Trichomycterus comprises about 170 valid species, but its monophyly has been challenged in the last decades. Bayesian Inference and Maximum Likelihood analyses comprehending mitochondrial genes COI and CYTB and nuclear genes GLYT, MYH6 and RAG2 from 71 Trichomycterinae terminal taxa and eight outgroups were performed. The analyses highly supports a clade containing Trichomycterusnigricans, the type species of the genus, and several other congeners endemic to eastern and northeastern Brazil, herein considered as the genus Trichomycterus, the sister clade the southern Brazil and adjacent areas clade; the latter clade comprises two subclades, one comprising species of the genus Scleronema and another comprising species previously placed in Trichomycterus, herein described as a new genus. Cambevagen. n. is distinguished from all other trichomycterines by the presence of a bony flap on the channel of the maxillo-dentary ligament, the interopercle shorter than the opercle, a deep constriction on the basal portion of the antero-dorsal arm of the quadrate, absence of teeth in the coronoid process of the dentary, the maxilla shorter than the premaxilla, the cranial fontanel extending from the the medial posterior of frontal to the medial region of supraoccipital, and absence of the postorbital process of the sphenotic-prootic-pterosphenoid.

Trichomycteridae is a well-corroborated catfish family that comprises about 300 valid species distributed in eight subfamilies. The phyletic status of the Trichomycterinae is uncertain, with different hypothesis regarding the position of the miniaturized Trichomycterus hasemani group. This group comprises four valid species, and neither its monophyly nor its positioning among the Trichomycteridae was tested in a phylogenetic framework. Bayesian Inference and Maximum Likelihood analyses of a molecular data set comprising the mitochondrial genes 12S and 16S and the nuclear genes H3, MYH6 and RAG2 (2983 bp) for 26 taxa highly supported the miniature catfish T. hasemani group as monophyletic and sister to the Tridentinae, consequently recognized as a new genus of this subfamily. Potamoglanis gen. nov. is diagnosed by seven character states: an angle of 35-40° between the main longitudinal axis of the head and the main axis of the autopalatine; thin tubular shape of the second ceratobranchial; presence of six or seven anal-fin rays; eyes dorsally placed on head; opercular and interopercular odontodes patches not juxtaposed; absence of a distal process on the hyomandibula and presence of a long process on the anterior region of the hyomandibula. Potamoglanis gen. nov is similar to the Tridentinae genera by the presence of a wide cranial fontanelle; presence of a short ventral process in the opercular bone and by the origin of the dorsal fin placed in a vertical through the anal-fin origin. K E Y W O R D S miniaturization, molecular phylogeny, Potamoglanis, Trichomycteridae, Trichomycterus hasemani, Tridentinae

Three distinct and independent molecular-based species delimitation analyses were performed among the species and populations included within theAustraloherosautranigroup, based on sequences of the mitochondrial gene Cytochrome b: a tree-based method proposed by Wiens and Penkrot (WP), a Character-based DNA Barcoding (CBB) and coalescent species delimitation method termed the Bayesian Implementation of the Poisson tree processes (bPTP). The congruence of WP and CBB delimited 11 independent lineages (species), while the bPTP delimited just nine lineages. We did not favour any of the methods, and we considered the possibility of two slightly variant scenarios. A time-calibrated phylogenetic analysis is proposed based on the predominant congruence of the results of these three species delimitation methods herein applied. The monophyly of theA.autranispecies group was highly supported with maximum node support value and diagnosed by 11 nucleotide substitutions. The sister clade of theA.autranispecies group is the clade comprisingA.sp. Timbé do Sul andA.minuano. The phylogenetic analysis supports three main clades within theA.autranispecies group, supported by maximum node support value, with the Southern Mata Atlântica clade as the most basal clade. Divergence time estimates indicate that the diversification of theAustraloherosoriginated during the early Neogene, but only in the late Neogene did the processes of diversification in the southeast and north regions occur. Diversification within theAustraloherosautranispecies group occurred synchronically for the three main clades during the beginning of the Quaternary. It is demonstrated that molecular characters are valuable tools for species recognition, particularly in speciose groups with inconspicuous or difficult to record morphological characters. The resulting phylogeny of theAustraloherosautranigroup is highly compatible with the geological and biogeographic scenarios proposed for the Neogene and Quarternary shaping of the extant river basins of eastern Brazil. Despite the origin of theA.autranigroup being dated to the late Miocene, species level diversification occurred in the Pleistocene and was probably driven by headwater capture events and sea-level fluctuations.

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Interstitial trichomycterid catfishes of the Glanapteryginae and Sarcoglanidinae with uncommon morphology have been known for long time from taxa endemic to the Amazon. In most recent decades, two genera, Listrura and Microcambeva, respectively, placed in Glanapteryginae and Sarcoglanidinae on the basis of morphological characters, have been described from the Atlantic Forest of eastern South America, about 1,500 km from the area inhabited by those Amazon taxa. Herein, we first test the phylogenetic positioning of Listrura and Microcambeva using a multigene data set, including two nuclear and three mitochondrial genes for nine species of Listrura and Microcambeva and 11 species representing all closely related subfamilies (TSVSG‐clade), as well as five used as outgroups. The phylogenetic analyses generated a robust tree with high support values in all nodes, where monophyly of Glanapteryginae and Sarcoglanidinae is refuted. In contrast, Listrura and Microcambeva form a highly supported clade, herein formally described as a new subfamily, sister to a clade containing taxa representing the Glanapteryginae, Sarcoglanidinae, Stegophilinae, Tridentinae and Vandelliinae. This study also indicates that Microcambeva and Listrura exhibit divergent evolutionary trends in ecological and morphological attributes. Species of Microcambeva inhabit patches of loose sand and possess morphological traits that were convergently acquired by Amazon sand‐dwelling sarcoglanidines, including loss of body pigmentation and long maxilla. Species of Listrura live burrowed inside small stretches of dense leaf litter and have morphological traits that were convergently acquired by Amazon glanapterygines inhabiting leaf litter bottom rivers, including elongate body, with numerous vertebrae and loss or reduction of all fins.

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.

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.

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