Chromosomal DNA sequences of the Pacific saury genome: versatile resources for fishery science and comparative biology.

Pacific saury (Cololabis saira) is a commercially important small pelagic fish species in Asia. In this study, we conducted the first-ever whole genome sequencing of this species, with single molecule, real-time (SMRT) sequencing technology. The obtained high-fidelity (HiFi) long-read sequence data, which amount to ~30-folds of its haploid genome size that was measured with quantitative PCR (1.17 Gb), were assembled into contigs. Scaffolding with Hi-C reads yielded a whole genome assembly containing 24 chromosome-scale sequences, with a scaffold N50 length of 47.7 Mb. Screening of repetitive elements including telomeric repeats was performed to characterize possible factors that need to be resolved towards 'telomere-to-telomere' sequencing. The larger genome size than in medaka, a close relative in Beloniformes, is at least partly explained by larger repetitive element quantity, which is reflected in more abundant tRNAs, in the Pacific saury genome. Protein-coding regions were predicted using transcriptome data, which resulted in 22,274 components. Retrieval of Pacific saury homologs of aquaporin (AQP) genes known from other teleost fishes validated high completeness and continuity of the genome assembly. These resources are available at https://treethinkers.nig.ac.jp/saira/ and will assist various molecular-level studies in fishery science and comparative biology.

Intra-population variability of the saccular, utricular and lagenar otoliths of the garfish Belone belone (Linnaeus, 1760) from South-Western Ionian Sea (Central Mediterranean Sea).

The garfish Belone belone represents the only valid endemic Belone species for the Mediterranean Sea and the eastern Atlantic Ocean. It shows a wide global distribution range, with a high commercial value and ecological relevance in the pelagic domain. Despite this, there needs to be more knowledge regarding the otoliths of this species, with the total absence of descriptions regarding asterisci and lapilli from Mediterranean populations and a lack of studies on the reliability of shape analysis on its sagittae. The present paper aims to provide the first main contours description of the three otoliths pairs from a Mediterranean population, providing an accurate investigation of morphology, morphometry, and intra-specific variability of sagittae, lapilli, and asterisci. Results showed (i) the absence of directional bilateral asymmetry and sexual asymmetry for the three otoliths pairs, (ii) a different morphology and morphometry of sagittae, lapilli and asterisci than those described in the literature, and (iii) an enhanced variability between sagittae morphometry and shape between the three investigated size classes. All these data confirmed the reliability of the studied species of shape analysis, showing a geographical and size-related variability of otoliths features probably related to genetics, environmental conditions, and life habits variations.

Clinical Reasoning: A 24-Year-Old Woman With Penetrating Neck Injury From a Needlefish.

Evaluating patients with a traumatic spinal cord injury can be complicated by other injuries. In this case, a 24-year-old woman injured by a needlefish presented with combined motor and sensory defects, cranial nerve deficits, and a blunt vascular injury. This case highlights the importance of neurologic and vascular localizations and an understanding of spinal cord injuries involving various ascending and descending tracts. Appreciation of these anatomical considerations through this case illustrates the diagnostic approach to neurologic evaluation. While we present a traumatic etiology for multiple neurologic syndromes, this case gives readers an opportunity to develop a comprehensive differential diagnosis and tailor investigations for other relevant etiologies. Readers walking through this stepwise process will ultimately arrive at several distinct but related diagnoses.

Molecular species delimitation of marine trematodes over wide geographical ranges: Schikhobalotrema spp. (Digenea: Haplosplanchnidae) in needlefishes (Belonidae) from the Pacific Ocean and Gulf of Mexico.

Geographical distribution plays a major role in our understanding of marine biodiversity. Some marine fish trematodes have been shown to have highly restricted geographical distributions, while some are known to occur over very wide ranges; however, very few of these wide distributions have been demonstrated genetically. Here, we analyse species of the genus Schikhobalotrema (Haplosplanchnidae) parasitizing beloniforms from the tropical west Pacific, the eastern Pacific and the Gulf of Mexico (GoM). We test the boundaries of these trematodes by integrating molecular and morphological data, host association, habitat of the hosts and geographical distribution, following a recently proposed and standardized delineation method for the recognition of marine trematode species. Based on the new collections, Schikhobalotrema huffmani is here synonymized with the type-species of the genus, Schikhobalotrema acutum; Sch. acutum is now considered to be widely distributed, from the GoM to the western Pacific. Additionally, we describe a new species, Schikhobalotrema minutum n. sp., from Strongylura notata and Strongylura marina (Belonidae) from La Carbonera coastal lagoon, northern Yucatán, GoM. We briefly discuss the role of host association and historical biogeography of the hosts as drivers of species diversification of Schikhobalotrema infecting beloniforms.

Redescription and molecular characterization of Mothocya parvostis Bruce, 1986 (Crustacea: Isopoda: Cymothoidae) parasitic on Japanese halfbeak, Hyporhamphus sajori (Temminck & Schlegel, 1846) (Hemiramphidae) with Mothocya sajori Bruce, 1986 placed into synonymy.

Two species of Mothocya have previously been recorded from Hyporhamphus sajori: M. parvostis Bruce, 1986 and M. sajori Bruce, 1986. Mothocya parvostis is re-described based on the ovigerous female type and additional materials collected from the host from in and around the type locality. Morphological re-examination of fresh specimens and the type materials together with genetic data show that the M. sajori and M. parvostis are the same species, differing primarily in size, therefore we have placed Mothocya sajori Bruce, 1986 into a junior synonym of Mothocya parvostis Bruce, 1986. Mothocya parvostis is characterized by the following combinations of characters: 1) body slightly to moderately twisted to one side; 2) pereonite 7 posterior margin moderately to deeply recessed; 3) uropodal rami extending to pleotelson posterior margin; and 4) uropod rami bluntly rounded, exopod 1.5 times as long as peduncle. The differences of four morphological features for M. parvostis and M. sajori was quantified. Furthermore, a total of 635 isopods infesting H. sajori were collected from all over Japan to conduct quantitative morphological and molecular sequence analyses (mitochondrial cytochrome c oxidase subunit I and 16S rRNA). Although the four quantitative features did not overlap between the two species in type specimens, all quantitative morphological values of newly collected specimens in this study did not display a bimodal distribution. In addition, our molecular analyses found only a single clade for our newly collected specimens in neighbor-joining tree.

Mothocya kaorui n. sp. (Crustacea: Isopoda: Cymothoidae), a fish-parasitic isopod with unique antennules from the Izu Islands, Japan.

A new species of fish-parasitic isopod in the family Cymothoidae is described from the Izu Islands, Japan. Mothocya kaorui n. sp. is reported from the gill cavities of the keeled needlefish, Platybelone argalus platyura (Bennett). Despite its unique morphological characters, such as completely article-fused antennules, mitochondrial DNA analysis indicated that it belongs to Mothocya Costa. The new species is clearly distinguished from all other species of Mothocya by having completely fused, stout antennules and partially fused, slender antennae; maxilla mesial lobe with 3 or 4 recurved robust setae, lateral lobe with 4-6 recurved robust setae; maxilliped with 5-8 robust setae on article 3; coxae 2 and 3 wide; black subtriangular pleotelson; and black uropods.

Challenging foreign body surgery: residual needlefish jaws.

We report a case of a needlefish jaws retained near the C5-C6 joint that was associated with chronic pain and inflammation and seen confirmed by FDG-PET scan. Two unsuccessful surgeries using an anterior approach were complicated by vascular and nerve injuries. We used image-guided surgery with a posterior approach.

Axinids (Monogenoidea: Mazocraeidea: Microcotylinea) infecting the gill lamellae of some beloniform fishes in the Gulf of Mexico, with descriptions of Axine buccina n. sp. from Hyporhamphus unifasciatus (Ranzani) and Nudaciraxine timucua n. sp. from Strongylura timucu (Walbaum).

Five species of Axinidae (Monogenoidea: Mazocraeidae) were recovered from the gill lamellae of four of six species of needlefishes and halfbeaks examined from the Gulf of Mexico off Florida: Axine buccina n. sp. from a common halfbeak Hyporhamphus unifasciatus (Ranzani); Nudaciraxine gracilis (Linton, 1940) Price, 1962 (minimum prevalence 60%) from the Atlantic needlefish Strongylura marina (Walbaum); Nudaciraxine timucua n. sp. (36%) from the timucu Strongylura timucu (Walbaum); and Axinoides raphidoma Hargis, 1956 (29%) and Chlamydaxine truncata (Hargis, 1956) Unnithan, 1957 (29%) both from the houndfish Tylosurus crocodilus (Péron & LeSueur). The American halfbeak Hyporhamphus meeki Banford & Collette (24 specimens examined) and the redfin needlefish Strongylura notata (Poey) (94 specimens) were uninfected with axinids. The two new axinid species were figured and described. The current status of the Axinidae was explored, which suggested that an objective evaluation of its position within the Monogenoidea is needed.

A new species of Prosorhynchoides Dollfus, 1929 (Digenea: Bucephalidae) from Xenentodon cancila Hamilton, 1822 in Mizoram, Northeast India.

Prosorhynchoides aspinosus n. sp., a new species of digenean trematode, is described based on morphological, ultrastructural and molecular data from the freshwater fish, Xenentodon cancila Hamilton, 1822, of Tuikum and Tuirial river in Mizoram, Northeast India. It differs from its congeners in the absence of tegumental spines and the length of cirrus sac. These unique morphological characteristics were further supported by the ultrastructural data showing distinct knob-like protrusions in the tegument. Each knob-like protrusion is without cutting plates or spines and appears granulated at higher magnification. The molecular data analyses, along with the sequences of other Prosorhynchoides available in the Genbank, using internal transcribed spacer 2 and 28S rDNA revealed a gap of 4% K2P (Kimura 2 parameter) distance with its closest congener, P. karvei, confirming the novelty of the species, and thus, clearly differentiates the new species from all other valid Prosorhynchoides spp.

How to stay attached-Formation of the ricefish plug and changes of internal reproductive structures in the pelvic brooding ricefish, Oryzias eversi Herder et al. (2012) (Beloniformes: Adrianichthyidae).

Teleost fishes show an enormous diversity of parental care, ranging from no care to viviparity with maternal provisioning of embryos. External brooders carry their developing eggs attached to their bodies. This requires the formation of novel morphological structures to support attachment. The pelvic brooding ricefish Oryzias eversi evolved such a structure, called the "plug." The plug anchors attaching filaments from the fertilized eggs inside the female reproductive system, allowing the female to carry the embryos until hatching. Using histological sections and µ-computed tomography scanning, we show that the plug is formed by several types of interstitial cells, blood capillaries, and collagen fibrils that encapsulate the end of the attaching filaments in the anterior part of the gonoduct. Even 15 days after the loss of the protruding attaching filaments, the plug remains. In addition, the developed plug contains multinucleated giant cells that are derived from fusing macrophages. We thus hypothesize that the ricefish plug, which is vital for egg attachment in O. eversi, evolved due to an inflammatory reaction. We assume that it forms similar to a foreign body granuloma, as a reaction to irritation or injury of the gonoduct epithelium by the attaching filaments. Our study further corroborates that pelvic brooding entails a complex set of adaptations to prolonged egg-carrying in the female reproductive system. During brooding, for instance, ovulation in the ovary is suppressed and the anterior part of the gonoduct is characterized by an intricate, recessed folding.

Effects of oceanographic environment on the distribution and migration of Pacific saury (Cololabis saira) during main fishing season.

The Pacific saury (Cololabis saira) is one of the most commercially important pelagic fishes in Asia-Pacific countries. The oceanographic environment, especially the Oyashio Current, significantly affects the distribution of Pacific saury, and may lead to variations in their migration route and the formation of fishing grounds in Japanese coastal region and the high seas. In this study, six oceanographic factors, sea surface temperature (SST), sea surface chlorophyll-a concentration (SSC), sea surface salinity (SSS), sea surface height (SSH), mixed layer depth (MLD), and eddy kinetic energy (EKE), were associated with the monthly catch per unit effort 1 (monthly CPUE1, ton/vessel) and the monthly CPUE2 (ton/day) of Pacific saury from Chinese fishing vessels during the optimal fishing periods (September-November) in 2014-2017. The gradient forest analysis showed that the performance of monthly CPUE1 was higher than monthly CPUE2 and SST was the most important oceanographic factor influencing monthly CPUE1, followed by EKE. The generalized additive model indicated that SST, SSH, and EKE negatively affected monthly CPUE1, whereas SSC, SSS, and MLD induced dome-shaped increases in monthly CPUE1. The distributions of fishing locations are likely to form along Offshore Oyashio current and meanders, especially in October and November. Synchronous trends in the relationship between the intrusion area of the Oyashio and relative abundance variation index suggest that an increase in the intrusion area of the Oyashio causes more Pacific saury to migrate to the Japanese coastal region, and vice versa. These findings extend our understanding of the effects of the oceanographic environment on Pacific saury.

The light-dependent daily cycle of ovulation in the oviparous medaka fish, Oryzias latipes (Atherinomorpha: Beloniformes: Adrianichthyidae) artificially pregnant with developing embryos.

In the oviparous medaka fish, Oryzias latipes, mature spermatozoa that were artificially introduced into the ovarian cavity retaining ovulated eggs could internally fertilize these eggs. This enabled us to examine the effect of ovarian gestation on the ovulation cycle. Most freshly ovulated eggs could be internally fertilized in the ovarian cavity. Yet eggs ovulated 24 h after single insemination remained unfertilized in the ovarian cavity. Artificially pregnant females persisted in a daily cycle of ovulation, which occurred shortly before the onset of light under the present reproductive conditions. Females continuously ovulated a certain number of eggs despite ovarian gestation, that is, the presence of embryos within the ovarian cavity. Repeated cycles of ovulation led to crowding in the ovarian cavity because the group of fertilized eggs, with their hardened egg envelope (chorion or zona radiata), plugged the genital orifice. The development of fertilized eggs was retarded and ceased around the initiation stage of blood circulation, but when they were transferred from the ovarian cavity into regular saline, they regained their ability to develop normally up to hatching. These results show that in oviparous female medaka, ovarian gestation exerted little effect on the time of ovulation and the number of ovulated eggs.

A review of the flying fish genus Cypselurus (Beloniformes: Exocoetidae). Part 2. Revision of the subgenus Poecilocypselurus Bruun, 1935 with descriptions of three new species and five new subspecies and reinstatement of Exocoetus apus Valenciennes and E. neglectus Bleeker.

The second part of the review of flying fishes of the genus Cypselurus Swainson, 1838 covers the following: C. oligolepis (Bleeker, 1865) is a composite of six different species: C. oligolepis, C. izumii sp. nov., C. clariangulatus sp. nov., C. neglectus (Bleeker, 1865), C. nossibe sp. nov. (here placed in the subgenus Cypselurus s.str.) and Cypselurus sp.. Two of these species were found to be polytypic: C. oligolepis (with subspecies C. o. oligolepis, C. o. apus (Valenciennes, 1847), C. o. persicus subsp. nov. and C. o. georgii subsp. nov.) and C. neglectus (with subspecies C. n. neglectus and C. n. shcherbachevi subsp. nov.). Cypselurus poecilopterus (Valenciennes, 1847) is also polytypic and is divided into three subspecies: C. p. poecilopterus, C. p. arabicus subsp. nov. and C. p. crassus subsp. nov. Exocoetus apus Valenciennes (as a subspecies) and E. neglectus Bleeker are reinstated as valid. The morphology of C. starksi Abe, 1953, C. oligolepis, C. izumii, C. clariangulatus, C. neglectus and C. nossibe at different stages of ontogeny is described and maps of their geographical distribution provided. Lists of synonymy and bibliography for these species and C. poecilopterus, C. simus (Valenciennes, 1847) and C. callopterus (Gnther, 1866) are compiled. A key for identification of species and subspecies of the subgenus Poecilocypselurus Bruun, 1935 and C. nossibe is provided.

New trematode species Lecithostaphylus halongi n. sp. (Zoogonidae, Microphalloidea) and Gymnotergestia strongyluri n. sp. (Fellodistomidae, Gymnophalloidea) from beloniform fishes in Vietnam.

In this study we described two new trematode species, Lecithostaphylus halongi n. sp. (Zoogonidae, Lecithostaphylinae) and Gymnotergestia strongyluri n. sp. (Fellodistomidae, Tergestiinae), on the basis of morphological and molecular data. Adult worms of these two species were collected from, respectively, Hemiramphus spp. (Hemiramphidae) and Strongylura strongylura (Belonidae) caught in the coastal waters of Vietnam. Adult worms of L. halongi n. sp. are morphologically close to Lecithostaphylus gibsoni Cribb, Bray & Barker, 1992 ex Abudefduf whitleyi from Heron Island and Lecithostaphylus depauperati Yamaguti, 1970 ex Hemiramphus depauperatus from Hawaii, but differ from these species in having a larger cirrus sac and a different arrangement of vitelline fields. They also differ from Lecithostaphylus brayi Cabañas-Granillo, Solórzano-García, Mendoza-Garfias & Pérez-Ponce de León, 2020 in the 28S ribosomal DNA (rDNA) sequence data at the interspecific level. Adult worms of G. strongyluri n. sp. ex S. strongylura are morphologically similar to Gymnotergestia chaetodipteri, the only previously known species of this genus, described from Chaetodipterus faber in Jamaica. The new species differs from G. chaetodipteri in body shape, testicular arrangement and the size of the pharynx and eggs. The 28S rDNA-based phylogenetic analysis indicates that G. strongyluri n. sp. is closely related to Tergestia spp., rendering Tergestia paraphyletic. Genetic divergence values between G. strongyluri n. sp. and Tergestia spp. are similar to those among species in the genera Tergestia, Steringophorus and Proctoeces. Our molecular results indicate that G. strongyluri n. sp. and Tergestia spp. may belong the same genus, but additional molecular data are needed for the final conclusion.

Redescription of Ptychobothrium belones (Dujardin, 1845) (Cestoda: Bothriocephalidea) from needlefishes (Beloniformes: Belonidae) in the Mediterranean Sea.

The bothriocephalidean tapeworm Ptychobothrium belones (Dujardin, 1845) Lönnberg, 1889 is redescribed on the basis of new materials collected from the intestine of the Mediterranean needlefish Tylosurus imperialis (Rafinesque) (Beloniformes: Belonidae) off Tunisia in the central Mediterranean Sea. This species is characterised by a laterally compressed hexagonal to fan-shaped scolex with an apical disc and two well-developed bothria, an oval ovary and numerous testes arranged in lateral and median fields. The typical diagnostic feature of P. belones is the medullary yolk follicles located between the muscle fibres of the internal longitudinal muscles (paramuscular) and the uterine duct strongly sinuous, S-shaped in mature proglottides. New molecular data (partial sequence of nuclear large subunit ribosomal RNA gene) confirmed the close relationship with specimens previously collected by Brabec et al. (2006, 2015) from the banded needlefish Strongylura leiura (Bleeker) off the Maldives, Indian Ocean, but these specimens are most likely another species. Thus, Ptychobothrium belones as previously reported represents most likely more than one species and its cosmopolitan distribution and host specificity revised by Kuchta et al. (2008b) should be revisited. The type material of P. belones was reported as collected in Mediterranean Sea off Sète, France, from Belone belone (Linnaeus); however, this host was probably misidentified, being confused with morphologically similar small specimens of T. imperialis. This study confirms that P. belones is an exclusive parasite of needlefishes (Belonidae) but at least one further species infecting S. leiura may exist.

Penetrating occipitocervical injury caused by a needlefish.

Penetrating injuries caused by needlefish are very uncommon. Most of them have been reported in the Indo-Pacific region. We report a case of an occipito-cervical penetrating injury that occurred in the Mexican Tropical Pacific, and we describe the treatment of this injury.

Las heridas penetrantes por pez aguja son poco comunes. La mayor parte de los reportes han sido en la región Indo-Pacífico. Reportamos un caso de herida penetrante occipitocervical ocurrida en el Pacífico tropical mexicano y se describe el tratamiento de esta lesión.

Traumatic Neck Injury: An Accidental Impalement by a Needlefish.

Encounters between marine animals and humans can result in critical injury and fatal complications. We highlight a 20-y-old male who sustained a penetrating injury to the neck as a result of impalement by needlefish (Tylosurus sp) while snorkeling. He sustained a penetrating injury in the posterior triangle of the neck. On presentation, he was stabilized and received empirical antibiotics, analgesia, and antitetanus toxoid injection before being transferred to a tertiary center. On presentation to the tertiary hospital, the patient was hemodynamically stable with no clinical evidence of injury to surrounding neck structures, and this was confirmed using computed tomography. The patient underwent local wound exploration and retrieval of the needlefish beak under general anesthesia. The wound was left open to heal by secondary intention. The patient was discharged with oral antibiotics and went on to make a complete recovery.

Flying fishes (Beloniformes: Exocoetidae) of the Socotra Archipelago with comments on status of Exocoetus socotranus Steindachner.

A checklist of the flying fishes found in the waters off Socotra Archipelago, northwestern part of the Indian Ocean, is provided based on published and original data. Thirteen species from five genera occur in the study area, and four more species found nearby. Keys for the species identification are provided. The type specimen of Exocoetus socotranus Steindachner, 1902 was examined and is determined to be a junior synonym of Cypselurus naresii (Günther, 1889).

Morphological and genetic description of two new species of philometrid nematodes (Philometridae) parasitic in needlefishes (Belonidae) from estuaries of Florida, USA.

Two new species of philometrid nematodes (Philometridae) from needlefishes (Belonidae) in Florida are described based on morphological and genetic characteristics: Philometra aequispiculata sp. n. (males and females) collected from the ovary of Strongylura marina (Walbaum) (type host) and Strongylura notata (Poey), and Philometra notatae sp. n. (females) from the swimbladder of S. notata. Both species are described and illustrated based on light and scanning electron microscopical examinations. Morphologically, P. aequispiculata sp. n. differs from all congeners mainly in the unique structure of the distal tip of the gubernaculum, whereas P. notatae sp. n. is mainly characterised by the presence of eight markedly large cephalic papillae of the outer circle in gravid and subgravid females, the body length of the gravid female (54 mm) and by the absence of caudal projections. Molecular characterisation of the new species was assessed from phylogenetic analysis of mitochondrial cytochrome c oxidase I (COI) and SSU rRNA small-subunit ribosomal RNA (SSU) sequences among closely related philometrids by way of Bayesian inference. Phylogenetic reconstructions based on COI and SSU sequences show each of the new species comprise discrete ancestor-descendent lineages.