Hiroshi Kajihara

Hokkaido University | Hokudai · Faculty of Science

We establish the new podocerid genus Capropodocerus gen. nov. for the two new species Capropodocerus tagamaru gen. et sp. nov. (collected from 775–800 m depth in the Kumano Sea, Japan) and Capropodocerus kamaitachi gen. et sp. nov. (collected from 840–873 m depth off the eastern coast of Miyagi, Japan). Capropodocerus shares elongate pereonites 1–3...

In this study, we describe a new species of elongated marine flatworm, Eucestoplana ittanmomen sp. nov., collected from the inter-tidal zone of the Okinawa Islands, Japan. Eucestoplana ittanmomen sp. nov. is distinguished from other congeners based on the following characteristics: i) its translucent body lacking coloration, ii) its dome-shaped pen...

The familial affiliation of the echinorhynchid palaeacanthocephalan genus Metacanthocephalus has been uncertain, with the three families Echinorhynchidae, Leptorhynchoididae, and Rhadinorhynchidae having been suggested as its parent taxon. In this study, adult individuals of Metacanthocephalus ovicephalus from the intestine of the cresthead flounde...

We establish a new interstitial polyclad species, Theama japonica sp. nov., based on specimens collected from coarse-sandy habitats in three Japanese main islands (Hokkaido, Honshu, and Shikoku) along the coasts of the Pacific Ocean and the Sea of Japan. Theama japonica is characterized by i) two pairs of cerebral eyespots and four to six precerebr...

We provide a morphological and molecular-based description of the eumonostiliferous hoplonemertean Oerstedia fuscosparsa sp. nov. based on two specimens dredged from a depth between 11 and 18 m off Kouyatsu, Tateyama, Chiba, Japan. This Oerstedia differs from its congeners by having a deep brownish pigmentation in the head, four orange ocelli, and...

A recent algal survey in the intertidal zone along the Levantine Mediterranean shore of Israel revealed four species of ribbon worms, Baseodiscus delineatus, Evelineus mcintoshii, Lineus sanguineus, and Zygonemertes algensis. Citizen scientists' (Fellow scientists) sighting information contributed the fifth species, namely, Notospermus annulatus, f...

The cheilostome bryozoan Cauloramphus magnus is common in the rocky intertidal habitat from southeastern Alaska to northern Japan. We examined its phylogeography by analyzing 576 bp of the mitochondrial COI (cox1) gene sequenced for 298 colonies from 16 localities in northern Japan. A maximum-likelihood phylogeny detected three main clades (A, B, C...

The genus Ototyphlonemertes Diesing, 1863, consisting of 33 named species and numerous unnamed morphospecies/molecular entities, is a unique group of nemerteans that possess cerebral statocysts and specifically live in coarse-grained sands. Only eight named species of this genus have yet been recorded from the Indo-Polynesian biogeographic province...

Tiny animals in various metazoan phyla inhabit the interstices between sand and/or gravel grains, and adaptive traits in their body plan, such as simplification and size reduction, have attracted research attention. Several possible explanations of how such animals colonized interstitial habitats have been proposed, but their adaptation to this env...

We report a histology-free description of the eumonostiliferous hoplonemertean Tetrastemma parallelos sp. nov. based on a single specimen dredged from a depth between 11 and 18 m off Kouyatsu, Tateyama, Chiba, Japan. Dorsally, T. parallelos sp. nov. is characterised by the presence of two orange-pigmented parallel lines in addition to a reddish cep...

We describe a new species of polyclad, Emprosthopharynx lysiosquillae sp. nov., based on specimens collected from the body surface of the mantis shrimp Lysiosquilla maculata (Fabricius, 1793) captured in Kujuzaki, Urasoe, Okinawa Island, Japan. This is the first report of symbiotic polyclads collected from stomatopods. The polyclads were collected...

We describe two new species of Armatoplana Faubel, 1983, namely, A. albomaculata sp. nov. and A. kaburakii sp. nov., from Japan. This is the first record of the genus from the West Pacific. Armatoplana albomaculata sp. nov. has the following characteristics: i) no nuchal tentacles; ii) white spots on the dorsal surface of the body; iii) an elongate...

Nemerteans, or ribbon worms, have been reported from intertidal to hadal depths, often showing bathymetrically wide distribution in genus levels. Although current nemertean systematics practices require to provide DNA sequences and infer phylogenetic relationships with suitable molecular markers, previous molecular systematics on nemerteans are mos...

With about 480 known species, Pilidiophora (phylum Nemertea) has been regarded as consisting of Hubrechtiiformes (~20 spp.) and Heteronemertea (~460 spp.). Most (~87%) of the latter belong to Lineidae (> 400 spp.), while the systematics of non-lineid heteronemerteans remains largely untouched. To explore the phylogeny of non-hubrechtiiformid, non-l...

The cotylean polyclad flatworm Bulaceros porcellanus Newman & Cannon, 1996 has so far only been recorded in a few tropical locations in the Indo-Pacific Ocean, including the Lakshadweep Islands (India), the Great Barrier Reef (Australia), and the Marshall Islands (Republic of the Marshall Islands). In this study, we report B. porcellanus for the fi...

We describe two new polyclad species, Pericelis lactea sp. nov. and P. maculosa sp. nov., from Japan. Pericelis lactea sp. nov. is characterized by (i) a translucent white body, (ii) the male and female gonopores opening separately and (iii) a conical penis papilla. Pericelis maculosa sp. nov. is distinguished from its other congeners by (i) a tran...

The carcinonemertid monostiliferan Ovicides paralithodis Kajihara and Kuris, 2013 was originally described as an egg predator of the red-king crab Paralithodes camtschaticus (Tilesius, 1815) in the Sea of Okhotsk, the Bering Sea, and the Gulf of Alaska. In the present study, several carcinonemertid specimens were obtained from the egg mass of the s...

We performed molecular phylogenetic analyses using nucleotide sequence data from five genes (16S rRNA, cytochrome c oxidase subunit I, 18S rRNA, 28S rRNA, histone H3) determined from 36 specimens representing 25 (10 named, 15 unnamed) species of lineid heteronemerteans collected in Sagami Bay, Japan, along with other sequences obtained from public...

The palaeonemertean genus Tubulanus Renier, 1804 currently harbors 35 species inhabiting the intertidal to the hadal zones. During a faunal survey in Sagami Bay, Japan, a single specimen of undescribed tubulanid having uniformly pale-colored body with a single dark-colored stripe on the dorsal surface was collected by dredging at depths of 116-211...

The three heteronemertean nominal species Ascaris longissima Gunnerus, 1770, Borlasia angliae Oken, 1815, and Nemertes borlasii Cuvier, 1816 have been considered as synonymous, denoting the same species to which the valid name Lineus longissimus (Gunnerus, 1770) has been applied. These three nominal species are the type species of the genus-group n...

Taxonomic studies on marine invertebrates have been prominent in Japan since the 19th century. Globally, taxonomy was reported to have been in recession since the early 21st century, but it is not clear if it is still in hardship or is making a recovery in recent years in Japan. In order to comprehend the status quo of taxonomic studies on marine i...

Tetrastemma Ehrenberg, 1828, is one of the most speciose (~110 spp.) genera within the phylum Nemertea, comprising marine monostiliferans generally having four eyes. Monophyly of Tetrastemma remains open to question, having been tested to date only with 18S rRNA gene sequences targeting 13 species. Here, we examine the clade Tetrastemma with additi...

The heteronemertean Cerebratulus marginatus Renier, 1804 is a well-known representative of the family Lineidae (Nemertea) inhabiting sandy or muddy sediments throughout the world. Due to its wide geographic distribution and the lack of distinctive external morphological features among different populations, the species has been considered cosmopoli...

We provide a histology-free description of the eumonostiliferous hoplonemertean Tetrastemma cupido sp. nov. based on specimens collected subtidally at a depth of 100 m in Sagami Bay, Japan. In T. cupido sp. nov., the ocelli are arranged in two, anterior and posterior, pairs of clusters, each consisting of up to eight and four ocelli, respectively....

Originally described from the masked greenling Hexagrammos octogrammus (Pallas, 1814), the palaeacanthocephalan Echinorhynchus hexagrammi Baeva, 1965 has so far been known from seven species in six families of marine teleosts distributed in the Sea of Okhotsk off Sakhalin and in the Northwestern Pacific off Hokkaido, Japan. In this study, we examin...

The present study provides morphological descriptions of four species of Prosthiostomum (Polycladida, Prosthiostomidae)—P. auratum Kato, 1937; P. hibana sp. n.; P. cf. ostreae Kato, 1937; and P. vulgare Kato, 1938—based on specimens collected among branching coralline algae and kelp holdfasts in Misaki, Japan. The new species P. hibana sp. n. is ch...

For rescue or endoscope applications, snake-like robots have been extensively studied to access and explore confined spaces, such as small-diameter holes or complicated debris. Among them, toroidal structures that eversion the surface flexible membrane exhibit high-mobility performance, even in fragile or soft ground because they can move without f...

Among ~1300 species of world nemerteans, seven species in five genera of lineid heteronemerteans have been known to possess a branched proboscis. In this paper, we describe the eighth branched-proboscis species: Gorgonorhynchus citrinus sp. nov. from Okinawa, Japan. We also report Gorgonorhynchus cf. repens Dakin & Fordham, 1931 with uniformly oran...

We establish a new genus of planocerid polyclad, Heteroplanocera gen. nov., based on a new species, H. katoi sp. nov., collected at a depth of 245 m off the coast of the Izu Peninsula, West Pacific, Japan. Heteroplanocera gen. nov. is distinguished from other planocerid genera by the following characteristics: (i) a pair of nuchal tentacles, (ii) a...

The heteronemertean Kulikovia alborostrata (Takakura, 1898) was originally described as Lineus alborostratus based on material from Misaki, Japan. Although this species was regarded as consisting of two color variants, purple and brown-yellow, the identity of these variants has never been examined based on topotypes. In this study, we performed a m...

The nemertean order Monostilifera consists of 594 species in 127 genera and is distributed worldwide. Within the Monostilifera, two suborders have been recognized, Cratenemertea and Eumonostilifera. Within the latter, two, unranked clade names, Oerstediina and Amphiporina, were recently proposed without formal taxonomic definition. In this article,...

We describe a new species of polyclad flatworm, Pericelis flavomarginata sp. nov., from the intertidal and subtidal zones along localities on the Pacific coast of Japan. Pericelis flavomarginata sp. nov. is characterized by i) the dorsal surface of the body fringed by a lemon-yellow line except for the tip of tentacles, with a narrow brown midline...

A new species of tubulanid palaeonemertean, Tubulanus izuensis sp. nov., is described as the sixth member of the genus in Japanese waters, based on materials dredged at depths of 244–436 m. It can be differentiated from all the known congeners by the unique burnt-orange dorsal pattern consisting of a median longitudinal stripe and transverse bands...

Soft robots have attracted much attention in recent years owing to their high adaptability. Long articulated soft robots enable diverse operations, and tip-extending robots that navigate their environment through growth are highly effective in robotic search applications. Since the robot membrane extends from the tip, these robots can lengthen with...

The three currently recognized species comprising the pelagic polystiliferous hoplonemertean genus Protopelagonemertes Brinkmann, 1917 are supposedly distinguishable chiefly with respect to the number of proboscis nerves: 29 (varying from 22 to 30) in P. hubrechti (Brinkmann, 1917); 19–21 (varying from 19 to 22) in P. beebei Coe, 1936; and 36 in P....

A new species of flabelligerid polychaete, Lamispina miurai sp. nov., has been described based on material collected at a depth of 226-228 m in the Pacific Ocean, off Aomori, Japan. Lamispina miurai sp. nov. can be differentiated from other congeners by the following features: i) the body is not covered with sand or large sediment particles; ii) th...

The ribbon worm Evelineus mcintoshii is reported for the first time from the Mediterranean Sea. Observations that took place, during two algal surveys, on the intertidal abrasion platforms at the middle of the Levantine Sea of Israel indicated that this species is hiding inside a mixture of local and non-indigenous marine seaweeds. It is probably a...

Three species of nemerteans, Balionemertes cf. australiensis Sundberg, Gibson, and Olsson, 2003 (Palaeonemertea), Prosadenoporus olympiae sp. nov. (Hoplonemertea: Eumonostilifera), and Coella gloriae sp. nov. (Hoplonemertea: Polystilifera: Reptantia), are reported based on material collected intertidally at a rocky shore in Cebu Island, Republic of...

Members of the lineid heteronemertean genus Euborlasia Vaillant, 1890 are relatively large-bodied ribbon worms, often with mottled, dark coloration. We describe Euborlasia maycoli sp. nov. from Bocas del Toro, Panama, which represents the 11th member, as well as the first Caribbean representative of the genus. We infer the phylogenetic position of...

Tiny annelids identified as the marine meiobenthic polychaete Dinophilus gyrociliatus (Schmidt, 1857) have been reported not only from shallow water sediments but also artificial environments such as experimental aquaria almost all around the world; the species has thus been regarded to show a cosmopolitan distribution. However, various types of ci...

We describe a new species of ilyplanid polyclad, Zygantroides serpulidicola sp. nov., from Amakusa, Kumamoto, Japan. This is the third member of Zygantroides Faubel, 1983 and the first record of the genus from the Pacific Ocean. Zygantroides serpulidicola sp. nov. is characterized by i) the mouth opening near the common gonopore, ii) the sperm duct...

The monostiliferous hoplonemertean Proamphiporus kaimeiae sp. nov. is described based on a single specimen collected from the bottom of the Northwest Pacific, 262 m deep, off Tohoku in Japan, by use of a remotely operated vehicle during a cruise organized by Tohoku Ecosystem-Associated Marine Sciences (TEAMS) research project in 2019. The position...

Having been reported in 1898 for the first time from Japanese waters, the lineid heteronemertean Lineus longifissus auct. is known to inhabit tidal flats under the influence of the warm Kuroshio Current along the coasts of Honshu and southwestward, characteristically with a uniformly raisin-colored to black body lacking a caudal cirrus. The taxonom...

The heteronemertean Cerebratulus orochi sp. nov. is described based on material collected intertidally at a muddy beach in Akkeshi, northern Japan. For the last 80 years, the species has been confused with Cerebratulus marginatus Renier, 1804; the latter was originally described from the Adriatic and once believed to occur in many places in the nor...

Up to now, 19 species in eight genera and two families (Dorvilleidae and Oenonidae) of polychaetes are known to be endoparasitic in the body of other polychaetes. In this paper, we describe Endovermis seisuiae gen. et sp. nov. as the first representative of Phyllodocidae parasitizing other polychaetes. Specimens of E. seisuiae were found in the bod...

Lacydonia japonica sp. nov. (Annelida, Lacydoniidae) is described based on material found in sediments collected off the Pacific coast of northern Honshu, Japan, at depths of 262 m and 407 m. The sediments were obtained by a remotely operated vehicle equipped with a suction sampler during a Tohoku Ecosystem-Associated Marine Sciences (TEAMS) projec...

The polyclad flatworm Stylostomum ellipse (Dalyell, 1853) has hitherto been recorded from the Antarctic region, Mediterranean Sea, Patagonian region, Scandinavia, South Africa, and South Georgia Island. In this study, we report S. ellipse for the first time from the Pacific Ocean based on specimens collected in Hokkaido, northern Japan. Our specime...

Acotylea is a suborder of Polycladida (Rhabditophora, Platyhelminthes) characterized by lack of a cotyl (sucker-like structure) on the ventral surface of the body. We newly determined partial sequences of two mitochondrial (16S ribosomal RNA and cytochrome c oxidase subunit I) and two nuclear (18S and 28S ribosomal RNA) genes from 24 acotylean spec...

The Antarctic heteronemertean Parborlasia corrugata (McIntosh, 1876) (originally Lineus corrugatus) shows a circumpolar distribution in the Southern Ocean, putatively with high dispersal capacity of the planktonic larva. From the eastern coast of Lützow-Holm Bay near Syowa Station (69°00′S, 39°35′E), several records of heteronemerteans have been ma...

A single specimen of a monostiliferous hoplonemertean, collected from a depth of 25 m in Akkeshi Bay, northern Japan, represents the first record of Gurjanovella littoralis Uschakov, 1926 from the Northwest Pacific. The species has been known only from the type locality, White Sea, Russia, although some planktonic larvae from Oregon, USA, and a juv...

We describe a new species of polyclad flatworm, Enchiridium daidaisp. nov. , from the rocky subtidal zone in the East China Sea along the coasts of the Kyushu and Okinawa Islands, Japan. Enchiridium daidaisp. nov. is characterized by i) the entire periphery of the dorsal surface narrowly fringed with orange, ii) a marginal-eyespot band extending to...

We report the freshwater heteronemertean Apatronemertes albimaculosa Wilfert & Gibson, 1974 for the first time from Taiwan based on specimens collected under stones and rocks on gravelly bottom near the shore of a brook in Nantun District, Taichung City. Species identification was corroborated by mitochondrial cytochrome c oxidase subunit I gene se...

Acoetid polychaetes were collected from shallow waters off Kochi Prefecture and Wakayama Prefecture, Japan. The specimens could be assigned to the genus Polyodontes Blainville, 1828, but are different from all the known species of the genus by the following characters: ommatophores with short neck; palps with minute papillae; parapodia without bran...

In the originally published version of the article, Figure 1 caption contains errors. Fig. 1 is shown below with the correct caption.

The heteronemertean genus Dushia Corrêa, 1963 was established for what was identified as D. atra (Girard, 1851) (originally Meckelia atra) based on material from littoral, shallow waters in Curaçao, while the nominal species Meckelia atra was originally described from deep water off Florida Cape. In this paper, we conclude that the type species for...

The valenciniid heteronemertean Baseodiscus delineatus (Delle Chiaje, 1825) was originally described from Naples, Italy, and shows a circumglobal distribution from tropical to temperate seas in both hemispheres. To investigate its reproductive biology, we performed intermittent year-round sampling from 2014 to 2018 in Misaki on the Pacific coast of...

A new genus of Holothuroidea, Notostichopus, from Australia is described and its phylogenetic relationship examined. The new genus is based on two species within the family Stichopodidae, previously attributed to Stichopus. Notostichopus is characterized by the absence of rosette ossicles and the presence of table ossicles with at most one crossbea...

The subgenus Setihenricia Chichvarkhin and Chichvarkhina, 2017 currently consists of 32 out of 94 species of sea stars in the genus Henricia Gray, 1840. However, only 10 have been molecularly ascertained as to the phylogenetic position. Based on seven mitochondrial gene markers (16S rRNA, COI, tRNA-Ala, tRNA-Leu, tRNA-Asn, tRNA-Gln, and tRNA-Pro),...

We describe a new species of polyclad flatworm, Prosthiostomum torquatum sp. nov., from the rocky intertidal zone in Shirahama, on the Pacific coast of middle Honshu, Japan. Prosthiostomum torquatum is characterised by a unique dorsal colouration, which is comprised of i) numerous orange maculae and blue dots dispersed all over the dorsal surface,...

We describe a new species of polyclad flatworm, Paraplehniaseisuiaesp. nov., from 298-310 m depths in the Sea of Kumano, West Pacific, Japan. Paraplehniaseisuiaesp. nov. is characterized by i) a developed muscular wall proximally occupying about one-third of the prostatic vesicle, ii) no common duct between the spermiducal bulbs and the prostatic v...

The hydrothermal vent-endemic polychaete Archinome jasoni Borda et al., 2013 is known from the Atlantic, Indian, and Southwest Pacific oceans. In this study, we report A. jasoni from Okinawa Trough, Japan, which represents the first record of this species and the genus from the Northwest Pacific. We determined 16S and 28S rRNA gene sequences from 1...

Two species of styelid colonial ascidians in the genus Syncarpa Redikorzev, 1913 are known from the northwest Pacific. The valid status of the lesser known species, Syncarpacomposita (Tokioka, 1951) (type locality: Akkeshi, Japan), is assessed here. To assess the taxonomic identity of S.composita, we compared one of the syntypes and freshly collect...

The taxonomic identity of the palaeonemertean Cephalothrix linearis (Rathke, 1799) has been obscure for nearly two centuries, because its original description applies to almost any congeners, including Cephalothrix filiformis (Johnston 1828) and Cephalothrix rufifrons (Johnston, 1837), which occur commonly in the North Sea and adjacent waters. In t...

Outbreaks of ribbon worms observed in 2013, 2015, and 2017-2019 in the Han River Estuary, South Korea, have caused damage to local glass-eel fisheries. The Han River ribbon worms have been identified as Yininemertes pratensis (Sun & Lu, 1998) based on not only morphological characteristics compared with the holotype and paratype specimens, but also...