Rhachidelus Boulenger, 1908, is a monotypic snake genus belonging to the tribe Pseudoboini and the family Dipsadidae, distributed only in South America. The genus and the species were described by Boulenger (1908) based on a single male specimen from the state of São Paulo, Brazil, sent at the time by Vital Brazil, a physician and public health officer. In the description, Boulenger was succinct, basing it on data from scalation (number of ventrals, subcaudals, supralabials, infralabials, and postoculars), coloration, biometry, and scale topography. In the present study, based on data collected from 11 new specimens, we propose an emended diagnosis for the species, as well as track its holotype. Rhachidelus brazili can be differentiated from other species of the tribe Pseudoboini by the combination of the following characters: (1) midbody dorsal scales in 25 rows; (2) smooth dorsal scales with two apical pits; (3) enlarged vertebral row; (4) mixed subcaudals (single and divided); (5) single cloacal scale; (6) divided nasal scales; (7) one preocular; (8) two postoculars; (9) two or three preventrals; (10) darkened dorsum; (11) dorsal coloration invading the lateral sides of the ventral scales. In addition, we tracked the holotype of Rhachidelus brazili, since in the description, Boulenger (1908) did not assign a registration number to the specimen, only mentioning that it would be deposited at the British Museum of Natural History, in London. Through contact with the curatorship of the institution's Reptile Collection and through photographs, it was possible to identify the label with the name of Vital Brazil, indicating that it is the only individual sent by him and used by Boulenger to describe the genus and the species. With this, it becomes possible to officially link registration number 1946.1.9.35 to the holotype of Rhachidelus brazili.

A population of Laimaphelenchus was isolated from the dead bark of a healthy oak tree, a site potentially favorable for fungal growth. This species is morphologically characterized by a body length of 621–796 µm, a stylet measuring 10.5–13 µm, three lateral lines, the presence of a vulval flap, and a post-uterine sac 50–78 µm long (2.2–3.6 times the vulval body width). Males exhibit a four-part tail terminus, a (2+2+2) arrangement of genital papillae, and spicules measuring 18.5–20 µm. Based on morphometric and morphological features, this population closely resembles L. hyrcanus and L. belgradiensis. However, it differs from the original description of L. belgradiensis by having a shorter stylet (10.5–13 µm vs. 13.6–15.2 µm) and a longer post-uterine sac (50–78 µm vs. 17.6–48 µm). In comparison with L. hyrcanus, the post-uterine sac is also shorter (50–78 µm vs. 97–152 µm). Previous studies on Laimaphelenchus populations from decaying oaks in Iran highlighted variability in post-uterine sac length and its potential limitations for species-level discrimination. A re-evaluation of species boundaries led to a redescription of L. belgradiensis and the proposal that L. hyrcanus may represent a junior synonym. In the present study, phylogenetic analysis based on the D2–D3 expansion segments of the LSU gene placed this population within a highly supported clade (posterior probability = 1.00), supporting the synonymy—unless additional genomic regions suggest otherwise.

DNA barcode data support species identification, aid in local fauna inventories, and inform the management of protected areas and monitoring of invasive species. As part of the InBuiLT project (“Invertebrate Fauna of Bulgaria and Adjacent Regions – DNA-based Barcoding of Under-represented in Reference Libraries Taxa”), materials from several underrepresented invertebrate groups from Bulgaria and neighboring countries were collected and provided for sequencing. Among the sampled taxa, several rare ant species from Bulgaria were also collected and barcoded. One of them is Oxyopomyrmex krueperi Forel, 1911. It is a rare, thermophilous ant species distributed in arid grasslands of the northeastern part of the Mediterranean Basin and the Near East. It is a reported species for Bulgarian myrmecofauna from a single locality near the town of Tzarevo. Here, we present the first DNA barcodes (COI-5P region) for the species, based on four worker ants hand-collected in different colonies along the southern Black Sea Coast of Bulgaria near the town of Primorsko. Images, metadata, and four DNA sequences (658 bp) were provided to the Barcode of Life Data System (BOLD). Bioinformatics analysis revealed three distantly related Oxyopomyrmex spp., with approximately 90% identity, confirming the genetic distinctiveness of the species. The phylogenetic relationships based on DNA barcodes with the currently available closest species are discussed. These findings represent the first global molecular record for O. krueperi and expand the known range of the genus. The data provide a valuable reference for future taxonomic and phylogenetic studies on Myrmicinae ants from arid and semi-arid regions.

The slender racer snake genus Platyceps Blyth, 1860, with about 33 valid species, is distributed in northern and northeastern Africa, southern and southeastern Europe, Central Asia, southwestern Asia, and India. Among colubrid non-venomous snakes, the genus Platyceps is distinguished by such characteristics as high speed in movement, round pupils, loreal scales present, the uppermost scale in front of the eye connected to the frontal scale, seven or more upper labial scales, and 19 dorsal scales, smooth or slightly serrated. Five species of this genus occur on the Iranian Plateau as follows: Platyceps karelini (Brandt, 1838), P. mintonorum (Mertens, 1969), P. najadum (Eichwald, 1831), P. rhodorachis (Jan, 1863), and P. schmidtleri (Schätti & Mccarthy, 2001). Based on morphological and molecular characteristics, the taxonomic status of the subspecies P. k. mintonorum and P. n. schmidtleri was changed to a full species. The data used for the distribution maps were based on all available bibliographic records and personal field observations. The results showed that among the five species located in Iran, P. rhodorachis has the most widespread distribution and habitat diversity, and P. mintonorum has a very limited distribution along the border of Iran, Afghanistan, and Pakistan.

Tetrigidae is a caeliferan family of Orthoptera constituting a diverse and relatively ancient lineage of small Orthopterans, which are at their highest diversity in tropical and subtropical areas. However, so far, no studies have been conducted on the identification and description of Tetrigidae species in Ethiopia, and even less molecular data is available. Hence, we performed the first DNA barcoding study of species belonging to the genera Paratettix, Leptacrydium, Dasyleurotettix, and Morphopoides from Ethiopia. We provide 35 new sequences of the COI gene belonging to six species of these genera. We show that Ethiopian Tetrigidae can be successfully identified using DNA barcodes, even in cryptic genera such as Paratettix: species delimitation based on this gene was strongly congruent with the morphological assignments. We report the three species Dasyleurotettix infaustus (Walker, 1871), Morphopoides tessmanni Günther, 1939, and M. folipes (Hancock, 1908) from Ethiopia for the first time. In addition, we describe three new species, which are confirmed both with morphological and genetic data: Paratettix tanai sp. nov., Paratettix geminus sp. nov., and Leptacrydium naqamteensis sp. nov. Paratettix macrostenus is considered a new synonym of P. subpustulatus. Future integrative taxonomic studies including more material from diverse regions and more comprehensive taxon sampling need to be performed to understand the diversity of Tetrigidae across Africa.

Introduction

Groups of closely related species are often sources of uncertainty in taxonomy. Lake Baikal amphipods (Crustacea: Amphipoda: Gammaroidea) are a perfect example. They comprise over 350 morphological species and subspecies, two conflicting taxonomies, and no comprehensive identification key. Here, we concentrate on conflicting views on the composition of the scavenger amphipods of the genus Ommatogammarus sensu Takhteew and try to resolve the conflict with molecular data.

Methods

We sequenced the standard barcode sequence, the mitochondrial cytochrome c oxidase subunit I 5’ fragment, as well as the 18S rRNA gene fragment as an additional barcode, in representatives of all subspecies. Three of them were analyzed for the first time. In addition, we performed low-coverage whole-genome sequencing for the three most abundant species and assembled full mitochondrial genomes for Ommatogammarus flavus, Ommatogammarus albinus, and Ommatogammarus carneolus melanophthalmus to obtain a time-calibrated phylogeny of the genus.

Results

The obtained phylogenies show that the last common ancestor of all species existed about 6 million years ago, and O. flavus sensu Takhteew (=Abludogammarus flavus sensu Kamaltynov) was the first to split from the rest of the species. Four O. carneolus subspecies sensu Takhteew (= three Pretiositus species + Eulimnogammarus hyacinthinus according to Kamaltynov) were close but formed two clusters of related sequences instead of four, while the sequences of 18S fragments were identical between these clusters.

Conclusions

The genus Ommatogammarus sensu Takhteew contains at least three clearly separated species. The relationship within O. carneolus containing two lineages needs further investigation, but at the moment, we do not have conclusive evidence to recommend splitting this species complex. Importantly, the reassignment of O. hyacinthinus to the genus Eulimnogammarus is not supported by molecular data.

Widespread species with visibly variable phenotypes often conceal significant evolutionary diversity. The Yellow-throated Woodpecker Piculus flavigula is a Neotropical species distributed across the Amazon and the Atlantic Forests, and is currently classified into three allopatric subspecies: P. f. flavigula (northern Amazonia), P. f. magnus (southern Amazonia), and the Atlantic P. f. erythropis. Although these groups are diagnosed based on geography and general appearance, their morphological and vocal distinctiveness have not yet been formally evaluated. We assessed their phenotypic and acoustic variation using traditional morphometric and vocal traits, combined with automated color pattern segmentation and machine learning-based acoustic analysis. A total of 113 specimens (65 males and 48 females) were measured for wing chord, tail, culmen, and tarsus length. Plumage color patterns were analyzed using the R package recolorize, which enables segmentation from uncalibrated standardized photographs. Additionally, 117 recordings were analyzed for five acoustic parameters (bandwidth, duration, peak, and minimum and maximum frequencies) and further processed through BirdNET, a neural network-based algorithm that extracts 1,024-dimensional feature embeddings. Multivariate statistical tests (MANOVA, LDA) and supervised classification (SVM) were used to assess group separability. We found significant morphometric differences among subspecies, particularly in culmen and tail length (MANOVA p = 0.016). While P. f. erythropis showed the most distinctive phenotype, including a unique barred ventral pattern and higher peak frequencies (p < 0.001), comparisons between P. f. flavigula and P. f. magnus also revealed consistent, but subtler, differences in tail (p = 0.022), culmen (p = 0.015), and vocal parameters. These two Amazonian subspecies showed partial overlap in morphological measurements but moderate separation in acoustic space. Classification models based on BirdNET embeddings achieved 86% accuracy in distinguishing vocalizations among groups. These findings support the phenotypic and acoustic distinctiveness of P. f. erythropis, while also suggesting divergence between P. f. flavigula and P. f. magnus, providing robust evidence for a re-evaluation of taxonomic limits within the Piculus flavigula species complex.

Ergasilidae is among the most recorded families of parasitic copepods on fish worldwide. Besides its impressive species richness of 281 species, morphological and genetic phylogenies have demonstrated the lack of monophyly in some genera, as well as other taxonomic deadlocks. This scenario highlights the need to conduct new analysis to better understand the evolutionary history of the family and to improve its systematics. The present analysis comprised 31 ergasilid species plus the outgroup, Hemicyclops tanakai. A morphological matrix containing 27 characters and an alignment of 18S rDNA genetic sequences were used for phylogenetic reconstruction in BEAST 2.5 using Bayesian Inference. The characters and their states were traced in the tree using Tracer. The integrated tree showed a Consistency Index (CI) (homoplasy rate) of 0.55, thus moderately informative. The most informative features (CI>0.60) were the presence of posterolateral processes on cephalosome, segmentation of antennule, terminal armature of antenna and segmentation of leg 4 rami. Species from Neotropical and Ethiopian realms formed distinct lineages, partially supported by morphological traits. Even integrating morphological data, Ergasilus maintained its polyphyletic status, indicating that the current morphological diagnosis does not reflect its real evolutionary history. The same occurred for Neoergasilus. Giving the present results, at least 5 new genera would be erected to allocate Ergasilus spp., but no morphological feature combination appeared to support them. Paraergasilus and Sinergasilus were monophyletic, supported mainly by morphological traits currently used in their diagnosis. The present results reinforced features that must keep distinguishing genera within the Ergasilidae, but also highlighted others, such as segmentation of rami on leg 4, that could also have taxonomic value. Nonetheless, the poor genetic sampling within the family limited the analysis, highlighting that more sequences must be generated to allow the production of more elucidative results in the future.

This study contributes to the knowledge of digenean diversity by documenting newly recorded species in Algerian waters, either through new host associations or from previously unreported localities.

The trematode Lecithocladium excisum (Rudolphi, 1819), originally described from Scomber scombrus Linnaeus, 1758 (Scombridae) off Rimini, Italy, is a cosmopolitan species widely distributed across tropical and temperate marine environments. It has been reported from the same host in the Atlantic Ocean and in various parts of the Mediterranean Sea, including the Turkish coast.

Lecithocladium excisum exhibits a euryxenous host specificity, infecting a wide range of teleost fishes across multiple families such as Stromateidae, Carangidae, Mullidae, Scombridae, Triglidae, Sparidae, Pristigasteridae, Bothidae, and Nemipteridae.
In the present study, L. excisum is reported for the first time in Algerian waters, parasitizing a new host species, Capros aper (Linnaeus, 1758), from the family Caproidae Bonaparte, 1835. Morphological data are provided to support this new host and locality record, enriching the parasitological inventory of Mediterranean marine fishes.

A study was conducted between May 2020 and April 2022 in an attempt to investigate the diversity of digeneans infecting the digestive tract of the gilthead sea bream Sparus aurata (Linnaeus, 1758) (Sparidae) off the Algerian coast. Four species belonging to the family Opecoelidae Ozaki, 1925, were collected: Macvicaria obovata (Molin, 1859) Bartoli, Bray & Gibson, 1989; Macvicaria maillardi Bartoli, Bray & Gibson, 1989; Bartoli & Gibson, 2007; Macvicaria maamouriae Antar, Georgieva, Gargouri & Kostadinova, 2015 and Allopodocotyle pedicellata (Stossich, 1887) Pritchard, 1966. Algeria is a new
geographical record for M. obovata and A. pedicellata, whereas M. maillardi has already been reported on the Algerian coast, but not from its type host S. aurata. We provide a redescription of these species based on newly collected specimens, which were identified using only morphological features such as the distribution of vitelline follicles and uterus, the position and shape of the cirrus sac, and the presence or absence of the metraterm.