The microturbellarian flatworm Gyratrix hermaphroditus (Kalyptorhynchia: Polycystididae) has long been hypothesised to constitute a vast species complex, a view recently confirmed by molecular evidence. However, to date, the complex has not yet been formally split, as its taxonomy is complicated by multiple nested species hypotheses and by the fact that distinguishing features often consist of very subtle morphological differences in the sclerotised male copulatory organ. Here, building on the existing molecular framework, we present a large integrative effort to resolve the species complex. We add new DNA sequences from specimens collected near the type locality of G. hermaphroditus, expand the previously published morphometric dataset with additional measurements and statistical analyses, and use Scanning Electron Microscopy (SEM) to visualise and clarify morphological differences within the complex. As such, we delineate 14 species of Gyratrix, originating from freshwater, brackish, and marine habitats across the taxon’s global range. Species boundaries are primarily defined by variation in the morphology of the copulatory organ, which is especially evident in the high-resolution SEM images. These morphological differences are robustly supported by molecular and morphometric evidence. Finally, we assess the practical value of our new delineations by testing whether they enable reliable identification of both historical and newly collected specimens in the absence of molecular data.

Schizorhynchia is a taxon of marine free-living platyhelminthes that is generally characterized by having a divided proboscis; however, current taxonomy fails to accurately represent the evolutionary history of species within Schizorhynchia. Here, we present an integrative taxonomic revision and phylogenetic analysis of the genus Baltoplana Karling, 1949 (Cheliplanidae). We collected specimens from various locations around the world, including Australia, Brazil, Spain, France, Italy, and the United States. The specimens were extracted from sandy substrates on beaches. After collection, the specimens were placed in 500 mL wide-mouth flasks and processed using the MgCl₂ decantation method. Live specimens were observed under a microscope, and we took photographs, videos, and detailed anatomical drawings to support subsequent species identification. Each observed specimen was fixed in lactophenol and sealed for later observations under differential interference contrast (DIC) microscopy. Phylogenetic work based on newly acquired 18S and 28S rDNA sequences confirms that the family Cheliplanidae is monophyletic, for the first time positions Baltoplana within Cheliplanidae, and reveals Baltoplana as the sister taxon of Cheliplana. We describe seven new species and provide new morphometric data of known species. The new species of Baltoplana are mainly distinguished by the shape and size of the (un)armed cirrus, the presence or absence of accessory cirri, and the presence or absence of sclerotized tissue (cap) in the distal region of the male copulatory bulb.

Rhabdocoel flatworms constitute one of the most ecologically diverse and speciose groups of microturbellarians (Platyhelminthes). Within this clade, Schizorhynchia, a monophyletic group of nearly 200 species worldwide, remains taxonomically challenging, with a poorly resolved phylogeny and a classification that does not accurately reflect the taxon’s evolutionary history. In this contribution, we describe a new schizorhynch genus from Cuba and the southeastern coast of the United States, integrating morphological data with new molecular phylogenetic evidence. Species of this new genus exhibit a conjuncta-duplex type male copulatory organ, which terminates in a sclerotised cap and comprises a prostate vesicle, cirrus, and stylet. The female system features an elaborate bursa that proximally opens to the digestive parenchyma through an internal pore. The three new species described here are primarily distinguished by differences in bursa morphology and stylet length. Morphologically, members of this new genus most closely resemble species of Schizochilus Boaden, 1963, yet molecular evidence clearly separates them in the phylogeny. Our analyses further demonstrate that the current concept of Schizochilus is non-monophyletic, splitting it into two distinct lineages. To resolve this, we here propose to transfer two previously described species to the new genus and hypothesize that several additional species of Schizochilus will ultimately require reassignment once molecular data become available.

In this study, we present the first molecular records of the freshwater jellyfish Craspedacusta sowerbii (Cnidaria, Hydrozoa) for Argentina and Brazil, obtained from specimens collected at Dique Berta Vidal de Battini (San Luis Province), Ariranha do Ivaí (Paraná State), and Videira (Santa Catarina State), respectively. These results are highly relevant, as previous reports in both countries are scarce and lack genetic confirmation.

The phylogenetic analysis, based on the mitochondrial COI marker, showed that the Argentine sequences form a well-supported clade together with Brazilian samples from Paraná, suggesting a biogeographic connection and genetic cohesion among these groups. These samples also integrate into a broader lineage that includes records from Chile, Japan, Italy, and Canada, reaffirming the cosmopolitan nature and invasive potential of C. sowerbii.

The differences observed between the Santa Catarina and Paraná populations could be attributed to several factors: geographic barriers and distinct hydrographic basins that limited direct genetic exchange. The genetic proximity among Argentina, Paraná, and Chile may reflect both historical dispersal and human-mediated colonization. In contrast, the genetic divergence observed in the Santa Catarina population could be explained not only by its isolation due to naturals barriers but also by following a dispersal route different from Paraná and Argentina, which has kept it more genetically separated.

These preliminary results should be interpreted with caution, as they are based on a single marker and a limited number of samples. However, given the ecological impact of the species, monitoring its presence is crucial to understanding potential alterations in local communities. This context highlights the importance of expanding molecular and ecological studies, integrating hydrological and anthropogenic information, which will guide management strategies that respect regional conservation practices.

This study represents an essential starting point for understanding the genetic structure, dispersal pathways, and potential ecological impact of C. sowerbii in local freshwater ecosystems.

Introduction:
The emperors (Lethrinus, Osteichthyes: Lethrinidae) are ecologically and commercially important reef fishes distributed across the Indo-Pacific. Species delimitation remains problematic due to morphological similarity, synonymy, and broad ranges. DNA barcoding using cytochrome oxidase I (COI) offers a powerful tool for exploring genetic divergence, phylogeographic structure, and potential species complexes. This study analyses COI sequences of Lethrinus to evaluate intra- and interspecific variability and highlight taxonomic ambiguities.

Methods:
COI sequences representing multiple Lethrinus species were retrieved from GenBank, spanning the Indo-Pacific (Indonesia, Philippines, China, Malaysia, Australia, Japan, India, Mozambique, South Africa, Madagascar, Seychelles, Mauritius, Myanmar, Saudi Arabia, Israel, Pakistan, Fiji, Micronesia, and French Polynesia). Sequences were aligned in BioEdit and trimmed to a 648 bp fragment. Phylogenetic reconstruction was performed in MEGA7 using Maximum Likelihood (ML) with the best-fit substitution model and 1,000 bootstrap replicates. Pairwise genetic divergence was calculated in MEGA7 using the Kimura-2-Parameter (K2P) model.

Results:
Intraspecific distances were low across validated species (0.0–0.005), consistent with species-level cohesion. Interspecific distances ranged from 0.083 to 0.204, supporting a clear barcode gap. However, unusually low divergence occurred among L. ornatus, L. obsoletus, L. lentjan, and L. harak (0.082–0.098), indicating a potential species complex. In contrast, L. genivittatus (0.150–0.204 vs. congeners) and L. olivaceus (0.146–0.202 vs. congeners) were well differentiated. The ML tree supported these findings, showing distinct clades for Red Sea/Arabian Gulf populations of L. lentjan and L. nebulosus relative to Indo-Pacific counterparts, as well as regional structuring in L. harak, L. rubrioperculatus, and L. olivaceus.

Conclusion:
The COI-based phylogeny and distance analysis reveal both robust species separations and zones of ambiguity within Lethrinus. The ornatus–obsoletus–lentjan–harak group appears as a taxonomic complex requiring integrative revision, while deep geographic structuring in several widespread species suggests historical isolation and potential cryptic diversity. These results underscore the need for combined morphological, multilocus, and ecological approaches to refine species boundaries and better understand the evolutionary biogeography of Indo-Pacific emperors.

The grasshopper Trimerotropis pallidipennis (Orthoptera: Acrididae) exemplifies the challenges of species delimitation in widely distributed taxa with low morphological differentiation. This species extends from North to South America, frequently inhabiting high-altitude Andean environments. Although only four species have been formally recognized, cytogenetic and molecular evidence suggest that T. pallidipennis represents a complex of multiple evolutionary lineages.

To investigate this, I reanalyzed genome-wide SNP datasets generated through ddRAD-seq using unsupervised machine learning (UML) approaches. Multiple clustering algorithms and dimensionality-reduction methods were implemented to evaluate whether UML can improve species delimitation compared with traditional model-based validation methods.

Those analyses revealed that UML consistently identified lineage-level divergences and signals of admixture, supporting the existence of cryptic diversity within T. pallidipennis complex. In contrast to model-based approaches, which tended to oversplit taxa, UML successfully grouped samples according to major evolutionary lineages.

Overall, this study highlights the complexity of species boundaries in the T. pallidipennis complex and underscores the importance of integrative frameworks that combine morphology, cytogenetics, and genomic data. By demonstrating the capacity of UML to recover cryptic diversity while avoiding artificial over-partitioning, our findings provide methodological and conceptual advances for species delimitation in complex taxonomic systems.

We report a new country record of Uperodon assamensis (a globally threatened species, previously considered endemic to India), with a taxonomic description, from south-central Bangladesh. The newly recorded specimen was identified by having a distinct yellowish dorsal vertebral stripe, an absent or non-visible tympanum, rounded and moderately large choanae, an absence of vomerine teeth, an oval tongue with rounded tips and papillae, and a distinct supratympanic fold that extends from the eyes' posterior corner to the supra-axillary region. The boxplot of the morphometric measurements of the type specimens from distant geo-locations reveals substantial variability in snout–vent length, head width, head depth, tibia length, and axillary–groin distance. In contrast, the eye diameter, internarial distance, eye-to-nostril distance, and eye-to-snout distance show less variability. Besides this, we compiled its known occurrence records and confirmed the current global distribution in three South Asian countries: India, Nepal, and Bangladesh. This study contributes to understanding the geographic distribution of U. assamensis and intraspecific morphological and morphometric diversity, highlighting the importance of continued field surveys in uncovering the biodiversity of underexplored regions in South Asia.

The Iberian Peninsula and Macaronesia represent one of the richest regions in the European Union in terms of Auchenorrhyncha diversity and endemism. However, a comprehensive catalogue compiling the current knowledge on the distribution and taxonomy of this group is still lacking — a gap that limits both biodiversity conservation efforts and the effective management of vector species in agriculture. This study presents an extensive bibliographic analysis of publications containing primary taxonomic data, from Linnaeus to the present, focusing on the Iberian Peninsula (Andorra, Spain, Portugal, Gibraltar, including Balearic Islands) and the Macaronesian archipelagos (Azores, Canary Islands, Madeira, Cape Verde, Selvagens). Through a thorough review of multiple literature sources, we identified approximately 800 publications with original data on distribution and taxonomy of Auchenorrhyncha covering about 900 species. We compiled a detailed database and evaluated each work in terms of publication type, authorship, country of origin and historical period. This work provides the basis for a forthcoming annotated bibliographic catalogue of the group. The finding offers a solid foundation for future taxonomic, biogeographic, and applied studies on Auchenorrhyncha, and will contribute to both conservation strategies and sustainable agricultural management in the region.

Public DNA barcode databases such as GenBank and BOLD are invaluable tools for taxonomic and biodiversity research. However, inconsistencies in species identification and labelling can undermine their reliability, particularly for morphologically similar taxa like Lethrinus, a diverse genus of reef-associated fishes of family Lethrinidae prevalent throughout the Indo-Pacific. This study examines the consistency of species-level identifications in public COI sequence data of Lethrinus using molecular phylogenetic evidence. Over 200 COI sequences, representing more than 30 nominal species of the genus Lethrinus, were retrieved from GenBank and BOLD and used to construct a maximum likelihood (ML) tree in MEGA X. Sequences were annotated by species name and country of origin to detect taxonomic conflicts and potential mislabelling. Lutjanus argentimaculatus was included as an outgroup. The ML tree revealed several instances of taxonomic redundancy and probable misidentification. Sequences labelled as Lethrinus atkinsoni appeared in at least four divergent clades, with representatives from Indonesia, Australia, and the Philippines failing to cluster together—indicating either cryptic diversity or mislabelling. Likewise, L. obsoletus sequences from Micronesia and Australia were found in multiple, non-monophyletic lineages. Unresolved entries such as Lethrinus sp. (e.g., BOLD:AAC1547 from Mozambique and JN311945 from Australia) were placed within established species clades, suggesting unclear or incomplete identifications. Additionally, overlapping clades between nominal species—such as L. rubrioperculatus and L. conchyliatus, or L. olivaceus and L. genivittatus—raised questions regarding the validity of current species boundaries. These results demonstrate notable taxonomic inconsistencies within public COI records of the genus Lethrinus. This underscores the urgent need for rigorous database curation, voucher-backed identifications, and integrative taxonomic frameworks combining morphology, molecular data, and geographic context to ensure accurate species delimitation and dependable molecular reference libraries.

Bats are members of the mammalian fauna, known for their high species richness and diversity, and play a crucial role as reservoirs of emerging and reemerging zoonotic pathogens. Thirty-five bat species have been reported in the coastal ecoregion of Restinga, in the state of Rio de Janeiro. Trachops cirrhosus is a carnivore/insectivore, feeding primarily on insects, lizards, and frogs. Desmodus rotundus is a hematophagous bat, feeding on the blood of other mammals (domestic and wild). Nematodes of the genus Tricholeiperia have been reported in bats of the families Noctilionidae and Phyllostomidae. The objective of this study is to contribute to the detailed ultrastructure of T. leiperi by performing a detailed characterization using scanning electron and confocal microscopy, in addition to reporting parasitism in D. rotundus for the first time. A total of 11 T. cirrhosus and 33 D. rotundus specimens were captured over five nights using mist nets. After euthanasia, the recovered helminths were preserved in 70% ethanol and subsequently examined for their morphological characteristics. Eight T. cirrhosus specimens were parasitized by T. leiperi, while only two D. rotundus specimens were parasitized. The helminths were identified through morphological and morphometric taxonomic characteristics, such as the shape of the cephalic vesicle, the presence of cervical papillae, the division at the distal end of the spicules, the size and arrangement of the bursa rays, the conspicuous vulva flap, and the presence of tubercles on the tip of the female's tail. The observed morphological characteristics involve the species T. leiperi previously described in T. cirrhosus, and this is the first report of T. leiperi in D. rotundus. This finding highlights the importance of studying parasite biodiversity in hosts across different biomes, particularly in heavily impacted ecosystems such as Restinga.