A great diversity of small fish species inhabiting shallow aquatic biotopes of the South American Atlantic Forest have been reported in recent years, but records of interstitial catfishes of the genus Listrura for the southern subtropical Brazilian region are still rare. During field inventories in this region, two new species were collected, which are herein described. The new species are distinguished from congeners by a combination of morphological characters, including caudal peduncle morphology, number of vertebrae, relative position of fins, and bone morphology. The findings here described indicate that the scarcity of records of Listrura for the subtropical Atlantic Forest is probably due to the absence of collecting efforts in specialised biotopes, since species of Listrura are leaf litter dwellers. Both new species are probably more closely related to L. depinnai than to other congeners as all three uniquely possess an expanded skin fold supporting the procurrent caudal-fin rays, making the caudal peduncle deeper than the body region anterior to the dorsal and anal fins. However, only one of the new species shares with L. depinnai the presence of a process on the dorsal surface of the autopalatine articular facet for the mesethmoid, a condition not occurring in any other congener. The two new species are easily distinguished from L. depinnai by the absence of a dorsal fin in the latter species. http://www.zoobank.org/urn:lsid:zoobank.org:pub:F68F2A3E-B5F7-418E-BFA6-EA6752BAB543 http://www.zoobank.org/urn:lsid:zoobank.org:pub:F703D95A-0F7E-4261-8B97-5EAAAD9BD698

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.

During a field inventory directed at trichomycterine habitats, two new species of the genus Cambeva, C. alphabelardense sp. nov. and C. betabelardense sp. nov., were found in the Rio Chapecó drainage, an area under high environmental decline due to intensive soya monoculture. These species share a peculiar head morphology and some unique osteological features, besides having a size that is smaller than in any other congener, being herein considered to be more closely related to each other than to other taxa. They differ from each other by several characters, including head shape, fin morphology, number of jaw teeth and opercular odontodes, and mesethmoid and metapterygoid shape. Furthermore, they were found in the same area, but in distinct biotopes, with one species found buried in the remnants of tree ferns and other plants on the stream bottom, restricted to a small residual fragment of the original forest, and the other species inhabiting a stream with gravel and small stones on the bottom. Field studies indicate that these species are threatened with extinction. Robust phylogenetic studies are still necessary to test relationship hypotheses involving the new taxa here described.

Numerous species in fast–flowing streams of southern Brazil have not been described to date. As some of these species inhabit areas under pressure due to the ongoing, intense process of environmental degradation, formal descriptions are urgently needed so as to elaborate strategies for their conservation. We describe a new species, Cambeva gamabelardense n. sp., found in the middle Rio Chapecó drainage, Uruguay River basin, in an area where intense deforestation and soya plantation is endangering fish species. The new species is considered closely related to C. panthera, a species occurring in an isolated coastal basin about 380 km from the area inhabited by the new species, as the two species share a unique jaguar–like pattern on the flank. The new species differs from C. panthera by having shorter barbels, a different position of the origin of the dorsal–fin, more vertebrae, and osteological features that are unique among congeners.

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.

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.