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Mountainous regions typically host a great diversity of small-ranged species, often contributing for delineating world biodiversity hotspots. Species of trichomycterine catfishes have been recorded for several high-altitude areas of tropical South America, but field inventories in top mountains of southern Brazil are still rare. Here we report four new small-ranged species collected in streams of the Rio Iguaçu at Serra do Espigão (RISE) in altitudes between about 970 and 1020 m asl, one in the eastern portion of RISE and three in the western portion. A molecular phylogenetic analysis indicated that these species belong to the Cambeva beta-clade, which comprises all species endemic to the Rio Iguaçu drainage, but together not forming a monophyletic group. The analysis also indicated that species endemic to high altitudes are variably related to species from lower altitudes. The only eastern RISE species appears in a basal position of a well-supported clade (Cambeva beta1-clade), with the western RISE species appearing in a subclade of the Cambeva beta1-clade with species occurring in a vast area of southern Brazil. New species are diagnosed by combinations of morphological character states, including meristic, colouration, latero-sensory system, and osteological data.

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

The Brazilian Atlantic Forest, one the five main biodiversity hotspots in the world, still houses many organisms that are rare and unknown to science, mostly concentrated in mountain ranges. Herein, we describe a rare new species of Cambeva from the Rio Tietê drainage at the Serra da Mantiqueira, exhibiting a caudal fin color pattern comprising a light-yellowish–white bar posteriorly edged by a black pigmented area. A similar color pattern was described for C. castroi, C. diabola, and C. melanoptera, also endemic to the Rio Paraná basin, and considered evidence of close relationships among these three species. However, other morphological characteristics highly suggest that the new species is not closely related to C. castroi, C. diabola, and C. melanoptera). Herein, we perform a molecular phylogenetic analysis using two mitochondrial genes and one nuclear gene, including all species with that bicolored caudal pattern. The analysis strongly supports the new species as a member of the alpha-clade, and therefore as distantly related to those three species belonging to the beta-clade, indicating that this color pattern has homoplastically arisen in Cambeva. The data reported here reinforce the urgent need for field studies to better understand the different evolutionary patterns found in the genus, since an intense process of environmental degradation is in course.

Psammocambeva exhibits the largest geographical distribution amongst the subgenera of Trichomycterus s.s., with its present northernmost represented by Trichomycterus tete, endemic to the upper Rio de Contas Basin in the Chapada Diamantina Region, north-eastern Brazil. Herein, we describe a new species recently collected in the Chapada Diamantina Region, but in the Rio Paraguaçu Basin, about 100 km north of the area inhabited by T. tete. A molecular phylogeny using one nuclear and two mitochondrial genes (2430 bp) supported the new species as sister to T. tete; both species are distinguished by colour patterns, morphometric data, relative position of dorsal and anal fins and osteological character states. The clade comprising the new species and T. tete, endemic to the semi-arid Caatinga biogeographical province, is supported as sister to a clade comprising species from the Rio Doce and Rio Paraíba do Sul Basins, in the Atlantic Forest biogeographical province. This study corroborated the Chapada Diamantina Region, a well-known mountainous biodiversity centre, as an important centre of endemism for trichomycterid catfishes.

Colouration is an important tool for systematists inferring species limits and phylogenetic relationships of teleost fishes, but the use of colouration variation in trichomycterine catfish systematics has generated some controversy. We first report and describe the occurrence of four, geographically disjunct colour morphs in Trichomycterus albinotatus, endemic to south-eastern Brazil, as well as ontogenetic colouration change in each morph. A phylogenetic analysis using a cytb fragment (1098 bp) for 23 specimens representing all colour morphs and four outgroups did not support any correlation between colour morphs and lineages, with different colour morphs sharing identical haplotypes. This study indicated that young adult specimens found in lighter habitats had white and brown to black spots on the flank, whereas similar-sized specimens inhabiting darker habitats had white spots inconspicuous or absent and dark brown or black spots expanded. Individuals above about 65 mm SL of all populations had flank white marks less conspicuous or absent and cryptic habits during daylight, contrasting with smaller individuals with white marks and actively swimming above the substrate. Literature data indicate that ontogenetic colouration and habit changes occur in different trichomycterid lineages. Our data thus show that colouration may be problematic in taxonomical studies, although often being consistently used to diagnose species and clades. We conclude that colouration should not be discarded a priori as evidence of trichomycterine relationships and species limits, but should be used with caution in systematic studies, being necessary additional evidence, such as osteological characters or molecular data.

The Cambeva variegata group (CVG) is endemic to a region situated in the intersection of two endangered biodiversity hotspots, Cerrado and Atlantic Forest, and drained by two important South American river basins, the upper Rio Paraná and upper Rio São Francisco basins. Presently, CVG comprises two nominal species, besides some still undescribed. We first performed a molecular phylogenetic analysis (total of 3368 bp) for five species of the CVG and 30 outgroups, which supported the monophyly of the CVG and its inclusion in Cambeva. Most morphological character states distinguishing the CVG from congeners are also present in Scleronema, possibly consisting of plesiomorphic features. We also performed the first time-calibrated phylogeny of the group, which supported possible relationships between present geographical distribution patterns and palaeogeographical events. The estimated time of origin of CVG in the Middle Miocene is nearly contemporaneous to a past hydrographical configuration when part of the upper Rio Paraná basin was connected to the Rio São Francisco basin. The first CVG lineage split occurring in the Miocene end corresponds to a major break in that palaeo basin. Species diversification between the Pliocene and early Pleistocene is compatible with final drainage rearrangement. This study highlights the urgent need for more detailed studies on the diversity and phylogenetic relationships of still poorly known organisms in this highly diverse and threatened region.

Psammocambeva, a subgenus of Trichomycterus s.s., includes a clade endemic to south-eastern Brazil, the Psammocambeva alpha-clade (PAC), containing species with similar colour pattern and fin morphology, making difficult their identification without accurate examination. The greatest diversity of PAC species occurs in the Rio Paraíba do Sul basin area (RPSA), situated within the Atlantic Forest, one of the most important and endangered biodiversity centres in the world. Herein, we: perform a multigene phylogeny focusing on species of PAC; revise morphological characters diagnosing species of PAC from the RPSA, with special attention to those equivocally synonymised in a recent study; describe two new species, and provide a key for species identification. Molecular and morphological evidence supported the recognition of eight valid species belonging to four species complexes. Data indicated that T. auroguttatus, T. travassosi, and T. longibarbatus are valid species. Finally, we discuss the negative impacts of underestimating species diversity in regions under the intense process of natural habitat loss, concluding that integrative approaches are important tools to estimate species diversity, but they should include a range of morphological characters informative to delineate and diagnose groups and their respective species, in association with phylogenies generated by robust molecular datasets.

The Brazilian Cerrado highlands shelter the headwaters of the three largest South American hydrographic basins, where a great species diversity is concentrated, but some biological groups are still insufficiently known. The focal taxa of this study are trichomycterid catfishes of the subgenus Cryptocambeva, genus Trichomycterus, endemic to mountain areas of south-eastern Brazil. The primary objective of this study is to test through a molecular phylogeny if a new species collected in streams of the upper Rio Paraná basin draining the Serra da Canastra is sister to T. macrotrichopterus, endemic to the upper Rio São Francisco at another facet of the Serra da Canastra, as suggested by morphological data. The analysis corroborated sister group relationships between these two species, besides supporting four main clades in Cryptocambeva, each of them endemic to distinct mountain regions. A time-calibrated analysis supported the divergence timing between the new species and T. macrotrichopterus at the Pliocene, which is chronologically compatible with the final period of intense fluvial configuration re-arrangement, when São Francisco headwater streams were captured by the Paraná basin. The new species herein described is similar to T. macrotrichopterus and distinguished from all other species of Cryptocambeva by having a long pectoral-fin filament. These two species are distinguished from each other by characteristics of the latero-sensory system, colour pattern and bone morphology.

A new species of the catfish genus Trichomycterus is described from the Rio Paraíba do Sul, south-eastern Brazil. This species exhibits some morphological character states that are unique amongst congeners, including a robust opercle and a long interopercle with numerous odontodes (50–60 opercular and 90–100 interopercular), a black bar on the basal portion of the caudal fin and a dark brown flank with a well delimited dorsal yellow stripe. It also exhibits some morphological traits that are uncommon amongst congeners, such as the presence of nine pectoral-fin rays. The presence of a shallow hyomandibular outgrowth and a ventrally expanded pre-opercular ventral flap suggests that this species is closely related to T. melanopygius, T. pradensis and T. tete. The new species also differs from T. melanopygius, T. pradensis and T. tete by having an emarginate caudal fin and a single median supra-orbital pore S6. Anecdotal evidence suggests that T. largoperculatus and T. pradensis have migratory habits, a condition not previously reported for eastern South American trichomycterines.

The Rio Doce basin is situated in a biodiversity hotspot, with some fish groups still superficially known. The intense process of habitat loss and water contamination justifies efforts to speed up the pace of describing fish species diversity. Herein, we focus on a clade of trichomycterine catfishes, subgenus Psammocambeva, genus Trichomycterus, performing a multigene phylogenetic analysis, which integrated to a comparative morphological analysis corroborates monophyly and relationships of four species complexes. Five new species are recognised and described. Species distribution patterns support the recognition of five areas of endemism for trichomycterines, most of which are well-known biodiversity centres: Serra do Espinhaço, Serra do Brigadeiro, Serra do Caparaó, Serra do Castelo, and upper-middle Rio Doce. Trichomycterine diversity in the Rio Doce basin, with 16 species, of which 15 belong to Psammocambeva, is lower than in the smaller neighbouring Rio Paraíba do Sul basin, with 21 species in five subgenera. Data suggest that species diversification in the former basin is relatively younger, following the initial diversification of Psammocambeva in the Miocene, whereas diversification in the latter basin has been estimated to have occurred during the Oligocene. This study reinforces the importance of naming new taxa and delimitating areas of endemism as primary tools for conservation strategies.

The Microcambevinae are a catfish subfamily endemic to the Brazilian Atlantic Forest, comprising rare species with interstitial habits. Microcambevines have been classified in two genera, Listrura and Microcambeva, but the relationships among included intrageneric lineages are still poorly understood. The objectives of this study are to conduct a phylogenetic analysis integrating morphological characters and a multigene dataset, and to propose a classification better reflecting morphological diversity and phylogenetic relationships. Phylogenetic analyses combining 57 morphological characters and a 2563 bp molecular dataset generated similar phylogenetic trees with high support values for most clades, including the two genera and some intrageneric groups. Six morphologically distinctive infrageneric lineages, three in Listrura and three in Microcambeva, are classified as subgenera, as well as two new species are described. The morphological diversity here recorded integrated to available information about habitat indicate high level of divergent specialisation among lineages. The analyses indicate a series of convergent morphological traits between Listrura and other teleosts sharing a fossorial lifestyle, as well as specialised traits independently occurring within Listrura lineages. Similarly, a great diversity of morphological traits occurs convergently in Microcambeva lineages and other teleosts sharing psammophilic habits. This study shows that combining molecular and morphological data yields well-supported phylogenies, making possible to unambiguously diagnose clades and to establish evolutionary hypothesis on morphological evolution.

The Rio Grande drainage plays a key role in supplying water and electricity to large urban centres, but some components of its rich ichthyofauna are still poorly known. Based on our field inventories in the middle section of the drainage, we recognised 10 trichomycterine endemic species, of which 6 species are new and described herein. A molecular analysis (2600 bp for 43 taxa) indicated that the species of both subgenera do not form monophyletic groups. One species of the subgenus Cryptocambeva is closely related to species from the inner Brazilian Plateau, whereas other species of this subgenus are closely related to species endemic to smaller coastal basins. The species of the subgenus Paracambeva belong to different lineages of a clade endemic to the Rio Grande drainage. These species are diagnosed by the characters of their external morphology and osteology. A key to species identification is provided. The species distribution patterns support delimitation of three areas of endemism, which may have a relevant role for proposals of conservation strategies: the Uberaba, the São João-Sapucaí, and the Tamborete areas. The last one, a small area confined between the Serra da Canastra and the Rio Grande at the Furnas dam, is particularly important for sheltering three endemic trichomycterines and two loricariid catfishes.

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

The fauna and flora of the Brazilian Atlantic Forest have been intensively inventoried since the 19th century, but some components of this rich biota are still poorly known, and some areas have been poorly sampled. Recent studies on a rich collection of mountain catfishes of the genus Cambeva have revealed a high diversity of species still undescribed in the region. Here we provide formal descriptions for two of these species, found in areas inserted in a broad gap of the presently known genus distribution. The first one is endemic to small coastal river basins of Santa Catarina state, southern Brazil; it is tentatively placed in an intrageneric clade, also including C. castroi, C. davisi, C. guareiensis and C. zonata, by all sharing the presence of a flat small process on the dorsal margin of the quadrate, laterally overlapping metapterygoid and situated just posterior to the syncondrial joint between the metapterygoid and the quadrate. Phylogenetic relationships of the second new species, endemic to the Rio Itajaí-Mirim basin, are still obscure, but it shares a derived morphology of the mesethmoid with some species of the C. balios group. Although species of Cambeva have little external morphological variation when compared to other trichomycterine groups, the present study once more shows the importance of recording and using osteological characters to diagnose externally similar trichomycterine species.

A recent field inventory focusing on catfishes of the trichomycterine genus Cambeva detected the occurrence of two morphotypes, C. barbosae and C. cubataonis, in the Guaratuba-Babitonga-Itapocu area (GBIA) of southern Brazil, reporting some discordance with results of coalescent-based approaches for species delimitation that indicated different estimates of species number. Contrastingly, based on examination of characters taken from the external morphology and osteology, we here recognised six species of Cambeva in GBIA: C. cf. botuvera, a polymorphic and geographically widespread species; C. cubataonis, endemic to the Rio Cubatão do Norte; and four new species, two endemic to the Rio Itapocu basin, one endemic to the Baía de Babitonga system and one endemic to the Baía de Guaratuba system. We performed a molecular phylogenetic analysis indicating that Cambeva comprises three major clades, the alpha-, beta- and gama-clades, with C. cf. botuvera and a clade comprising C. cubataonis and three new species belonging to the beta-clade and another new species belonging to the gama-clade. We concluded that species here recognised are not in fact incongruent with results of that recent study when taxa are correctly identified by a representative sample of morphological characters, highlighting the importance of osteological characters for delimiting trichomycterine species.

A third pelvic-less species of Cambeva from river basins draining the Geral mountain range in southern Brazil is described. It is distinguished from other congeners lacking pelvic fin and girdle, C. pascuali and C. tropeiro, by having six pectoral-fin rays, 20–23 dorsal procurrent caudal-fin rays, 15–20 opercular and 25–30 interopercular odontodes and a different colour pattern consisting of flank dark brownish-grey with two irregular horizontal rows of small pale yellow grey marks. Whereas available molecular evidence indicates that C. pascuali is more closely related to C. zonata, a species with well-developed pelvic fin, and C. tropeiro is more closely related to C. balios, another species also with well-developed pelvic fin; osteological data strongly suggest that the new species herein described is more closely related to C. diatropoporos than to other congeners. Therefore, this study indicates that the pelvic fin and pelvic-fin support have been lost independently in each of these three species of Cambeva, which corresponds to 11% of all describe species. This result highly contrasts with the closely-related trichomycterine genera Trichomycterus, in which only one in 50 species lost pelvic fin and girdle (0.2%) and Scleronema with all the nine included species having well-developed pelvic fin. These data suggest a stronger tendency to losing pelvic fin in Cambeva, but factors favouring this evolutionary event are still unknown.

Ammoglanis obliquus sp. nov., a minute catfish species reaching a maximum adult size of 15.5 mm, is described from the Rio Preto da Eva drainage in the central Brazilian Amazon. It is distinguished from all of its congeners in possessing an exclusive combination of character states, including the presence and number of premaxillary and dentary teeth, number of interopercular and opercular odontodes, presence of cranial fontanel, number of dorsal-fin rays, number of anal-fin rays, number of caudal-fin rays, number of pelvic-fin rays, number of pectoral-fin rays, absence of pelvic splint, antorbital morphology, and absence of supraorbital and autopalatine morphology. It is considered to be a member of a clade also including A. pulex and A. amapaensis due to the unique oral, antorbital, and autopalatine morphology. Ammoglanis obliquus is regarded as more closely related to A. pulex than to any other congener, as both species exhibit a similar colour pattern, an absence of the metapterygoid, and the presence of two finger-like projections on the chin region.

Specimens found between 1985 and 1988 in the Magé River Basin, south-eastern Brazil were misidentified as L. splendens. The recent rediscovery of other specimens in the Estrela River Basin near the type locality of L. splendens has clarified the species’ concept, making it possible to recognise the Magé River Basin specimens as a new species. The new species is herein described as Leptopanchax sanguineus sp. nov. and is distinguished from all other cynopoecilines by a unique colour pattern in males, including red bars with sinuous margins. It was collected in a well-preserved, temporary shallow swampy area within dense moist forest, but since 1990 the species has not been found again. Leptopanchax sanguineus sp. nov. is one of three species of cynopoeciline killifishes living in lowland moist forests of the coastal plains of Rio de Janeiro State, where the greatest diversity of endemic cynopoecilines is concentrated. Each of these species has been recorded a single time in the last 30 years, a surprisingly low record attributable to intense deforestation during the last several decades resulting in small fragmented lowland moist forests of today. This study indicates that seasonal killifishes adapted to uniquely live in this kind of habitat should be regarded with special concern in studies evaluating conservation priorities.

A great diversity of animal species adapted to life in the semi-arid Caatinga of northeastern Brazil, including seasonal killifishes, has been reported in the last three decades. More recently, field and molecular data have shown a high occurrence of cryptic species. The killifish group herein analysed, the Hypsolebias magnificus species complex, is endemic to the middle and southern portion of the Caatinga, occupying about 120 km along the floodplains of the middle São Francisco River and some adjacent tributaries. Species of this complex are rare and presently considered threatened with extinction, being uniquely found in pools protected by trees and bushes. Single-locus delimitation methods were used to test species limits of populations displaying different colour patterns along the whole distribution of the complex. All analyses consistently supported the three nominal species and two new, herein described: H. gardneri Costa, sp. n., from the floodplains of the middle São Francisco River and H. hamadryades Costa, sp. n., from the Gorotuba River floodplains. The phylogenetic analysis highly supports H. hamadryades as sister to a clade comprising H. gardneri and H. harmonicus. Our field observations suggest that H. hamadryades is a miniature species. This study indicates that the H. magnificus complex comprises cryptic species apparently endemic to small areas and extremely vulnerable to environmental changes, deserving high concern.

The miniature seasonal killifish Spectrolebias costae, first described for the middle Araguaia River basin, has been also recorded from two areas in the middle Tocantins River basin, from where male specimens exhibit some differences in their colour pattern. Analyses directed to species delineation (GMYC and bPTP), using a fragment of the mitochondrial gene COI, strongly support two species, S. costae from the Araguaia River basin and a new species from the Tocantins River basin. Spectrolebias gracilis sp. n. is described on the basis of specimens collected from two localities separated by about 530 km, Canabrava River floodplains near Alvorada do Tocantins and Tocantins River floodplains near Palmeirante. Field inventories were unsuccessful in finding additional populations in the region, which is attributed to the high environmental degradation, including several large dams that have permanently inundated typical killifish habitats. Spectrolebias gracilis is member of a clade also including S. costae, S. inaequipinnatus, and S. semiocellatus, diagnosed by having the dorsal and anal fins in males with iridescent dots restricted to their basal portion, caudal fin in males hyaline, and caudal-fin base with two pairs of neuromasts. Within this clade, a single miniaturisation event is supported for the most recent common ancestor of the subclade comprising S. costae and S. gracilis, which differ from other congeners by reaching only about 20 mm standard length as maximum adult size.

Two new species of Cynolebias are described from temporary pools of the Verde Grande River drainage, São Francisco basin, in the semiarid Caatinga, a phytogeographical province of northeastern Brazil. Cynolebias elegans sp. n., a member of the C. gilbertoi group, is considered as the smallest species of the genus, reaching about 38 mm of standard length; it is distinguished from all other species of the group by the long unpaired fins, relative position of anal fin and vertebrae, and morphometric data. Cynolebias gorutuba sp. n. belongs to the Cynolebias zeta-clade, a group of large species supposedly feeding on smaller sympatric seasonal killifishes; it differs from other species of the group by the female colour pattern, relative position of dorsal fin and vertebrae, and cephalic neuromast pattern. Both species herein described were not found in recent collecting trips, after their habitats had been drastically modified, and are also possibly highly endangered if not already extinct. Field data relative to gradual habitat decline in the type locality region of C. elegans indicate that after pools lose the dense vegetation that provides shelter to small species, these species such as C. elegans become exposed to larger sympatric predatory species and are extirpated. These data support the hypothesis that small seasonal killifish species specialised in living within marginal shaded areas of temporary pools are more susceptible to environmental changes than other congeners.

Structures of the external morphology and skeleton of the annual fish genera Nematolebias and Simpsonichthys are described and illustrated. Phylogenetic relationships among all included species of both genera and other cynolebiatins are estimated, based on 116 morphological characters in a total of 50 terminal taxa. Nematolebias is hypothesized to be the sister group of a clade including Simpsonichthys, Austrolebias , Megalebias, and Cynolebias, which is diagnosed by ventral portion of mesopterygoid not overlapping quadrate, third neural spine approximately as wide as fourth neural spine, ventral condyle of coracoid narrow, scales slightly extending over anal-fin base, loss of vomerine teeth, loss of neuromast anterior to infraorbital series, ventral process of the angulo-articular short and narrow, and dorsal portion of cleithrum elongated. Simpsonichthys is divided into five subgenera, including Spectrolebias, previously considered a separate genus, Simpsonichthys, and three new subgenera, Xenurolebias, Ophthalmolebias, and Hypsolebias. Monophyly of Simpsonichthys is supported by a small pointed dorsal process on the palatine, unbranched fin rays on the tip of the dorsal and anal fins in males, and frontal Escales overlapped.

Trichomycterus caipora, new species, is described from rio Macabu basin, lagoa Feia drainage, serra de Macaé, southeastern Brazil. The new species is distinguished from its congeners from southern and southeastern Brazil by the combination of: the presence of nine pectoral-fin rays, caudal fin emarginated and high number of opercular and interorpecular odontodes. Ecological notes are presented and putative phylogenetic relationships and characters shared with congeners are discussed.

Rivulus kirovskyi, new species, from the central Amazon, lower rio Negro drainage, northern Brazil, is described. It is a member of an assemblage that includes R. amanapira, R. atratus, R. ornatus, R. rectocaudatus, R. romeri, R. tecminae, and R. uakti, and is diagnosed by a unique pattern of frontal squamation and a derived color pattern of the infraorbital region. Relationships of the new species with other taxa of the group are unclear at the present. It is similar to R. atratus, R. ornatus, and R. romeri in having an apomorphic reduction of anal-fin rays and by the absence of caudal spot in females, and similar to R. amanapira, R. rectocaudatus, R. romeri, R. tecminae, and R. uakti, by the absence of preopercular canal and dermosphenotic. Rivulus kirovskyi differs from all other species of the group by its unique color pattern of the caudal fin in males.

Austrolebias paucisquama is described from the rio Vacacaí drainage, a tributary to the rio Jacuí, Rio Grande do Sul, Brazil. The new species belongs to the Austrolebias alexandri species-group, by sharing the apomorphic bright blue iridescence and dark gray pectoral fins in males. It is distinguished from other species of this group by having fewer scales around caudal peduncle (12) and fewer dorsal-fin rays in males (17-21). The lack of contact organs on the inner surface of the pectoral fin in males and the color pattern of females - ground color light brownish, sides of body with a variable number of relatively large dark black spots distributed mostly on posterior portion of body - distinguish A. paucisquama from all other species of the genus.

Seven new species of the Rivulus punctatus group collected during recent field studies in central Brazil are described. Rivulus dapazi n. sp., from the upper rio Correntes drainage, rio Paraguay basin, is diagnosed by a unique color pattern of the anal and caudal fins in males; R. cyanopterus n. sp., from the upper rio São Lourenço drainage, rio Paraguay basin, is diagnosed by a unique color pattern of the anal fin in both sexes; R. rossoi n. sp., from the rio Inhanduí drainage, rio Paraná basin, is diagnosed by a unique color pattern of the caudal fin in males and a reduced number of gill rakers on the first branchial arch; R. litteratus n. sp., from the upper rio Araguaia basin, is diagnosed by unique color patterns of flank in males and caudal fin in females; R. rutilicaudus n. sp., from the rio Verde drainage in Goiás, rio Paraná basin, is diagnosed by a unique color pattern of the caudal fin in females; R. scalaris n. sp., from the rio Sucuruí, rio Aporé, rio Correntes and rio Taquari drainages, rio Paraná basin, is diagnosed by a unique color pattern of the flank in males; and, R. egens n. sp., from the upper rio Verde drainage in Mato Grosso do Sul, rio Paraná basin, is distinguished by a combination of frontal E-scale pattern and the absence of red marks on the caudal fin in males. Combinations of other color patterns and morphological features, including number of scales of the longitudinal series, number of dorsal, anal, caudal and pectoral fin-rays, relative position of dorsal-fin origin and anal-fin rays, and number of vertebrae, are also useful in identification of the new species, but phylogenetic relationships among them are unknown at the present. A key to identification of species of Rivulus from the rio Paraná-Paraguay basin and adjacent headstreams is provided.

Cynolebias parnaibensis from the Canindé River drainage, Parnaíba River basin, northeastern Brazil, is described. It is considered to be a member of a clade endemic to the Caatinga. The clade is diagnosed, e. g., by a series of structural modifications of the pharyngeal jaw apparatus, which is related to the sound production exhibited by males during courtship behavior. The courtship sound of C. parnaibensis consists of a single pulse named as thump (duration 0.031-0.133s; interthump intervals 0.020-8.319s; dominant frequency 70.3-93.8 Hz). The new species is distinguished from all other congeners by a combination of 27-31 neuromasts around eye, 29-33 supraorbital neuromasts, 16-18 dorsal-fin rays and 19 anal-fin rays in males, 28-31 caudal-fin rays, 33-36 scales in the longitudinal series, 3+10 gill-rakers in the first branchial arch, absence of second pharyngobranchial teeth, absence of contact organs on the flank scales, 34-35 vertebrae, absence of teeth on vomer, and presence of transverse series of scales on the anal-fin base.

Austrolebias varzeae n. sp. is described from rio da Várzea floodplains, upper rio Uruguay basin, southern Brazil. It seems to be closely related to A. carvalhoi (Myers), with which it shares a similar color pattern of male and an apomorphic morphology of the autopalatine. The new species differs from A. carvalhoi by having more anal-fin rays in males and more caudal-fin rays. Austrolebias varzeae is distinguished from all other species of the genus by a unique color pattern, in which there are three distinctively darker and narrower bars on the anterior portion of male flank. Putative close relationships between A. varzeae and A. carvalhoi suggest a closely related biogeographic history between upper Uruguay and upper Iguaçu River basins, corroborated by a biogeographic pattern of the anablepid genus Jenynsia.

Kryptolebias, new name, is proposed to replace Cryptolebias Costa, 2004, preoccupied by Cryptolebias Gaudant, 1978, a monotypic genus of European fossil fish. As a consequence, Kryptolebiatinae is erected, substituting Cryptolebiatinae Costa.