Halichoeres sanchezi n. sp., a new wrasse from the Revillagigedo Archipelago of Mexico, tropical eastern Pacific Ocean (Teleostei: Labridae).

A new labrid fish species, Halichoeres sanchezi n. sp., is described from eight specimens collected in the Revillagigedo Archipelago in the tropical eastern Pacific Ocean, off the coast of Mexico. The new species belongs to the Halichoeres melanotis species complex that is found throughout the region, differing by 2.4% in the mtDNA cytochrome c oxidase I sequence from its nearest relative, H. melanotis from Panama, and 2.9% from Halichoeres salmofasciatus from Cocos Island, off Costa Rica. The complex is distinguished from others in the region by having a black spot on the opercular flap and a prominent black area on the caudal fin of males. The juveniles and initial phase of the new species closely resemble those of H. salmofasciatus and Halichoeres malpelo from Malpelo Island of Colombia, differing in having an oblong black spot with a yellow dorsal margin on the mid-dorsal fin of initial-phase adults as well as on juveniles. In contrast, the terminal-phase male color pattern is distinct from other relatives, being vermilion to orangish brown with dark scale outlines, a white patch on the upper abdomen, and a prominent black band covering the posterior caudal peduncle and base of the caudal fin. The new species adds to the list of endemic fish species for the isolated archipelago and is an interesting case of island endemism in the region. The discovery was made during the joint 2022 collecting expedition to the archipelago, which featured a pioneering collaborative approach to an inventory of an island ichthyofauna, specifically including expert underwater photographers systematically documenting specimens in situ, before hand-collection, and then photographed fresh, tissue-sampled, and subsequently vouchered in museum collections.

Environmental filters explain the ecomorphological patterns of stream fish in the southern Amazon

ABSTRACT The ecomorphology reflects morphological variations that may indicate significant ecological processes. In this study, the influence of environmental variables on the ecomorphological composition of stream fish was tested. The study was developed in ten streams within a conservation area in the Juruena River sub-basin, in Mato Grosso state, Brazil. The sampling occurred during the drought period in July 2012. The fish were sampled with simple sieves and trawl nets. We analyzed 17 variables of the physical habitat and 14 morphological indices based on morphometric measurements of the fish. In total, 753 specimens were collected, comprising four orders, 14 families, and 27 species. Only fine sediments influenced the ecomorphological composition of the fish assemblages. This substrate variable acted as a filter for the ecomorphology of fish that usually inhabit slow waters, have a morphology adapted towards a good stabilization capacity and maneuverability, fins capable of large and rapid impulses, and that feed close to the surface. Our results can contribute to the understanding of the ecological processes that drive the composition of fish assemblages in conserved Amazonian streams.

RESUMO A ecomorfologia reflete variações morfológicas que podem indicar processos ecológicos significativos. Neste estudo, testamos a influência de variáveis ambientais na composição ecomorfológica de peixes de riachos. O estudo foi desenvolvido em dez riachos em uma área de conservação na sub-bacia do Rio Juruena, estado de Mato Grosso, Brasil. A amostragem ocorreu durante o período de estiagem em julho de 2012. Os peixes foram amostrados com redes de peneira e redes de arrasto. Foram analisadas 17 variáveis do habitat físico e 14 índices morfológicos baseados em medidas morfométricas dos peixes. No total, foram coletados 753 exemplares de quatro ordens, 14 famílias e 27 espécies. Apenas sedimentos finos influenciaram a composição ecomorfológica das assembleias de peixes. Esta variável de substrato funcionou como um filtro para a ecomorfologia de peixes que normalmente habitam águas lentas, têm uma morfologia adaptada a uma boa capacidade de estabilização e manobrabilidade, nadadeiras capazes de impulsos grandes e rápidos, e que se alimentam junto à superfície. Nossos resultados podem contribuir para a compreensão dos processos ecológicos que estruturam as assembléias de peixes em riachos amazônicos conservados.

NEOTROPICAL FRESHWATER FISHES: A dataset of occurrence and abundance of freshwater fishes in the Neotropics.

The Neotropical region hosts 4225 freshwater fish species, ranking first among the world's most diverse regions for freshwater fishes. Our NEOTROPICAL FRESHWATER FISHES data set is the first to produce a large-scale Neotropical freshwater fish inventory, covering the entire Neotropical region from Mexico and the Caribbean in the north to the southern limits in Argentina, Paraguay, Chile, and Uruguay. We compiled 185,787 distribution records, with unique georeferenced coordinates, for the 4225 species, represented by occurrence and abundance data. The number of species for the most numerous orders are as follows: Characiformes (1289), Siluriformes (1384), Cichliformes (354), Cyprinodontiformes (245), and Gymnotiformes (135). The most recorded species was the characid Astyanax fasciatus (4696 records). We registered 116,802 distribution records for native species, compared to 1802 distribution records for nonnative species. The main aim of the NEOTROPICAL FRESHWATER FISHES data set was to make these occurrence and abundance data accessible for international researchers to develop ecological and macroecological studies, from local to regional scales, with focal fish species, families, or orders. We anticipate that the NEOTROPICAL FRESHWATER FISHES data set will be valuable for studies on a wide range of ecological processes, such as trophic cascades, fishery pressure, the effects of habitat loss and fragmentation, and the impacts of species invasion and climate change. There are no copyright restrictions on the data, and please cite this data paper when using the data in publications.

A new species of deep-sea grunt, Rhonciscus pauco (Lutjaniformes: Haemulidae), from Puerto Rico.

A fourth species of the genus Rhonciscus (Lutjaniformes: Haemulidae) is described from various specimens collected by small-scale fishers from the insular upper slope of western Puerto Rico. The new species was molecularly recovered as sister to the Eastern Pacific R. branickii, to which it bears many morphological similarities. It is distinguished from other Rhonciscus species by the number of scale rows between the dorsal fin and the lateral line (7), larger and thus fewer scales along the lateral line (48-50), large eyes (9.4-10.4 times in SL), longer caudal peduncle (15.2-20% of SL), larger sized penultimate (14.7-19.1% in SL) and last (7.4-9.5% in SL) dorsal fin spines which translates to a less deeply notched dorsal fin, and its opalescent silver with golden specks live coloration. This grunt, only now recognized by ichthyologists, but well known by local fishers that target snappers and groupers between 200 and 500 m in depth, occurs in far deeper waters than any western Atlantic grunt.

Contribution to a reference library of DNA barcodes of Colombian freshwater fishes.

BACKGROUND: The Barcode of Life initiative was originally motivated by the large number of species, taxonomic difficulties and the limited number of expert taxonomists. Colombia has 1,610 freshwater fish species and comprises the second largest diversity of this group in the world. As genetic information continues to be limited, we constructed a reference collection of DNA sequences of Colombian freshwater fishes deposited in the Ichthyology Collection of the University of Antioquia (CIUA), thus joining the multiple efforts that have been made in the country to contribute to the knowledge of genetic diversity in order to strengthen the inventories of biological collections and facilitate the solution of taxonomic issues in the future. NEW INFORMATION: This study contributes to the knowledge on the DNA barcodes and occurrence records of 96 species of Colombian freshwater fishes. Fifty-seven of the species represented in this dataset were already available in the Barcode Of Life Data System (BOLD System), while 39 correspond to new species to the BOLD System. Forty-nine specimens were collected in the Atrato River Basin and 708 in the Magdalena-Cauca asin during the period 2010-2020. Two species (Loricariichthysbrunneus (Hancock, 1828) and Poeciliasphenops Valenciennes, 1846) are considered exotic to the Atrato, Cauca and Magdalena Basins and four species (Oncorhynchusmykiss (Walbaum, 1792), Oreochromisniloticus (Linnaeus, 1758), Parachromisfriedrichsthalii (Heckel, 1840) and Xiphophorushelleri Heckel, 1848) are exotic to the Colombian hydrogeographic regions. All specimens are deposited in CIUA and have their DNA barcodes made publicly available in the BOLD online database. The geographical distribution dataset can be freely accessed through the Global Biodiversity Information Facility (GBIF).

Fishes of the Mitú Region: middle basin of the río Vaupés, Colombian Amazon / Peces de la región de Mitú: cuenca media del río Vaupés, Amazonia colombiana

Abstract: The Amazon River basin hosts the most diverse freshwater ichthyofauna in the world, and yet huge areas of the basin remain unexplored. This is the case for the upper tributaries of the rio Negro, especially those draining the Colombian territory. Here we present a list of 224 species derived from the examination of specimens collected in the Mitú region (Vaupés Department, Colombia), the middle basin of the río Vaupés. Of the species identified in our study, 10 species are recorded from Colombia for the first time, and 26 species are newly recorded from the Colombian Amazon. The number of species we present here comprise almost one-third of the known species diversity of the Colombian Amazon and nearly a tenth of the total number of those known across the entirety of the Amazon basin. The most diverse orders were Characiformes (120 species) and Siluriformes (65 species), and the remaining six orders comprised less than 20% of total species. The study area comprised blackwater systems, which are considered to be nutrient-poor environments. We discuss some ecological aspects that might explain how this highly diverse ichthyofauna originates and is maintain in less productive systems. The list presented here adds an important number of new records and complements the information derived from previous studies, carried out thus far with regards to the fish fauna of the Colombian Amazon.

Resumo: La cuenca del río Amazonas alberga la ictiofauna dulceacuícola más diversa del mundo, sin embargo, grandes áreas de la cuenca permanecen inexploradas. Este es el caso de los afluentes de la parte alta del río Negro, especialmente los sistemas que drenan el territorio colombiano. A continuación, presentamos un listado de 224 especies derivadas del análisis de especímenes recolectados en la región de Mitú, cuenca media del río Vaupés (Departamento de Vaupés, Colombia). De las especies identificadas, 10 especies se registran en Colombia por primera vez y 26 especies para la Amazonía colombiana. El número de especies que presentamos aquí comprende casi un tercio de las especies conocidas para la Amazonía colombiana y casi una décima parte del total de las conocidas para la gran cuenca del Amazonas. Los órdenes más diversos fueron Characiformes (120 especies) y Siluriformes (65 especies), y los seis órdenes restantes comprendieron menos del 20% del total de especies. El área de estudio comprende sistemas de aguas negras que se consideran ambientes poco productivos por sus bajos contenidos de nutrientes. Discutimos aquí algunos aspectos ecológicos que podrían explicar cómo esta ictiofauna tan diversa tiene su origen y es mantenida en estos sistemas poco productivos. La información derivada del presente estudio adiciona nuevos registros de especies de peces para Colombia, y complementa la información derivada de los estudios realizados a la fecha en la Amazonía colombiana.

Anatomia do tubo digestório da espécie Acestrorhynchus lacustres (Ostaryohisi, Characiformes) Lütken, 1875 do Rio de Ondas, Oeste da Bahia, Brasil} / Digestive tract anatomy of the species Acestrorhynchus lacustris (Ostaryohisi, Characiformes) Lütken, 1875 from Ondas River, Western Bahia, Brazil / Anatomía del tubo digestorial de la especie Acestrorhynchus lacustris (Ostaryohisi, Characiformes) Lütken, 1875 de Rio de Ondas, Oeste de Bahia, Brasil

O presente estudo visa descrever e mensurar o tubo digestório da espécie Acestrorhynchus lacustris. Foram utilizados 10 exemplares da espécie, coletados em diferentes trechos da bacia hidrográfica do rio de Ondas, localizada no Oeste do Estado da Bahia, na ecorregião aquática do rio São Francisco. Foram realizadas mensuração e pesagem dos peixes. A cavidade bucofaríngea e os órgãos digestórios pós-faríngeos: esôfago, estômago, cecos pilóricos e intestino foram analisados, descritos e mensurados. Para definição do tamanho dos órgãos da espécie, independente do tamanho do exemplar, foi calculado o comprimento relativo dos órgãos, exceto dos cecos pilóricos. A espécie A. lacustris apresenta boca terminal, fenda bucal e cavidade bucofaringea amplas, dentes cônicos e caninos; esôfago curto, musculoso e distensível; estômago alongado, musculoso, do tipo cecal, com formato de “Y”; sete a 15 cecos pilóricos que aparecem como evaginações no intestino; e intestino curto, musculoso e bastante espesso. Os dados obtidos demonstram que o tamanho dos órgãos que compõe o tubo digestório da espécie não está relacionado ao tamanho do exemplar. O estudo das características anatômicas do tubo digestório ampliou o conhecimento biológico e ecológico da espécie estudada, auxiliando na compreensão do desempenho desta espécie em ecossistemas naturais e na elaboração de propostas para a preservação ou manejo da espécie.(AU)

This study aims to describe and measure the digestive tract of the species Acestrorhynchus lacustris. Ten specimens of the species were used, captured in different parts of the river basin of the Ondas river, located west of the State of Bahia, in the aquatic ecoregion of the São Francisco river. Fish measurements and weighing were carried out. The oropharyngeal cavity and postpharyngeal digestive organs were analyzed, described and measured: esophagus, stomach, pyloric cecum and intestine. To define the size of the organs of the species, regardless of the size of the sample, the relative length of the organs, except the pyloric cecum, was calculated. The species A. lacustris has a terminal mouth, a wide oral cleft and oropharyngeal cavity, conical and canine teeth; short, muscular, and compliant esophagus; elongated, muscular stomach, cecal type, shaped like a "Y"; seven to fifteen pyloric cecum that appear as bowel movements; and intestine short, muscular and quite thick. The data obtained show that the size of the organs that make up the digestive tract of the species is not related to the size of the specimen. The study of the anatomical characteristics of the digestive tract expanded the biological and ecological knowledge of the studied species, helping to understand the performance of this species in natural ecosystems and in the elaboration of proposals for the preservation or management of the species.(AU)

Este estudio tiene como objetivo describir y medir el tubo digestivo de la especie Acestrorhynchus lacustris. Se utilizaron diez ejemplares de la especie, capturado en diferentes partes de la cuenca hidrográfica del río del Ondas, situado al oeste del Estado de Bahía, en la ecorregión acuática del río São Francisco. Se realizaron mediciones y pesaje de peces. Se analizaron, describieron y midieron la cavidad bucofaríngea y los órganos digestivos posfaríngeos: esófago, estómago, ciego pilórico e intestino. Para definir el tamaño de los órganos de la especie, independientemente del tamaño de la muestra, se calculó la longitud relativa de los órganos, excepto el ciego pilórico. La especie A. lacustris tiene boca terminal, hendidura bucal amplia y cavidad bucofaríngea, dientes cónicos y caninos; esófago corto, musculoso y distensible; estómago alargado, musculoso, tipo cecal, en forma de “Y”; de siete a quince ciegos pilóricos que aparecen como evacuaciones intestinales; e intestino corto, musculoso y bastante grueso. Los datos obtenidos demuestran que el tamaño de los órganos que componen el tubo digestivo de la especie no está relacionado con el tamaño del espécimen. El estudio de las características anatómicas del tubo digestivo amplió el conocimiento biológico y ecológico de las especies estudiadas, ayudando a comprender el desempeño de esta especie en ecosistemas naturales y en la elaboración de propuestas para la preservación o manejo de la especie.(AU)

A new species of pikeblenny (Blenniiformes: Chaenopsidae: Chaenopsis) from the tropical eastern Pacific and a key to all species.

The genus Chaenopsis presently includes 10 species, four in the eastern Pacific and six in the western Atlantic. Five individuals of an undescribed species of this genus were obtained at Gorgona Island in the eastern Pacific of Colombia, in depths between 3 and 5 m. This new species differs from all the Eastern Pacific species in an array of traits including meristic, coloration and morphometric characters. Chaenopsis celeste new species differs from its only sympatric species, C. deltarrhis, in having fewer pectoral rays, fewer dorsal spines and more dorsal-fin soft rays and anal-fin elements. This new species is found over shallow sandy, rubble and small rocks bottoms from Costa Rica to Colombia.

Anatomia do tubo digestório da espécie Acestrorhynchus lacustres (Ostaryohisi, Characiformes) Lütken, 1875 do Rio de Ondas, Oeste da Bahia, Brasil} / Digestive tract anatomy of the species Acestrorhynchus lacustris (Ostaryohisi, Characiformes) Lütken, 1875 from Ondas River, Western Bahia, Brazil / Anatomía del tubo digestorial de la especie Acestrorhynchus lacustris (Ostaryohisi, Characiformes) Lütken, 1875 de Rio de Ondas, Oeste de Bahia, Brasil

O presente estudo visa descrever e mensurar o tubo digestório da espécie Acestrorhynchus lacustris. Foram utilizados 10 exemplares da espécie, coletados em diferentes trechos da bacia hidrográfica do rio de Ondas, localizada no Oeste do Estado da Bahia, na ecorregião aquática do rio São Francisco. Foram realizadas mensuração e pesagem dos peixes. A cavidade bucofaríngea e os órgãos digestórios pós-faríngeos: esôfago, estômago, cecos pilóricos e intestino foram analisados, descritos e mensurados. Para definição do tamanho dos órgãos da espécie, independente do tamanho do exemplar, foi calculado o comprimento relativo dos órgãos, exceto dos cecos pilóricos. A espécie A. lacustris apresenta boca terminal, fenda bucal e cavidade bucofaringea amplas, dentes cônicos e caninos; esôfago curto, musculoso e distensível; estômago alongado, musculoso, do tipo cecal, com formato de “Y”; sete a 15 cecos pilóricos que aparecem como evaginações no intestino; e intestino curto, musculoso e bastante espesso. Os dados obtidos demonstram que o tamanho dos órgãos que compõe o tubo digestório da espécie não está relacionado ao tamanho do exemplar. O estudo das características anatômicas do tubo digestório ampliou o conhecimento biológico e ecológico da espécie estudada, auxiliando na compreensão do desempenho desta espécie em ecossistemas naturais e na elaboração de propostas para a preservação ou manejo da espécie.

This study aims to describe and measure the digestive tract of the species Acestrorhynchus lacustris. Ten specimens of the species were used, captured in different parts of the river basin of the Ondas river, located west of the State of Bahia, in the aquatic ecoregion of the São Francisco river. Fish measurements and weighing were carried out. The oropharyngeal cavity and postpharyngeal digestive organs were analyzed, described and measured: esophagus, stomach, pyloric cecum and intestine. To define the size of the organs of the species, regardless of the size of the sample, the relative length of the organs, except the pyloric cecum, was calculated. The species A. lacustris has a terminal mouth, a wide oral cleft and oropharyngeal cavity, conical and canine teeth; short, muscular, and compliant esophagus; elongated, muscular stomach, cecal type, shaped like a "Y"; seven to fifteen pyloric cecum that appear as bowel movements; and intestine short, muscular and quite thick. The data obtained show that the size of the organs that make up the digestive tract of the species is not related to the size of the specimen. The study of the anatomical characteristics of the digestive tract expanded the biological and ecological knowledge of the studied species, helping to understand the performance of this species in natural ecosystems and in the elaboration of proposals for the preservation or management of the species.

Este estudio tiene como objetivo describir y medir el tubo digestivo de la especie Acestrorhynchus lacustris. Se utilizaron diez ejemplares de la especie, capturado en diferentes partes de la cuenca hidrográfica del río del Ondas, situado al oeste del Estado de Bahía, en la ecorregión acuática del río São Francisco. Se realizaron mediciones y pesaje de peces. Se analizaron, describieron y midieron la cavidad bucofaríngea y los órganos digestivos posfaríngeos: esófago, estómago, ciego pilórico e intestino. Para definir el tamaño de los órganos de la especie, independientemente del tamaño de la muestra, se calculó la longitud relativa de los órganos, excepto el ciego pilórico. La especie A. lacustris tiene boca terminal, hendidura bucal amplia y cavidad bucofaríngea, dientes cónicos y caninos; esófago corto, musculoso y distensible; estómago alargado, musculoso, tipo cecal, en forma de “Y”; de siete a quince ciegos pilóricos que aparecen como evacuaciones intestinales; e intestino corto, musculoso y bastante grueso. Los datos obtenidos demuestran que el tamaño de los órganos que componen el tubo digestivo de la especie no está relacionado con el tamaño del espécimen. El estudio de las características anatómicas del tubo digestivo amplió el conocimiento biológico y ecológico de las especies estudiadas, ayudando a comprender el desempeño de esta especie en ecosistemas naturales y en la elaboración de propuestas para la preservación o manejo de la especie.

Two new catfish species of typically Amazonian lineages in the Upper Rio Paraguay (Aspredinidae: Hoplomyzontinae and Trichomycteridae: Vandelliinae), with a biogeographic discussion

Two new species of particular biogeographic significance are described from the upper rio Paraguay basin, one of the genus Paracanthopoma (Trichomycteridae, Vandelliinae) and the other of the genus Ernstichthys (Aspredinidae, Hoplomyzontinae). The two species occur sympatrically in the Rio Taquarizinho, tributary of the Rio Taquari, in the upper Paraguay system. Paracanthopoma saci is distinguished from its only congener, P. parva, by a spatulate caudal peduncle; a minuscule premaxillary dentition (reduced to three delicate teeth); the supraorbital latero-sensory canals opening as two separate s6 pores; the caudal fin slightly convex or truncate with round edges; the skull roof entirely open, unossified; the origins of dorsal and anal fins approximately at same vertical; and the pelvic fin with three rays. Ernstichthys taquari is diagnosed among congeners by the narrow bony shields on dorsal and ventral series, not overlapping or contacting each other; by the presence of seven or eight serrations on the posterior margin of the pectoral spine; and by the pectoral-fin spine only slightly larger than subsequent soft rays. Both Paracanthopoma and Ernstichthys were previously unknown outside of the Greater Amazonian river systems (Amazon, Orinoco, Essequibo and smaller surrounding drainages). Their presence restricted to the Rio Taquari is unexpected and suggests a peculiar biogeographical history. Ancestral geographic distributions were reconstructed using S-DIVA and BBM methods in RASP. A majority of resulting hypotheses support that the two species reached the Paraguay from the Amazon. The alternative explanation accounts for their presence in the Paraguay by vicariant events. In no case, their presence in the Paraguay is an ancestral distribution with subsequent Amazonian dispersal. Though unusual, this pattern is also seen in a few other fish taxa, showing that the Rio Taquari is biogeographically hybrid, combining elements from both the Paraguay and Amazon drainages.(AU)

Two new, remarkably colored species of the Neotropical catfish genus Cetopsorhamdia Eigenmann & Fisher, 1916 (Siluriformes, Heptapteridae) from Chapada dos Parecis, western Brazil, with an assessment of the morphological characters bearing on their phylogenetic relationships

Two new species of heptapterid catfish genus Cetopsorhamdia are described from close localities in western Brazil, at Chapada dos Parecis, an area with extremely high level of endemism. One species is from the upper Rio Madeira system, Rondônia State, and the other from the upper Rio Tapajós system, Mato Grosso State. The two species are diagnosed, among several other features, by their markedly distinctive color patterns, with the former having well-defined quadrangular marks in trunk flanks while the latter bearing irregular, vertical bars along the trunk. The monophyly of Cetopsorhamdia is discussed, with two putative synapomorphies being proposed to support the genus. Potentially informative morphological characters to resolve the internal relationships of the genus are presented and discussed. Despite the striking external differences between the two species herein described, they are found to likely form a clade.(AU)

Pectoral-fin glands and delivery apparatus in the catfish genus Brachyrhamdia Myers, 1927 (Siluriformes: Heptapteridae)

The Siluriformes, popularly known as catfishes, are probably the vertebrate group with the highest diversity of venomous animals, even though only approximately a hundred venomous catfishes are reported to date. Venomous catfishes might present a delivery system apparatus, formed by an unbranched ray at the leading edge of pectoral and dorsal fins (spine), which can be stiffened and pungent, while venom glands can be present at the surface of such spines and/or the axillary region. This work investigated the presence, morphology and distribution of glands and pectoral-fin delivery apparatus in the heptapterid Brachyrhamdia genus. Pectoral-fin spine external morphology was compared across all valid species in the genus, histological sections of the pectoral-fin spine and axillary regions of B. heteropleura and B. marthae were produced, and dissections of the pectoral girdle region of the mentioned species were analyzed. The histological sections confirmed the presence of pectoral-fin glands at the surface of the pectoral-fin spine of Brachyrhamdia species, and cellular morphology indicates these glands are probably venomous. Also, we found a piriform gland at the axillary region, whose cell morphology is like the reported for other catfishes. However, we cannot currently confirm or deny axillary gland participation in the venom delivery apparatus. This work constitutes the first report of venom glands in Brachyrhamdia, and the first description of Heptapteridae axillary glands.(AU)

The rediscovery of Pimelodella longipinnis (Borodin, 1927), an enigmatic Atlantic Rainforest catfish species from Southeastern Brazil (Siluriformes: Heptapteridae)

This article is a redescription of Pimelodella longipinnis, an enigmatic catfish previously known only from its holotype and with uncertain type locality. The species is redescribed based on recently collected materials from streams of the Mata Atlântica bioregion, in Santos municipality, São Paulo State, Brazil. Pimelodella longipinnis is assigned to a putatively monophyletic group, the Pimelodella leptosoma-group, diagnosed by the presence of a supraoccipital process not reaching the anterior nuchal plate, with a gap of ca. 20-25% of the supraoccipital process total length, and whose tip notably surpasses the midpoint of the complex vertebra in dorsal view. We also present a list of fish species described from a shipping sent to the American Museum of Natural History from the former Museu Paulista (now Museu de Zoologia da Universidade de São Paulo), of which P. longipinnis was part.(AU)

Two new, remarkably colored species of the Neotropical catfish genus Cetopsorhamdia Eigenmann & Fisher, 1916 (Siluriformes, Heptapteridae) from Chapada dos Parecis, western Brazil, with an assessment of the morphological characters bearing on their phylogenetic relationships

Abstract Two new species of heptapterid catfish genus Cetopsorhamdia are described from close localities in western Brazil, at Chapada dos Parecis, an area with extremely high level of endemism. One species is from the upper Rio Madeira system, Rondônia State, and the other from the upper Rio Tapajós system, Mato Grosso State. The two species are diagnosed, among several other features, by their markedly distinctive color patterns, with the former having well-defined quadrangular marks in trunk flanks while the latter bearing irregular, vertical bars along the trunk. The monophyly of Cetopsorhamdia is discussed, with two putative synapomorphies being proposed to support the genus. Potentially informative morphological characters to resolve the internal relationships of the genus are presented and discussed. Despite the striking external differences between the two species herein described, they are found to likely form a clade.

Two new catfish species of typically Amazonian lineages in the Upper Rio Paraguay (Aspredinidae: Hoplomyzontinae and Trichomycteridae: Vandelliinae), with a biogeographic discussion

Abstract Two new species of particular biogeographic significance are described from the upper rio Paraguay basin, one of the genus Paracanthopoma (Trichomycteridae, Vandelliinae) and the other of the genus Ernstichthys (Aspredinidae, Hoplomyzontinae). The two species occur sympatrically in the Rio Taquarizinho, tributary of the Rio Taquari, in the upper Paraguay system. Paracanthopoma saci is distinguished from its only congener, P. parva, by a spatulate caudal peduncle; a minuscule premaxillary dentition (reduced to three delicate teeth); the supraorbital latero-sensory canals opening as two separate s6 pores; the caudal fin slightly convex or truncate with round edges; the skull roof entirely open, unossified; the origins of dorsal and anal fins approximately at same vertical; and the pelvic fin with three rays. Ernstichthys taquari is diagnosed among congeners by the narrow bony shields on dorsal and ventral series, not overlapping or contacting each other; by the presence of seven or eight serrations on the posterior margin of the pectoral spine; and by the pectoral-fin spine only slightly larger than subsequent soft rays. Both Paracanthopoma and Ernstichthys were previously unknown outside of the Greater Amazonian river systems (Amazon, Orinoco, Essequibo and smaller surrounding drainages). Their presence restricted to the Rio Taquari is unexpected and suggests a peculiar biogeographical history. Ancestral geographic distributions were reconstructed using S-DIVA and BBM methods in RASP. A majority of resulting hypotheses support that the two species reached the Paraguay from the Amazon. The alternative explanation accounts for their presence in the Paraguay by vicariant events. In no case, their presence in the Paraguay is an ancestral distribution with subsequent Amazonian dispersal. Though unusual, this pattern is also seen in a few other fish taxa, showing that the Rio Taquari is biogeographically hybrid, combining elements from both the Paraguay and Amazon drainages.

Two new catfish species of typically Amazonian lineages in the Upper Rio Paraguay (Aspredinidae: Hoplomyzontinae and Trichomycteridae: Vandelliinae), with a biogeographic discussion

Abstract Two new species of particular biogeographic significance are described from the upper rio Paraguay basin, one of the genus Paracanthopoma (Trichomycteridae, Vandelliinae) and the other of the genus Ernstichthys (Aspredinidae, Hoplomyzontinae). The two species occur sympatrically in the Rio Taquarizinho, tributary of the Rio Taquari, in the upper Paraguay system. Paracanthopoma saci is distinguished from its only congener, P. parva, by a spatulate caudal peduncle; a minuscule premaxillary dentition (reduced to three delicate teeth); the supraorbital latero-sensory canals opening as two separate s6 pores; the caudal fin slightly convex or truncate with round edges; the skull roof entirely open, unossified; the origins of dorsal and anal fins approximately at same vertical; and the pelvic fin with three rays. Ernstichthys taquari is diagnosed among congeners by the narrow bony shields on dorsal and ventral series, not overlapping or contacting each other; by the presence of seven or eight serrations on the posterior margin of the pectoral spine; and by the pectoral-fin spine only slightly larger than subsequent soft rays. Both Paracanthopoma and Ernstichthys were previously unknown outside of the Greater Amazonian river systems (Amazon, Orinoco, Essequibo and smaller surrounding drainages). Their presence restricted to the Rio Taquari is unexpected and suggests a peculiar biogeographical history. Ancestral geographic distributions were reconstructed using S-DIVA and BBM methods in RASP. A majority of resulting hypotheses support that the two species reached the Paraguay from the Amazon. The alternative explanation accounts for their presence in the Paraguay by vicariant events. In no case, their presence in the Paraguay is an ancestral distribution with subsequent Amazonian dispersal. Though unusual, this pattern is also seen in a few other fish taxa, showing that the Rio Taquari is biogeographically hybrid, combining elements from both the Paraguay and Amazon drainages.

Two new, remarkably colored species of the Neotropical catfish genus Cetopsorhamdia Eigenmann & Fisher, 1916 (Siluriformes, Heptapteridae) from Chapada dos Parecis, western Brazil, with an assessment of the morphological characters bearing on their phylogenetic relationships

Abstract Two new species of heptapterid catfish genus Cetopsorhamdia are described from close localities in western Brazil, at Chapada dos Parecis, an area with extremely high level of endemism. One species is from the upper Rio Madeira system, Rondônia State, and the other from the upper Rio Tapajós system, Mato Grosso State. The two species are diagnosed, among several other features, by their markedly distinctive color patterns, with the former having well-defined quadrangular marks in trunk flanks while the latter bearing irregular, vertical bars along the trunk. The monophyly of Cetopsorhamdia is discussed, with two putative synapomorphies being proposed to support the genus. Potentially informative morphological characters to resolve the internal relationships of the genus are presented and discussed. Despite the striking external differences between the two species herein described, they are found to likely form a clade.

The rediscovery of Pimelodella longipinnis (Borodin, 1927), an enigmatic Atlantic Rainforest catfish species from Southeastern Brazil (Siluriformes: Heptapteridae)

Abstract This article is a redescription of Pimelodella longipinnis, an enigmatic catfish previously known only from its holotype and with uncertain type locality. The species is redescribed based on recently collected materials from streams of the Mata Atlântica bioregion, in Santos municipality, São Paulo State, Brazil. Pimelodella longipinnis is assigned to a putatively monophyletic group, the Pimelodella leptosoma-group, diagnosed by the presence of a supraoccipital process not reaching the anterior nuchal plate, with a gap of ca. 20-25% of the supraoccipital process total length, and whose tip notably surpasses the midpoint of the complex vertebra in dorsal view. We also present a list of fish species described from a shipping sent to the American Museum of Natural History from the former Museu Paulista (now Museu de Zoologia da Universidade de São Paulo), of which P. longipinnis was part.

Pectoral-fin glands and delivery apparatus in the catfish genus Brachyrhamdia Myers, 1927 (Siluriformes: Heptapteridae)

Abstract The Siluriformes, popularly known as catfishes, are probably the vertebrate group with the highest diversity of venomous animals, even though only approximately a hundred venomous catfishes are reported to date. Venomous catfishes might present a delivery system apparatus, formed by an unbranched ray at the leading edge of pectoral and dorsal fins (spine), which can be stiffened and pungent, while venom glands can be present at the surface of such spines and/or the axillary region. This work investigated the presence, morphology and distribution of glands and pectoral-fin delivery apparatus in the heptapterid Brachyrhamdia genus. Pectoral-fin spine external morphology was compared across all valid species in the genus, histological sections of the pectoral-fin spine and axillary regions of B. heteropleura and B. marthae were produced, and dissections of the pectoral girdle region of the mentioned species were analyzed. The histological sections confirmed the presence of pectoral-fin glands at the surface of the pectoral-fin spine of Brachyrhamdia species, and cellular morphology indicates these glands are probably venomous. Also, we found a piriform gland at the axillary region, whose cell morphology is like the reported for other catfishes. However, we cannot currently confirm or deny axillary gland participation in the venom delivery apparatus. This work constitutes the first report of venom glands in Brachyrhamdia, and the first description of Heptapteridae axillary glands.

Pectoral-fin glands and delivery apparatus in the catfish genus Brachyrhamdia Myers, 1927 (Siluriformes: Heptapteridae)

Abstract The Siluriformes, popularly known as catfishes, are probably the vertebrate group with the highest diversity of venomous animals, even though only approximately a hundred venomous catfishes are reported to date. Venomous catfishes might present a delivery system apparatus, formed by an unbranched ray at the leading edge of pectoral and dorsal fins (spine), which can be stiffened and pungent, while venom glands can be present at the surface of such spines and/or the axillary region. This work investigated the presence, morphology and distribution of glands and pectoral-fin delivery apparatus in the heptapterid Brachyrhamdia genus. Pectoral-fin spine external morphology was compared across all valid species in the genus, histological sections of the pectoral-fin spine and axillary regions of B. heteropleura and B. marthae were produced, and dissections of the pectoral girdle region of the mentioned species were analyzed. The histological sections confirmed the presence of pectoral-fin glands at the surface of the pectoral-fin spine of Brachyrhamdia species, and cellular morphology indicates these glands are probably venomous. Also, we found a piriform gland at the axillary region, whose cell morphology is like the reported for other catfishes. However, we cannot currently confirm or deny axillary gland participation in the venom delivery apparatus. This work constitutes the first report of venom glands in Brachyrhamdia, and the first description of Heptapteridae axillary glands.