A new species of mailed catfish of genus Rhadinoloricaria (Siluriformes: Loricariidae: Loricariinae) from Rio Negro basin, Brazil.

During a recent collection expedition to the Rio Negro, in the state of Amazonas, Brazil, eight individuals of an unknown species were collected, with a combination of characteristics that placed the species in the genus Rhadinoloricaria. Furthermore, the presence of two autapomorphic characteristics, including numerous elongated papillae on the lower lip and unbranched barbelets on the margin of lower lip, suggests that it is a new species. From morphological and phylogenetic analyses, including the sequencing of specific genes to calculate the maximum likelihood analyses, coupled with osteological computed tomography (CT) scan analyses, the authors corroborated that the specimens represent a new species of Rhadinoloricaria, described in the present study.

Integrative taxonomy of Imparfinis (Siluriformes, Heptapteridae) from the Upper Paraná River basin, Brazil, with description of a new species.

The Neotropical family Heptapteridae comprises 228 valid species widely distributed in South America. Imparfinis is one of the most diverse genera of this family, with 25 valid species widely distributed, inhabiting streams from Costa Rica to Argentina. Old descriptions coupled with lack of recent systematic studies of the species of Imparfinis from the Upper Paraná river basin have led to a taxonomic impediment and hindered the advancement of studies in other areas, such as ecology, cytogenetic, phylogenetic, and evolution. We conducted the first integrative study analyzing both molecular and morphological data of Imparfinis from the Upper Paraná River basin. Our analyses strongly support the existence of four independent evolutionary lineages in this river system, three of them are the nominal species I. mirini, I. schubarti, and I. piperatus, and a new species from Goiás state described herein.

Molecular and morphological diversity in species of Kronichthys (Teleostei, Loricariidae) from Atlantic coastal rivers of Brazil.

The Neotropical catfish genus Kronichthys contains three species distributed along coastal rivers of southern and southeastern Brazil. Although phylogenetic hypotheses are available, the molecular and morphological diversity and species boundaries within the genus remain unexplored. In this study, the authors generated mitochondrial data for 90 specimens combined with morphometric and meristic data to investigate species diversity, species boundaries and putative morphological signatures in Kronichthys. Phylogenetic and species delimitation results clearly show the presence of four genetic lineages, three within Kronichthys heylandi along the coast from Rio de Janeiro to southern São Paulo and a single lineage encompassing both the nominal species Kronichthys lacerta and Kronichthys subteres from the Ribeira de Iguape basin to Santa Catarina in southern Brazil. Nonetheless, morphological data show overlapped ranges in morphometrics and a definition of only two morphotypes, with clear phenotypic differences in the teeth number: K. heylandi differs from K. subteres + K. lacerta by the higher number of premaxillary teeth (30-52 vs. 19-28) and higher number of dentary teeth (28-54 vs. 17-28). Headwater captures and connections of paleodrainages because of sea-level fluctuations represent the two major biogeographic processes promoting species diversification and lineage dispersal of Kronichthys in the Atlantic coastal range of Brazil.

A new species of Phenacorhamdia Dahl 1961 (Siluriformes: Heptapteridae) from the Paranapanema River basin, southeastern Brazil.

A new species of Phenacorhamdia is described from Paranapanema River, Upper Paraná River basin, southeastern Brazil. The new species is distinguished from congeners by the combination of following characters 45-46 vertebrae; an entirely dark-brown body; nine pleural ribs; eight branched rays in upper lobe of caudal fin; seven branched rays in pectoral fin; 13 anal-fin rays with 9-10 branched; first basal radial inserted at the 13th vertebrae and eight branchiostegal rays.

Description of a new species of Hisonotus (Loricariidae: Siluriformes) from rio Araguaia basin.

A new species of Hisonotus is described from headwaters of rio Araguaia basin, municipality of Barra do Garças, Mato Grosso state, Brazil. The new species is distinguished from its congeners by a V-shaped spinelet, yellowish teeth, absence of unpaired platelets at typical adipose fin position, the caudal-fin color hyaline with three transverse dark bars, one abdominal median plate series, and by morphometric and meristic characters.

Phylogenomic analysis of trichomycterid catfishes (Teleostei: Siluriformes) inferred from ultraconserved elements.

The family Trichomycteridae is one of the most diverse groups of freshwater catfishes in South and Central America with eight subfamilies, 41 genera and more than 300 valid species. Its members are widely distributed throughout South America, reaching Costa Rica in Central America and are recognized by extraordinary anatomical specializations and trophic diversity. In order to assess the phylogenetic relationships of Trichomycteridae, we collected sequence data from ultraconserved elements (UCEs) of the genome from 141 specimens of Trichomycteridae and 12 outgroup species. We used a concatenated matrix to assess the phylogenetic relationships by Bayesian inference (BI) and maximum likelihood (ML) searches and a coalescent analysis of species trees. The results show a highly resolved phylogeny with broad agreement among the three distinct analyses, providing overwhelming support for the monophyletic status of subfamily Trichomycterinae including Ituglanis and Scleronema. Previous relationship hypotheses among subfamilies are strongly corroborated, such as the sister relationship between Copionodontinae and Trichogeninae forming a sister clade to the remaining trichomycterids and the intrafamilial clade TSVSG (Tridentinae-Stegophilinae-Vandelliinae-Sarcoglanidinae-Glanapteryginae). Monophyly of Glanapteryginae and Sarcoglanidinae was not supported and the enigmatic Potamoglanis is placed outside Tridentinae.

A new species of Parotocinclus (Loricariidae: Hypoptopomatinae) from Rio Tocantins basin, Brazil.

A new species of Parotocinclus is described from the Rio Tocantins basin, Tocantins State, Brazil. The new species is distinguished from congeners by a combination of characters such as: (1) a unique pattern of body coloration with five transverse dark bars; (2) absence of an adipose fin or small platelet at typical adipose-fin region; (3) absence of conspicuous dark dots broadly distributed on the body; (4) absence of a triangular dark blotch at the anterior base of the dorsal fin; and (5) presence of a V-shaped spinelet.

Phylogenomic reappraisal of the Neotropical catfish family Loricariidae (Teleostei: Siluriformes) using ultraconserved elements.

Neotropical freshwaters host more than 6000 fish species, of which 983 are suckermouth armored catfishes of the family Loricariidae - the most-diverse catfish family and fifth most species-rich vertebrate family on Earth. Given their diversity and ubiquitous distribution across many habitat types, loricariids are an excellent system in which to investigate factors that create and maintain Neotropical fish diversity, yet robust phylogenies needed to support such ecological and evolutionary studies are lacking. We sought to buttress the systematic understanding of loricariid catfishes by generating a genome-scale data set (1041 loci, 328,330 bp) for 140 species spanning 75 genera and five of six previously proposed subfamilies. Both maximum likelihood and Bayesian analyses strongly supported the monophyly of Loricariidae. Our results also reinforced the established backbone of loricariid interrelationships: Delturinae as sister to all other analyzed loricariids, with subfamily Rhinelepinae diverging next, followed by Loricariinae sister to Hypostominae + Hypoptopomatinae. Previous DNA-based relationships within Hypostominae and Loricariinae were strongly supported. However, we evaluated for the first time DNA-based relationships among many Hypoptopomatinae genera and found significant differences with this subfamily's current genus-level classification, prompting several taxonomic changes. Finally, we placed our topological results within a fossil-calibrated temporal context indicating that early Loricariidae diversification occurred across the Cretaceous-Paleogene boundary ∼65 million years ago (Ma). Our study lays a strong foundation for future research to focus on relationships among species and the macroevolutionary processes affecting loricariid diversification rates and patterns.

New species of Neoplecostomus (Neoplecostomini: Loricariidae) lacking adipose fin from upper Rio Paraná basin, central Brazil.

In the present study, we describe a new species of Neoplecostomus from central Brazil. The new species is known from Córrego Cachoeira a right tributary of the upper Rio Paraná basin. It can be distinguished from all congeners by absence of adipose fin or azygous plates on the dorsum surface of the caudal peduncle. Additionally, the new species differs from N. botucatu and N. paranensis by having a dark caudal fin with a unique v-shaped hyaline vertical area and a larger lower lip. A discussion on the morphological variation of adipose fin among species of Neoplecostomus is also provided.

A new species of Hisonotus (Siluriformes: Loricariidae) from Aripuanã river, Amazon basin, Brazil.

A new species of Hisonotus from rio Juma, located at the right margin of the lower rio Aripuanã, rio Madeira basin is described. The new species is distinguished from its congeners mainly by a reddish-tipped premaxillary and dentary teeth, a V-shaped spinelet, three lateral plates in abdominal series, the coloration pattern of caudal fin with three transversal dark bars, and by morphometric characters.

Two new species of Corumbataia (Hypoptopomatinae: Loricariidae) from Rio Corrente, upper Rio Paraná basin, Brazil.

We describe two new species of Corumbataia from Central Brazil. The new species are known from Rio Corrente, a tributary of the upper Rio Paraná basin. Furthermore, the two species are distinguished from congeners, mainly by the presence of a broad naked area without plates or odontodes on the dorsal portion of the snout. Additionally, the two new species described here can be distinguished from each other by the caudal-peduncle depth, number of infraorbitals plates series and by the general color pattern of caudal fin.

A new species of Tetragonopterus (Characiformes: Characidae) from Central Amazon lowlands, Brazil

A new species of Tetragonopterus is described from lowland rivers of Central Amazon. It differs from congeners by having a vertically-oriented patch of dark pigmentation limited to posterior portion of the caudal peduncle and by bearing five thin and sharp teeth on dentary, along with other morphometric and meristic features. We hypothesize that the new taxon belongs to the herein named "Tetragonopterus anostomus clade" that includes T. anostomus, T. denticulatus, T. kuluene, and T. juruena.(AU)

Uma espécie nova de Tetragonopterus é descrita de rios de terra baixa da Amazônia Central. Ela difere de suas congêneres por possuir uma mancha escura orientada verticalmente, limitada à porção posterior do pedúnculo caudal, e por possuir cinco dentes principais finos e afiados no dentário, além de outras características morfométricas e merísticas. Nós levantamos a hipótese que o novo táxon pertença ao clado Tetragonopterus anostomus, o qual inclui T. anostomus, T. denticulatus, T. kuluene e T. juruena.(AU)

Description of two new species of Lithoxus (Hypostominae: Loricariidae) from rio Jari and rio Amapá basins, Brazilian Guiana Shield.

Two new species of Lithoxus, a genus diagnosed by possessing a dorsoventrally depressed body, a large round oral disk, and small tooth cusps with few teeth, are described from two drainages of the Guiana Shield: Lithoxus jariensis from the rio Jari basin and L. raso from the rio Raso, rio Amapá basin. The new species, L. jariensis, is distinguished from congeners by having an adipose fin, by the number of branched anal-fin and caudal-fin rays, by color pattern of the body, number of teeth, adipose-fin length, dorsal adipose-caudal distance, caudal peduncle depth, cleithral width, and dorsal-anal distance. Lithoxus raso can be diagnosed from congeners by coloration pattern, by having an adipose fin, by the number of branched anal-fin rays, number of teeth, adipose-fin length, dorsal adipose-caudal distance, caudal peduncle depth, and cleithral width. Greater genetic divergence in mitochondrial cytochrome oxidase subunit I (COI) confirms L. jariensis and L. raso as two new species.

Two new species of Curculionichthys (Siluriformes: Loricariidae) from the rio Amazonas basin, Brazil.

In the present study, we describe two new species of Curculionichthys from rio Tapajós and rio Tocantins basins in Brazil. Both species present all diagnostic features of Curculionichthys. Furthermore, both species C. tukana and C. itaim are distinguished from congeners by the combination of seven characters: (1) a higher number of plates in abdominal lateral plates series; (2) the absence of large conspicuous odontodes forming rows on head and trunk; (3) the anterior profile of the head pointed; (4) a higher number of dentary teeth; (5) the lack of contrasting dark spots at the anterodorsal region of body; (6) the absence of an irregular concentration of chromatophores that entirely cover the anal-fin origin and adjacent region, and distal portion of the first unbranched anal-fin ray; and (7) the presence of odontodes forming aligned rows, more evident in the dorsal portion of head and in the lateral portion of caudal peduncle. Furthermore, C. tukana can be further distinguished from congeners by three characters: (1) the papillae aligned in series that extends from the distal portion of lower lip to dentary; (2) the absence of dark-brown spots scattered over the body; and (3) a higher number of maxillary teeth. The species C. itaim also can be further distinguished from congeners by five characters: (1) the papillae randomly distributed throughout the lower lip; (2) a smaller number of medial plates series on lateral portion of the body following the lateral line; (3) a smaller number of median plates series in abdomen; (4) the absence of dark-brown spots scattered over the body; and (5) the absence of one unpaired platelet on the dorsal portion of the caudal peduncle.

Description of a new species of Gymnotocinclus from the rio Tocantins basin with phylogenetic analysis of the subfamily Hypoptopomatinae (Siluriformes: Loricariidae).

Gymnotocinclus canoeiro n. sp. of the Hypoptopomatinae is described from small tributaries of the upper rio Tocantins basin. It is distinguished from G. anosteos by having five characters: (1) the presence of body dermal plates, (2) the pectoral girdle not exposed in ventral view, (3) the pelvic spine longer than pectoral spine in males, (4) the pectoral fin with seven to eight branched rays, and (5) the presence of an adipose fin. Furthermore, maximum likelihood (ML) analysis was used to estimate a molecular phylogeny from previously published data of one nuclear (F-Reticulon 4) and three mitochondrial (16S RNA, COI and CytB) genes. The phylogenetic results revealed the new species as a sister taxon of Gymnotocinclus anosteos within the Otothyrini. We also included samples of Nannoplecostomus eleonorae that appeared sister group to all other Neoplecostomini species, and Plesioptopoma curvidens that appeared within the Neoplecostomini forming a sister clade to all species of Neoplecostomus, except N. ribeirensis and the species of Pareiorhina, except P. rudolphi.

Shift from slow- to fast-water habitats accelerates lineage and phenotype evolution in a clade of Neotropical suckermouth catfishes (Loricariidae: Hypoptopomatinae).

Identifying habitat characteristics that accelerate organismal evolution is essential to understanding both the origins of life on Earth and the ecosystem properties that are most critical to maintaining life into the future. Searching for these characteristics on a large scale has only recently become possible via advances in phylogenetic reconstruction, time-calibration, and comparative analyses. In this study, we combine these tools with habitat and phenotype data for 105 species in a clade of Neotropical suckermouth catfishes commonly known as cascudinhos. Our goal was to determine whether riverine mesohabitats defined by different flow rates (i.e., pools vs. rapids) and substrates (plants vs. rocks) have affected rates of cascudinho cladogenesis and morphological diversification. In contrast to predictions based on general theory related to life in fast-flowing, rocky riverine habitats, Neoplecostomini lineages associated with these habitats exhibited increased body size, head shape diversity, and lineage and phenotype diversification rates. These findings are consistent with a growing understanding of river rapids as incubators of biological diversification and specialization. They also highlight the urgent need to conserve rapids habitats throughout the major rivers of the world.

New species of Parotocinclus (Siluriformes: Loricariidae) from coastal drainages of Rio de Janeiro, southeastern Brazil.

A new species of Parotocinclus is described from tributaries of rio São João, an Atlantic coastal river of Rio de Janeiro, southeastern Brazil. The new species is distinguished from its congeners by the possession of a triangular patch of dark pigmentation on the anterior portion of the dorsal-fin base, a fully developed adipose fin, complete exposure of the ventral surface of the pectoral girdle, and a distinctive pigmentation pattern of the caudal fin. The caudal fin has a hyaline background with a large black blotch covering its anterior portion, tapering irregularly through distal portions of the ventral lobe with a hyaline rounded area, and a small patch of dark pigmentation on distal portions of the dorsal lobe.

Revision of the South American genus Tetragonopterus Cuvier, 1816 (Teleostei: Characidae) with description of four new species.

The systematics of the characid genus Tetragonopterus is reviewed based on morphological and molecular data of specimens from its entire geographical range encompassing all major South American river drainages from Orinoco basin southward to the La Plata basin. Eight previously described species (T. anostomus, T. araguaiensis, T. argenteus, T. carvalhoi, T. chalceus, T. denticulatus, T. georgiae n. comb., and T. rarus) are recognized as valid, four of which are redescribed (T. argenteus, T. chalceus, T. georgiae, and T. rarus), and four new species from the Brazilian Shield in the Amazon and São Francisco river basins are herein described. We also provide evidence for the reallocation of Moenkhausia georgiae into Tetragonopterus and recognize T. akamai as junior synonym of T. anostomus. DNA barcodes of Tetragonopterus revealed genetic support for each recognized species and provided valuable population-level information within T. argenteus, T. chalceus, T. georgiae, and T. rarus.

Description of a new species of Parotocinclus (Siluriformes, Hypoptopomatinae) from the rio Tapajós basin.

A new species of Parotocinclus is described from three small tributaries of the rio Tapajós basin, Mato Grosso State, Brazil. The new species can be distinguished from its congeners by presenting the following characters: (1) a triangular dark blotch at the anterior base of the dorsal fin, (2) the absence of an adipose fin but presence of one small platelet at typical adipose-fin region, (3) the abdomen completely covered by dermal plates, (4) a pectoral girdle totally exposed, (5) a single series of bicuspid teeth, and (6) the higher number of bicuspid premaxillary and dentary teeth.