Catfish Family Research Articles

Acoustic communication in fishes: Effects of temperature

Ambient temperature affects peripheral and central mechanisms of signal production and detection in ectothermic animals. The effects of temperature on sound production have been investigated in representatives of at least 8 families of teleosts, namely, piranhas, thorny catfishes, toadfishes, gurnards, sculpins, gobies, croakers, and gouramis, mostly under laboratory conditions. Temperature affects calling behaviour and characteristics of vocalizations, but only a few general trends are evident. Calling activity may increase with rising temperature (toadfish, sculpins, catfish), or may not be affected (triglids) or even drop (toadfish), indicating that behavioral contexts and seasonal factors other than temperature influence activity. Temperature affects sound duration differently in different species. In contrast, pulse period usually decreases and the fundamental frequency of drumming sounds therefore increases as temperature rises. The dominant frequency increases as well, whereas sound pressure level ...

Cryptic diversity in the Indian clade of the catfish family Pangasiidae resolved by the description of a new species

Among 22 species of the genus Pangasius, distributed in Southeast and South Asia, only one species, Pangasius pangasius, is known to exist in South Asia. Phylogenetic analysis based upon COI and Cytb sequences suggested that the P. pangasius species clade consists of two subclades. Based upon the genetic and the following morphological evidence, we conclude that these DNA sequence based sister subclades represent two distinct species, P. pangasius and an undescribed species from river Krishna, named as P. silasi. Morphologically, P. silasi is differentiated from its congener P. pangasius by a combination of characters, such as vomero-palatal teeth confluent as an uninterrupted curved band (vs two lunate vomero-palatal teeth patches on each side with a wide gap in the center) and vertebral count of 48 (vs 44). For several morphological characters, P. silasi is also distinct from P. myanmar, which is reported from Myanmar and has overlapping distribution with P. pangasius. Finally, the vomero-palatine dentition in P. silasi is distinct from the dentition structures reported for all the other Pangasius species. The biogeographical significance of finding this new species, P. silasi, in a river of the Indian peninsula is also discussed in this report.

The complete mitochondrial genome of the surubim Pseudoplatystoma corruscans (Siluriformes: Pimelodidae) and mitochondrial phylogenomics of catfishes confirm monophyly of Siluriformes families

Surubim (Pseudoplatystoma corruscans) is a large catfish that can reach 120 Kg. Their populations have been declining lately. Here, we describe for the first time the complete mitochondrial genome for an individual from this species. The circularized mitogenome followed the expected pattern for vertebrates, being 16,123 bp in length. It contained 13 protein-coding genes, 2 rRNA genes, 22 tRNAs and a putative non-coding control region. A maximum-likelihood phylogenomic tree was constructed using a supermatrix dataset contaning all protein-coding genes concatenated for the mitogenome of 36 Siluriformes species and 2 outgroups. The tree provided insights about the relationship of surubim to other catfishes and it is consistent with previous phylogenies. It evidenced monophyly for all 11 catfish families analyzed. Further studies using nuclear markers should be performed to clarify sister relations inside Siluriformes clade.

Karyotype Diversity in Doradidae (Siluriformes, Doradoidea) and Presence of the Heteromorphic ZZ/ZW Sex Chromosome System in the Family.

Karyotypes and other chromosomal markers as revealed by conventional and molecular cytogenetic protocols in four species of the catfish family Doradidae from the Araguaia-Tocantins river basin, namely Hassar wilderi, Leptodoras cataniae, Tenellus leporhinus and Tenellus trimaculatus were examined. All species had diploid chromosome number 2n = 58 and karyotypes dominated by biarmed chromosomes, simple NOR phenotype, that is, one chromosome pair bearing this site in terminal position, but some differences in karyotypes and distribution of constitutive heterochromatin, position of rDNA sites. Such characteristics appeared species-specific. A ZZ/ZW sex chromosome system was found in Tenellus trimaculatus, resulting likely from the amplification of the heterochromatin, followed by a paracentric inversion. Our results confirmed low karyotype differentiation observed until now among representatives of this endemic catfish family.

Multilocus molecular phylogeny of the ornamental wood-eating catfishes (Siluriformes, Loricariidae, Panaqolus and Panaque) reveals undescribed diversity and parapatric clades

Approximately two-dozen species in three genera of the Neotropical suckermouth armored catfish family Loricariidae are the only described fishes known to specialize on diets consisting largely of wood. We conducted a molecular phylogenetic analysis of 10 described species and 14 undescribed species or morphotypes assigned to the wood-eating catfish genus Panaqolus, and four described species and three undescribed species or morphotypes assigned to the distantly related wood-eating catfish genus Panaque. Our analyses included individuals and species from both genera that are broadly distributed throughout tropical South America east of the Andes Mountains and 13 additional genera hypothesized to have also descended from the most recent common ancestor of Panaqolus and Panaque. Bayesian and maximum likelihood analyses of two mitochondrial and three nuclear loci totaling 4293bp confirmed respective monophyly of Panaqolus, exclusive of the putative congener ‘Panaqolus’ koko, and Panaque. Members of Panaqolus sensu stricto were distributed across three strongly monophyletic clades: a clade of 10 generally darkly colored, lyretail species distributed across western headwaters of the Amazon Basin, a clade of three irregularly and narrowly banded species from the western Orinoco Basin, and a clade of 11 generally brown, broadly banded species that are widely distributed throughout the Amazon Basin. We erect new subgenera for each of these clades and a new genus for the morphologically, biogeographically and ecologically distinct species ‘Panaqolus’ koko. Our finding that perhaps half of the species-level diversity in the widespread genus Panaqolus remains undescribed illustrates the extent to which total taxonomic diversity of small and philopatric, yet apparently widely distributed, Amazonian fishes may remain underestimated. Ranges for two Panaqolus subgenera and the genus Panaque overlap with the wood-eating genus Cochliodon in central Andean tributaries of the upper Amazon Basin, which appear to be a global epicenter of wood-eating catfish diversity.

A new genus of Neotropical rheophilic catfishes, with four new species (Teleostei: Siluriformes: Pseudopimelodidae)

ABSTRACT Rhyacoglanis, a new genus of the South American freshwater catfish family Pseudopimelodidae is described from cis-Andean portions of the continent. Rhyacoglanis is distinguished from other genera of the family by three synapomorphies: presence of a light blotch on the cheek; a connection between the middle of the dark caudal-fin stripe and the dark caudal-peduncle pigmentation; and 30-35 total vertebrae. Species of Rhyacoglanis are rheophilic and strongly associated with rapids and other swift-flowing waters. A phylogenetic analysis based on 41 morphological characters yields a hypothesis of monophyly of the Pseudopimelodidae and Rhyacoglanis. Pimelodus pulcher Boulenger, 1887, from the western Amazon basin is designated as type-species of the new genus and redescribed. Four new species are described: Rhyacoglanis annulatus, from the río Orinoco basin, with a nearly ringed dark band on the caudal peduncle, and a larger distance between anus and anal-fin origin; R. epiblepsis, from the rio Madeira basin, with numerous dark spots scattered on the body, and rounded caudal-fin lobes; R. paranensis, from the upper rio Paraná basin, with three distinct dark bands on the body, and 31-33 total vertebrae; and R. seminiger, from the rio Juruena basin, with subdorsal and subadipose dark bands fused anteroposteriorly, and a separate dark band on the caudal peduncle.

Molecular diagnostic markers of Tachysurus fulvidraco and Leiocassis longirostris and their hybrids.

BackgroundBagridae is an important family of catfishes and has a high market demand. Recently, more cultivable Bagridae fishes are being exploited in China, and hybridization of some species has been carried out to achieve better growth performance, favorable sex ratios and better disease resistance. Yet, these hybrids have further increased the difficulties of taxonomy identification due to morphological indistinguishableness.ResultsIn this study, the molecular identification technologies for Tachysurus fulvidraco, Leiocassis longirostris sand their hybrids were successfully established by using mitochondrial COI and nuclear ITS sequences to identify the maternal and paternal lineage, respectively.ConclusionThese molecular diagnostic methods could also be used to manage breeding plans of hybrids, monitor and minimize the negative impacts of hybridization programs in aquaculture. Furthermore, our study could also provide a reference for establishing detection technique for hybrids in other groups of fishes.

A Time-Calibrated Mitogenome Phylogeny of Catfish (Teleostei: Siluriformes)

A very significant part of the world’s freshwater ichthyofauna is represented by ancient, exceptionally diverse and cosmopolitan ray-finned teleosts of the order Siluriformes. Over the years, catfish have been established as an exemplary model for probing historical biogeography at various scales. Yet, several tantalizing gaps still exist in their phylogenetic history, timeline and mode of diversification. Here, we re-examine the phylogeny of catfish by assembling and analyzing almost all publicly available mitogenome data. We constructed an ingroup matrix of 62 full-length mitogenome sequences from 20 catfish families together with four cypriniform outgroups, spanning 15,557 positions in total. Partitioned maximum likelihood analyses and Bayesian relaxed clock dating using fossil age constraints provide some useful and novel insights into the evolutionary history of this group. Loricarioidei are recovered as the first siluriform group to diversify, rendering Neotropics the cradle of the order. The next deepest clade is the South American Diplomystoidei placed as a sister group to all the remaining Siluroidei. The two multifamilial clades of “Big Asia” and “Big Africa” are also recovered, albeit nodal support for the latter is poor. Within “Big Asia”, Bagridae are clearly polyphyletic. Other interfamilial relationships, including Clariidae + Heteropneustidae, Doradidae + Auchenipteridae and Ictaluridae + Cranoglanididae are robustly resolved. Our chronogram shows that siluriforms have a Pangaean origin, at least as far back as the Early Cretaceous. The inferred timeline of the basal splits corroborates the “Out-of-South America” hypothesis and accords well with the fossil record. The divergence of Siluroidei most likely postdated the final separation of Africa and South America. An appealing case of phylogenetic affinity elaborated by biogeographic dispersal is exemplified by the Early Paleogene split between the Southeast Asian Cranoglanididae and Ictaluridae, with the latter radiating into North America’s freshwater realm by Eocene. The end of Cretaceous probably concludes the major bout of diversification at the family level while with the dawn of the Cenozoic a prolific radiation is evident at the generic level.

Multiple across-strain and within-strain QTLs suggest highly complex genetic architecture for hypoxia tolerance in channel catfish

The ability to survive hypoxic conditions is important for various organisms, especially for aquatic animals. Teleost fish, representing more than 50% of vertebrate species, are extremely efficient in utilizing low levels of dissolved oxygen in water. However, huge variations exist among various taxa of fish in their ability to tolerate hypoxia. In aquaculture, hypoxia tolerance is among the most important traits because hypoxia can cause major economic losses. Genetic enhancement for hypoxia tolerance in catfish is of great interest, but little was done with analysis of the genetic architecture of hypoxia tolerance. The objective of this study was to conduct a genome-wide association study to identify QTLs for hypoxia tolerance using the catfish 250K SNP array with channel catfish families from six strains. Multiple significant and suggestive QTLs were identified across and within strains. One significant QTL and four suggestive QTLs were identified across strains. Six significant QTLs and many suggestive QTLs were identified within strains. There were rare overlaps among the QTLs identified within the six strains, suggesting a complex genetic architecture of hypoxia tolerance. Overall, within-strain QTLs explained larger proportion of phenotypic variation than across-strain QTLs. Many of genes within these identified QTLs have known functions for regulation of oxygen metabolism and involvement in hypoxia responses. Pathway analysis indicated that most of these genes were involved in MAPK or PI3K/AKT/mTOR signaling pathways that were known to be important for hypoxia-mediated angiogenesis, cell proliferation, apoptosis and survival.

Evaluation of the fossil fish-specific diversity in a chadian continental assemblage: Exploration of morphological continuous variation in Synodontis (Ostariophysi, Siluriformes).

In the fossil record, the quantification of continuous morphological variation has become a central issue when dealing with species identification and speciation. In this context, fossil taxa with living representatives hold great promise, because of the potential to characterise patterns of intraspecific morphological variation in extant species prior to any interpretation in the fossil record. The vast majority of catfish families fulfil this prerequisite, as most of them are represented by extant genera. However, although they constitute a major fish group in terms of distribution, and ecological and taxonomic diversity, the quantitative study of their past morphological variation has been neglected, as fossil specimens are generally identified based on the scarcest remains, that is, complete neurocrania that bear discrete characters. Consequently, a part of freshwater catfish history is unprospected and unknown. In this study, we explored the morphological continuous variation of the humeral plate shape in Synodontis catfishes using Elliptic Fourier Analysis (EFA), and compared extant members and fossil counterparts. We analysed 153 extant specimens of 11 Synodontis species present in the Chad basin, in addition to 23 fossil specimens from the Chadian fossiliferous area of Toros Menalla which is dated around 7 Ma. This highly speciose genus, which is one of the most diversified in Africa, exhibits a rich fossil record with several hundred remains mostly identified as Synodontis sp. The analysis of the outline of the humeral plate reveals that some living morphological types were already represented in the Chad Basin 7 My ago, and allows for the discovery of extinct species. Beside illuminating the complex Neogene evolutionary history of Synodontis, these results underline the interest in the ability of isolated remains to reconstruct a past dynamic history and to validate the relevance of EFA as a tool to explore specific diversity through time. J. Morphol. 277:1486-1496, 2016. © 2016 Wiley Periodicals, Inc.

Cytogenetics of the Thorny Catfish Trachydoras paraguayensis (Eigenmann & Ward, 1907), (Siluriformes, Doradidae): Evidence of Pericentric Inversions and Chromosomal Fusion

The karyotype and chromosomal characteristics of Trachydorasparaguayensis, a representative of the South American catfish family Doradidae, were analyzed by conventional (Giemsa staining, silver staining, C-banding) and molecular (FISH with rDNA and telomeric probes) cytogenetic techniques. The diploid chromosome number was 2n = 56, with 36 metacentric, 16 submetacentric, and 4 subtelocentric chromosomes in both sexes; however, a remarkable heteromorphism in pair 22 (submetacentric and metacentric elements) was detected in 6 individuals. Compared to other representatives of Doradidae which mostly have 58 chromosomes, the karyotype of T. paraguayensis suggests a reduction in 2n due to chromosomal fusion, as could be deduced from the presence of an interstitial telomere sequence in the submetacentric pair 19. Pale heterochromatic blocks were present in the terminal regions of some chromosomes, very similar to other species of Doradidae. The interstitial position of the NORs observed in the karyotype of T. paraguayensis differs from those reported for most Doradidae species, indicating that it is a derived character. FISH with 5S rDNA revealed 2 interstitial fluorescent signals in the submetacentric pair 22, and the polymorphism of these sites likely resulted from a pericentric inversion.

Vaccination of Full‐sib Channel Catfish Families Against Enteric Septicemia of Catfish with an Oral Live Attenuated Edwardsiella ictaluri Vaccine

AbstractThis study evaluated the efficacy of an oral live attenuated Edwardsiella ictaluri vaccine against enteric septicemia of catfish in 20 full‐sib fingerling channel catfish families. The vaccine was delivered orally by feeding fish a diet coated with an attenuated E. ictaluri isolate. Sixty‐nine days postvaccination, control and vaccinated fish were challenged with virulent E. ictaluri and mortality was examined for 21 d postchallenge. Vaccinated fish had significantly lower mortality than nonvaccinated fish following challenge (P < 0.001). Mortality of vaccinated fish was 1.7 ± 1.4% as opposed to 47.8 ± 28.7% in nonvaccinated fish. Relative percent survival ranged from 87.7 to 100% with an average of 95.2 ± 4.0% (±SE) among the 20 families of fish. There were significant differences in mortality among families in nonvaccinated fish (P < 0.01) while there were no differences among vaccinated families of fish. Results indicate that the live attenuated E. ictaluri vaccine is effective at reducing mortality in channel catfish exposed to virulent E. ictaluri. These data demonstrate that genetic differences among healthy families of channel catfish are not major considerations in developing an effective vaccination program utilizing the oral vaccination platform described in this study.

The complete mitochondrial genome of the threatened Neotropical catfish Lophiosilurus alexandri (Silurifomes: Pseudopimelodidae) and phylogenomic analysis indicate monophyly of Pimelodoidea.

Lophiosilurus alexandri is an endemic catfish from the São Francisco River Basin (Brazil) popularly known as pacamã, which has economic potential for aquaculture farming. The mitochondrial genome was sequenced for the threatened Neotropical catfish L. alexandri. Assembly into scaffolds using MIRA and MITObim software produced the whole, circularized mitochondrial genome, which comprises 16,445 bp and presents the typical gene arrangement of Teleostei mitochondria. A phylogenomic analysis was performed after the concatenation of all proteins obtained from whole mitogenomes of 20 Siluriformes and two outgroups. The results confirmed the monophyly of nine families of catfishes and also clustered L. alexandri as a sister group to the family Pimelodidae, thus confirming the monophyly of the superfamily Pimelodoidea. This is the first mitochondrial phylogenomics study for Pimelodoidea and the first mitogenome described for the Pseudopimelodidae family, representing an important resource for phylogeography, evolutionary biology, and conservation genetics studies in Neotropical fishes.

Molecular phylogeny of the highly diversified catfish subfamily Loricariinae (Siluriformes, Loricariidae) reveals incongruences with morphological classification

The Loricariinae belong to the Neotropical mailed catfish family Loricariidae, the most species-rich catfish family. Among loricariids, members of the Loricariinae are united by a long and flattened caudal peduncle and the absence of an adipose fin. Despite numerous studies of the Loricariidae, there is no comprehensive phylogeny of this morphologically highly diversified subfamily. To fill this gap, we present a molecular phylogeny of this group, including 350 representatives, based on the analysis of mitochondrial and nuclear genes (8426 positions). The resulting phylogeny indicates that Loricariinae are distributed into two sister tribes: Harttiini and Loricariini. The Harttiini tribe, as classically defined, constitutes a paraphyletic assemblage and is here restricted to the three genera Harttia, Cteniloricaria, and Harttiella. Two subtribes are distinguished within Loricariini: Farlowellina and Loricariina. Within Farlowellina, the nominal genus formed a paraphyletic group, as did Sturisoma and Sturisomatichthys. Within Loricariina, Loricaria, Crossoloricaria, and Apistoloricaria are also paraphyletic. To solve these issues, and given the lack of clear morphological diagnostic features, we propose here to synonymize several genera (Quiritixys with Harttia; East Andean members of Crossoloricaria, and Apistoloricaria with Rhadinoloricaria; Ixinandria, Hemiloricaria, Fonchiiichthys, and Leliella with Rineloricaria), to restrict others (Crossoloricaria, and Sturisomatichthys to the West Andean members, and Sturisoma to the East Andean species), and to revalidate the genus Proloricaria.

Amino acid specificity of fibers of the facial/trigeminal complex innervating the maxillary barbel in the Japanese sea catfish, Plotosus japonicus

The Japanese sea catfish, Plotosus japonicus, possesses taste and solitary chemoreceptor cells (SCCs) located on the external body surface that detect specific water-soluble substances. Here, we identify two major fiber types of the facial/trigeminal complex that transmit amino acid information to the medulla. Both single and few fiber preparations respond to amino acid stimulation in the 0.1 μM to mM range. One fiber type responds best to glycine and l-alanine (i.e. Gly/Ala fibers) whereas the other fiber type is best stimulated by l-proline and glycine betaine (hereafter referred to only as betaine) (i.e. Pro/Bet fibers). We demonstrate that betaine, which does not alter the pH of the seawater and therefore does not activate the animals' highly sensitive pH sensors (Caprio et al., Science 344:1154-1156, 2014), is sufficient to elicit appetitive food search behavior. We further show that the amino acid specificity of fibers of the facial/trigeminal complex in P. japonicus is different from that in Ariopsis felis (Michel and Caprio, J. Neurophysiol. 66:247-260, 1991; Michel et al., J. Comp. Physiol. A. 172:129-138, 1993), a representative member of the only other family (Ariidae) of extant marine catfishes.

Mandibular, hyoid and pectoral musculature of thorny catfishes (Siluriformes: Doradidae)

ABSTRACT. This paper reports the results of a comparative study of the mandibular, hyoid, and pectoral musculature of South American Doradidae. Sixty-one species of Doradidae were examined including representatives of all the genera. Twenty muscles are described including their ontogenetic origin, function, area of origin and insertion, and parts. Seven muscles from the cranial region: adductor mandibulae, extensor tentaculi, levator arcus palatini, dilatator operculi, levator operculi, adductor operculi, and adductor arcus palatini; six muscles from the ventral region: intermandibularis, protractor hyoidei, hyohyoides inferioris, hyohyoidei abductores, hyohyoidei adductores, and sternohyoideus; and seven muscles from the pectoral fin: adductor superficialis, adductor profundus, abductor superficialis, abductor profundus, arrector ventralis, arrector dorsalis, and abductor rotator. Comparisons between Doradidae and other catfish families (e.g. Auchenipteridae, Aspredinidae) were made in order to understan...

Agonistic sounds and swim bladder morphology in a malapterurid electric catfish

AbstractSeveral catfish families possess an elastic spring apparatus (ESA) morphology that is assumed to function as a swim bladder drumming sound production mechanism. Although they have an ESA, drumming sounds in the electric catfish (Malapteruridae) have not been described. We have recorded several different sound types in Malapterurus beninensis and we examined the morphology of the swim bladder, the ESA and the ultrastructure of the protractor muscle. The protractor muscle contains small rounded muscle fibers with abundant mitochondria, narrow myofibrils, elaborated sarcoplasmic reticula and sometimes sarcoplasmic cores. Contractions of the protractor muscle should pull the Müllerian ramus (MR) and attached swim bladder anteriorly. Further, the MR possesses an anterior fulcrum that abuts upon the vertebral complex. Several sound types were elicited during agonistic interactions in the laboratory. We observed ratchet, click train and mouth sounds. Mouth sounds are single event, low‐frequency (mean dominant frequency 176 Hz) sounds that coincide with a bite‐like motion. Ratchet and click sounds are high‐frequency (mean dominant frequency 1568 and 3739 Hz, respectively) and occur in trains. Ratchet and click train sound characteristics are not indicative of a muscle‐driven drumming sound predicted by ESA morphology. We propose several hypotheses for these sound production mechanisms. Click sounds, in particular, could result from gas movement through the neck between the anterior and posterior swim bladder chambers.

Sex-specific differences in agonistic behaviour, sound production and auditory sensitivity in the callichthyid armoured catfish Megalechis thoracata.

BackgroundData on sex-specific differences in sound production, acoustic behaviour and hearing abilities in fishes are rare. Representatives of numerous catfish families are known to produce sounds in agonistic contexts (intraspecific aggression and interspecific disturbance situations) using their pectoral fins. The present study investigates differences in agonistic behaviour, sound production and hearing abilities in males and females of a callichthyid catfish.Methodology/Principal FindingsEight males and nine females of the armoured catfish Megalechis thoracata were investigated. Agonistic behaviour displayed during male-male and female-female dyadic contests and sounds emitted were recorded, sound characteristics analysed and hearing thresholds measured using the auditory evoked potential (AEP) recording technique. Male pectoral spines were on average 1.7-fold longer than those of same-sized females. Visual and acoustic threat displays differed between sexes. Males produced low-frequency harmonic barks at longer distances and thumps at close distances, whereas females emitted broad-band pulsed crackles when close to each other. Female aggressive sounds were significantly shorter than those of males (167 ms versus 219 to 240 ms) and of higher dominant frequency (562 Hz versus 132 to 403 Hz). Sound duration and sound level were positively correlated with body and pectoral spine length, but dominant frequency was inversely correlated only to spine length. Both sexes showed a similar U-shaped hearing curve with lowest thresholds between 0.2 and 1 kHz and a drop in sensitivity above 1 kHz. The main energies of sounds were located at the most sensitive frequencies.Conclusions/SignificanceCurrent data demonstrate that both male and female M. thoracata produce aggressive sounds, but the behavioural contexts and sound characteristics differ between sexes. Sexes do not differ in hearing, but it remains to be clarified if this is a general pattern among fish. This is the first study to describe sex-specific differences in agonistic behaviour in fishes.

Cytogenetic study of heptapterids (Teleostei, Siluriformes) with particular respect to the Nemuroglanis subclade.

The catfish family Heptapteridae (order Siluriformes) is endemic to the Neotropics and is one of the most common of the fish families in small bodies of water. Although over 200 species have been identified in this family, very few have been characterized cytogenetically. Here, we analyze the chromosome genomes of four species of Heptapteridae: Cetopsorhamdia iheringi (Schubart & Gomes, 1959), 2n = 58, comprising 28 metacentric (m) + 26 submetacentric (sm) + 4 subtelomeric (st) chromosomes; Pimelodella vittata (Lütken, 1874), 2n = 46, comprising 16m + 22sm + 8st; Rhamdia prope quelen (Quoy & Gaimard, 1824), 2n = 58 comprising 26m + 16sm + 14st + 2 acrocentric; and Rhamdiopsis prope microcephala (Lütken, 1874), 2n = 56, comprising 12m + 30sm + 14st. The nucleolus organizer regions (NORs) were located in a single chromosome pair in all species. The two species that belonged to the subclade Nemuroglanis, Cetopsorhamdia iheringi and Rhamdia prope quelen, had a diploid chromosome number of 58 and an interstitial NOR adjacent to a C+ block located on one of the larger chromosome pairs in the complement. Our results from conventional cytogenetic techniques in combination with FISH using 18S and 5S rDNA probes corroborated the taxonomical hypothesis for the formation of the Nemuroglanis subclade.

Complete mitochondrial genome of the Neotropical catfish Pseudoplatystoma magdaleniatum (Siluriformes, Pimelodidae)

The Neotropical freshwater fish Pseudoplatystoma magdaleniatum is a trans-Andean species that belongs to the family of long-whiskered catfishes (family Pimelodidae). In this study, the complete mitochondrial genome of P. magdaleniatum was sequenced using the MiSeq Illumina platform. The complete circular mitogenome is 16,568 bp in length, exhibiting an average GC content of 44.19% and codes for 13 proteins, 2 ribosomal RNA genes and 22 transfer RNA genes. Additionally, it exhibits perfect synteny and similar length with the mitogenome of Pimelodus pictus.