ABSTRACT
Three new species, of three different genera of loricariids, are described from the headwaters of Serra da Mantiqueira and Cadeia do Espinhaço, in Southeastern Minas Gerais State, Brazil. In this region, the Serra da Mantiqueira and the Complexo do Espinhaço are the highest points of the Brazilian Shield and delimits the headwaters of four drainages: São Francisco, Paraná, Doce and Paraíba do Sul basins. Harttia intermontana, n. sp., is described from the headwaters of the Rio Doce basin and is the first record of the genus in this basin. The new species can be distinguished from its congeners by the pattern of abdominal covering, presence of preanal plates, presence and pattern of ornamentation of canal plate, and some characteristics related to sexual dimorphism. Pareiorhaphis togoroi, n. sp., is described from the headwaters of the Rio das Mortes basin, tributary to the Rio Grande, in the upper Rio Paraná drainage, and represents the first record of the genus to this drainage, thus expanding its geographic distribution. It can be distinguished from most congeners by the absence of preadipose azygous plates, and characteristics related to secondary sexual characters of mature males: presence of odontodes on the lateral margin of head plus the absence of long hypertrophied odontodes on pectoral-fin spine. Neoplecostomus pirangaensis, n. sp., is described from the headwaters of the Rio Piranga, Rio Doce basin. The new species differs from all congeners by the much-reduced dermal platelets on the abdomen, devoid of developed odontodes between the insertions of the pectoral and pelvic fins. Neoplecostomus pirangaensis can also be distinguished from all congeners, except N. botucatu and N. paranensis, due to the complete absence of vestiges of the adipose fin (vs. vestiges, or adipose fin moderate to well developed and always present). The new species differs from N. botucatu by the absence of conspicuous dark spots all over the body and the presence of common dorsal bands in juveniles, and almost totally black in adults. It differs from N. paranensis by the bigger and less numerous teeth. Additionally, the new species differs from Neoplecostomus doceensis by the absence of enlarged fleshy folds between dentaries, and absence of a lateronasal plate.
Subject(s)
Catfishes , Animals , Brazil , Color , Male , Sex CharacteristicsABSTRACT
The characteristic and morphologically variable pectoral-fin spine of catfishes (order Siluriformes) has been well-investigated based on later developmental stages (juveniles and adults) but information on the earliest life stages are lacking. Here, we document the ontogeny of pectoral-fin spines in four siluroid (Ictalurus punctatus, Noturus gyrinus, Silurus glanis and Akysis vespa) and two loricarioid catfishes (Corydoras panda and Ancistrus sp.). To further our understanding of pectoral-fin spine development, we also examined adult and juvenile specimens representing 41 of the currently 43 recognized families of catfishes. Development of the pectoral-fin spine is similar in all catfishes and resembles the development of a typical soft fin ray. Fusion between hemitrichia of the anteriormost lepidotrichium occurs proximally first, forming the spine proper, with growth of the spine occurring through the subsequent fusion of developing distal hemitrichial segments that comprise the spurious ray. The variation of pectoral-fin spine morphology observed is largely attributed to the presence/absence of five traits, which either develop as part of the hemitrichial segments that are added to the distal tip of the spine during growth (distal rami, anterior/posterior serrae) or develop independent of these segments (denticuli and odontodes).
Subject(s)
Animal Fins/embryology , Catfishes/embryology , Animals , PhenotypeABSTRACT
Three new species of Harttia from the Rio Xingu basin in the region of Serra do Cachimbo, Pará State, Brazil, are described. Harttia rondoni n. sp., H. panara n. sp. and H. villasboas n. sp. were collected in the Rio Curuá, a tributary of Rio Iriri, Rio Xingu drainage. Harttia rondoni was additionally recorded from the Rio Fresco basin, a tributary of the middle Rio Xingu. The three new species represent the first records for the genus in this drainage. Harttia rondoni differs from H. panara and H. villasboas by having the abdomen partially covered by plates. Harttia panara differs from H. rondoni and H. villasboas by having a larger body depth and interorbital distance. Harttia villasboas differs from H. rondoni and H. panara by having the anterior profile of the head elliptical in dorsal view and a more elongated snout. Additionally, the 26 species of Harttia described are organized in three species group based on the pattern of abdominal covering.
Subject(s)
Catfishes , Animals , BrazilABSTRACT
Callichthyidae comprises the subfamilies Callichthyinae and Corydoradinae, both of which are morphologically distinct and monophyletic. Although there is consensus regarding the monophyly of the family, the relationships of about 80% of its species, currently included in the genus Corydoras, remain poorly known. Despite the vast amount of osteological information for Teleostei, knowledge regarding the phylogenetic implications of encephalon anatomy is sparse and represents a poorly explored source of potential characters. The present study aims to describe the encephalon morphology in members of the Callichthyidae in order to propose new characters that may help address phylogenetic questions regarding this group. In addition to representatives of Callichthyidae, specimens belonging to the Nematogenyidae, Trichomycteridae, Scoloplacidae, Astroblepidae and Loricariidae were dissected for comparative purposes. Head dissection revealed information on the structure of the medulla spinalis, rhombencephalon, mesencephalon, diencephalon and telencephalon. The conditions observed on the encephalons examined suggest that representatives of Callichthyidae have great taste perception and processing, while Corydoradinae stand out for visual acuity and Callichthyinae for mechanoreception processing subunits. Our results also indicate that the encephalon has important features for systematic studies of the family bringing greater resolution to current phylogenetic hypotheses.(AU)
Callichthyidae é composto por Callichthyinae e Corydoradinae, ambos morfologicamente distintos e monofiléticos. Apesar do consenso em relação ao mofiletismo da família, as relações de cerca de 80% de suas espécies, atualmente incluídas no gênero Corydoras, permanecem pouco conhecidas. Apesar da grande quantidade de informação osteológica sobre Teleostei, o conhecimento sobre as implicações filogenéticas da anatomia do encéfalo é escasso e, por isso, considerado uma fonte inexplorada de caracteres. O objetivo do presente estudo é a descrição morfológica dos encéfalos de Callichthyidae, fornecendo novos caracteres que podem elucidar questões filogenéticas para o grupo. Além dos representantes de Callichthyidae, espécimes pertencentes a Nematogenyidae, Trichomycteridae, Scoloplacidae, Astroblepidae e Loricariidae foram dissecados para fins comparativos. A dissecção do crânio revelou informações sobre a estrutura da medulla spinalis, rhombencephalon, mesencephalon, diencephalon e telencephalon. As condições observadas nos encéfalos sugerem que representantes de Callichthyidae possuem grande capacidade de percepção e processamento químico, enquanto os Corydoradinae se destacam pela acuidade visual e os Callichthyinae pelas unidades de processamento mecanoreceptoras. Nossos resultados indicam que os encéfalos detêm características importantes para contribuir com estudos sobre a sistemática da família, trazendo maior resolução para as hipóteses atuais de reconstrução filogenética.(AU)
Subject(s)
Animals , Catfishes/anatomy & histology , Catfishes/classification , Brain/anatomy & histology , Spinal CordABSTRACT
Ituglanis australis new species, is described from tributaries of the Laguna dos Patos and Río Uruguay, in Brazil and Uruguay. This represents the southernmost record of the genus and the first occurrence of a species of Ituglanis in those systems. It is distinguished from all its congeners, except Ituglanis parahybae and Ituglanis cahyensis, by its body pigmentation with three well-defined dark brown stripes running along each flank. Ituglanis australis differs from I. parahybae and I. cahyensis in the pectoral- and pelvic-fin ray counts, the pattern of the cephalic laterosensory system and the number of dorsal-fin basal radials. The new species, as well as several other examined congeners, has the levator internus IV muscle attached to the dorsal face of the posttemporo-supracleithrum; a condition that corroborates the inclusion of Ituglanis into a large trichomycterine clade that also includes Bullockia, Hatcheria, Scleronema and several species of Trichomycterus. Previous proposals of the affinities within Ituglanis are reviewed and, despite some advances, the phylogenetic relationships among species of the genus remain largely unknown.
Subject(s)
Catfishes/anatomy & histology , Catfishes/classification , Phylogeny , Animal Fins , Animals , Brazil , Pigmentation , Rivers , UruguayABSTRACT
A new species of Harttia, tribe Harttiini, is described from tributaries of upper portions of rio Paraná drainage. The new species, the smallest known species of the genus, attaining up to 74.0 mm of standard length, can be distinguished from its congeners by the combination of the following characters: abdomen completely covered by plates, a single preanal plate, plates of the gular area in broad contact with the canal plate. Harttia absaberi is the second species of the genus known from the upper portion of rio Paraná drainage.
Uma espécie nova de Harttia, tribo Harttiini, é descrita dos tributários da porção superior da drenagem do rio Paraná. A espécie nova, a menor espécie conhecida do gênero, alcançando até 74,0 mm de comprimento padrão, pode ser diferenciada de suas congêneres pela combinação dos seguintes caracteres: abdômen completamente coberto por placas ósseas, uma única placa preanal, placas da região gular em contato amplo com a placa portadora de canal. Harttia absaberi é a segunda espécie do gênero conhecida da porção superior da drenagem do rio Paraná.
Subject(s)
Animals , Rivers , Species Specificity , FishesABSTRACT
The "decoupling hypothesis" has been proposed as a mechanistic basis for the evolution of novel structure and function. Decoupling derives from the release of functional constraints via loss of linkages and/or repetition of individual elements as redundant design components, followed by specialization of one or more elements. Examples of apomorphic decoupling have been suggested for several groups of organisms, however there have been few empirical tests of explicit statements concerning functional and morphological consequences of decoupling. Using the loricarioid catfishes, we tested one particular consequence of decoupling, the prediction that clades possessing decoupled systems having increased biomechanical complexity will exhibit greater morphological variability of associated structures than outgroups having no such decoupled systems. Morphometric procedures based on interlandmark distances were used to quantify morphological variance at three levels of design at successive nodes in the loricarioid cladogram. Additional landmark-based procedures were used to localize major patterns of shape change between clades. We report significantly greater within-group morphometric variance at all three morphological levels in those lineages associated with decoupling events, confirming our predictions under the decoupling hypothesis. Two of 12 comparisons, however, yielded significant variance effects where none were predicted. Localization of the major patterns of shape change suggests that disassociation between morphological and functional evolution may contribute to the lack of fit between variance predictions and decoupling in these two comparisons.
