著者

Kakui Keiichi Kajihara Hiroshi Kobayashi Norio

出版者

The Crustacean Society

雑誌

Journal of Crustacean Biology (ISSN:02780372)

巻号頁・発行日

vol.32, no.1, pp.127-139, 2012-01

被引用文献数

10

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Lack of an ischium on pereiopods 1–6 was previously considered a synapomorphy for the tanaidacean superfamily Tanaoidea, although descriptions of Arctotanais alascensis (Richardson, 1899), the sole species in Arctotanais, indicated presence or absence of the ischium. To resolve this ambiguity, we examined newly collected specimens of A. alascensis (including males, which had not previously been described) from Hokkaido, Japan, using light and scanning electron microscopy. We also conducted molecular phylogenetic analyses based on partial sequences of the 18S rRNA gene to examine the phylogenetic position of A. alascensis. Here we describe in detail the morphology of the male of A. alascensis, which proved to be similar to that of the females. This species bears an ischium on pereiopods 1–6, which contradicts the current diagnoses of Tanaoidea and Tanaidae, although other synapomorphies remain valid. Molecular phylogenetic analyses strongly supported the placement of A. alascensis in Tanaoidea, and consequently we amended the diagnoses for Tanaoidea and Tanaidae to include either presence or absence of the ischium on the pereiopods.

著者

Okamoto Nobuya Kakui Keiichi

出版者

Springer

雑誌

Biologia (ISSN:00063088)

巻号頁・発行日

vol.77, no.9, pp.2497-2506, 2022-06-23

被引用文献数

4

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We describe a new tanaidid species, Zeuxo molybi sp. n., from Kominato, Chiba, Japan. Zeuxo molybi closely resembles the Japanese congener Zeuxo ezoensis, but differs in having (1) the pereopod-1 carpus without dorsodistal spiniform setae; (2) two or three ventrodistal simple setae on the pereopod-1 propodus in females, and three or four in males; and (3) the pereopod-6 propodus with four or five flattened denticulate setae. The two species also differ in the pattern of dorsal pigmentation on the carapace. Kimura 2-parameter distances between the two species were 15.6-16.9% for the cytochrome c oxidase subunit I (COI) gene and 2.8% for the 18S rRNA gene; the former value is much greater than intraspecific distances previously reported for Z. ezoensis (0-1.5%), confirming our conclusion from morphology that Z. molybi and Z. ezoensis are not conspecific. In a COI-based maximum-likelihood phylogenetic tree, the Japanese taxa Z. molybi, Z. ezoensis, and Z. cf. normani did not form a clade.

著者

Kakui Keiichi Hiruta Chizue

出版者

Zoological Society of Japan

雑誌

Zoological Science (ISSN:02890003)

巻号頁・発行日

vol.39, no.1, 2022-02

被引用文献数

6

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We describe a new typhlotanaid species, Hamatipeda kohtsukai sp. nov., collected from between 167 and 488 m depth in the Sagami Sea, Japan. This is the first record of Hamatipeda from the northern hemisphere. Hamatipeda kohtsukai resembles Hamatipeda trapezoida from the Subantarctic region in having pereonites 1–3 widest anteriorly (not rectangular), but differs from it in the length ratio of antennal articles 4/5; the number of setae on the dactyli of pereopods 1–3, ischia of pereopods 4–6, and carpi of pereopods 4–6; the shape of the unguis of pereopods 4–6; and the shape of the uropodal endopod. We determined partial sequences for the cytochrome c oxidase subunit I (COI; cox1) and 18S rRNA (18S) genes in H. kohtsukai. A phylogenetic reconstruction based on the 18S sequences recovered a highly supported Typhlotanaidae clade containing H. kohtsukai and Typhlotanais mixtus, with Paranarthrura sp. (Agathotanaidae) as the sister taxon. A key to species of Hamatipeda is presented.

著者

Shimada Daisuke Kakui Keiichi

出版者

Zoological Society of Japan

雑誌

Zoological Science (ISSN:02890003)

巻号頁・発行日

vol.39, no.1, 2022-02

被引用文献数

1

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We describe three free-living marine nematode species from Sagami Bay, Japan. Wiesoncholaimus jambio sp. nov. is the second species of this genus. It differs from the type species, Wiesoncholaimus mawsonae Inglis, 1966, by its dorsal tooth, which is as long as the other two teeth; its conicocylindrical tail, which is as long as 4.6–4.8 cloacal body diameters; and the absence of the gubernaculum. Thalassironus cf. britannicus de Man, 1889 agrees well with a redescription of Thalassironus britannicus de Man, 1889 based on specimens collected near the type locality. However, as it is possible that T. britannicus sensu lato includes two or more species, our species may not be conspecific to T. britannicus sensu stricto. Vasostoma cf. longispicula Huang and Wu, 2010 closely resembles Vasostoma longispicula Huang and Wu, 2010 originally described from China, but minor differentiations are observed in body diameter, body cuticle thickness, and type of precloacal supplements.

著者

Kakui Keiichi Hiruta Chizue

出版者

NRC Research Press (Canadian Science Publishing)

雑誌

Canadian Journal of Zoology (ISSN:00084301)

巻号頁・発行日

vol.100, no.8, pp.481-487, 2022

被引用文献数

3

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Hermaphroditism has been widely reported in the Crustacea, but protogyny, in which females change to males, is apparently rare and restricted to the peracarid orders Isopoda and Tanaidacea. In the latter, protogyny has been demonstrated in only seven species representing six genera by rearing experiments and indicated for several other genera and species through morphology. Here, we show through rearing experiment and histological observations, protogynous hermaphroditism in the tanaidacean species Nesotanais sp. aff. ryukyuensis Kakui, Kajihara and Mawatari, 2010. Our rearing experiment and size distribution data for wild individuals showed that females can change sex at various sizes (= ages). We found one individual identified externally as a female containing both ovaries and testes, indicating that overt female individuals undergo a short transitional phase as simultaneous hermaphrodites before the sex-change molt. We discuss the relationship among the wide size distribution of sex-changing females, the short life span of males, and the tube-dwelling mode of life.

著者

Shiraki Shoki Shimomura Michitaka Kakui Keiichi

出版者

Sociedade Brasileira de Carcinologia

雑誌

Nauplius (ISSN:23582936)

巻号頁・発行日

vol.30, pp.e2022023, 2022

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We describe Kupellonura tamago sp. nov., collected from the North Pacific off the southern coast of the Boso Peninsula, Japan, at a depth of 445–407 m. This is the first record of Hyssuridae not only for Japan but also for the Temperate Northern Pacific ecoregion. Female K. tamago closely resembles Kupellonura gidgee Poore and Lew Ton, 1988 and Kupellonura indonesica Annisaqois and Wägele, 2021 in the shape of the uropodal exopod but differs from them in having a broader uropodal exopod (length/width ratio 1.47), a broader uropodal endopod (length/width ratio 1.64), and the telson margins smooth. We transfer Kupellonura flexibilis (Pasternak, 1982), originally described in Ananthura Barnard, 1925 but provisionally transferred to Kupellonura Barnard, 1925, to Anthelura Norman and Stebbing, 1886 in Antheluridae, as Anthelura flexibilis (Pasternak, 1982) comb. nov.

著者

Kakui Keiichi Kano Yasunori

出版者

Zoological Society of Japan

雑誌

Zoological Science (ISSN:02890003)

巻号頁・発行日

vol.38, no.3, pp.267-272, 2021-06

被引用文献数

3

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We present a complete mitochondrial genomic sequence for the tanaidacean Arctotanais alascensis (Richardson, 1899); this is the first complete mitogenome reported from the order Tanaidacea. The mitogenome is 13,988 bp long and contains 13 protein coding and two ribosomal RNA genes (as is typical for animal mitogenomes), and 21 of 22 transfer RNAs; we did not detect an isoleucine transfer RNA (trnI) gene. The gene order differed markedly from the hypothetical ground pattern for Pancrustacea; only four clusters (trnM + nad2; trnC + trnY + cox1 + trnL2 + cox2; trnD + atp8 + atp6 + cox3; trnH + nad4 + nad4l) ancestrally present were retained. In a malacostracan phylogenetic tree reconstructed from mitogenome data, basal relationships were marginally supported or incongruent with the traditional morphology-based classification and the latest phylogenetic reconstructions from large transcriptomic datasets. Relationships involving more recent divergences were better supported in our tree, suggesting that complete mitogenome sequences are more suitable for phylogenetic analyses within malacostracan orders, presumably including Tanaidacea.

著者

Okamoto Nobuya Oya Yuki Kakui Keiichi

出版者

Taylor & Francis

雑誌

Marine Biology Research (ISSN:17451000)

巻号頁・発行日

vol.16, no.5, pp.411-422, 2020

被引用文献数

5

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We describe Zeuxo ezoensis sp. nov. from Hokkaido, Japan. This species closely resembles Z. phytalensis, Z. shitipingensis and Z. turkensis in having the pleopodal endopod with one inner plumose seta, maxillipedal palp article 4 with one outer simple seta, the left mandible with a wide, denticulate lacinia mobilis and one bifurcate accessory seta, and the right mandible with a peg-like lacinia mobilis and two accessory setae. It differs from them in having (1) antennal article 6 longer than wide, (2) the distal region of the maxillipedal endite with four spiniform setae and two circumplumose setae, (3) maxillipedal palp article 2 with one outer simple seta, (4) the chelipedal carpus with three or four dorsodistal simple setae, (5) the chelipedal dactylus with one inner simple seta, (6) the pereopod-1 basis with one or two ventrodistal simple setae, (7) the pereopod-1 carpus with one ventrodistal simple seta, and (8) the uropod with four or five articles (basal article plus three or four ramus articles). Partial nucleotide sequences for the cytochrome c oxidase subunit I (COI) gene (655 nt) from Z. ezoensis specimens from four localities in Hokkaido showed Kimura 2-parameter (K2P) divergences of 0–0.5% and 0.6–1.5% within and between populations, respectively. Based on the COI data, we examined the phylogenetic position of Z. ezoensis within Zeuxo. Six specimens used for morphological observations and 10 specimens used for COI sequencing showed a similar dorsal pigmentation pattern on carapace. We briefly discuss the validity of using this pattern as a diagnostic character in Zeuxo taxonomy.

著者

Kakui Keiichi Fujita Yoshihisa

出版者

Taylor & Francis

雑誌

Marine Biology Research (ISSN:17451000)

巻号頁・発行日

vol.16, no.3, pp.195-207, 2020-03-20

被引用文献数

3

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We describe Paradoxapseudes shimojiensis sp. nov. from a submarine limestone cave at Shimoji-jima Island, Ryukyu Islands, southwestern Japan. This species resembles five species (P. basibidens, P. bassoprofundo, P. bermudeus, P. edgari, and P. heroae, among 17 congeners) that bear a long pleotelson, but differs from them in having (i) a naked antennal article 1, (ii) the maxillipedal basis with one inner distal plumose seta, (iii) the chelipedal basis with one dorsodistal and one ventro-subproximal simple setae, (iv) the pereopod-1 basis with four dorsal simple setae longer than the width of the pereopod-1 basis, but without ventrodistal spiniform setae, (v) the pereopod-1 merus with three mid-inner ventral simple setae, and (vi) the pleopodal protopod with two inner plumose setae. We determined partial nucleotide sequences for the cytochrome c oxidase subunit I (COI) and 18S rRNA (18S) genes in P. shimojiensis for future use in DNA barcoding and phylogeny. Paradoxapseudes shimojiensis has serial ridges on the inner surfaces of the left and right chelipedal bases that quite resemble the stridulatory organs in harvestmen (Opiliones); by analogy, we speculate that these ridges may be stridulatory sound-producing organs. Two specimens had both a fully-developed marsupium and genital cone, suggesting that P. shimojiensis is simultaneously hermaphroditic.

著者

Kakui Keiichi Hiruta Chizue Uyeno Daisuke

出版者

Wiley

雑誌

Invertebrate Biology (ISSN:10778306)

巻号頁・発行日

vol.138, no.3, pp.e12257, 2019-09

被引用文献数

3

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With more than 40,000 species, Malacostraca is the most diverse crustacean class. Most malacostracans are gonochoristic, but simultaneous hermaphrodites are also known. Tanaidacea is one of two malacostracan orders that includes simultaneously hermaphroditic species; so far, simultaneous hermaphroditism has been confirmed externally and internally in only two tanaidacean species, both in the genus Apseudes (Apseudidae). Here we show, through external and internal morphological observations of fixed specimens, that the apseudid Falsapseudes bowmani is a simultaneous hermaphrodite, making Falsapseudes the second tanaidacean genus in which simultaneous hermaphroditism has been confirmed both externally and internally. In this species, the epistome (a projection on the clypeus) was thick and elongate in large specimens but was thin and spiniform in smaller specimens; the brooding of eggs or embryos was observed only in thin-epistome individuals, although a pair of ovaries was confirmed in both thick- and thin-epistome individuals. This suggests that individuals with a thick epistome may act as males while also retaining the female reproductive organs.

著者

木村 妙子 木村 昭一 自見 直人 角井 敬知 冨岡 森理 大矢 佑基 松本 裕 田邊 優航 長谷川 尚弘 波々伯部 夏美 本間 理子 細田 悠史 藤本 心太 倉持 利明 藤田 敏彦 小川 晟人 小林 格 石田 吉明 田中 颯 大西 はるか 締次 美穂 吉川 晟弘 田中 正敦 櫛田 優花 前川 陽一 中村 亨 奥村 順哉 田中 香月 Kimura Taeko Kimura Shoichi Jimi Naoto Kakui Keiichi Tomioka Shinri Oya Yuki Matsumoto Yu Tanabe Yuki Hasegawa Naohiro Hookabe Natsumi Homma Riko Hosoda Yushi Fujimoto Shinta Kuramochi Toshiaki Fujita Toshihiko Ogawa Akito Kobayashi Itaru Ishida Yoshiaki Tanaka Hayate Onishi Haruka Shimetsugu Miho Yoshikawa Akihiro Tanaka Masaatsu Kushida Yuka Maekawa Yoichi Nakamura Toru Okumura Junya Tanaka Kazuki

出版者

三重大学大学院生物資源学研究科

雑誌

三重大学フィールド研究・技術年報 = Annals of Field Research and Technology Mie University (ISSN:13496824)

巻号頁・発行日

vol.16, pp.1-32, 2018-10

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In this study, we had investigated the benthic deep-sea fauna using the dredge and beam trawl in the region from the continental shelf to the continental slope of the Sea of Kumano, Mie Prefecture, during the No.1722 research voyage of the training ship Seisui-Maru of Mie University. The survey was carried out at 16 stations covering a depth range of 113-1059 m. The results of the survey, 14 phyla had been confirmed. Arthropod, echinoderm, annelid and molluscan macrobenthos were collected from all of the stations. The phylum number of each station was in the range from 4 to 11. The largest number of phyla had been confi rmed at St.10D of boulders bottom(768-800 m depth). Meiobenthos confi rmed in our sample were kinorhynchs, nematodes, tardigrades, loriciferans and small arthropods such as tanaidaceans, copepods and cumaceans. In addition to free-living species, parasitic copepods, isopods, platyhelminthes, acanthocephalans and nematodes had been found in fish, crustaceans and polychaetes.

著者

Tomioka Shinri Kakui Keiichi Kajihara Hiroshi

雑誌

Zoological Science (ISSN:02890003)

巻号頁・発行日

vol.35, no.5, pp.436-445, 2018-10

被引用文献数

4

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Capitellids have emerged as monophyletic in most but not all recent molecular phylogenies, indicating that more extensive taxon sampling is necessary. In addition, monophyly of most or all capitellid genera was questionable, as some diagnostic characters vary ontogenetically within individuals. We tested the monophyly of Capitellidae and eight capitellid genera using phylogenetic analyses of combined 18S, 28S, H3, and COI gene sequences from 36 putative capitellid species. In our trees, Capitellidae formed a monophyletic sister group to Echiura, and Capitella was also monophyletic, separated by a long branch from other capitellids. Well-supported clades each containing representatives of different genera, or containing a subset of species within a genus, indicated that Barantolla, Heteromastus, and Notomastus are likely not monophyletic. We mapped three morphological characters traditionally used to define capitellid genera (head width relative to width of first segment, number of thoracic segments, and number of segments with capillary chaetae) onto our tree. While Capitella showed unique character states, states in the other genera were decidedly not phylogenetically informative. Morphology-based capitellid taxonomy will require a fine-scale reevaluation of character states and detection of new characters.

著者

Kakui Keiichi Fujita Yoshihisa

出版者

PeerJ

雑誌

Peerj (ISSN:21678359)

巻号頁・発行日

vol.6, pp.e4720, 2018-04-26

被引用文献数

5

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We establish a new pseudozeuxid genus Haimormus gen. nov. based on a new species Haimormus shimojiensis sp. nov. which was collected from a submarine limestone cave with the entrance at 35 m depth, in the Northwestern Pacific Ocean. H. shimojiensis differs from the other confamilial members, Pseudozeuxo belizensis Sieg, 1982 and Charbeitanais spongicola Bamber & Bird, 1997, in having the pleonite 1 without the pleopod, the pereopods 2 and 3 propodus with a ventral spiniform seta, and the pereopods 4-6 propodus with one long and two short dorsodistal setae. A key to females of species of Pseudozeuxidae is presented. This is the first tanaidacean report from submarine caves around Japan.

著者

Kakui Keiichi Katoh Toru Hiruta Shimpei F. Kobayashi Norio Kajihara Hiroshi

雑誌

Zoological Science (ISSN:02890003)

巻号頁・発行日

vol.28, no.10, pp.749-757, 2011

被引用文献数

34

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Phylogenetic relationships within Tanaidacea were analyzed based on sequence data for the 18S rRNA gene. Our results strongly supported a monophyletic group composed of Neotanaidae, Tanaoidea, and Paratanaoidea, with the first two taxa forming a clade. These results contradict three previously suggested hypotheses of relationships. Based on the molecular results, and considering morphological similarities/differences between Neotanaidomorpha and Tanaidomorpha, we demoted Suborder Neotanaidomorpha to Superfamily Neotanaoidea within Tanaidomorpha; with this change, the classification of extant tanaidaceans becomes a two-suborder, four-superfamily system. This revision required revision of the diagnoses for Tanaidomorpha and its three superfamilies. The results for Apseudomorpha were ambiguous: this taxon was monophyletic in the maximum likelihood and Bayesian analyses, but paraphyletic in the maximum parsimony and minimum evolution analyses.

著者

Kakui Keiichi Hayakawa Yoshinobu Katakura Haruo

雑誌

Zoological Science (ISSN:02890003)

巻号頁・発行日

vol.34, no.2, pp.129-136, 2017-04

被引用文献数

5

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We investigated the life cycle of the tanaidid Zeuxo sp. 1 (Crustacea: Peracarida: Tanaidacea), which lives epiphytically in dwelling tubes on the algae Sargassum spp. and Neorhodomela aculeata in Oshoro Bay, Hokkaido, Japan. We obtained data on its population size distribution, age structure, and reproductive phenology through monthly sampling from April 2011 to June 2012. From these data, we detected an overwintering group (F0) that arises from mancae that are released in autumn, overwinters, reproduces the following spring, and then disappears. The overwintering group produces mancae (F1) that reach maturity and themselves reproduce within six weeks after release; the F1, mancae give rise to an F2 and possibly an F3 generation within a single summer. We refer to individuals that reproduce in the same summer that they were released as the ‘annual group’. Reproduction overall was restricted to the period from May to October, when the seasurface temperature exceeded 10°C. During both years, overwintering females first became reproductive in May. Reproduction in the annual group began in June and continued through mid-October. Mancae were observed in samples from June through October. The two groups differed significantly in size at reproduction; compared to the annual group, females in the overwintering group reproduced at larger minimum and average body sizes, and males began to express enlarged chelae, a secondary sexual character, at a larger size. The difference in size at maturity may be related to the differences in water temperature during the main period of growth and maturation.

著者

KAKUI KEIICHI SHIMADA DAISUKE

出版者

Magnolia Press

雑誌

Zootaxa (ISSN:11755326)

巻号頁・発行日

vol.4282, no.2, pp.324, 2017

被引用文献数

10

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We describe Tanaopsis japonica sp. nov. from intertidal and nearshore habitats around Hokkaido Island, northern Japan. This species closely resembles T. chotkarakde Bird & Bamber, 2000 and T. rawhitia Bird, 2011 in having the uropod with the endopod biarticulate and the exopod uniarticulate, but differs from them in the following characters: pereonite 4 as long as pereonite 5; mandibles lacking the molar; the number of simple setae on the antenna, propodal palm, and dactylus of pereopods 1–3; the number of spiniform setae on the cutting surface of the chelipedal dactylus; and the number of setae on the pleopods. We also determined a nearly complete nucleotide sequence for the 18S rRNA gene in T. japonica. In both sexes, Tanaopsis japonica sp. nov. bears serial ridges and grooves on the chela, antennule, and antenna. Parallel, fringed hatch marks on the chelipedal dactylus may function in stridulation. A series of denticulate ridges on the dorsal surface of antennal article 2 faces the ventral side of article 1 of the antennule, where there is a ventral series of slight grooves. Although the ranges of motion of the antennule and antenna were unclear, the ridges and grooves on the antenna and antennule may also function in producing sound. Two outer series of ridges on the chela, together with an outer furrow on the chela, may function in digging, by allowing bottom-sediments to be efficiently pushed aside.

著者

Kakui Keiichi Hiruta Chizue

雑誌

Naturwissenschaften (ISSN:00281042)

巻号頁・発行日

vol.100, no.9, pp.891-894, 2013-09

被引用文献数

9

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The crustacean class Malacostraca,with over 22,000 species, includes commercially important members, such as crabs, shrimps, and lobsters. A few simultaneous hermaphrodites are known in this group, but self-fertilization was unknown. Here we show, through microscopy and breeding experiments, that the simultaneously hermaphroditic malacostracan Apseudes sp. (order Tanaidacea) can self-fertilize; individuals reared in isolation become hermaphroditic via a male-like phase and produce eggs that develop into fertile adults. Although selfing occurs in crustaceans like the Branchiopoda, in which simultaneous hermaphrodites have the sex ducts united, in decapods the separation of gonadal ducts and gonopores, specialized mating organs, and complex mating behavior appear to have constrained the evolution of selfing. In contrast, in most tanaidaceans, sperm is released externally by a male and reaches the eggs in the female brood pouch, where fertilization occurs. This mode of fertilization permitted Apseudes sp. to achieve selfing without large modifications in morphology or behavior.