Resolution of cryptic species complexes within the genus Metagonimus (Trematoda: Heterophyidae) in Japan, with descriptions of four new species.

A nationwide fish survey was conducted in Japan to detect metacercariae of the genus Metagonimus (Trematoda: Heterophyidae). The metacercariae were subjected to DNA barcoding for molecular species identification. A phylogeny inferred from the sequences of mitochondrial cytochrome c oxidase subunit 1 (cox1) prompted us to recognize three cryptic species complexes (i.e., the M. miyatai complex, the M. takahashii complex, and the M. katsuradai complex). Each complex included one or two undescribed species. For morphological description, adult flukes of each species were raised through the experimental infections of immunosuppressed mice. We propose M. saitoi n. sp., M. kogai n. sp., M. shimazui n. sp., and M. kinoi n. sp., based on their phylogeny, morphology, biogeography, and ecology (host-parasite relationships). The originally described species, M. miyatai, was split into M. miyatai sensu stricto and M. saitoi n. sp. The former is distributed mainly in eastern Japan and uses the sweetfish (Plecoglossus altivelis) and daces (Pseudaspius hakonensis and Ps. sachalinensis) as principal second intermediate hosts, while the latter is in western Japan and its principal fish hosts are the dark chub (Nipponocypris temminckii) and the pale chub (Opsariichthys platypus). The present survey resolves a long-standing controversy on the microtaxonomy of Metagonimus in Japan since the first discovery of Metagonimus yokogawai in 1912, and shows that 10 species of Metagonimus are still distributed in Japan, although human metagonimiasis is almost eradicated.

Two new species of the snake eel genus Bascanichthys (Anguilliformes: Ophichthidae) from the northwestern Pacific.

Two new species of the elongate snake eel genus Bascanichthys are described from the northwestern Pacific. Bascanichthys kabeyawan sp. nov. is described based on a single specimen collected from estuary of southern Taiwan. It is characterized by having head 4.6% TL; tail 52.3% TL; body depth at gill opening 1.1% TL; predorsal-fin length 58.4% HL; snout length 10.9% HL; body bicolored, head without bands; lateral-line pores anterior to anus 104; vertebral formula 4-103-224. Bascanichthys ryukyuensis sp. nov. is described based on two specimens collected from the shallow water of Okinawa-jima Island, Ryukyu Islands of southern Japan. It is characterized by having head 3.7-4.3% TL; tail 43.3-44.2% TL; predorsal-fin length 40.7-45.4% HL; snout length 11.3-13.1% HL; body pale brown, head without distinct dark bands after preservation; lateral-line pores anterior to anus 114-118; total vertebrae 207-216, mean vertebral formula 2-116-212; and dorsal-fin origin before middle of head.

Morphology, Diet, and Reproduction of Coastal Hydrophis Sea Snakes (Elapidae: Hydrophiinae) at Their Northern Distribution Limit.

The Ryukyu Archipelago represents the northern distribution limit for hydrophiine sea snakes, the largest group of marine reptiles. Ryukyuan sea snakes may have developed distinct local adaptations in morphology and ecology, but they have been poorly studied. We examined preserved specimens of 111 Hydrophismelanocephalusand 61 Hydrophis ornatusfrom the Ryukyu Archipelago to obtain data on morphology, diet, and reproduction. Sexual size dimorphism was detected in H. melanocephalus (mean ± standard deviation of adult snout-vent length: SVL, females 1062 ± 141 mm vs. males 959 ± 96 mm) but not in H. ornatus. Female H. melanocephalus had larger head widths and shorter tail lengths relative to SVL compared to males. Relative girth was low in neonates of both species (1.0-1.3), but increased in adults to about 1.7-2.6 in H. melanocephalus and 1.3-1.8 in female H. ornatus. Stomach contents of H. melanocephalus consisted of ophichthid and congrid eels, a sand diver, and gobies, whereas in H. ornatus, gobies and a goat fish were found. Litter size of three reproductive H. melanocephalus ranged from five to seven, and parturition seems to occur from August to October. Litter size of six H. ornatus ranged from two to seven, and was correlated with maternal SVL. Parturition in H. ornatus probably occurs around November. Different selective forces related to locomotion, feeding and predation risk, which influence the pregnant mother and neonates, may have resulted in having few, long but slender offspring that show positive allometric growth in hind-body girth.

Resurrection of Ophichthus zophistius (Actinopterygii: Anguilliformes: Ophichthidae), with a revised diagnosis of O. altipennis.

Pisoodonophis zophistius Jordan and Snyder 1901 is redescribed as a valid species of Ophichthus Ahl 1789 based on 46 specimens including the holotype. Although this name has been synonymized under Ophichthus altipennis (Kaup 1856), the former can be distinguished from the latter by a relatively acute snout (vs. strongly acute), presence of irregular obscure bars on the body (vs. bars absent), 11-13 predorsal and 61-63 preanal vertebrae (vs. 8-9 and 52-58, respectively) and 10-14 predorsal and 59-64 preanal lateral-line pores (vs. 7-9 and 55-61, respectively), dorsal-fin origin usually above or behind the pectoral-fin insertion (vs. anterior to the insertion), and tail broad and tapered slowly (vs. becoming slender and tapered rapidly). Furthermore, Ophichthys intermedius Regan 1905 and Microdonophis fasciatus Chu, Wu and Jin 1981 are junior synonyms of O. zophistius, and Ophichthus melanochir Bleeker 1864 is that of O. altipennis.

Description of a new species of deep-water snake eel, Ophichthus mccoskeri (Ophichthidae: Ophichthinae) from Andaman Sea, India.

A deep-sea species of snake eel (family Ophichthidae, subfamily Ophichthinae) Ophichthus mccoskeri sp. nov. is described based on 6 specimens (331-447 mm total length) trawled at 314-363 m depth in Andaman waters, India. This species is differentiated from its deep-water congeners by a combination of characters such as its large eyes, dorsal-fin origin a short distance behind pectoral-fin tip, anal fin black posteriorly, three preopercular pores, maxillary and mandibular teeth ending as triserial, and in a vertebral formula of 20/55/153.

A new species of Muraenichthys (Anguilliformes: Ophichthidae) from Taiwan, with redescription of Muraenichthys thompsoni Jordan amp; Richardson, 1908.

Muraenichthys longirostris sp. nov. is described based on a single specimen 206 mm total length (TL) collected from off Dong-gang, southwestern Taiwan. The species is characterized by a long and slender snout (18% of head length), unique within the genus. It is also characterized by its position of the dorsal-fin origin (positioned at 2/5 of trunk; horizontal distance from the origin to a vertical through mid-anus 113% of head length), long tail (67% TL), and vertebrae 23-41-131. In addition, Muraenichthys thompsoni Jordan Richardson, 1908 is redescribed based on the holotype and 63 specimens from Fiji to Madagascar, north to Japan. Muraenichthys malabonensis Herre, 1923 is recognized as a junior synonym of M. thompsoni.

Two new species of the genus Ophichthus from the western central Pacific Ocean, with a redescription of Ophichthus megalops Asano, 1987 (Anguilliformes: Ophichthidae).

Two new species similar to Ophichthus megalops Asano, 1987 with dark-tipped anal fins, are described on the basis of one specimen of each species. Ophichthus semilunatus sp. nov. from northeastern Taiwan is characterized by having 176 total vertebrae, three rows of teeth on the maxilla, one + three supraorbital pores, two preopercular pores, a brownish anterior-nostril tube, and a blotch on the anterior margin of anus. Ophichthus brevidorsalis sp. nov. from New Caledonia is characterized by having two preopercular pores, one + three supraorbital pores, smaller eyes 2.7 in head, a short head 9.5% of total length, a long tail 59.8% of total length, a slightly short snout 19.4% of head, and 43 predorsal vertebrae. A redescription of O. megalops is provided based on the holotype and 18 specimens newly collected from Taiwan. Selected characters of all nine Ophichthus with a dark-tipped anal fin are provided. In addition, partial COI sequences of five species is provided.

A New Species of the Snake Eel Genus Ophichthus, with Additional Records from Viet Nam (Anguilliformes: Ophichthidae).

A new species of snake eel, Ophichthus vietnamensis sp. nov., is described on the basis of two specimens collected from off Ky Ha, central coast of Viet Nam. The new species is distinguishable from four similar congeners by having two preopercular pores, a less elongate body (both depth 20-25 times in TL) and the following combination of characters: tail length 56% TL; teeth moderately large and conical, biserial along the entire upper jaw, biserial anteriorly and uniserial posteriorly on lower jaw, uniserial on vomer, and total vertebrae 121-130. Five Ophichthus species are also found in Vietnamese waters, including O. asakusae, O. erabo, O. lithinus, O. rutidoderma and O. urolophus. Detailed descriptions are provided for all species.

Description of a new catfish, Silurus tomodai (Siluriformes: Siluridae) from central Japan.

A new catfish, Silurus tomodai, is described based on 37 specimens; 132-514 mm > 139-514 mm [132-514 mm standard length (SL)] collected from streams of Mie, Aichi, Gifu, Shizuoka and Nagano prefectures of central Honshu Island, Japan. Although S. tomodai is closely related to S. lithophilus (Tomoda, 1961) based on partial mitochondrial DNA sequences, the former can be distinguished from the latter by the position of dorsal fin (predorsal-fin length 28.5-32.1% vs. 30.1-33.7% SL), a shorter head (18.5-21.2% vs. 19.5-22.2% SL) that is more broadly rounded in ventral view, a more slender body (depth at 10th anal-fin ray 12.9-18.3% vs. 15.7-18.8% SL, and 86.8-100.3% vs. 97.2-109.7% of body depth at anal-fin origin), longer mandibular barbel [20.4-47.7% vs. 10.7-35.3% of head length (HL)], shorter anal-fin rays (10th anal-fin ray length 32.2-38.3% vs. 37.3-45.3% HL), eye slightly protruding laterally beyond profile in dorsal view, and the shape of medial depression on anterior face of mesethmoid (deep and narrow vs. shallow and wide). Silurus tomodai differs from S. asotus, a species widely distributed in Japan including central Honshu Island, in the shape of vomerine-tooth band (typically separated into two distinct lenticular patches vs. continuous), the shape and size of teeth (small and slightly recurved vs. relatively large and recurved), snout length (34.7-38.9% vs. 33.0-36.5% HL), the length of lower jaw (110-124% vs. 124-138% of snout length), interorbital width (53.0-61.3% vs. 46.3-52.8% HL), eye location (vertical through anterior margin of pupil usually posterior vs. anterior terminus of lips), inter-mandibular barbel width (24.7-32.5% vs. 21.7-26.7% HL), vertebral count (62-65 vs. 58-63), pigmentation on underside of head (usually mottled with dark pigmentation vs. uniformly white, rarely dark with pale band along posteroventral margin of lower jaw) and eggs yellow (vs. light green).

Checklist of eels of Taiwan (orders Anguilliformes and Saccopharyngiformes): An update.

The eel fauna (orders Anguilliformes and Saccopharyngiformes) of Taiwan is increased to 14 families, 79 genera and 232 species. Previous studies (Ho et al., 2015b, c) showed Taiwan had the highest diversity of eels in the world: this is further supported in the present updated work. Elsewhere in this volume, 16 species are newly described and 13 species are newly added to the Taiwanese ichthyofauna, mainly in the families Congridae and Synaphobranchidae. In addition, one new genus and four new species are described from adjacent waters in the Pacific Ocean. A total of 58 new species of the two eel orders are described from Taiwan; 52 of them are valid, and 37 are only found in Taiwan. Four names previously recorded in Taiwan are described as new in present special issue and are removed from the fauna of Taiwan accordingly. This work provides a foundation for the study of eel diversity in Taiwan.

Two new elongate unpatterned moray eels from Taiwan and Vietnam, with notes on two congeners (Anguilliformes: Muraenidae).

Two new species of elongate unpatterned moray eels related to Gymnothorax prolatus are described. Gymnothorax pseudoprolatus sp. nov. is described from one specimen collected off southwestern Taiwan and Gymnothorax vietnamensis sp. nov. is described from seven specimens collected off central Vietnam. Both differ from other species in the group in the number of vertebrae, position of anus, and dentition. Gymnothorax pseudomelanosomatus Loh et al., 2015 is reported from southern Taiwan for the first time; it was previously known from the type series collected off the northeastern tip of Taiwan. Gymnothorax angusticauda (Weber de Beaufort 1916) is reported for the first time in Taiwan and the Philippines.

Note on rare snake eels (Anguilliformes: Ophichthidae) and additional data on three Neenchelys recently described from Taiwan.

Three rare snake eel species, Allips concolor McCosker, 1972, Neenchelys daedalus McCosker, 1982, and Apterichtus    moseri (Jordan Snyder, 1901), were newly collected from Taiwan. The distribution ranges of the first two species are now extended to the South China Sea off southern Taiwan and that of the third is extended southward to off northwestern Taiwan. Supplemental data for three recently described species, Neenchelys diaphora, N. gracilis and N. similis, from Taiwan are provided.

A new species of Apterichtus (Anguilliformes: Ophichthidae) from the Marquesas Islands.

A new finless ophichthid eel, Apterichtus succinus sp. nov., is described based on a single specimen collected from the Marquesas Islands. The new species closely resembles A. klazingai Weber, 1913 in the shape and coloration of its head and its total vertebral count. The former differs from the latter in having more preopercular pores (4 vs. 3), fewer preanal vertebrae (54 vs. 56-63), a single tooth on the prevomer (generally absent), a shorter head (14.8 in TL vs. 12-14 in TL), and larger spots on its head and nape. Three species of Apterichtus (A. succinus, A. klazingai, and Apterichtus mysi McCosker & Hibino, 2015) are recognized from the Marquesas Islands.

Three new species of the genus Chlopsis (Anguilliformes: Chlopsidae) from the Indo-Pacific.

Three new species of false moray eels belonging to the genus Chlopsis, family Chlopsidae, are described and illustrated. Chlopsis sagmacollaris, from Western Australia, is characterized by its distinct color pattern with a unique dark saddle on the nape and paler body pigmentation than all other congeners. Chlopsis nanhaiensis, from Taiwan, has a bicolored body with its dorsal-fin origin behind a vertical through posterior margin of gill opening. These characters are shared with C. apterus, C. bicolor, C. bidentatus and C. orientalis sp. nov., but C. nanhaiensis has fewer total vertebrae than other bicolored species (ca. 120 in C. nanhaiensis vs. 125-140 in other four species). Chlopsis orientalis, from Vietnam, is distinguished from all other congeners except C. bicolor by its simple bicolored body, head length (ca. 10% of total length), position of dorsal-fin origin (distinctly behind a vertical through posterior margin of gill opening), and counts of preanal and total vertebrae (35 and 135). Although C. orientalis resembles C. bicolor in meristics and morphometrics, it differs in its pigmentation and possession of stouter intermuscular bones. These new species represent the first records of the genus Chlopsis from the northwestern Pacific Ocean and the eastern Indian Ocean.

A new genus and species of worm eels, Sympenchelys taiwanensis (Anguilliformes: Ophichthidae: Myrophinae), from the northwestern Pacific Ocean.

A new genus and species of ophichthid eel, Sympenchelys taiwanensis is described. The genus is distinguishable from all other myrophine genera by having neural and haemal spines with well-developed paddle-like tips, and from two closely similar genera, Mureaenichthys Bleeker 1853 and Skythrenchelys Castle & McCosker 1999, by the following combination of characters: an unconstricted gill opening; a minute flap just posterior to the gill opening; a slender cleithrum; three preopercular pores; a slender and distinctly tapered maxilla; an undeveloped supraoccipital crest; and large and recurved teeth on jaws and vomer. Sympenchelys taiwanensis is described from five specimens collected from Taiwan, the northwestern Pacific Ocean.

A new species of Neenchelys (Anguilliformes: Ophichthidae: Myrophinae) from the eastern Indian Ocean.

A new worm eel, Neenchelys andamanensis, is described based on a single specimen collected from a depth of 520-531 m, Andaman Sea, eastern Indian Ocean. The new species is similar to N. daedalus, N. nudiceps, and N. similis in its total vertebral count and slender body, however, it differs from the latter three in having a shorter tail (60% TL vs. 70-76%), more numerous preanal vertebrae (77 vs. 59-71), and shorter pectoral fins (2.4% HL vs. 21-27%). Although the new species resembles N. mccoskeri in some proportional characters, the former species is distinguishable from the latter by its higher total vertebral count (221 vs. 172-184), position of the dorsal-fin origin (horizontal distance from the origin to a vertical through mid-anus 65% of trunk length vs. 46-59%) and width of the interorbital region (4.5% of head length vs. 8.2-16%). A revised key to the species of Neenchelys is provided.

A new species of Muraenichthys (Anguilliformes: Ophichthidae) from the Indo-Pacific, with revised generic diagnosis.

A new worm eel (Ophichthidae, Myrophinae), Muraenichthys velinasalis, is described based on five specimens (97.9-281.0 mm of total length) collected from Taiwan, Philippines, northeastern Australia, Vanuatu, and Sri Lanka. Muranichthys velinasalis is most similar to M. philippinensis and M. schultzei in the position of the dorsal-fin origin behind a vertical through mid-anus, but can be easily distinguished from the latter two species by the condition of the posterior nostril, unique character of M. velinasalis within Muraenichthys, and by the shape of the teeth on the innermost row of the upper jaw (relatively robust and slightly pointed vs. slender and pointed), arrangement of upper-jaw teeth (irregularly biserial anteriorly and uniserial posteriorly vs. completely uniserial in M. philippinensis, biserial or triserial in M. schultzei), and its more numerous or fewer preanal and total vertebrae (44-51 vs. 59-60 in M. philippinensis, 42-47 in M. schultzei; 136-139 vs. 128-130 in M. philippinensis, 119-128 in M. schultzei). The genus Muraenichthys is re-defined based on all currently valid species by the following combination of characters: eyes located anterior to mid-jaw; inner hole of posterior nostril above upper lip, and outer hole usually outside of mouth, with a prominent but short projected flap anteriorly; a single pore between anterior and posterior nostrils; three preopercular pores; teeth on jaws, vomer, and intermaxillary area; tooth shape variable, blunt to pointed but not distinctly recurved and tooth length equal or less than a half of eye diameter; teeth on jaws and vomer arranged in one to five rows; gill opening constricted, its height<170% of eye diameter; pectoral fins absent.

Annotated checklist of eels (orders Anguilliformes and Saccopharyngiformes) from Taiwan.

An annotated checklist of eels, orders Anguilliformes and Saccopharyngiformes, occurring in Taiwanese waters is presented. The checklist is the result of a series of systematic studies conducted by the authors in the past few years. The eel fauna of Taiwan is one of the richest in the world with a total of 206 species in 74 genera and 13 families in Anguilliformes and a single species in Saccopharyngiformes. The most species-rich families are the Muraenidae with 71 species, followed by the Ophichthidae with 60 species, the Congridae with 29 species, and the Synaphobranchidae with 17 species. Moreover, three genera and 42 species have been described based on at least one type specimen collected from Taiwan. Of these, 36 species are recognized as valid and 23 species are known only from Taiwanese waters at present. Historical records of all Taiwanese eel species are reviewed by examining the original descriptions and figures, vouchers, as well as the recently collected specimens, where available. This represents the first detailed checklist of eels from Taiwanese waters.

A review of the finless snake eels of the genus Apterichtus (Anguilliformes: Ophichthidae), with the description of five new species.

The 18 species of finless snake eels of the genus Apterichtus (family Ophichthidae, subfamily Ophichthinae) are reviewed. Included are: A. anguiformis from the Mediterranean and eastern Atlantic; A. ansp from the Carolinas to Brazil in the western Atlantic; A. australis from South and Central Pacific islands, including Japan; A. caecus from the Mediterranean and eastern Atlantic; A. equatorialis from the eastern Pacific; A. flavicaudus from Hawaii, Midway Island, and possibly Australia and Seychelles; A. gracilis from the eastern central Atlantic; A. hatookai from Japan and China; A. kendalli from the western Atlantic and St. Helena Island; A. klazingai from South Africa to Hawaii; A. monodi from the eastern Atlantic; A. moseri from Japan; and A. orientalis from Japan. Five new species are described and illustrated: A. dunalailai from Vanuatu and Fiji at 291-450 m; A. jeffwilliamsi from Vanuatu at 4-16 m; A. malabar from New South Wales, Australia at 44-66 m; A. mysi from the Marquesas Islands at 35-64 m; and A. nariculus from Ambon Island, Indonesia at 28-30 m. A neotype is designated for Apterichtus caecus. An identification key is provided. The synonymy of the genus Apterichtus is reviewed. Apterichtus keramanus Machida, Hashimoto & Yamakawa 1997, is referred to ----------------Ichthyapus.

Concurrent chemoradiotherapy with a novel fluoropyrimidine, S-1, and cisplatin for locally advanced esophageal cancer: long-term results of a phase II trial.

OBJECTIVES: A phase II study was performed to investigate the safety and efficacy of concurrent chemoradiotherapy (CCRT) combined with an orally active fluoropyrimidine, S-1, plus cisplatin for locally advanced esophageal cancer (LAEC). METHODS: CCRT comprised 2 courses, a 30-Gy radiotherapy over 3 weeks plus daily oral S-1 (80 mg/m(2)/day) for 2 weeks and a 24-hour cisplatin infusion (70 mg/m(2)) on day 8, and an identical course administered after a 2-week break. RESULTS: One hundred and sixteen patients, 12 with stage II, 71 with stage III, and 33 with stage IVa LAEC participated, and 106 of them (91.4%) completed the CCRT course. The most serious toxicity was myelosuppression: grade 3 and 4 neutropenia occurred in 28.4 and 9.5% of patients, respectively. Nonhematologic toxicity was moderate. Complete response rates in patients with stage II, III, and IVa LAEC were 91.7, 67.6, and 36.4%, respectively. The overall median survival time was 2.3 years and that of patients with stage II, III, and IVa cancer was 7.0, 2.6, and 1.3 years, respectively. CONCLUSIONS: CCRT combined with S-1 plus cisplatin showed promising safety and efficacy. Potentially, this combination therapy could become a baseline medication for patients with LAEC.