Species Of Trichomycterus Research Articles

A new rare catfish species from southeastern Brazil provides insights into the origins of similar colour patterns in syntopic, distantly related mountain trichomycterines (Siluriformes, Trichomycteridae)

Colour patterns are diverse in trichomycterine catfishes and are often used to diagnose species. Here, we analyse the first case of adults of two syntopic species of Trichomycterus sharing nearly identical colour patterns: a rare new species of the subgenus Paracambeva and Trichomycterus maculosus, a distantly related species of the subgenus Trichomycterus. Both species are endemic to the upper Rio Paraíba do Sul basin (RPSB), which had a different course until the Tertiary period and is situated within the Southeastern Brazilian Continental Rift, mostly active in the Eocene-Oligocene. A time-calibrated multigene analysis, 3144 bp, supported the new species as sister to Trichomycterus itatiayae, both comprising a lineage with Middle Miocene age, when that colour pattern would have first arisen. The new species is diagnosed by characters from the latero-sensory system and bone morphology. Our results, combined with available biogeographical data, indicated the colour pattern of T. maculosus arising in the Late Pliocene, following the dispersal of its group to the upper RPSB after river course changing. Two hypotheses for the independent origin of the same colour pattern are discussed. First, a case of evolutionary convergence for adaptation to live on a similarly coloured gravel substrate, giving some cryptic advantage against predators. Second, mimetic association through anti-predation features. In the latter case, although trichomycterids lack fin spines to inoculate venom as in other catfishes, the species here studied have a supposed axillary gland above the pectoral fin, just posterior to the opercular odontodes, but with properties and functions still unknown.

Pleistocene Aquatic Refuges Support the East–West Separation of the Neotropical Catfish Trichomycterinae (Siluriformes: Trichomycteridae) and High Diversity in the Magdalena, Guiana, and Paraná-Paraguay Basins

(1) Background: Trichomycterinae represent 60% of the species in the family and, while seven genera comprise 1–3 species each, Trichomycterus and Cambeva have over 180 known species between them. Although integrative studies aimed to clarify the relationships within the subfamily, the diversity of species of Trichomycterus remains an open question. Herein, we explored an unprecedented sample to investigate the divergence in the lineages of Trichomycterus. (2) Methods: we recovered the phylogenetic relationships of the subfamily using 566 sequences (999 bp) of the mitochondrial gene cytochrome b, calculated intra- and intergroup distance percentages, and estimated divergence times. (3) Results: we recovered 13 highly supported and geographically structured lineages; intergenus divergence was 11–20%, while interspecies divergence was 3–11%; Trichomycterus, Cambeva, Scleronema, Hatcheria, Eremophilus, and Ituglanis were recovered as monophyletic, with three other highly divergent clades: Guiana Shield, Magdalena basin, and Tapajós basin. (4) Conclusions: We propose that the trans-Andean austral clades be allocated into Hatcheria, and the Guiana clade supports a new genus. We also observed that the headwaters nearest the Magdalena and Orinoco basins showed a high diversity and endemism of Trichomycterinae lineages. We discussed the role of geomorphological events and the climatic features which may explain cladogenesis events in Trichomycterinae.

Phylogeny and historical biogeography of neotropical catfishes Trichomycterus (Siluriformes: Trichomycteridae) from eastern Brazil

The catfish subfamily Trichomycterinae is widely distributed in South America inhabiting several habitats, but specially mountain streams. Trichomycterus is the most speciose trichomycterid genus and recently due to his paraphyletic condition has been restricted to a clade from eastern Brazil called Trichomycterus sensu stricto comprising around 80 valid species distributed in seven areas of endemism of eastern Brazil. This paper aims to analyse the biogeographical events responsible for the distribution of Trichomycterus s.s., by reconstructing the ancestral data based on a time-calibrated multigene phylogeny. A multi-gene phylogeny was generated using 61 species of Trichomycterus s.s. and 30 outgroups, with divergence events calculated based on the estimated origin of Trichomycteridae. Two event-based analyses were applied to investigate the biogeographical events responsible the present distribution of Trichomycterus s.s. and suggest that the modern distribution of the group is a result of different vicariance and dispersal events. The diversification of Trichomycterus s.s. subgenera occurred in the Miocene, except for Megacambeva, with different biogeographical events shaping its distribution in eastern Brazil. An initial vicariant event split up the Fluminense ecoregion from the Northeastern Mata Atlantica + Paraíba do Sul + Fluminense + Ribeira do Iguape + Upper Paraná ecoregions. Dispersal events occurred mainly between Paraíba do Sul and neighboring river basins, with additional dispersal events from Northeastern Mata Atlantica to Paraíba do Sul, from São Francisco to Northeastern Mata Atlântica, and from Upper Paraná to São Francisco.

Comparative Osteology, Phylogeny and Classification of the Eastern South American Catfish Genus Trichomycterus (Siluriformes: Trichomycteridae)

Trichomycterus has been considered for a long time to be the most problematic genus of the diverse neotropical subfamily Trichomycterinae. Recently, Trichomycterus was restricted to a clade from eastern South America supported by molecular data, but no unique morphological character state was found to distinguish it, making it difficult to allocate new species based on morphology alone. The objectives of this study were to conduct an osteological comparative analysis comprising a large sample of valid species of Trichomycterus, to conduct a total evidence phylogenetic analysis, combining osteological characters and a multigene database, and to propose an intrageneric classification based on the results of the phylogenetic analysis. Fifty-two osteological characters were combined with a multigene molecular data set of 2974 bp for 44 species of Trichomycterus, and 21 outgroups generated a well-supported phylogenetic tree, making it possible to delimit and diagnose intrageneric lineages, of which six subgenera are recognized. The high morphological diversity of osteological structures herein first reported for Trichomycterus from eastern South America is possibly related to some ecological specializations. This study shows that osteological characters combined with molecular data may be useful to consistently delimit and distinguish between trichomycterines, shedding light on the still persistent problems in trichomycterine systematics.

Emerging patterns in phylogenetic studies of trichomycterid catfishes (Teleostei, Siluriformes) and the contribution of Andean diversity

AbstractConsensus is emerging among studies using DNA sequence data addressing problems in the taxonomy and relationships of trichomycterid catfishes, a dominant component of the Neotropical freshwater ichthyofauna, that have heretofore eluded efforts based on morphological data alone. No previous studies using molecular data have included representatives of Hatcheria and Silvinichthys, and none have included dense representation of the diverse Andean species of Trichomycterus. This study assembled both available and novel comparative DNA sequence data inclusive of Hatcheria, Silvinichthys, and additional Trichomycterus species not represented in previous studies to form the most taxonomically comprehensive molecular dataset of the Trichomycterinae at the genus level to date. Our results confirm previous findings of strong support for a monophyletic subfamily Trichomycterinae while rejecting the monophyly of its most diverse genus, Trichomycterus. Our results do not corroborate Trichomycterinae split into two reciprocally monophyletic groups, and we show strong support for a sister‐group relationship between Eremophilus mutisii and Trichomycterus bogotensis that suggests some degree of evolutionary distinctiveness for this clade of Colombian‐endemic species. Within Trichomycterus, we uncovered a novel clade of central Andean species and reveal a close relationship among southern Andean taxa that included a non‐monophyletic Silvinichthys, Bullockia, Hatcheria, plus a number of Trichomycterus species. Our results are broadly congruent with recent studies that have uncovered rampant polyphyly within the genus Trichomycterus and provide emerging evidence, as a result of increased taxonomic representation, for geographically circumscribed subclades of Trichomycterus species. Nevertheless, the widespread low support and resolution at most basal nodes pose a considerable challenge in understanding major patterns of intergeneric relationships, which in turn hinders our efforts to shed critical light on the biogeographic history of the group.

Relationships and Description of a New Species of Trichomycterus (Siluriformes: Trichomycteridae) from the Rio Paraíba do Sul basin, South-eastern Brazil.

A phylogenetic analysis using fragments of two nuclear and two mitochondrial genes strongly supported sister group relationships between a new species and Trichomycterus albinotatus, corroborated by unique colour patterns of adult specimens and juveniles, and morphology of the autopalatine bone. The new species is distinguished from its closest congener, T. albinotatus, by details of the colouration and number of branchiostegal rays. Both the new species and T. albinotatus are endemic to the Rio Paraíba do Sul basin, in the Atlantic Forest of south-eastern Brazil, but occur in distant and disjunct areas. The new species, herein described, is endemic to the upper section of the Rio Grande drainage, a right tributary of the lower Rio Paraíba do Sul, an area situated in the Órgãos Mountain Range. Trichomycterus albinotatus is endemic to an area about 200 km across, in the upper section of the Rio Preto that drains the Itatiaia Massif. However, both species are only known from localities above 1100 m asl, suggesting that they cannot survive in ecological conditions at lower altitudes. This study indicates that efforts are necessary to provide more accurate data on the species diversity and distribution of Trichomycterus in the biologically diverse and endangered Atlantic Forest of south-eastern Brazil.

Iterative taxonomy reveals a new species of Trichomycterus Valenciennes 1832 (Siluriformes, Trichomycteridae) widespread in Rio Doce basin: a pseudocryptic of T. immaculatus.

This paper reports on a new species of Trichomycterus from the Rio Doce basin. Unusually for new taxa in the genus during the past few decades, the new species is not narrowly endemic but instead widely distributed in its major drainage, the Rio Doce. The species has been collected and deposited in scientific collections for some years, but has been systematically misidentified as the more abundant Trichomycterus immaculatus or, to a lesser degree, as other morphologically similar species from south-eastern Brazil such as T. nigricans and T. pradensis. A combination of several morphological characteristics, such as vertebral number, pectoral-fin ray counts, pigmentation pattern and barcoding distance, were iteratively used and unambiguously distinguish the new species from all congeners. The present case reveals a pattern of diversity-discovery in which rare and narrowly endemic morphologically conspicuous species are discovered and described before visually inconspicuous taxa, even when the latter are more abundant and widespread. The morphological similarities among south-eastern Brazilian species with a uniform dark-grey color serve as basis for a brief discussion about the concepts of cryptic and pseudo-cryptic species in Trichomycterus and their consequences for potentially hidden diversity in the genus.

Parasites of Cambeva davisi (Siluriformes: Trichomycteridae) from the Cascavel stream, Neotropical area

The aim of the present study was to record the occurrence of parasites in Cambeva davisi (= Trichomycterus davisi) (Siluriformes: Trichomycteridae) from the Cascavel Stream, in the Iguacu River basin, municipality of Cascavel, state of Parana, Brazil, and present a review of the parasites reported infecting trichomycterids belonging to Cambeva and Trichomycterus species from the Neotropical region. Eighty-one fish specimens were collected using the electrofishing technique, with three standardized passes with a duration of 40 min, with extensions of 50 m for each site. In the laboratory, the fish were necropsied, and parasitological and histological analyses were conducted. Two parasite species were found and identified as nymphs of Sebekia oxycephala (Pentastomida) (Prevalence [P] = 8.54%) and Minilernaea floricapitella (Crustacea: Lernaeidae) (P = 1.23%), both representing new records of distribution and host-parasite relationships for genus Cambeva. The presence of the nymphs of S. oxycephala did not result in harmful histological changes or a significant inflammatory process in infected organs. Twenty-one taxa of parasites have been described parasitizing trichomycterids belonging to Trichomycterus (sensu stricto) and Cambeva from the Neotropical region. Nymphs of S. oxycephala have already been reported in freshwater fish belonging to 10 different orders, and M. floricapitella has been found parasitizing Brazilian fishes belonging to two orders. The nymphs of S. oxycephala did not cause histopathological changes and the new records of distribution and host-parasite relationships reported here enrich knowledge of the parasitic fauna of freshwater fish from the Neotropical region.

Taxonomical study of Trichomycterus (Siluriformes: Trichomycteridae) from the Ribeira de Iguape River basin reveals a new species recorded in the early 20th century.

A new species of Trichomycterus endemic to the Ribeira de Iguape River basin, southeastern Brazil, was studied based on morphological and molecular evidence. This species had an outer layer of coloration composed of scattered, round, black or dark-brown spots smaller or equivalent in size to the circumference of the eye; eight pectoral-fin rays; 28-29 opercular odontodes; 54-56 interopercular odontodes; and supraorbital line of the laterosensory system not interrupted, with pores s2 absent. Two other species of Trichomycterus from the Ribeira de Iguape River basin are recorded, and their taxonomic status is discussed: Trichomycterus alternatus and Trichomycterus jacupiranga were not differentiated using molecular analysis but may be consistently distinguished based on morphology. The phylogenetic relationships of the co-occurring species, T. alternatus and Cambeva zonata, were inferred using mitochondrial data, reinforcing the taxonomic status of these recently revised species that have a complex taxonomy. In addition, a new combination for Trichomycterus taroba with its inclusion in the genus Cambeva is recommended.

A new species of Trichomycterus Valenciennes 1832 (Trichomycteridae: Siluriformes) from the Rio Doce drainage with remarkable similarities with Bullockia and a CT-scan survey.

A new species of Trichomycterus is described from rocky and psammic sectors near the main channel of the middle and upper Rio Doce basin in Southeastern Brazil. Trichomycterus astromycterus n. sp., is distinguished from all congeners by a number of autapomorphic characters, such as the distally expanded maxilla; the short and thick mesethmoid cornua; and the elongated anterior process of the vomer. Additional characters (short barbels, large head, 33 vertebrae, ii+8 or ii+9 dorsal-fin rays, nine dorsal-fin pterygiophores, markedly enlarged lips, narrow caudal peduncle, bilobed caudal fin with the lower lobe longer than the upper one) also distinguish the new species from all its congeners in Southeastern Brazil and from most congeners anywhere. Examination of internal anatomy reveals that T. astromycterus shares some intriguing characteristics with the austral genus Bullockia Arratia et al., 1978. However, the phylogenetic significance of such similarities is still uncertain and will require further comparative study. For this reason, the new species is provisionally included in the all-encompassing genus Trichomycterus. An osteological description is presented on the basis of CT-scan imaging and cleared and stained specimens.

New species of Trichomycterus (Siluriformes: Trichomycteridae) from the High Andean Plateau of Argentina.

Trichomycterus varii new species, is described from a small tributary of the High Andean Plateau Region, Jujuy, Argentina. The new species is distinguished from other species of Trichomycterus by the following characters: the caudal peduncle expanded in the area of procurrent caudal-fin rays, distal tip of pelvic fin not reaching the anus when depressed, the presence of fronto-lachrymal tendon bone without lateral process, the first pectoral-fin ray terminating at the margin of the fin, the distal margin of pectoral-fin rounded, seven pectoral fin rays, 15-19 interopercular odontodes, the supraorbital sensory canal with the presence of pore s3, the infraorbital sensory canal segment with the presence of pores i1 and i3, the laterosensory canal of trunk with three sensory pores, 16 pairs of ribs, 11 precaudal vertebrae, and 25 caudal vertebrae. It closely resembles T. yuska and T. pseudosilvinichthys from northwestern Argentina and western Bolivia, but differs in head canal sensory pattern.

A new species of cave catfish, genus Trichomycterus (Siluriformes: Trichomycteridae), from the Magdalena River system, Cordillera Oriental, Colombia

A new species of troglomorphic catfish is described from de Gedania Cave, located in the middle Suarez River drainage, Magdalena River system, Colombia. The new species can be distinguished from its congeners by the combination of the following characters: reduction or loss of the cornea, reduction of eyes and skin pigmentation, very long nasal and maxillary barbels (maximum of 160% and 135% of HL, respectively), nine branched pectoral-fin rays, first unbranched ray of the pectoral fin prolonged as a long filament, reaching 80% of pectoral-fin length, anterior cranial fontanel connected with the posterior fontanel through an opening of variable length and width, first dorsal-fin pterygiophore inserted between neural spines of free vertebra 13-14 and free vertebrae 33-34. The presence of troglomorphisms such as regression of the eyes, reduction of skin pigmentation and long barbels suggest the troglobitic status of this species. A comparative analysis with other species of Trichomycterus from epigean and hypogean environments is presented.

Trichomycterus rosablanca (Siluriformes, Trichomycteridae) a new species of hipogean catfish from the Colombian Andes

Trichomycterus rosablanca is described as a new troglobitic catfish species from caves in southeastern Santander, Colombia. These caves are drained by the Carare River of the Magdalena River basin. The new species is characterized by the advanced condition in the typical troglomorphisms found in other congeneric cave-dwelling species, such as absence of eyes and pigmentation. Trichomycterus rosablanca is diagnosed by the following putative autapomorphies: 1) presence of a circular foramen in the main body of the interopercle, dorsal to the interopercular plate supporting the odontodes, and 2) presence of a single sensory pore in the posteriormost section of the infraorbital canal. Trichomycterus rosablanca can be distinguished from all known Trichomycterus species from Colombia by having the supraorbital canal interrupted in the nasal section, resulting in the pattern of s1, s2, s3, and s6 sensory pores, and the lachrimal/antorbital bone not enclosing the anteriormost section of the infraorbital canal. The genetic distinctiveness of Trichomycterus rosablanca is confirmed by GMYC and genetic distance method analyses of the cytochrome C oxidase subunit I gene sequence. The description of this species places Colombia as the second most diverse country in the continent in terms of number of cave fish species and calls the attention on the conservation efforts needed to guarantee the permanence of this remarkable diversity of hypogean fishes.

Intrapopulational variation in color pattern of Trichomycterus davisi (Haseman, 1911) (Siluriformes: Trichomycteridae) corroborated by morphometrics and molecular analysis

Color patterns of the body are commonly used to distinguish and identify species of Trichomycterus. Therefore, variation in color pattern in a population can cause doubt concerning species identification. With the purpose to test the hypothesis of high variation in color pattern of Trichomycterus davisi (Haseman, 1911), 118 specimens were collected in a stream of a private Ecological Park in southern Brazil, of which 88 were used in the morphological analysis and 30 for DNA barcoding analysis. Three phenotypic classes were determined analyzing the distribution, size and shape of dark brown spots and blotches. The results of morphometric analysis indicate a tendency of association of those pigmentation patterns with the standard length, evidencing ontogenetic variation of color pattern in the species. The results of K2P intraspecific genetic distance (<0.72%), haplotypes network and Bayesian phylogenetic tree corroborate the existence of only one species with a high variable color pattern.

Trichomycterus alterus (Marini, Nichols & La Monte, 1933) and T. corduvensis Weyenberg 1877 (Siluriformes: Trichomycteridae): new records from the High Andean Plateau

New records of two Trichomycterus species are herein added to the existing checklist of catfishes living at elevations above 3,000 m in the Andes of South America. Trichomycterus alterus and T. corduvensis are recorded at 3,430 m above sea level from the High Andean Plateau (or Puna) in a stream near Antofagasta de la Sierra, Provincia de Catamarca, Argentina. Morphometric and meristic data of examined specimens are included.

Microstructural chromosome reorganization in the genus Trichomycterus (Siluriformes: Trichomycteridae)

Trichomycterus is a specious fish genus within Trichomycterinae and displays remarkable karyotype diversity. However, knowledge about their genomic structure and location of repetitive sequence is still limited. In order to better understand the karyotype diversification, we analyzed nine species of Trichomycterus using classical and molecular cytogenetic techniques. Results revealed a conserved diploid chromosome number of 2n=54 chromosomes in all analyzed species, although remarkable differences on the constitutive heterochromatin distribution were observed. In addition, while the 18S rDNA showed a conserved distribution pattern, the 5S rDNA sites showed a quite diverse location considering the analyzed species. Remarkably, both ribosomal genes were co-located in all species, except in T . iheringi , suggesting that co-localization is probably an ancestral condition in Trichomycterus . Finally, three analyzed species showed heterochromatic B chromosomes, reinforcing the intense genomic reorganization occurring in Trichomycterus . Our results showed that chromosomal variations are not restricted to differences in karyotype formula as previously proposed, but also to modifications on the microstructural level of resolution.

A new species of Ituglanis representing the southernmost record of the genus, with comments on phylogenetic relationships (Teleostei: Siluriformes: Trichomycteridae)

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.

On the diet of two endemic and rare species of Trichomycterus (Ostariophysi: Trichomycteridae) in the Jordão River, Iguaçu River basin, southern Brazil

The diet and the eect of body size on the feeding habits of Trichomycterus crassicaudatus and Trichomycterus stawiarski, collected in the Jordão River, an import tributary of the Iguaçu River basin, were investigated. Samples were collected in august 2003 during the Jordão River Energetic Complex Aquatic Fauna Rescue and Monitoring program. Stomach contents were evaluated through the frequency of occurrence, permutational multivariate analysis of variance (PERMANOVA), si-milarity percentage analysis (SIMPER) and non-metric multidimensional scaling analysis (MDS) methods. A total of 86 stomach contents of T. stawiarski and 36 of T. crassicaudatus were assessed. The species presented an insectivorous feeding habit, with differences in the diet composition of the “smallest” and the “largest” individuals. Ephemeroptera nymphs, lar-vae and pupae of Diptera, organic detritus and plant fragments were the most important food items. Both species feeding habits were based mainly in benthic aquatic immature insects.

Trichomycterus macrophthalmus (Teleostei: Siluriformes: Trichomycteridae), a new species of catfish from the Paraíba do Sul river basin, southeastern Brazil

Trichomycterus macrophthalmus, new species is described from the upper Paraíba do Sul river basin, southeastern Brazil. It differs from all species of Trichomycterus from southeastern Brazil by possessing nine pleural ribs. Trichomycterus macrophthalmus is similar to T. travassosi from the same basin by both owning short nasal barbel, but the new species can be easily distinguished from it by head width, eye size, and colour pattern. The new species belongs to the T. travassosi species complex by displaying transverse dark marks on the dorsum.

Spermiogenesis and spermatozoal ultrastructure in Trichomycteridae (Teleostei: Ostariophysi: Siluriformes)

Spadella, M.A., Oliveira, C. and Quagio-Grassiotto, I. 2009. Spermiogenesis and spermatozoal ultrastructure in Trichomycteridae (Teleostei: Ostariophysi: Siluriformes). —Acta Zoologica (Stockholm) 91: 373–389. Siluriformes comprises the most diverse and widely distributed ostariophysan group, a fish assemblage that includes about three quarters of the freshwater fish of the world. In this study, the ultrastructural characterization of spermiogenesis and spermatozoa in specimens of Copionodontinae (the sister group to all other trichomycterids), Trichomycterinae (a derived trichomycterid group), and Ituglanis (a genus not assigned to any trichomycterid subfamily) is presented. The comparative analyses of the data show that trichomycterid species share six of seven analyzed spermiogenesis characters, reinforcing the monophyly of the group. Analyses of trichomycterid sperm ultrastructure showed that the species studied share the same character states for nine of seventeen characters analyzed. Copionodon orthiocarinatus and Ituglanis amazonicus each share more ultrastructural characters with species of Trichomycterus than with one another. Regarding the families of Loricarioidea, the species of Trichomycteridae share more characters of spermatogenesis, spermiogenesis, and sperm with representatives of the families Callichthyidae, Loricariidae, and Scoloplacidae than with Nematogenyidae, its hypothesized sister group. With the exception of the family Nematogenyidae, the character similarities observed reinforce the monophyly of the superfamily Loricarioidea.