic evolution can be seen among the subfamilies: Hypostominae and Loricariinae species present diversified karyotypic macrostructures, while the Ancistrinae appear to show more conserved karyotypes. Among the Hypostominae, the genus Hypostomus had a wide karyotypic variation (2n = 52 to 80), where centric fissions seem to play an important role in this chromosomal divergence. The nucleolar organizing regions were diversified, and occurrence of multiple NORs was frequent. Heteromorphic chromosomes belonging to distinct sex chromosome systems can also occur infrequently among the Loricariidae.     

Gross brain morphology of Hypoptopomatinae and Neoplecostominae (Siluriformes: Loricariidae): Comparative anatomy and phylogenetic implications

Hypoptopomatinae and Neoplecostominae include about 250 valid species, a substantial portion of loricariid catfishes. Although the relationships among the members of these subfamilies have been inferred by many authors, the most recent hypotheses based on morphological and molecular data differ widely. Herein, we provide new data on the morphology of the central nervous system, and evaluate the usefulness of these characters in phylogenetic inference. To accomplish this, we characterized the gross brain morphology of those catfishes, and analyzed 54 neuroanatomical characters in a total of 40 terminal taxa representing Hypoptopomatinae and Neoplecostominae, and also members of Delturinae and Hypostominae as outgroups. Hypoptopomatinae and Neoplecostominae are recovered as separate subfamilies, and most of our results are compatible with morphology‐based analyses. We conclude that neuroanatomy provides an informative source of new characters with strong phylogenetic signal at all recovered taxonomic levels.     

Population divergence and peculiar karyoevolutionary trends in the loricariid fish Hypostomus aff. unae from northeastern Brazil

Loricariidae (Siluriformes, Hypostominae) is one of the most diverse catfish families. In spite of the wide distribution of loricariids in South America, cytogenetic reports are available for only a few species, mostly from southern and southeastern Brazil. We made the first chromosomal analysis of Hypostomus aff. unae from the Contas River basin in northeastern Brazil. Four populations isolated by short distances but from distinct landscapes were studied based on conventional staining, C-banding, argyrophilic nucleolar organizer regions (Ag-NOR), CMA(3)/DAPI fluorochrome staining, and fluorescent in situ hybridization with 18S rDNA probes. Although sharing the same diploid number (2n = 76) and NOR locations, each population presented exclusive karyotype formulae and specific patterns of heterochromatic and AT-rich regions. The derived karyotypes of H. aff. unae (2n >54; high number of acrocentrics bearing AT-rich interstitial heterochromatin) indicated a divergent karyoevolution, mostly driven by centric fissions, pericentric inversions and particular heterochromatin dispersion models. This finding of distinct evolutionary units in H. aff. unae will be useful for understanding the natural history of loricariids from relatively unexplored coastal basins in South America.     

Heterochromatin characterization of four fish species of the family Loricariidae (Siluriformes)

The karyotypic structures and the composition and distribution of the heterochromatin in the karyotypes of four catfish species belonging to four Loricariidae subfamilies were analysed, namely: Neoplecostomus microps (Neoplecostominae) with 2n=54 chromosomes, Harttia loricariformis (Loricariinae) with 2n=56 chromosomes, Hypostomus affinis (Hypostominae) with 2n=66 chromosomes and Upsilodus sp. (Upsilodinae) with 2n=96 chromosomes. The amount and composition of heterochromatin was quite unequal among the studied species, being copious and mainly GC-rich in Upsilodus sp. and scarce and balanced in H. loricariformis. All of the H. affinis heterochromatin is GC-rich and related with nucleolar organizing regions. N. microps show low quantity of interstitial and GC-rich heterochromatin, one of them being related with NORs. Trends in the macrokaryotypic diversification as well as in the distribution pattern of the heterochromatin are discussed.     

Phylogenetic relationships of the suckermouth armoured catfishes (Loricariidae) with emphasis on the Hypostominae and the Ancistrinae

A phylogenetic analysis of nearly all genera of the Hypostominae and the Ancistrinae is provided based on osteology, external anatomy, and digestive tract anatomy. The results suggest that the Hypostominae is a paraphyletic assemblage. Delturus and Upsilodus form a monophyletic group sister to all other loricariids. Hemipsilichthys , Isbrueckerichthys , Kronichthys , and Pareiorhina form a monophyletic group with Neoplecostomus and the Hypoptopomatinae and are transferred to the Neoplecostominae. The remainder of the Hypostominae is made paraphyletic by the continuing recognition of the Ancistrinae. Ancistrinae is returned to the Hypostominae and recognized as a tribe, Ancistrini. In addition, four new tribes (Corymbophanini, Hypostomini, Pterygoplichthini, and Rhinelepini) are described. Hypostomus is also paraphyletic, the bulk of it forming a monophyletic clade with Aphanotorulus , Cochliodon , and Isorineloricaria . All of the potential monophyletic groups within Hypostomus grade into one another; therefore, Aphanotorulus , Cochliodon , and Isorineloricaria are placed in the synonymy of Hypostomus . Pterygoplichthys and Glyptoperichthys are also polyphyletic, and Liposarcus and Glyptoperichthys are recognized as synonyms of Pterygoplichthys . Sister to Pterygoplichthys is the Hemiancistrus annectens group (including Hypostomus panamensis ) which represents an undescribed genus. The phylogeny presented is compared with previous hypotheses.  © 2004 The Linnean Society of London, Zoological Journal of the Linnean Society , 2004, 141 , 1−80.     

Molecular systematic and historical biogeography of the armored Neotropical catfishes Hypoptopomatinae and Neoplecostominae (Siluriformes: Loricariidae)

The Neotropics possess the greatest freshwater fish diversity of the world, rendering the study of their evolutionary history extremely challenging. Loricariidae catfishes are one of the most diverse components of the Neotropical ichthyofauna and despite a long history of classification, major issues still need elucidation. Based on a nuclear gene, we present a robust phylogeny of two former loricariid subfamilies: Hypoptopomatinae and Neoplecostominae. Our results show that Neoplecostominae is nested within Hypoptopomatinae, and is the sister group to the former Otothyrini tribe. According to our results, supplemented by morphological observations, we erect two new subfamilies, the Otothyrinae and a new Hypoptopomatinae, and modify the Neoplecostominae by including the genus Pseudotocinclus. The uncovered evolutionary relationships allow a detailed analysis of their historical biogeography. We tested two Dispersal-Extinction-Cladogenesis models for inferring the distribution range evolution of the new subfamilies, and show that the model having no constrains performs better than a model constraining long-range dispersal. The Maximum Likelihood reconstructions of ancestral ranges showed a marked division between the Amazonian origin of the Hypoptopomatinae and the eastern coastal Brazil+Upper Paraná origin of the Neoplecostominae and Otothyrinae. Markedly few instances of dispersal across the border separating the Amazon basin and the Paraná-Paraguay+eastern coastal Brazil+Uruguay were reconstructed. This result is in clear contrast with the historical biogeography of many Neotropical fishes, including other Loricariidae. Part of the dispersal limitation may be explained by divergent ecological specialization: lowland rivers versus mountain streams habitats. Moreover, because most species of the new subfamilies are small, we hypothesize that body size-related effects might limit their dispersal, like predation and energetic cost to migration. Finally, morphological and anatomical features are presented that limit or, to the contrary, enhance dispersal capability in these small and fascinating catfishes.     

Delturinae, a new loricariid catfish subfamily (Teleostei, Siluriformes), with revisions of Delturus and Hemipsilichthys

A new subfamily, Delturinae, is described to accommodate the loricariid catfish genera Delturus Egenmann & Eigenmann, 1889 and Hemipsilichthys Eigenmann & Eigenmann, 1889, a clade recently demonstrated to be the sister group of all remaining loricariids except Lithogenes . The genus Hemipsilichthys is restricted to three species, H. gobio (Lütken, 1874), its sister species H. papillatus Pereira et al ., 2000, and H. nimius Pereira et al ., 2003. Relationships among species of Delturus were not resolved and a new species, D. brevis , is described from the Rio Jequitinhonha basin in eastern Brazil. The geographical distribution of Delturinae, exclusively on the south-eastern Brazilian Shield, indicates that south-eastern Brazil acts as either a refugium for basal loricariid taxa or a point of origin for the Loricariidae. Lectotypes are designated for D. parahybae Eigenmann & Eigenmann, 1889 and Plecostomus angulicauda Steindachner, 1877. Keys are presented for subfamilies of Loricariidae and for genera and species of Delturinae. Diagnoses are provided for all delturine clades and species.  © 2006 The Linnean Society of London, Zoological Journal of the Linnean Society , 2006, 147 , 277–299.     

Molecular phylogeny of the armored catfish family Callichthyidae (Ostariophysi, Siluriformes)

The family Callichthyidae comprises eight genera of fishes widely distributed across the Neotropical region. In the present study, sequences of the mitochondrial genes 12S rRNA, 16S rRNA, ND4, tRNAHis, and tRNASer were obtained from 28 callichthyid specimens. The sample included 12 species of Corydoras, three species of Aspidoras, two species of Brochis, Dianema, Lepthoplosternum, and Megalechis, and two local populations of Callichthys and Hoplosternum. Sequences of Nematogenys inermis (Nematogenyidae), Trichomycterus areolatus, and Henonemus punctatus (Trichomycteridae), Astroblepus sp. (Astroblepidae), and Neoplecostomus paranensis, Delturus parahybae, and Hemipsilichthys nimius (Loricariidae) were included as the outgroup. Phylogenetic analyses were performed by using the methods of maximum parsimony and maximum likelihood. The results of almost all analyses were very similar. The family Callichthyidae is monophyletic and comprises two natural groups: the subfamilies Corydoradinae (Aspidoras, Brochis, and Corydoras) and Callichthyinae (Callichthys, Dianema, Hoplosternum, Lepthoplosternum, and Megalechis), as previously demonstrated by morphological studies. The relationships observed within these subfamilies are in several ways different from those previously proposed on the basis of morphological data. Molecular results were compared with the morphologic and cytogenetic data available on the family.     

Evolutionary and biogeographic history of the subfamily Neoplecostominae (Siluriformes: Loricariidae)

Freshwater fish evolution has been shaped by changes in the earth's surface involving changes in the courses of rivers and fluctuations in sea level. The main objective of this study is to improve our knowledge of the evolution of loricariids, a numerous and adaptive group of freshwater catfish species, and the role of geological changes in their evolution. We use a number of different phylogenetic methods to test the relationships among 52 representative taxa within the Neoplecostominae using 4676 bps of mitochondrial and nuclear DNA. Our analysis revealed that the subfamily Neoplecostominae is monophyletic, including Pseudotocinclus, with three lineages recognized. The first lineage is composed of part of Pareiorhina rudolphi, P. cf. rudolphi, and Pseudotocinclus; the second is composed of Isbrueckerichthys, Pareiorhaphis, Kronichthys, and the species Neoplecostomus ribeirensis; and the third is composed of Pareiorhina carrancas, P. cf. carrancas, Pareiorhina sp. 1, a new genus, and all the species of the genus Neoplecostomus, except N. ribeirensis. The relaxed molecular clock calibration provides a temporal framework for the evolution of the group, which we use for a likelihood‐based historical biogeographic analysis to test relevant hypotheses on the formation of southeast Brazil. We hypothesize that headwater capture events and marine regressions have shaped the patterns of distribution within the subfamily Neoplecostominae throughout the distinct basins of southeast Brazil.     

Modern Distribution of Armored Catfishes (Siluriformes: Loricariidae) in Central Vietnam

The modern distribution of South American armored catfishes (Loricariidae) is studied in three provinces in Central Vietnam. In the investigated area, representatives of the genus Pterygoplichthys occur, and at present they have moved into all main river basins. During the last 2–5 years, alien species have entered into many water bodies isolated from the places of their first discovery by natural and manmade barriers. This indicates the important role of the human factor for the expansion of loricariids in the region.     

Trophic diversity in the evolution and community assembly of loricariid catfishes

ABSTRACT: BACKGROUND: The Neotropical catfish family Loricariidae contains over 830 species that display extraordinary variation in jaw morphologies but nonetheless reveal little interspecific variation from a generalized diet of detritus and algae. To investigate this paradox, we collected delta13C and delta15N stable isotope signatures from 649 specimens representing 32 loricariid genera (82 species) from 19 local assemblages distributed across South America. We calculated vectors representing the distance and direction of each specimen relative to the delta15N/delta13C centroid for its local assemblage, and then examined the evolutionary diversification of loricariids across assemblage isotope niche space by regressing the mean vector for each genus in each assemblage onto a phylogeny reconstructed from osteological characters. RESULTS: Loricariids displayed a total range of delta15N assemblage centroid deviation spanning 4.9per thousand, which is within the tissue-diet discrimination range known for Loricariidae, indicating that they feed at a similar trophic level and that delta15N largely reflects differences in their dietary protein content. Total range of delta13C deviation spanned 7.4per thousand, which is less than the minimum range reported for neotropical river fish communities, suggesting that loricariids selectively assimilate a restricted subset of the full basal resource spectrum available to fishes. Phylogenetic regression of assemblage centroid-standardized vectors for delta15N and delta13C revealed that loricariid genera with allopatric distributions in disjunct river basins partition basal resources in an evolutionarily conserved manner concordant with patterns of jaw morphological specialization and with evolutionary diversification via ecological radiation. CONCLUSIONS: Trophic partitioning along elemental/nutritional gradients may provide an important mechanism of dietary segregation and evolutionary diversification among loricariids and perhaps other taxonomic groups of apparently generalist detritivores and herbivores. Evolutionary patterns among the Loricariidae show a high degree of trophic niche conservatism, indicating that evolutionary lineage affiliation can be a strong predictor of how basal consumers segregate trophic niche space.     

Molecular Evolution of Satellite DNA CLsat in Lizards from the Genus Darevskia (Sauria: Lacertidae): Correlation with Species Diversity

The structure and evolution of a satellite DNA family was examined in lizards from the genus Darevskia(family Lacertidae). Comparison of tandem units of repeated DNA (satDNA), CLsat, in all species from the genus Darevskiahas shown that their variability is largely explained by single-nucleotide substitutions, which form about 50 diagnostic positions underlying classification of the family into three subfamilies. Maximum differences between the subfamilies reached 25%. At this level of tandem unit divergence in the subfamilies, no cross-hybridization between them was observed (at 65°C). The individual variability within one subfamily within the species was on average 5% while the variability between species consensuses within a subfamily was 10%. The presence of highly conserved regions in all monomers and some features of their organization show that satellites of all Darevskia species belong to one satDNA family. The organization of unit sequences of satellites CLsat and Agi160 also detected by us in another lizard genus, Lacerta s. str. was compared. Similarity that was found between these satellites suggests their relatedness and common origin. A possible pathway of evolution of these two satDNA families is proposed. The distribution and content of CLsat repeat subfamilies in all species of the genus was examined by Southern hybridization. Seven species had mainly CLsatI (83 to 96%); three species, approximately equal amounts of CLsatI and CLsatIII (the admixture of CLsatII was 2–5%); and five species, a combination of all three subfamilies in highly varying proportions. Based on these results as well as on zoogeographic views on the taxonomy and phylogeny of theDarevskia species, hypotheses on the evolution of molecular-genetic relationships within this genus are advanced.     

Ontogeny of the suspensorial and opercular musculature in the suckermouth armoured catfish <Emphasis Type="Italic">Ancistrus</Emphasis> cf. <Emphasis Type="Italic">triradiatus</Emphasis> (Loricariidae,Siluriformes)

Several morphological features characterizing Loricariidae or suckermouth-armoured catfishes (Siluriformes, Teleostei) are related to their ability to attach onto substrates with their sucker mouth, and to scrape algae and other food items from these substrates. Suspensorial and opercular muscles are among those muscles usually involved in respiration (and feeding). In several loricariids including the genus Ancistrus, the opercular musculature is decoupled from the respiratory mechanisms. Results show that the adductor arcus palatini is relatively large throughout the whole ontogeny, while the levator arcus palatini is minute. It develops in association with the dilatator operculi, which exhibits substantial growth only in the juvenile and adult stages. The levator and adductor operculi are connected during early ontogeny, and anterior fibres of the latter muscle differentiate into the adductor hyomandibulae, a muscle previously thought to be absent in loricariids. Relative muscle sizes and orientations, as well as articular transformations and the transition from cartilaginous to bony skeletal elements, indicate ontogenetic transformations in the skeleto-muscular system, affecting and steering functionalities.     

新疆巴里坤草原优势种蝗虫食性与蝗科中亚科分类系统关系的研究

本文报道了作者于１９７６、１９７９年在巴里坤草原自然和罩笼条件下,观察优势种蝗虫取食范围、取食程度等研究结果。根据斑腿蝗亚科蝗虫主要取食双子叶植物,蝗亚科蝗虫取食单子叶植物,而斑翅蝗亚科中一部分种类取食双子叶植物,一部分取食单子叶植物这个事实,提出：斑腿蝗亚科较原始,蝗亚科最进化,斑翅蝗亚科介于两者之间。这种系统是否与蝗虫的头部形态结构有关,值得深入研究。     

Distribution patterns of the Diaptomidae (Calanoida: Copepoda) in southern Africa

All freshwater calanoids in southern Africa belong to the family Diaptomidae of which there are two subfamilies, the Paradiaptominae (Lovenula, Paradiaptomus and Metadiaptomus) and Diaptominae (Tropodiaptomus and Thermodiaptomus). The Paradiaptominae are endemic to Africa, while the Diaptominae have one endemic African genus Thermodiaptomus, and the other genus Tropodiaptomus, occurs in other parts of the world as well as Africa. Knowledge of distribution of the Diaptomidae has been hampered by incomplete taxonomic knowledge and lack of co-ordination of available information. Distribution patterns of 19 described species and 11 new species confirm that the majority of species have a limited distribution, and that the Paradiaptominae are arid-adapted and belong to temporary pool communities. Six species are endemic to coastal pans and vleis of the western and southern Cape Province. Only those species with a wider distribution have been recorded as colonising man-made lakes. The four Lovenula species are predators and often co-exist with a Metadiaptomus species as prey. Synapomorphies of widely separated species of the Paradiaptominae, provide interesting insights into how their evolution may have been governed by vicariance, dispersal and palaeoenvironments of the African continent.     

Molecular evolution of satellite DNA CLsat in lizards of the Darevskia species (Sauria: Lacertidae): correlation with species diversity

The structure and evolution of a satellite DNA family was examined in lizards from the genus Darevskia (family Lacertidae). Comparison of tandem units of repeated DNA (satDNA), CLsat, in all species from the genus Darevskia has shown that their variability is largely based on single-nucleotide substitutions, which constitute about 50 diagnostic positions underlying classification of the family into three subfamilies. Maximum differences between the subfamilies reached 25%. At this level of tandem unit divergence between the subfamilies, no cross-hybridization between them was observed (at 65 degrees C). The individual variability of one subfamily within the species was on average 5% while the variability between species consensuses within a subfamily was 10%. The presence of highly conserved regions in all monomers and some features of their organization show that satellites of all Darevskia species belong to one satDNA family. The organization of unit sequences of satellites CLsat and Agi also detected by us in another lizard genus, Lacerts s. str. was compared. Similarity that was found between these satellites suggests their relatedness and common origin. A possible pathway of evolution of these two satDNA families is proposed. The distribution and content of CLsat repeat subfamilies in all species of the genus was examined by Southern blotting hybridization. Seven species had mainly CLsatI (83 to 96%); three species, approximately equal amounts of CLsatI and CLsatIII (the admixture of CLsatII was 2-3%); and five species, a combination of all three subfamilies in highly varying proportions. Based on these results as well as on zoogeographic views on phylogeny and taxonomy of the Darevskia species, hypotheses on the evolution of molecular-genetic relationships within this genus are advanced.     

Aspects of the phylogeny of the marine Tubificidae

A tentative phylogeny of the oligochaete family Tubificidae, with emphasis on the marine representatives, is presented. The scheme is based on the morphology and arrangements of prostate glands and the setal patterns. The rhyacodriline, more or less diffuse prostates are regarded as a primitive stage in prostate evolution, preceded only by the aprostate condition assumed for the ancestor of the family. An early split of the subfamily Rhyacodrilinae supposedly led to (1) a marine branch, from which evolved the highly diverse, exclusively marine subfamilies Phallodrilinae and Limnodriloidinae, and (2) a freshwater branch, which later divided into the Telmatodrilinae, Tubificinae and Aulodrilinae. The marine subfamilies invariably lack hair setae, whereas about half of the species within the other, freshwater subfamilies possess such setae in their dorsal bundles. Some marine genera, such as Monopylephorus (Rhyacodrilinae), Tubificoides and Clitellio (both Tubificinae) are regarded as recent off-shoots from the main freshwater stock.The families Naididae and Opistocystidae are considered likely to have evolved from rhyacodriline Tubificidae, whereas Phreodrilidae, the fourth family within the suborder Tubificina, is regarded as a sister group to the Tubificidae.