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As DNA-based phylogenetic analyses have exploded, historically phenotype-based evolutionary hypotheses throughout the tree of life have been rewritten. However, rarely are DNA-based phylogenetic hypotheses tested via the reanalysis of phenotypic data. Skeletons representing all four recognized genera of the Guiana Shield endemic suckermouth armored catfish clade Lithoxini were examined to test a recently published DNA-based phylogenetic hypothesis using morphological evidence. Phylogenetic analysis of 54 mostly osteological characters yielded a single most parsimonious tree of 90 steps that was congruent with the molecular hypothesis: (Avalithoxus, ((Exastilithoxus), (Lithoxus, Paralithoxus))). Lithoxini was a well-supported clade with 20 synapomorphies, as was each of the genera within this clade. Avalithoxus jantjae, which was originally described in Lithoxus, was found to be missing the unique synapomorphies of Lithoxus Paralithoxus: a spoon-shaped, ventrally oriented process on the metapterygoid and a process on the preoperculo-hyomandibular ridge.

A new species of Spatuloricaria is described from the Orinoco River basin, Colombia. The new species can be distinguished from its congeners by the following characters: a broad, dark brown stripe on the first pre-dorsal plate, which occupies the entire plate, reaching the preopercle, and sometimes reaching the second pre-dorsal plate; the possession of a small group of plates posterior to the urogenital pore; the abdominal surface with scattered, very small plates leaving naked areas; the possession of five transverse dark brown bands on the dorsal region; and four to five premaxillary teeth. The new species is the first valid species of Spatuloricaria distributed in the Orinoco River basin. Ecological notes of the species and comments regarding the taxonomy and phylogenetic relationships of the genus are offered.

Pareiorhaphis mucurina, new species, is described from the Preto River, a headwater tributary of the Mucuri River basin, Minas Gerais State, eastern Brazil. This description represents the first record of Pareiorhaphis in the Mucuri River basin, the intervening drainage between the Doce and the Jequitinhonha rivers, two large coastal drainages in eastern Brazil that are inhabited by six species of Pareiorhaphis. Pareiorhaphis mucurina, new species, is promptly diagnosed from all congeners by having a distinct, narrow area in the lower lip along and just posterior to each emergent tooth series of the dentary completely devoid of papillae and the lateral margin of the lower lip with a distinctly enlarged flap of skin, forming a continuous connection with most of the maxillary barbel. In addition, the new species can be further distinguished from all congeners by having the upper lip with distinctly shaped papillae, which are coalesced to form three or four transverse series of elongate skin folds. The well-developed dorsal-fin spinelet, the smaller orbital diameter, and features related to morphology of the fleshy lobes on the lateral portion of head of adult males, also distinguish the new species from most congeners.

The new Chaetostoma-group genera Andeancistrus and Transancistrus are described based on recently collected material from rivers draining the respective Amazonian and Pacific slopes of the Andes Mountains in Ecuador. Andeancistrus is diagnosable from all other members of the Chaetostoma group by having a fully plated snout, lacking cheek odontodes that extend past the opercular flap, and by having eight vs. nine branched dorsal-fin rays. The new species Andeancistrus eschwartzae is also described and diagnosed from its only congener (A. platycephalus) by having a black to dark gray base color of head and body (vs. light gray), irregularly shaped round to vermiculate yellow-gold spots smaller than half naris diameter evenly distributed across head, lateral and dorsal surfaces of the body and fin rays (vs. white to blue uniformly round spots), and by lacking enlarged clusters of odontodes at the posteromedial apex of most lateral body plates (vs. odontode clusters present). Transancistrus contains the speci...

The rubbernose-pleco genus Chaetostoma comprises 47 currently valid and many undescribed species distributed along Atlantic and Pacific slopes of the Andes Mountains from Panama to southern Peru, the Coastal Mountains of Venezuela, and drainages of the Guiana and Brazilian shields. We present a five-locus molecular phylogeny for 21 described and six undescribed species of Chaetostoma spanning the geographic range of the genus. Bayesian and maximum likelihood analyses found Chaetostoma to be well supported as monophyletic and sister to a clade of central and northern Andean genera that have also been hypothesized to be closely related based on morphology (i.e., Andeancistrus, Cordylancistrus, Dolichancistrus, Leptoancistrus, and Transancistrus). Species of Chaetostoma were divided into a trichotomy consisting of: a Pacific Coast, Central American, Magdalena Basin, Lake Valencia, and Guiana Shield clade; a western Orinoco, Lake Maracaibo, and Lake Valencia clade; and a widespread upper Amazon/Orinoco clade ...

A new neoplecostomine genus and species is described from headwater tributaries of the lower Rio Pardo basin, a coastal drainage in Bahia, eastern Brazil. Hirtella carinata is a small loricariid with a maximum standard length barely reaching 50 mm. The new genus and species are diagnosed among all other loricariids by a unique, remarkable pattern of sexual dimorphism in which adult males have five conspicuous longitudinal rows of bristle-like hypertrophied odontodes on the head and along the lateral dermal plates of the body. Hirtella is further distinguished from most loricariids by the anterior position of the pelvic fin, which originates in a vertical anterior to the nuchal plate, and by the possession of an elongate keel formed by 15–17 azygous plates along the mid-dorsal line between the dorsal and the caudal fins. Hirtella is additionally distinguished from other members of the Neoplecostominae by having a medium sized palatine splint, never reaching the anterior border of the nasal fossa. Phylogene...

The genus Spatuloricaria is diagnosed by a number of conspicuous characteristics that set it apart from other genera in the subfamily Loricariinae. The genus has a broad geographical distribution extending from Argentina to Panama. Despite the flood of new loricariid taxa described in the past decades, no new species of Spatuloricaria have been newly reported since 1945. In this paper, we report on a distinctive new species of the genus from the Rio Xingu and Rio Tapajos in the Amazon basin. The new species is distinguished from congeners by the lack of abdominal and preanal plates, in combination with the presence of five transversal dark-brown bands on the dorsum. It apparently is the only species in Spatuloricaria where males are smaller than females, a situation opposite of that in other species of the genus.

A taxonomic revision of Sturisomatichthys is presented. A total of 383 specimens including both type and non-type specimens of all valid species were examined. Sturisomatichthys was found to encompass ten valid species: Sturisomatichthys aureus, S. caquetae, S. citurensis, S. dariensis, S. festivus, S. frenatus, S. kneri, S. leightoni, S. panamensis, and S. tamanae. In addition, three new species are described: Sturisomatichthys reinae, new species, from the Baudo River, in northwestern Colombia, belonging to the Caribbean slope of the continent; Sturisomatichthys guaitipan, new species, from the upper and middle Magdalena River basin, Colombia; and Sturisomatichthys varii, new species, from the San Juan River basin in western Colombia, on the Pacific slope. Sturisomatichthys caquetae, from the Morelia River, upper Amazon, is transferred back from Sturisoma, and S. leightoni was found to be distributed, besides the Magdalena-Cauca basin, in the Orinoco basin; thus, Sturisomatichthys is shown to be distributed in both trans- and cis-Andean drainages. A neotype is designated for S. aureus from the lower Magdalena basin. New records of localities in the northwestern region of South America, as well as the redescription and taxonomic comments on all valid species, are provided. Maps with the species distributions and a key for identification of the species are provided.

Two new species of the suckermouth armored catfish genus Baryancistrus are described from the Jari River basin, at the border of Para and Amapa states, Brazil. The new species are the first representatives of the genus described from rivers draining the Guiana shield, and can be distinguished from their congeners by color pattern and a combination of nonexclusive characters. Baryancistrus micropunctatus, new species, has a color pattern similar to B. longipinnis from the Tocantins River, whereas Baryancistrus hadrostomus, new species, has a color pattern that is unique for the genus, with a gray to black body covered by small and widely spaced white points. The first exemplars of the two new species were collected in the late 1980s by INPA ichthyological staff, and in 2007 additional materials were collected by the Museu de Zoologia da Universidade de Sao Paulo (MZUSP), providing a foundation for this description of the new species.

A new species of the hypoptopomatine loricariid genus Parotocinclus is described based on material from the headwaters of the Rio Jequitinhonha, Minas Gerais State, eastern Brazil. The new species is distinguished from all congeners, except P. prata and P. robustus, by the absence of abdominal plates between the pectoral girdle and the anus. It differs from P. prata and P. robustus by having a smaller cleithral width (16.7–20.7 vs. 20.8–27.6% SL in P. prata and 25.9–28.8% SL in P. robustus) in addition to other morphological features. Uma nova especie de loricarideo hypoptomatineo do genero Parotocinclus e descrita com base em material das cabeceiras do Rio Jequitinhonha, no estado de Minas Gerais, leste do Brasil. A nova especie e diferenciada de todos os seus congeneres, exceto P. prata e P. robustus, pela ausencia de placas no abdomen entre a cintura peitoral e o ânus. Se distingue das especies acima pela menor largura cleitral (16.7–20.7 vs. 20.8–27.6% do Comprimento Padrao em P. prata e 25.9–28.8% do...

Nannoplecostomus eleonorae, a new genus and species of a miniature suckermouth armored catfish, is described based on specimens collected from the karst region of Sao Domingos, upper Rio Tocantins basin, Goias State, central Brazil. The new genus and species can be diagnosed among loricariids by presenting a unique reductive pattern of lateral dermal plates, with most of the body covered by only three series of plates (viz., dorsal, mid-ventral, and ventral). Based on the available published phylogenetic studies for the family, we provisionally consider Nannoplecostomus eleonorae as being an incertae sedis taxon within Loricariidae. Achieving a maximum standard length of 22.2 mm SL, Nannoplecostomus eleonorae is the smallest known loricariid catfish, and a list of the remaining smallest loricariids is provided. E descrito um novo genero e especie de cascudo miniaturizado, Nannoplecostomus eleonorae, baseado em especimes coletados na regiao de carste de Sao Domingos, bacia do alto rio Tocantins, estado de ...

A new species of Pareiorhaphis is described from the Ribeirao Caraca, a tributary to the Rio Piracicaba, upper Rio Doce basin in the State of Minas Gerais, eastern Brazil. The new taxon is promptly diagnosed from all other species of Pareiorhaphis by having a unique color pattern in both sexes. The color pattern consists of conspicuous dark brown blotches irregularly scattered over a yellowish tan background on head, along the dorsal surface of body and flanks. In addition, the new species can be further distinguished from all congeners except P. eurycephalus, P. nudulus, and P. vestigipinnis, by the absence of an adipose fin. From those species it is distinguished by morphometric traits. The new species is further compared to P. nasuta and P. scutula, which also occur in the Rio Doce system.

Peckoltia is one of the 26 genera that constitute the Ancistrini. Although Peckoltia has been reviewed recently, its taxonomic status is not fully resolved and not easily distinguished from Hemiancistrus. Neither Peckoltia nor Hemiancistrus have any recognized synapomorphies supporting their monophyly. In this paper we describe a new species of Ancistrini from Rio Xingu drainage, Para State, Brazil, and assign it to Peckoltia based on its deep body, presence of large odontodes on the cheeks, and lack of carenate plates on the body. The new species can be easily distinguished from all its congeners by its dorsal-fin color pattern (presence of dark thin stripes in the interradial membranes parallel to fin rays that fragment into small spots in larger specimens vs. bands, spots, dots, or membranes with a darker coloration in all other species). Peckoltia feldbergae, new species, differs from all its congeners except P. bachi, P. oligospila, and P. sabaji by having dark brown spots on the entire body (vs. pre...

A new small Loricariidae, Hypostomus careopinnatus, is described from the Rio Taquari drainage, upper Rio Paraguay basin, Mato Grosso, Brazil. The new species can be easily distinguished from all congeners, except Hypostomus levis, by the absence of adipose fin. Hypostomus careopinnatus is distinguished from H. levis mainly by the presence of slender bifid teeth, with mesial cusp large and rounded, and lateral cusp small and pointed (vs. spoon-shaped teeth). The new species described herein completely lacks the adipose fin and also lacks the median pre-adipose plates in almost all specimens examined. The absence of adipose fin is probably an independent acquisition for Hypostomus careopinnatus and Hypostomus levis.

Hisonotus bockmanni, new species, is described based on specimens collected in a sandbank in the Rio Cururu, a tributary to the Rio Teles Pires, one of the rivers forming the Rio Tapajos in the Amazon Basin. The new taxon is distinguished from its congeners by a unique color pattern, whose most striking features are: two elliptical white spots, anterior to nostrils; predorsal region darkly pigmented with five unpigmented spots arranged as anteriorly pointed chevron; and a rostrocaudally elongate cross along most of the caudal peduncle. The placement of the new species in Hisonotus as well as its possible affinities within that genus are discussed in light of the current knowledge of the phylogenetic relationships among the Hypoptopomatinae.

Loricaria coximensis, new species, is described from the Rio Paraguay basin, in Mato Grosso do Sul State, Brazil. It is distinguished from all other species of Loricaria, except L. holmbergi, L. lundbergi, L. parnahybae, and L. pumila by having abdominal plates confined to the pre-anal shield and posterior median abdominal area, usually loosely joined or separated by naked areas, pectoral girdle mostly naked, with isolated plates near base of pectoral fins and posterior to gill opening vs. abdominal plates well developed and tightly arranged across the entire median abdominal area, including the pectoral girdle. It is distinguished from these other four species by meristic counts and several morphometric proportions, particularly a broader head (19.4–21.3% SL vs. 14.1–19.1% SL). Loricaria coximensis becomes the third described paedomorphic species of Loricaria, along with L. nickeriensis and L. pumila, based on its small adult size (

The genus Chaetostoma is a species-rich group of armored catfishes that inhabits rivers and streams in montane forests of South America. Most species of Chaetostoma have been described based on only one or a few specimens from a single river system. Our aim was to determine if the lifting of the Fitzcarrald Arch, 4 Ma, triggered speciation between the disjunct populations of Chaetostoma lineopunctatum in two isolated river drainages: the Rio Ucayali and the Rio Madre de Dios. We addressed this question by quantifying morphological and molecular divergence among samples of C. lineopunctatum from four river systems, three of which drain into the Rio Ucayali drainage, including the type locality for the species, and one river system which drains into the Rio Madre de Dios drainage. Morphological divergence, based on measurements, was statistically significant in the MANOVAs for the samples grouped by locality (P < 0.025) and by river system (P < 0.025). However, neighbor-joining trees of specimens g...

Etsaputu relictum, a new genus and species sister to all other Ancistrini, is described from the upper Maranon River in Northern Peru. Etsaputu relictum can be diagnosed from all other Hypostominae by having a coracoid with a serrated posterior margin of the posterior process, an opercle with a process extending ventrolaterally from the ventral margin, and branchiostegals one and two fused. Etsaputu relictum is further distinguished by having cheek plates evertible to less than 45° from the sagittal plane, by having fewer than ten (typically zero or six) enlarged cheek-plate odontodes, by having enlarged cheek-plate odontodes straight and no longer than 15 times length of odontodes on lateral body plates, by having large eyes (mean 24.0% of head length, range 21.7–27.6% HL), and by having uniformly gold-brown to bronze base color with golden sheen when alive.

Two new ancistrin genera and species are described from main channels and tributaries of the upper Orinoco River in Amazonas, Venezuela. Micracanthicus vandragti is black with white spots and distinguished by its small body-size, large gas-bladder capsules, and highly protrusible mandibles with short tooth cups and five to eight long teeth per tooth cup. The known range of Micracanthicus vandragti is restricted to the lower Ventuari River and portions of the Orinoco River near its rocky, anastomose confluence with the Ventuari River. Soromonichthys stearleyi is green with small yellow-gold spots on the head and thin vertical bars on the body and has long dentary and premaxillary tooth cups with 39–69 teeth per tooth cup. It is distinguished by its coloration and by its unique pattern of plate loss on the snout: plates absent from mesethmoid surface and anteriormost margin of snout. Soromonichthys stearleyi is known only from Soromoni Creek, a northern tributary of the upper Orinoco draining south...

Paulasquama callis is a new genus and species of partially deplated ancistrin loricariid from the Waruma River, a tributary of the upper Mazaruni River, in northwestern Guyana. Paulasquama differs from all other described hypostomines by lacking plates in an oval area lateral to the mesethmoid, by having small plates in the dorsal series below the dorsal fin (less than half the typical size of other loricariids), and by having a fleshy keel on the preadipose plate and slightly anterior. The opercle of Paulasquama is sickle-shaped as in basal ancistrins, but has a posterior connection to the hyomandibula as in derived members of the Ancistrus clade.

A new species of Otocinclus (Loricariidae) is described from tributaries to the Rio Madeira, in the State of Amazonas, Brazil. The new taxon can be distinguished from its congeners by lacking middle abdominal plates between the lateral abdominal plates, and by having the dark spot at the base of the caudal fin separated from the midlateral stripe by an unpigmented or slightly pigmented area, and not extended posteriorly onto the middle caudal-fin rays.

The Panaque nigrolineatus group (subgenus Panaque) is revised; three nominal species—P. cochliodon, P. nigrolineatus, and P. suttonorum—are redescribed and three new species are described. Panaque armbrusteri, new species, is widespread in the Tapajos River and its tributaries in Brazil and is distinguished by having a supraoccipital hump, higher numbers of jaw teeth and an ontogenetic increase in interpremaxillary and intermandibular tooth-row angles, relatively short paired-fin spines, and dorsal margin of infraorbital six flared laterally. Panaque schaeferi, new species, is widespread in main-channel habitats of the upper Amazon (Solimoes) River basin in Brazil and Peru; it is distinguished by having a coloration consisting of dark or faded black spots evenly distributed on a pale gray to brown base, and by its large adult body size (>570 mm SL). Panaque titan, new species, is distributed in larger, lowland to piedmont rivers of the Napo River basin in Ecuador, and is distinguished by having a...

Loricaria birindellii, new species, is described based on two specimens from the Rio Curua, a tributary of the Rio Iriri in the lower Xingu basin of Brazil. In adults the new species is distinguished from all other congeners by having a combination of an elongate dorsal-fin spine (36.0% SL, based on the holotype vs. 16–29%, usually less than 26% SL) that is supported throughout most of its length by the first branched ray, and an inconspicuous (vs. prominent) post-orbital notch with minimum orbital diameter 95.4–97.2% (vs. 71.8–91.5%) of maximum orbital diameter. It is further distinguished from similar and geographically proximate species, L. lata and L. simillima, by having a more slender body, particularly head width (13.9–14.9% SL vs. 15.2–19.4% SL in L. simillima and 16.4–20.1% SL in L. lata). The larger specimen of L. birindellii exhibits male breeding characteristics known in other species of Loricaria, including expanded membranous portions of the lower lip, an increase in development of ...

Acestridium gymnogaster and A. scutatum are described as new from small tributaries to the middle Rio Madeira, Amazonas, Brazil. Acestridium gymnogaster is most similar to A. discus from which it differs in the number of medial unpaired predorsal plates, the arrangement of chromatophores in predorsal area, and the absence of contact midventrally between the lateral abdominal plates. Acestridium scutatum is most similar to A. triplax from which it differs in having a longer snout and by the shape of the preanal plate. A key to the species of Acestridium is provided. Acestridium gymnogaster e Acestridium scutatum, especies novas, sao descritas de pequenos rios tributarios do medio Rio Madeira, Estado do Amazonas, Brasil. Acestridium gymnogaster e mais semelhante a A. discus, de quem difere pelo numero de placas impares medias pre-dorsais, arranjo dos cromatoforos na area pre-dorsal, e a ausencia de contato entre as placas laterais abdominais na linha media. Acestridium scutatum e mais semelhante a ...

Baryancistrus beggini, new species, is described from the upper Rio Orinoco and lower portions of its tributaries, the Rio Guaviare in Colombia and Rio Ventuari in Venezuela. Baryancistrus beggini is unique within Hypostominae in having a uniformly dark black to brown base color with a blue sheen in life, and the first three to five plates of the midventral series strongly bent, forming a distinctive keel above the pectoral fins along each side of the body. It is further distinguished by having a naked abdomen, two to three symmetrical and ordered predorsal plate rows including the nuchal plate, and the last dorsal-fin ray adnate with adipose fin via a posterior membrane that extends beyond the preadipose plate up to half the length of the adipose-fin spine. Se describe una nueva especie, Baryancistrus beggini, del alto Rio Orinoco y las partes bajas de sus afluentes: el rio Guaviare en Colombia, y el rio Ventuari en Venezuela. Baryancistrus beggini es la unica especie entre los Hypostominae que ...

Hisonotus armatus, a new hypoptopomatine species, is described from the Laguna dos Patos basin, Rio Grande do Sul State, southern Brazil. The new species is distinguished from other Hisonotus species by aspects of the morphology of the rostral plate, the arrangement of abdominal plates, and the caudal-fin color pattern. Hisonotus armatus, nova especie de hipoptopomatineo, e descrita do sistema da laguna dos Patos, Rio Grande do Sul, sul do Brasil. A nova especie se diferencia das demais do genero Hisonotus pela morfologia da placa rostral, pelo arranjo das placas abdominais, e pelo padrao de colorido da nadadeira caudal.

Corumbataia veadeiros, new species, is described from the upper Rio Tocantins basin at the Chapada dos Veadeiros formation, Goias State, central Brazil. The new species is distinguished from all other species of Corumbataia by its lack of a raised tuft of enlarged odontodes on the supraoccipital, an infraorbital canal entering the infraorbital series via the sphenotic, and by the color pattern of the caudal fin, which is composed of vertical dark bars.

The species of Rineloricaria from the Laguna dos Patos drainage are reviewed. Four species are rediagnosed: R. strigilata, R. cadeae, R. microlepidogaster, and R. longicauda, and two new species are described: R. malabarbai and R. baliola. Rineloricaria malabarbai is distinguished from all other Rineloricaria species except R. maquinensis by its unique abdominal pattern, composed of a large naked area with a single preanal complex of plates and one or two small squarish platelets at the base of pelvic-fin spine and connecting the preanal complex to the lateral abdominal plates, and from R. maquinensis it is distinguished by a longer predorsal length, shorter postanal length, longer abdominal length, broader cleithral width, broader body width at anal-fin origin, deeper head, and shorter maxillary barbel. Rineloricaria baliola is distinguished by its unique color pattern composed of dark, wide bands covering most of the distal one-half of all fins, and by its snout with a roundish naked area, generally reaching to anteriormost pore of infraorbital ramus of sensory canal. The species in Rineloricaria are divided in two phenetic groups, based on general background color pattern, distribution of plates on abdomen, head and snout shape, shape of the naked area at tip of snout, number of lateral body series of plates, and presence of the dorsal-fin spinelet. Species illustrations and a taxonomic key for the Laguna dos Patos drainage are provided. Son revisadas las especies de Rineloricaria del sistema de la Laguna dos Patos. Cuatro especies son rediagnosticadas: R. strigilata, R. cadeae, R. microlepidogaster, y R. longicauda; y dos nuevas especies se describen para el sistema: R. malabarbai y R. baliola. Rineloricaria malabarbai se distingue de las otras especies de = = = =

Hypancistrus contradens, H. debilittera, H. furunculus, and H. lunaorum are described based on specimens from the upper Rio Orinoco of southern Venezuela. Hypancistrus furunculus differs from other Hypancistrus based on color pattern: distinct dark oblique stripes ending at posterior insertion of dorsal fin and vertical bands in caudal fin (vs. oblique stripes ending at end of caudal fin in H. zebra and thin, indistinct, light-colored bands and vermiculations on a dark background in H. debilittera) and color pattern dark with white spots in H. contradens, H. inspector, and H. lunaorum. Hypancistrus contradens and H. lunaorum differ from H. inspector by having the dorsal fin reaching the adipose fin when adpressed (vs. not reaching), having spots on the head the same size as the body or spots absent (vs. spots smaller on head) and by usually having 22-23 mid- ventral plates (vs. 24); and from H. debilittera, H. furunculus, and H. zebra by lacking bars, saddles, or stripes on the body and bands in the fins. Hypancistrus lunaorum differs from H. contradens by having white spots on the body smaller than nasal aperture diameter (vs. white spots larger than the nasal aperture diameter).

A new species of rubbernose armored catfish, collected by the Catherwood Foundation Peruvian Amazon Expedition from the upper Huallaga River (650 m elevation) in central Peru, is described herein. This new species differs from all other described Chaetostoma species in having a conspicuously banded dorsal fin and by the combination of the following characters: presence of fleshy excrescence on posterior tip of supraoccipital, typically nine branched dorsal-fin rays, and evertible cheek plates with two to four hypertrophied odontodes. Una nueva especie de carachama nariz de goma colectada por la Catherwood Foundation Peruvian Amazon Expedition, en el alto Rio Huallaga (650 m elevacion) en Peru central es descrita. Esta nueva especie difiere de todas las otras especies descritas de Chaetostoma por tener una aleta dorsal conspicuamente bandeada, y por la combinacion de los siguientes caracteres: presencia de una excresencia carnosa en el extremo posterior del supraoccipital; generalmente nueve radio...

Sturisoma kneri is a mailed catfish, endemic to the Lago Maracaibo drainage of northern South America. It was originally listed as Loricaria kneri and briefly diagnosed, cited as an unnamed species of Sturisoma in a type catalog of the Museo di Torino, Italy. In this work, the validity and authorship of the name Loricaria kneri are discussed, and S. kneri is made available. Sturisoma kneri is described as a new taxon and diagnosed based on interorbital width, osteological features of the roof of the skull, and number of plates in the midventral plate series.

A new species of Pareiorhina is described from the Ribeirao Grande and adjacent drainages, in the left bank of the Rio Paraiba do Sul basin, in Sao Paulo State, southeastern Brazil. Pareiorhina brachyrhyncha is uniquely diagnosed among its congeners by the reduction or absence of azygous plates in front of the nuchal plate. It also differs from its congeners by the presence of a minute lateral cusp in the teeth, wider body, anterior and lateral profile of head rounded, broad distal profile of the paired fins, and lower number of vertebrae. The species is considered to be closely related to the sympatric P. rudolphi, based on the lack of azygous dorsal plates above the caudal peduncle.

In Neotropical streams, benthic sediment affects community structure and may impose energetic costs for some species yet to be a resource for others. This study tested the hypothesis that removal of benthic sediment through ingestion by Rana palmipes (Ranidae), a detritivorous tadpole, facilitated the growth of Ancistrus triradiatus (Loricariidae), an algivorous armored catfish. We hypothesized that sediment removal by Rana would reduce energetic costs to respiration or digestion encountered by Ancistrus when grazing on periphyton and increase available periphyton biomass. Growth of Ancistrus was measured in a Venezuelan piedmont stream in enclosure cages in which the presence of Rana and ambient sediment levels were manipulated. Benthic sediment accumulation differed significantly between treatments. Growth of Rana was greater when sediments were present than when sediments were removed. However, there was no effect of sediment removal on Ancistrus growth. Total biomass of periphyton did not dif...

Hisonotus insperatus, new species, is distinguished from all the other species of the genus Hisonotus Eigenmann and Eigenmann by the combination of a pair of rostral plates at the tip of the snout, the complete median plate series to base of the caudal fin, a lateral line that is continuous along the middle of the body, a pectoral spine smooth and lacking odontodes along its posterior dorsal margin for a distance more than one-half of its width, and a scapular bridge that is completely exposed, sometimes with a very reduced median pair of arrector fossae.

A new species of the previously monotypic loricariid subfamily Lithogeninae is described from northern Venezuela. Lithogenes valencia is the first representative of the subfamily to be discovered subsequent to the discovery and description of Lithogenes villosus Eigenmann, 1909, from Guyana and extends the geographic distribution of the subfamily beyond the Guyana Shield region of northeastern South America. The new species shares several derived features with L. villosus that are not observed among other Loricariidae. It is diagnosed from L. villosus by the broader head, 27–29% SL (vs 22% SL), 25–29 premaxillary teeth (vs 9–10), the presence of nine (vs 8) branched pectoral-fin rays, anal fin rays ii,5 (vs ii,7), straight (vs sickle-shaped) lateropterygium, and by the presence of small plates in the dorsal and ventral series of the lateral trunk irregularly arranged and not contacting the plates of the median series (vs plates larger, regularly arranged in series, in contact with the median seri...