Fourteen names are assigned to the Sittasomus griseicapillus complex, yet no taxonomic revision has been conducted. We compared vocalization and morphology of the nominotypic population with those of southeastern South America (S. g. sylviellus and S. g. olivaceus), assessing potential divergences. Recordings were obtained from databases (WikiAves and Xeno-Canto) and analyzed based on loudsong duration, note number, pace, and minimum and maximum frequencies in Raven Pro 1.6.5. Morphology was compared through body color coding and morphometric analysis of specimens from Museu de Zoologia da Universidade de São Paulo. Using a caliper (0.01 mm), we measured culmen length, width, and height, and tarsus, remiges, and rectrices length. Multivariate analysis of variance (MANOVA) was used to test for differences in traits between populations, followed by Student’s t-test to assess distinctions within them. Some 38 recordings were examined (griseicapillus – 15; sylviellus – 23), revealing a statistically significant difference (F_1,2 = 3.4; p = 0.013) between populations. Song duration-related traits differed significantly (p = 0.017), with mean loudsong duration being shorter in griseicapillus (4.2 ± 0.9 s) than in sylviellus (5.5 ± 2.1 s), while note number was higher in the former (16.4 ± 5.1) compared to the latter (11.9 ± 5.9). The mean pace of griseicapillus was faster (3.9 ± 1.1) than that of the Atlantic population (2.5 ± 1.7). Some 40 specimens were analyzed (griseicapillus – 10; sylviellus – 28; olivaceus – 2). No morphometric differences were found (F_1,3 = 0.98; p > 0.05) among the three populations, but body coloration greatly differed. The upperpart and underpart of griseicapillus is grayish (2.5Y 4/2) whereas in sylviellus and obsoletus, these regions are olive-green (5Y 5/6). All populations are reddish brown (2.5 YR4/6 – griseicapillus; 2.5YR 3/4 – sylviellus) in remiges, rectrices, and uropygium. The significant vocal and morphological differentiation detected suggests that griseicapillus and sylviellus should be full species

The taxonomic classification of the genus Mazama Rafinesque, 1817, has been widely debated due to homoplastic morphological characters. Although six species have been described in Colombia based on morphology, integrative analyses combining genetic and morphological data are still lacking. This study aimed to analyze the species originally described as Mazama cita sanctaemartae Allen, 1915, and to characterize its phylogenetic and cytogenetic relationships. To achieve this, fibroblast cultures were established from the skin tissue of a recently collected specimen (ID: T467) seized from illegal wildlife trafficking in Barbosa, Antioquia, which exhibited morphological traits consistent with gray brocket deers from Colombian Caribbean. Chromosomal preparations were obtained, and Giemsa-stained karyotypes were analyzed. In addition, phylogenetic analysis was performed using a 660 bp fragment of the mitochondrial Cytochrome B (CytB) gene from individual T467, in comparison with other gray brocket deer from different genera: Subulo, Passalites, and Bisbalus. Cytogenetic analysis revealed a diploid number (2n) = 66 and a fundamental number (FN) = 69, showing chromosomal similarities with the karyotype of Bisbalus citus from northwestern Venezuela. Phylogenetic reconstruction using Bayesian inference placed individual T467 within the Bisbalus clade. Thus, the karyotypic and phylogenetic analyzes of our study suggest that all Colombian individuals assessed may belong to the genus Bisbalus. The cytogenetic results may be further complemented with molecular cytogenetic techniques and chromosome painting to identify specific chromosomal rearrangements. This study provides preliminary insights into the cytogenetic and phylogenetic identity of gray brocket deer from the Colombian Caribbean, contributing to clarifying their taxonomic status and informing future conservation and management strategies.

Within Rubiaceae, one of the most taxonomically problematic assemblages is the Psychotria–Palicourea complex, largely due to its high species richness, unstable generic boundaries, and marked morphological variability. The genus Mexocarpus was originally established to accommodate Palicourea tetragona, distinguished by its pyrenes bearing prominent ridges—an unusual trait compared to other members of Palicourea. This taxon occurs from southern Mexico to Central America and, apart from its distinctive pyrenes, is characterised by elongated white flowers with nocturnal anthesis and fruits that become tetragonal when dry. The species was first described under Cephaelis, later transferred to Palicourea, and subsequently placed in Mexocarpus. However, this last reassignment has been contested by some authors, who argue that pyrene morphology is too variable to justify generic separation. To clarify the phylogenetic position of Mexocarpus tetragonus, we performed phylogenetic analyses using two nuclear DNA markers (ETS and ITS) and one plastid marker (trnL–F) under Maximum Likelihood and Bayesian inference. The resulting molecular phylogeny indicates that M. tetragonus lacks phylogenetic support for generic distinction, forming an unresolved clade with P. tomentosa and P. faxlucens. Furthermore, comparative morphological assessments with closely related taxa demonstrate that pyrene characters are highly variable and show overlapping variation, rendering them unsuitable as diagnostic features for defining a separate genus. Based on combined molecular and morphological evidence, we therefore recommend treating Mexocarpus as a synonym of Palicourea.

Recent taxonomic studies of neotropical suboscine passerines have demonstrated the importance of integrative approaches, particularly for cryptic species complexes where traditional morphological characteristics show limited diagnostic value. Our investigation focused on three challenging Hemitriccus species (H. mirandae, H. furcatus, and H. nidipendulus) with disjunct distributions across Brazil. We combined bioacoustic analysis using convolutional neural networks (CNNs) with comprehensive morphological examination of 35 voucher specimens from the Museu de Zoologia da Universidade de São Paulo. Detailed morphometric analysis included six measurements: culmen length, width and height, tarsus, wing, and tail length. Multivariate analysis of variance (MANOVA) was used to assess differences among populations, while Student's t-tests were applied to evaluate pairwise population differences. Plumage coloration was assessed using standardized color catalogs. Hemitriccus mirandae specimens exhibited pale yellow underparts (2.5Y 8/4), which became lighter posteriorly, contrasting with their uniform greenish-olive dorsum (49-Greenish Olive). H. furcatus showed more complex plumage with a gray chest (N 6/0) grading to a light-gray abdomen (10Y 8/6), and upperparts featuring a brownish head (23 Raw Umber) transitioning to a greenish-olive body (49 Greenish Olive). H. nidipendulus displayed distinctive gray underparts (N 6/0) with prominent yellowish streaking (157 Sulfur Yellow) and consistent greenish-olive (49 Greenish Olive) upperparts. Statistical analysis revealed significant morphological differentiation between H. nidipendulus subspecies (F_1,1 = 5.9, p = 0.005), primarily driven by wing and tail dimensions (p < 0.001 and p = 0.003, respectively). However, the lack of corresponding plumage differences and the moderate (70-80%) classification accuracy of vocal signatures from CNN analysis suggest these may represent intraspecific variations rather than species-level divergence. These findings support the synonymization of H. n. paulistus with H. n. nidipendulus, while highlighting the need for additional sampling to clarify the taxonomic status of H. mirandae and H. furcatus populations.

The Restinga de Jurubatiba National Park is located on the northern coast of Rio de Janeiro state, and presents eighteen coastal lagoons with a wide range of environmental conditions, especially salinity levels and geographic orientation relative to the shoreline. This diversity makes the region an ideal setting for ecological and evolutionary studies. Hoplias malabaricus is a fish widely distributed throughout South America, being considered a taxonomic complex due to the difficulty in delineating its lineages, representing one of the main challenges for Neotropical ichthyofauna taxonomy. To revise this complex, we collected 22 individuals from six lagoons in the Restinga de Jurubatiba National Park, whose selection was mainly based on the variations of the salinity levels. Comparative anatomical analyses were performed with specimens of the Hoplias malabaricus complex from other basins in South and Central America. Furthermore, we extracted and sequenced the mitochondrial COI gene and compared it with data from BOLD and GENBANK databases. We observed significant osteological variation among the species within the species complex, especially the mandibular symphysis shaped like a “lock,” a lateral ethmoid with a slender process projecting ventrolaterally, and a huge jugular depression on the lateral surface of the braincase. Molecular analyses indicated genetic divergences of approximately 7.7% compared to the species from the Rio Doce group (MG) and 8.3% relative to H. malabaricus sensu stricto from the North-Northeast of Brazil, confirming considerable differences within the complex. The analyses revealed significant novel anatomical and molecular differences in the collected individuals. The combined approach of anatomical and genetic analysis is essential to clarify the taxonomy and to understand the evolution and distribution of species within the complex Hoplias malabaricus.

The genus Nemesia Vent. (Scrophulariaceae) comprises about 77 species, the majority of which are endemic to South Africa. Nemesia has garnered significant horticultural interest due to its diverse floral shapes, vibrant colours and ease of hybridization and cultivation. The genus was last revised in 1904 by Hiern and the only molecular phylogeny for Nemesia was published in 2008 by Datson and other researchers. Datson et al. grouped the 23 included species into 5 clades, highlighting evolutionary relationships and adaptive traits. Their ancestral state reconstruction suggested that multiple transitions occurred across a perennial life history in species occurring in the summer rainfall areas to an annual lifeform in species adapting to winter rainfall or seasonally dry conditions in the Cape Floristic Region and parts of the Karoo. It was hypothesised that Nemesia’s diversification may have been driven by climate change in the Cape Region during the Miocene and Pliocene. Our research aimed to generate a more comprehensive phylogeny incorporating as many Nemesia species as possible to deepen our understanding of the genus’s evolutionary history. The Bayesian Inference and Maximum Likelihood phylogenies were generated from gene regions ITS, ETS and trnL-intron, representing 48 species. The phylogeny was divided into two main clades with five subclades, each showing a clear geographic structuring, reflecting adaptations to distinct rainfall regimes. In this paper, we discuss the phylogeographic and morphological patterns within the clades and highlight the relationships of newly discovered taxa, offering fresh insights into Nemesia’s diversification.

The genus Phalloceros Eigenmann, 1907 is one of the 27 valid and described of the Poeciliidae family, representing 22 small size species distributed in South America. Among the species, Phalloceros uai Lucinda, 2008 is an endemic species to the Rio das Velhas basin, diagnosed autapomorphically by a distinctive large square lateral spot in larger specimens. However, subsequent studies have reported its occurrence in adjacent sub-basins, such as Piracicaba and Santo Antônio basins, and noted the presence of various phenotypes. Given these discrepancies in current understanding of its geographic distribution, morphological and genetic recognition, and the paucity of natural history data, this study aimed to assess the taxonomic status of Phalloceros uai specimens from the Quadrilátero Ferrífero using an integrative taxonomic approach. Specimens were collected between 2018 and 2021 from four localities across the upper Doce and São Francisco River basins. Morphological measurements included total and standard length, height, and gonopodium length in males. Osteological structures were examined via diaphanization and compared to the holotype, and molecular analyses were conducted using COI gene. Stomach content and gonads analyses were performed on randomly selected individuals. We identified six distinct lateral spot phenotypes, five divergent from the original diagnosis. No significant differences were observed in diet, reproductive characteristics, size, or gonopodium structure among specimens of varying phenotypes, sexes, or populations. Genetic sequences showed less than 2% divergence among Phalloceros uai sequences. Females exhibited viviparity and superfetation. The species' diet primarily consisted of autochthonous animal items. In conclusion, the studied populations did not present sufficient morphological or molecular distinctions to warrant species differentiation, aligning with the diagnosis of Phalloceros uai, despite partial deviations from the large square lateral spot autapomorphy. Therefore, we recommend expanding the diagnosis of Phalloceros uai to include the phenotypic and geographic variation found in this work.

The Neotropical electric fish Apteronotus albifrons is part of a species complex whose synapomorphy is the presence of two clear bands encircling the caudal region throughout their development. These species are very similar, differing mainly in subtle variations in body pigmentation. A. albifrons can be recognized by the absence of dark spots on the first clear band and an evenly dark body color. Although its taxonomic validity had not been questioned since its description until recently, there is currently no designated type material for A. albifrons sensu stricto, nor a proper diagnosis. We examined specimens previously identified as A. albifrons from various ichthyological collections from Brazilian universities. Each specimen was measured, photographed, and assessed with a focus on pigmentation patterns for comparison with other species, such as Apteronotus caudimaculosus. Morphological differences were observed among the specimens. However, what drew particular attention was the presence of dark spots on the first clear band in some individuals. Variation in the number and size of the spots was observed among these specimens, even among those collected from the same locality. This variability appears to be unrelated to either body size or geographic distribution. These results suggest that the main characters currently used to distinguish species within this complex may not be as discontinuous as previously thought. Since other studies have identified genetic differences between A. albifrons sensu stricto and A. caudimaculosus, they are probably distinct taxa whose morphology remains incompletely detailed. Further data are needed beyond pigmentation patterns—such as osteological data—to better understand these issues involving A. albifrons sensu stricto and its species complex.

The genus Buddleja L., described by Linnaeus in 1737 in honor of Adam Buddle, has experienced multiple taxonomic reclassifications, being placed in Loganiaceae, Buddlejaceae, and currently Scrophulariaceae. Despite its ecological and cultural relevance, species delimitation and classification remain contentious, reflecting persistent challenges in defining morphological and molecular boundaries. Estimates of species richness range from 100 to 150 taxa, with Plants of the World Online recognizing 111 accepted species, nearly half distributed in the Americas. In Mexico, 14 species are reported, including Buddleja cordata Kunth (tepozán), a tree of notable cultural and medicinal importance. We reviewed classical taxonomic literature, modern systematic studies, botanical databases (e.g., POWO), and ethnobotanical records to synthesize historical classifications, nomenclatural variants, species richness estimates, and cultural associations. Our analysis confirms that Buddleja is a taxonomically complex genus, characterized by wide morphological variation in vegetative and reproductive traits, further complicated by dioecy and hybridization. Mexican species exhibit multiple vernacular names, reflecting their strong cultural recognition. While B. cordata is widely employed in traditional medicine for renal, digestive, and inflammatory conditions, other taxa are valued for ornamental and ecological functions. Overall, Buddleja exemplifies broader challenges for plant taxonomy in the 21st century. Addressing these complexities is essential not only for biodiversity conservation and ecological restoration, but also for the preservation of traditional ecological knowledge.

The genus Ferricixius Hoch and Ferreira, 2012 was originally described based on a single troglobitic species found in iron-rich caves in southeastern Brazil. Subsequent collections revealed additional species with varying degrees of troglomorphism, including the first epigean/subtroglophilic species of the genus. More recently, four new species have been discovered in Brazilian caves, exhibiting marked variation in troglomorphic features. These findings make Ferricixius a valuable model for investigating processes of subterranean colonization and speciation in tropical cave environments.

The new species are known only from their type localities, located in caves of the Quadrilátero Ferrífero, Minas Gerais, Brazil. Specimens were collected using moistened brushes, transferred to vials containing 96% ethanol for preservation, and later stored in 70% ethanol. Morphological analyses focused on troglomorphic characters (reduction in eyes, wings, and body size) and male genital structures. Descriptions follow the criteria established by Hoch and Ferreira (2012), with adaptations according to Santos et al. (2023).

Four new species of Ferricixius are described, representing the first troglobitic species in the genus that still retain functional eyes—indicating that eye reduction does not follow a uniform pattern. Independent variation in the degree of troglomorphism was observed among species, suggesting environmental influence on selective pressures. Although male genitalia are generally similar among species, they exhibit diagnostic differences that support their separation, suggesting rapid speciation events.

The data suggest multiple subterranean colonization events by a common ancestor, possibly in response to climatic events, followed by rapid adaptive diversification. This discovery highlights the importance of conserving Brazilian caves in the face of increasing threats from mining activities.