Species of Dactylogyridae (Monogenoidea, Polyonchoinea) from the gills of haemulid and lutjanid fishes (Perciformes) from the Pacific coast of Mexico.

Examination of the gill lamellae of the Panama grunt Rhencus panamensis (Steindachner) (Haemulidae), golden snapper Lutjanus inermis (Peters), and yellow snapper Lutjanus argentiventris (Peters) (Lutjanidae) (Perciformes) from the coast of the Guerrero State (eastern Tropical Pacific) of Mexico revealed 5 species of Monogenoidea: Euryhaliotrema disparum n. sp. on R. panamensis; Haliotrematoides uagroi n. sp. on L. inermis; and E. anecorhizion Kritsky & Mendoza-Franco, 2012, E. fastigatum (Zhukov, 1976) Kritsky & Boeger, 2002, and E. paracanthi (Zhukov, 1976) Kritsky & Boeger, 2002 on L. argentiventris. Specimens found on R. panamensis were assigned within Euryhaliotrema as a new species possessing the atypical morphology of the male copulatory organ (i.e., a coiled tube with clockwise rings). Haliotrematoides uagroi n. sp. differs from Haliotrematoides striatohamus (Zhukov, 1981) Mendoza-Franco, Reyes-Lizama & Gonzalez-Solis, 2009 from Haemulon spp. (Haemulidae) from the Caribbean Sea (Mexico) in having inner blades on the distal shafts of the ventral and dorsal anchors. The present paper represents the first finding of a species of Euryhaliotrema (E. disparum n. sp.) on a species of Rhencus and the second species on a haemulid host, and H. uagroi n. sp. as the first monogenoidean species described on L. inermis. Euryhaliotrema anecorhizion, E. fastigatum, and E. paracanthi on L. argentiventris in the Pacific coast of Mexico represent new geographical records.

Structural basis of DNA polymerase θ mediated DNA end joining.

DNA polymerase θ (Pol θ) plays an essential role in the microhomology-mediated end joining (MMEJ) pathway for repairing DNA double-strand breaks. However, the mechanisms by which Pol θ recognizes microhomologous DNA ends and performs low-fidelity DNA synthesis remain unclear. Here, we present cryo-electron microscope structures of the polymerase domain of Lates calcarifer Pol θ with long and short duplex DNA at up to 2.4 Šresolution. Interestingly, Pol θ binds to long and short DNA substrates similarly, with extensive interactions around the active site. Moreover, Pol θ shares a similar active site as high-fidelity A-family polymerases with its finger domain well-closed but differs in having hydrophilic residues surrounding the nascent base pair. Computational simulations and mutagenesis studies suggest that the unique insertion loops of Pol θ help to stabilize short DNA binding and assemble the active site for MMEJ repair. Taken together, our results illustrate the structural basis of Pol θ-mediated MMEJ.

Larval study revealed diversity and life-history traits of crypto-benthic eel gobies.

Because adult and juvenile eel gobies usually hide within the burrows of muddy substrates, their diversity and life history have not yet been fully elucidated. We investigated larval specimens of the eel gobies collected on Okinawa Island in southern Japan. The genus Trypauchenopsis was previously thought to consist of only one species, but our larval collection identified two species, Trypauchenopsis limicola and Trypauchenopsis intermedia, distinguished by their species-specific melanophore arrangements and differences in their fin-ray counts. Taenioides kentalleni were previously known from only two specimens worldwide. A third specimen of this species has now been added from the larval collection. In addition to the three species above, Taenioides gracilis and Caragobius urolepis were identified and the larval morphologies of the five species were described for the first time. All the larvae collected in the present study were at late postflexion stage. T. limicola, T. intermedia and T. gracilis were presumably collected in the estuaries and beaches when approaching their adult habitats at the end of pelagic life. They were 8.5-10.3 mm in standard length, and otolith analysis suggests that their pelagic larval durations are a little longer than 1 month (average 34-37 days). The larval occurrence suggested that the spawning season of T. limicola is May-December, when the water temperature is warmer than approximately 20°C. Our work reveals that studying the larval stage can provide new information on the taxonomy and life history of the elusive cryptobenthic fish.

Identification of enigmatic Mediterranean fish Gobius ater Bellotti, 1888 (Teleostei: Gobiidae) based on morphology from underwater photographs.

Gobius ater Bellotti, 1888 is the Mediterranean gobiid species whose live appearance has remained unknown the longest since its description. A goby observed in southern France in 2021 is here identified as G. ater based on a diagnosis of morphological characters visible on high-quality underwater photographs. Then, the authors provide the first description of colouration in live G. ater and a species diagnosis based on colouration. This diagnosis allows the authors to validate a previous photographic record, also from France. Reviewing all claims of G. ater, they argue that only seven records are unambiguously valid, including the two photographic records presented here.

The Genetic Population Structure of Lake Tanganyika's Lates Species Flock, an Endemic Radiation of Pelagic Top Predators.

Understanding genetic connectivity plays a crucial role in species conservation decisions, and genetic connectivity is an important component of modern fisheries management. In this study, we investigated the population genetics of four endemic Lates species of Lake Tanganyika (Lates stappersii, L. microlepis, L. mariae, and L. angustifrons) using reduced-representation genomic sequencing methods. We find the four species to be strongly differentiated from one another (mean interspecific FST = 0.665), with no evidence for contemporary admixture. We also find evidence for strong genetic structure within L. mariae, with the majority of individuals from the most southern sampling site forming a genetic group that is distinct from the individuals at other sampling sites. We find evidence for much weaker structure within the other three species (L. stappersii, L. microlepis, and L. angustifrons). Our ability to detect this weak structure despite small and unbalanced sample sizes and imprecise geographic sampling locations suggests the possibility for further structure undetected in our study. We call for further research into the origins of the genetic differentiation in these four species-particularly that of L. mariae-which may be important for conservation and management of this culturally and economically important clade of fishes.

Phylogenetics and the evolution of terrestriality in mudskippers (Gobiidae: Oxudercinae).

The initial vertebrate conquest of land by stegocephalians (Sarcopterygia) allowed access to new resources and exploitation of untapped niches precipitating a major phylogenetic diversification. However, a paucity of fossils has left considerable uncertainties about phylogenetic relationships and the eco-morphological stages in this key transition in Earth history. Among extant actinopterygians, three genera of mudskippers (Gobiidae: Oxudercinae), Boleophthalmus, Periophthalmus and Periophthalmodon are the most terrestrialized, with vertebral, appendicular, locomotory, respiratory, and epithelial specializations enabling overland excursions up to 14 h. Unlike early stegocephalians, the ecologies and morphologies of the 45 species of oxudercines are well known, making them viable analogs for the initial vertebrate conquest of land. Nevertheless, they have received little phylogenetic attention. We compiled the largest molecular dataset to date, with 29 oxudercine species, and 5 nuclear and mitochondrial loci. Phylogenetic and comparative analyses revealed strong support for two independent terrestrial transitions, and a complex suit of ecomorphological forms in estuarine environments. Furthermore, neither Oxudercinae nor their presumed sister-group the eel gobies (Amblyopinae, a group of elongated gobies) were monophyletic with respect to each other, requiring a merging of these two subfamilies and revealing an expansion of phenotypic variation within the "mudskipper" clade. We did not find support for the expected linear model of ecomorphological and locomotory transition from fully aquatic, to mudswimming, to pectoral-aided mudswimming, to lobe-finned terrestrial locomotion proposed by earlier morphological studies. This high degree of convergent or parallel transitions to terrestriality, and apparent divergent directions of estuarine adaptation, promises even greater potential for this clade to illuminate the conquest of land. Future work should focus on these less-studied species with "transitional" and other mud-habitat specializations to fully resolve the dynamics of this diversification.

First adult record of the barracudina Lestidiops extremus (Ege, 1953), based on a specimen from the Philippines (Teleostei: Paralepididae).

The adult morphology of Lestidiops extremus (Ege, 1953), a barracudina originally described based on postlarvae from Indonesia, has long been a mystery. An adult specimen collected from off the Philippines represents the first confirmed record of an adult of this species. Observations on the holotype and a detailed description of the adult are provided. The location of the pelvic-fin origin in the adult, clearly behind the posterior end of the dorsal-fin base, is unique within this genus and the entire subfamily Lestidiinae. The present find extends the known range of the species from northwestern New Guinea, Indonesia, to seas east of the Philippines.

Comprehensive Draft Genome Analyses of Three Rockfishes (Scorpaeniformes, Sebastiscus) via Genome Survey Sequencing.

Sebastiscus species, marine rockfishes, are of essential economic value. However, the genomic data of this genus is lacking and incomplete. Here, whole genome sequencing of all species of Sebastiscus was conducted to provide fundamental genomic information. The genome sizes were estimated to be 802.49 Mb (S. albofasciatus), 786.79 Mb (S. tertius), and 776.00 Mb (S. marmoratus) by using k-mer analyses. The draft genome sequences were initially assembled, and genome-wide microsatellite motifs were identified. The heterozygosity, repeat ratios, and numbers of microsatellite motifs all suggested possibly that S. tertius is more closely related to S. albofasciatus than S. marmoratus at the genetic level. Moreover, the complete mitochondrial genome sequences were assembled from the whole genome data and the phylogenetic analyses genetically supported the validation of Sebastiscus species. This study provides an important genome resource for further studies of Sebastiscus species.

Comparative Phylogeography and Phylogeny of Pennah Croakers (Teleostei: Sciaenidae) in Southeast Asian Waters.

A broad-scale comparative phylogeographic and phylogenetic study of pennah croakers, mainly Pennahia anea, P. macrocephalus, and P. ovata was conducted to elucidate the mechanisms that may have driven the diversification of marine organisms in Southeast Asian waters. A total of 316 individuals from the three species, and an additional eight and six individuals of P. argentata and P. pawak were employed in this study. Two genetically divergent lineages each of P. argentata and P. anea (lineages L1 and L2) were respectively detected from the analyses based on mitochondrial cytochrome b gene data. Historical biogeography analysis with a multi-gene dataset revealed that Pennahia species most likely originated in the South China Sea and expanded into the eastern Indian Ocean, East China Sea, and northwestern Pacific Ocean through three separate range expansions. The main diversifications of Pennahia species occurred during Miocene and Pliocene periods, and the occurrences of lineage divergences within P. anea and P. argentata were during the Pleistocene, likely as a consequence of cyclical glaciations. The population expansions that occurred after the sea level rise might be the reason for the population homogeneity observed in P. macrocephalus and most P. anea L2 South China Sea populations. The structure observed between the two populations of P. ovata, and the restricted distributions of P. anea lineage L1 and P. ovata in the eastern Indian Ocean, might have been hampered by the northward flowing ocean current at the Malacca Strait and by the distribution of coral reefs or rocky bottoms. While our results support S. Ekman's center-of-origin hypothesis taking place in the South China Sea, the Malacca Strait serving as the center of overlap is a supplementary postulation for explaining the present-day high diversity of pennah croakers centered in these waters.

Phylogeny of the damselfishes (Pomacentridae) and patterns of asymmetrical diversification in body size and feeding ecology.

The damselfishes (family Pomacentridae) inhabit near-shore communities in tropical and temperature oceans as one of the major lineages in coral reef fish assemblages. Our understanding of their evolutionary ecology, morphology and function has often been advanced by increasingly detailed and accurate molecular phylogenies. Here we present the next stage of multi-locus, molecular phylogenetics for the group based on analysis of 12 nuclear and mitochondrial gene sequences from 345 of the 422 damselfishes. The resulting well-resolved phylogeny helps to address several important questions about higher-level damselfish relationships, their evolutionary history and patterns of divergence. A time-calibrated phylogenetic tree yields a root age for the family of 55.5 mya, refines the age of origin for a number of diverse genera, and shows that ecological changes during the Eocene-Oligocene transition provided opportunities for damselfish diversification. We explored the idea that body size extremes have evolved repeatedly among the Pomacentridae, and demonstrate that large and small body sizes have evolved independently at least 40 times and with asymmetric rates of transition among size classes. We tested the hypothesis that transitions among dietary ecotypes (benthic herbivory, pelagic planktivory and intermediate omnivory) are asymmetric, with higher transition rates from intermediate omnivory to either planktivory or herbivory. Using multistate hidden-state speciation and extinction models, we found that both body size and dietary ecotype are significantly associated with patterns of diversification across the damselfishes, and that the highest rates of net diversification are associated with medium body size and pelagic planktivory. We also conclude that the pattern of evolutionary diversification in feeding ecology, with frequent and asymmetrical transitions between feeding ecotypes, is largely restricted to the subfamily Pomacentrinae in the Indo-West Pacific. Trait diversification patterns for damselfishes across a fully resolved phylogeny challenge many recent general conclusions about the evolution of reef fishes.

Establishment and Characterization of a Novel Gill Cell Line, LG-1, from Atlantic Lumpfish (Cyclopterus lumpus L.).

The use of lumpfish (Cyclopterus lumpus) as a cleaner fish to fight sea lice infestation in farmed Atlantic salmon has become increasingly common. Still, tools to increase our knowledge about lumpfish biology are lacking. Here, we successfully established and characterized the first Lumpfish Gill cell line (LG-1). LG-1 are adherent, homogenous and have a flat, stretched-out and almost transparent appearance. Transmission electron microscopy revealed cellular protrusions and desmosome-like structures that, together with their ability to generate a transcellular epithelial/endothelial resistance, suggest an epithelial or endothelial cell type. Furthermore, the cells exert Cytochrome P450 1A activity. LG-1 supported the propagation of several viruses that may lead to severe infectious diseases with high mortalities in fish farming, including viral hemorrhagic septicemia virus (VHSV) and infectious hematopoietic necrosis virus (IHNV). Altogether, our data indicate that the LG-1 cell line originates from an epithelial or endothelial cell type and will be a valuable in vitro research tool to study gill cell function as well as host-pathogen interactions in lumpfish.

Complete Mitochondrial Genome of Pseudocaranx dentex (Carangidae, Perciformes) Provides Insight into Phylogenetic and Evolutionary Relationship among Carangidae Family.

Pseudocaranx dentex (white trevally) which belongs to the Carangidae family, is an important commercial fishery and aquaculture resource in Asia. However, its evolution and population genetics have received little attention which was limited by the mitogenome information absence. Here, we sequenced and annotated the complete mitochondrial genome of P. dentex which was 16,569 bp in length, containing twenty-two tRNAs (transfer RNAs), thirteen PCGs (protein-coding genes), two rRNAs (ribosomal RNAs), and one non-coding region with conservative gene arrangement. The Ka/Ks ratio analysis among Carangidae fishes indicated the PCGs were suffering purify selection and the values were related to the taxonomic status and further influenced by their living habits. Phylogenetic analysis based on the PCGs sequences of mitogenomes among 36 species presented three major clades in Carangidae. According to the phylogenetic tree, we further analyzed the taxonomic confusion of Carangoides equula which was on the same branch with P. dentex but a different branch with Carangoides spp. We inferred Kaiwarinus equula should be the accepted name and belong to the independent Kaiwarinus genus which was the sister genus of Pseudocaranx. This work provides mitochondrial genetic information and verifies the taxonomic status of P. dentex, and further helps to recognize the phylogenetic relationship and evolutionary history of Carangidae.

Population-level morphological variation of Anisotremus interruptus (Gill, 1862) (Perciformes: Haemulidae) in the Tropical Eastern Pacific, with the description of two new species.

The family Haemulidae is a wide-ranging group of marine fishes that are of significant commercial value in the Tropical Eastern Pacific (TEP). Phylogenetic studies on the species Anisotremus interruptus have revealed high levels of genetic diversity as well as divergence among populations in the TEP, which suggests that the taxonomic diversity of A. interruptus could be underestimated. Anisotremus interruptus has a large distribution, ranging from central Baja California, Mexico to northern Peru, including all oceanic islands except Clipperton. Recent genetic studies on this taxon indicate the presence of a species complex of at least three distinctive lineages. We performed a comparative study of the population-level meristic and morphometric variation of A. interruptus in the TEP to evaluate and identify possible morphological features concordant with the genetic differentiation of populations. Our results provide evidence of the presence of two new species of the genus Anisotremus, A. perezponcedeleoni sp. n. from the Revillagigedo Archipelago and A. espinozai sp.n. from Galapagos Archipelago-Cocos Island.

Five new species of Western Atlantic stardrums, Stellifer (Perciformes: Sciaenidae) with a key to Atlantic Stellifer species.

Five new species of Stellifer are described from the Caribbean Sea and tropical southwestern Atlantic. Among the previously recognized stelliferine genera, Stellifer is unique by having a pair of variably developed appendages on the posterior margin of the anterior gas chamber, which is lacking in Bairdiella, Corvula, Elattarchus, Odontoscion and Ophioscion. However, recent genetic studies indicated that Stellifer and Ophioscion are not monophyletic. The genus Ophioscion Gill, 1863 is recognized herein as a junior synonym of Stellifer Oken, 1817. Of the five new species described, Stellifer cervigoni n. sp., S. collettei n. sp., and S. musicki n. sp. have a pair of knob-like diverticula along the posterior margin of the anterior gas chamber, which is absent in S. macallisteri n. sp., and S. menezesi n. sp. Stellifer cervigoni n. sp. is found along the southern Caribbean coast of Colombia and Venezuela; it can be distinguished from other species by having a jet-black roof of mouth and inner opercular lining. Stellifer collettei n. sp. is found from Surinam to southeastern Brazil, while S. musicki n. sp. is endemic to northern Brazil. Stellifer macallisteri n. sp. has an oblique, terminal mouth and it is found in Colombia, Venezuela and Dominican Republic. Stellifer menezesi n. sp. has a subterminal mouth and is found from northeastern to southeastern Brazil. These results bring the number of valid species of Stellifer in the Atlantic to 18, and a key to the identification of these species is included.

A review of the Glossogobius giuris complex in Australia, with wider discussion on nomenclature and possible synonymies.

Two species that had previously been referred to as Glossogobius giuris from Australia are redescribed and tentatively treated as Glossogobius giuris and Glossogobius laticeps. The two species are largely allopatric in Australia with G. laticeps found on the east coast of Queensland and some rivers of the Northern Territory, while G. giuris is distributed from the Northern Territory to rivers of the west coast of Western Australia. The two species are known to be genetically distinct and with some differences in colour patterns. Morphological features separating the species are minor and there is considerable overlap in many of the characters separating them. High variation in the Hammersley Ranges and Kimberley region of Western Australia further complicates separation of the species. The status of the Glossogobius giuris group from India is discussed as a key area to resolving an overall "giuris" species complex. Information is provided on the current identity of a number of species that had previously been considered synonyms of Glossogobius giuris. Extant types and difficulties assigning the types of known species are also discussed. A key is provided to aid identification of Australian species of Glossogobius.

Description of a new eelpout Pachycara angeloi sp. nov. (Perciformes: Zoarcidae) from deep-sea hydrothermal vent fields in the Indian Ocean.

A new species of eelpout genus Pachycara Zugmayer, 1911 is described based on five specimens caught at a depth of 24193275 m along the Central and Southeast Indian Ridges in the Indian Ocean. The specimens were collected during the INDEX cruises in 2016, 2018 and 2019, respectively. The new species is distinguished from its congeners by the following combination of characters: scales and pelvic fins absent; lateral line configuration mediolateral; dorsal fin origin associated with vertebrae 79 with no free predorsal pterygiophores; vertebrae 2728 + 5759 = 8587; dorsal-fin rays 7880, anal-fin rays 5862; pectoral fin rays 1315. DNA sequences of a mitochondrial COI gene fragment showed low intra-specific variation ranging from 00.3 % sequence divergence and do not reflect different vent sites. This is the 29th species of Pachycara, which is the fifth to be described from specimens collected only from chemosynthetic environments and the sixth known from the Indian Ocean.

A new species of tadpole-goby, Benthophilus persicus sp. nov. (Teleostei: Gobiidae) from the southern Caspian Sea.

A new gobiid species, Benthophilus persicus sp. nov., is described from the southern Caspian Sea, Iran. The new species is diagnosed by the following character states: dermal fold on cheek well-developed, large, rectangular; chin barbel 1/32/3 of eye diameter; maximum body width 15.122.9% of standard length; mouth width, 36.355.8% of head length; second dorsal fin I+78; origin of anal fin in front of vertical through origin of second dorsal fin; dermal tubercles present on body, clearly larger than granules, with two posterior rows of spinules forming an acute angle, always less than right angle; dorsal row of tubercles complete, 2229; ventral row of tubercles 2225; ventrolateral row of tubercles absent; tubercles not present on temporal and occipital head regions; granules not present on flanks; transversal suborbital row 6i below posterior end of row b; anterior interorbital transversal row pa with one or two papillae and anterior interorbital transversal papilla row pp with two or three papillae; body with 2022 transversal ltm rows starting anteriorly behind pectoral axilla and alternating anteriorly with three longitudinal llm rows.

The biogeographic history of eelpouts and related fishes: Linking phylogeny, environmental change, and patterns of dispersal in a globally distributed fish group.

Modern genetic data sets present unprecedented opportunities to understand the evolutionary origins of diverse taxonomic groups. When the timing of key events is known, it is possible to investigate biogeographic history in the context of major phenomena (e.g., cooling of a major ocean). In this study, we investigated the biogeographic history of the suborder Zoarcoidei, a globally distributed fish group that includes species inhabiting both poles that produce antifreeze proteins to survive chronic subfreezing temperatures. We first generated a multi-locus, time-calibrated phylogeny for the group. We then used biogeographic modeling to reconstruct ancestral ranges across the tree and to quantify the type and frequency of biogeographic events (e.g., founder, dispersal). With these results, we considered how the cooling of the Southern and Arctic Oceans, which reached their present-day subfreezing temperatures 10-15 million years ago (Mya) and 2-3 Mya, respectively, may have shaped the group's evolutionary history, with an emphasis on the most speciose and widely distributed family, eelpouts (family Zoarcidae). Our phylogenetic results clarified the Zoarcoidei taxonomy and showed that the group began to diversify in the Oligocene ~31-32 Mya, with the center of origin for all families in north temperate waters. Within-area speciation was the most common biogeographic event in the group's history (80% of all events) followed by dispersal (20%). Finally, we only found evidence, albeit limited, for ocean cooling underpinning diversification of eelpouts living in the high Antarctic over the last 10 million years.

Hierarchical genetic structure in an evolving species complex: Insights from genome wide ddRAD data in Sebastes mentella.

The diverse biology and ecology of marine organisms may lead to complex patterns of intraspecific diversity for both neutral and adaptive genetic variation. Sebastes mentella displays a particular life-history as livebearers, for which existence of multiple ecotypes has been suspected to complicate the genetic population structure of the species. Double digest restriction-site associated DNA was used to investigate genetic population structure in S. mentella and to scan for evidence of selection. In total, 42,288 SNPs were detected in 277 fish, and 1,943 neutral and 97 tentatively adaptive loci were selected following stringent filtration. Unprecedented levels of genetic differentiation were found among the previously defined 'shallow pelagic', 'deep pelagic' and 'demersal slope' ecotypes, with overall mean FST = 0.05 and 0.24 in neutral and outlier SNPs, respectively. Bayesian computation estimated a concurrent and historical divergence among these three ecotypes and evidence of local adaptation was found in the S. mentella genome. Overall, these findings imply that the depth-defined habitat divergence of S. mentella has led to reproductive isolation and possibly adaptive radiation among these ecotypes. Additional sub-structuring was detected within the 'shallow' and 'deep' pelagic ecotypes. Population assignment of individual fish showed more than 94% agreement between results based on SNP and previously generated microsatellite data, but the SNP data provided a lower estimate of hybridization among the ecotypes than that by microsatellite data. We identified a SNP panel with only 21 loci to discriminate populations in mixed samples based on a machine-learning algorithm. This first SNP based investigation clarifies the population structure of S. mentella, and provides novel and high-resolution genomic tools for future investigations. The insights and tools provided here can readily be incorporated into the management of S. mentella and serve as a template for other exploited marine species exhibiting similar complex life history traits.

Redescription and molecular characterization of two species of Pauciconfibula (Monogenea, Microcotylidae) from trachinid fishes in the Mediterranean Sea.

Many Pauciconfibula spp. have a long and complicated taxonomic history. The remaining unsolved taxonomic confusion in this genus is impelled by the host range and status of Pauciconfibula spp. from trachinid fishes: Pauciconfibula trachini and Pauciconfibula draconis, from Trachinus radiatus and Trachinus draco (Trachinidae), respectively. Pauciconfibula trachini was reported on Trachinus draco, type host of Pauciconfibula draconis suggesting thus a stenoxenic specificity for the former monogenean and the occurrence of two congeneric polyopisthocotyleans on a single host. Moreover, the validity of Pauciconfibula draconis was repeatedly questioned by several authors, unjustified synonymy between the two species was proposed, and the delimitations between the two species remained unsolved. Original descriptions were also incomplete and poorly illustrated. In this study, we provide a detailed illustrated redescription of both species based on newly collected specimens of Pauciconfibula trachini and Pauciconfibula draconis collected from their type hosts from off three Mediterranean localities: Algeria, Tunisia, and Italy. Integrative taxonomy using COI sequences was applied to resolve the delimitation between Pauciconfibula trachini and P. draconis. This study provides the first DNA barcoding for members of this genus.