Researcher Database

Keiichi KAKUI
Faculty of Science Biological Sciences Biodiversity

Researcher Profile and Settings


  • Faculty of Science Biological Sciences Biodiversity

Job Title

  • Lecturer


  • Ph. D(Hokkaido University)

Research funding number

  • 70723360


J-Global ID

Research Interests

  • Phylogeny   Taxonomy   Crustacea   Tanaidacea   

Research Areas

  • Life sciences / Biodiversity and systematics / Phylogeny and Taxonomy of Crustaceans

Association Memberships


Research Activities

Published Papers

  • Kakui K, Uyeno D
    Zootaxa 4852 (1) 143 - 144 1175-5326 2020/09/14 [Refereed][Not invited]
    Markevich (1940) established Pseudolepeophtheirus Markevich, 1940 for Pseudolepeophtheirus longicauda Markevich, 1940 based on copepods collected from the pleuronectid fish Platichthys stellatus (Pallas, 1787). Dojiri & Ho (2013) synonymized the genus and the species with Lepeophtheirus Nordmann, 1832 and Lepeophtheirus parvicruris Fraser, 1920, respectively. Later, Homma et al. (2020) resurrected Markevich’s species as a member of Lepeophtheirus, i.e., as L. longicauda (Markevich, 1940). The last component of the names of both genera is ‘phtheirus’ (transliterated from the Greek φθειρ; Nordmann 1832: 30), a masculine noun, and thus under Article 30.1.2 of the International Code of Zoological Nomenclature (hereinafter, Code; International Commission on Zoological Nomenclature 1999), both generic names are also masculine. The species-group name longicauda might be regarded as either a noun in apposition or as an adjective in the feminine gender, and Markevich (1940) did not specify his intention in this regard. Bearing in mind that ‘cauda’, meaning ‘tail’, actually is a feminine Latin noun and that Markevich did not change the final ‘-a’ to ‘-us’ to match the masculine gender of the genus, we deem that longicauda Markevich, 1940 is a noun in apposition, a position supported by Article 31.2.2 of the Code.
  • Ko Tomikawa, Keiichi Kakui, Yoshihiro Fujiwara
    ZooKeys 965 37 - 53 1313-2989 2020/09/03 [Refereed][Not invited]
    A new pardaliscid amphipod, Nicippe beringensis, is described from the Bering Sea at depths between 520 and 536 m, and N. tumida Bruzelius, 1859 is redescribed based on specimens from Fredrikshald, Norway, near the species’ type locality. Nucleotide sequences of mitochondrial cytochrome c oxidase subunit I (COI) from the holotype and a paratype of N. beringensissp. nov. are reported. While N. beringensissp. nov. is similar to N. tumida, it differs from the latter in having an asetose palp article 1 of maxilla 1, a gnathopod 1 coxa with a straight distal edge, and in the posterior margin of the basis of gnathopods 1 and 2, and pereopod 3, being heavily setose in females. A key to species of Nicippe is provided.
  • Kakui K, Fujiwara Y
    Zoological Science 37 (4) 303 - 306 0289-0003 2020/08/03 [Refereed][Not invited]
  • Homma R, Uyeno D, Kakui K
    Parasitology International 78 102135  1383-5769 2020/07/24 [Refereed][Not invited]
  • Kakui K
    Bulletin of the Kitakyushu Museum of Natural History and Human History Series A (Natural History) 18 1 - 4 2020/03/31 [Refereed][Not invited]
  • First record of Conchoderma auritum (Linnaeus, 1767) (Crustacea: Cirripedia: Lepadidae) from Rishiri Island
    Tomioka S, Kakui K, Kado R, Sato M
    Rishiri Studies 39 7 - 10 2020/03 [Not refereed][Not invited]
  • Kakui K
    Zoological Science 36 468 - 470 0289-0003 2019/12 [Refereed][Not invited]
  • Tanabe Y, Kakui K
    Species Diversity 24 181 - 187 2189-7301 2019/11 [Refereed][Not invited]
  • Kimura Taeko, Kimura Shoichi, Kakui Keiichi, Hookabe Natsumi, Kuramochi Toshiaki, Fujita Toshihiko, Ogawa Akito, Kobayashi Itaru, Jimi Naoto, Okanishi Masanori, Yamaguchi Haruka, Hirose Masato, Yoshikawa Akihiro, Fukuchi Jun, Shimomura Michitaka, Kashio Sho, Uyeno Daisuke, Fujiwara Kyoji, Naruse Tohru, Kushida Yuka, Kise Hiroki, Maekawa Yoichi, Nakamura Toru, Okumura Junya, Tanaka Kazuki
    Annals of Field Research and Technology Mie University 三重大学大学院生物資源学研究科 17 (17) 1 - 29 1349-6824 2019/11 [Not refereed][Not invited]
    Preliminary results of the deep-sea faunal survey conducted from the TR/V Seisui-maru of Mie University in April 2019 are presented. A total of 20 taxonomists and ecologists working on a wide variety of animal taxa participated in this survey. Surveyed areas included the Kumano Sea(off Mie Prefecture)and south of the Kii Strait(off Tanabe Bay, Wakayama Prefecture), at depths of 112-775 m. Sampling gears employed were beam trawl and biological dredge. The collection is represented by macrobenthos and meiobenthos from nine animal phyla, including echinoderms, arthropods, molluscans and annelids. The number of phyla occurring in each station varied from seven to eight. The station with most diverse fauna at the phylum level was St. 3B(south of the Kii Strait, 775-661 m depth, mud bottom).Meiofauna includes priapulids, nematodes and small arthropods such as copepods, tanaidaceans, amphipods, isopods and cumaceans. In addition to freeliving species, cnidarians symbiotic on a gastropod and an antipatharian, and crustaceans parasitic on a fi sh and sea urchins were also collected. Preliminary identifi cations are given for Asteroidea, Ophiuroidea, Holothuroidea, Crinoidea, Cyclopoida, Siphonostomatoida, Tanaidacea, Isopoda, Decapoda, Mollusca, polychaetes, Bryozoa, Cnidaria and Nemertea.
  • Kakui K, Nakano T
    Species Diversity 24 179 - 180 2189-7301 2019/11 [Refereed][Not invited]
  • Kakui K, Hiruta C, Uyeno D
    Invertebrate Biology Wiley 138 e12257  2019/09 [Refereed][Not invited]
  • Shimada D, Kakui K
    Zootaxa 4608 484 - 500 1175-5326 2019/05 [Refereed][Not invited]
  • Kakui K, Shimomura M, Kimura S, Kimura T
    Species Diversity 24 103 - 108 2189-7301 2019/05 [Refereed][Not invited]
  • Kakui K, Uyeno D, Naruse T
    Species Diversity 24 49 - 60 2189-7301 2019/05 [Refereed][Not invited]
  • First record of Hemichela nanhaiensis (Pycnogonida: Ammotheidae) from Japanese waters, with the first description of females
    Hosoda Y, Tomioka S, Kakui K
    Species Diversity 23 215 - 218 2018/11 [Refereed][Not invited]
  • 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
    Annals of Field Research and Technology Mie University 三重大学大学院生物資源学研究科 16 (16) 1 - 32 1349-6824 2018/10 [Not refereed][Not invited]
    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.
  • Shinri Tomioka, Keiichi Kakui, Hiroshi Kajihara
    ZOOLOGICAL SCIENCE 35 (5) 436 - 445 0289-0003 2018/10 [Refereed][Not invited]
    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.
  • Chizue Hiruta, Keiichi Kakui, Knut E. Tollefsen, Taisen Iguchi
    Genes to Cells 23 (6) 494 - 502 1365-2443 2018/06/01 [Refereed][Not invited]
    The microcrustacean Daphnia pulex is an important model for environmental, ecological, evolutionary and developmental genomics because its adaptive life history displays plasticity in response to environmental changes. Even though the whole-genome sequence is available and omics data have actively accumulated for this species, the available tools for analyzing gene function have thus far been limited to RNAi (RNA interference) and TALEN (the transcription activator-like effector nuclease) systems. The development of the CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats/CRISPR-associated 9) system is thus expected to further increase the genetic tractability of D. pulex and to advance the understanding of this species. In this study, we developed a genome editing system for D. pulex using CRISPR/Cas9 ribonucleoprotein complexes (Cas9 RNPs). We first assembled a CRISPR single-guide RNA (sgRNA) specific to the Distal-less gene (Dll), which encodes a homeodomain transcription factor essential for distal limb development in invertebrates and vertebrates. Then, we injected Cas9 RNPs into eggs and evaluated its activity in vivo by a T7 endonuclease I assay. Injected embryos showed defective formation of the second antenna and disordered development of appendages, and indel mutations were detected in Dll loci, indicating that this technique successfully knocked out the target gene.
  • Keiichi Kakui, Shinri Tomioka
    Species Diversity 23 (1) 61 - 68 1342-1670 2018 [Refereed][Not invited]
    We establish the new anarthrurid genus Tsuranarthrura gen. nov. based on the new species T. shinsei sp. nov. collected from 1890 m depth offthe eastern coast of Japan, northwestern Pacific Ocean. Tsuranarthrura gen. nov. is the third paratanaoid genus with members having a fused segment composed of pereonite 6 and the pleon, a character state previously restricted to the genera Coalecerotanais Larsen, 2003 (Family incertae sedis) and Metagathotanais Bird and Holdich, 1988 (Family Agathotanaidae). Among anarthrurid genera, Tsuranarthrura gen. nov. is similar to Anarthrura Sars, 1882, Anarthrurella Bird, 2004, and Crenicarpus Drumm and Bird, 2016 in having the labrum not laterally compressed and the antenna with naked fourth and fifth articles from the distal end. However it differs from the latter three in having pereonite 6 fused with the pleon, the maxillipedal endite with a distal seta, the chelipedal merus with a ventral simple seta, and the merus naked on pereopods 2 and 3. We also present the nucleotide sequence for part of the cytochrome c oxidase subunit I (COI) gene in T. shinsei for future use in DNA barcoding or phylogeny.
  • Keiichi Kakui, Yoshihisa Fujita
    PeerJ 2018 (4) e4720  2167-8359 2018 [Refereed][Not invited]
    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.
  • Hiroaki Nakano, Hideyuki Miyazawa, Akiteru Maeno, Toshihiko Shiroishi, Keiichi Kakui, Ryo Koyanagi, Miyuki Kanda, Noriyuki Satoh, Akihito Omori, Hisanori Kohtsuka
    BMC Evolutionary Biology 18 (1) 1471-2148 2017/12/18 [Refereed][Not invited]
    After publication of Nakano et al. (2017) [1], the authors became aware of the fact that the new species-group name erected for the two specimens of a Japanese xenoturbellid species in the article is not available because Nakano et al. (2017) [1] does not meet the requirement of the amendment of Article 8.5.3 of the International Code of Zoological Nomenclature (the Code) [2]. The authors therefore describe the two xenoturbellids as a new species again in this correction article. Methods for morphological observation, DNA extraction and sequencing were as described in Nakano et al. (2017) [1]. The holotype and paratype specimens are deposited in the National Museum of Nature and Science, Tsukuba (NSMT), Japan. The DNA sequences obtained were deposited in the International Nucleotide Sequence Database (INSD). Genus Xenoturbella Westblad, 1949 [3] Xenoturbella japonica sp. nov. 60729A85A (Figs. 1-3, Additional files 1-3 in Nakano et al. (2017) [1]) Etymology. Named for the locality where the specimens were collected. Holotype.NSMT-Xe 2, female (Figs. 1, 3, Additional files 1, 2 in Nakano et al. (2017) [1]), off Jogashima, Miura, Kanagawa, Japan, 35°06.93" N 139°33.72" E to 35°06.95" N 139°33.33" E, 380-554 m depth, December 9th, 2015. Paratype. NSMT-Xe 1, juvenile, sex unknown (Figs. 2, 3, Additional files 1, 3 in Nakano et al. (2017) [1]), Sanriku coast, Iwate, Japan, 39°37.86" N 142°18.22" E to 39°37. 00" N 142°17.60" E, 517-560 m depth, July 18th, 2013. Description of female. Based on holotype. Body 5.3 cm in length pale orange with coloration getting darker toward the anterior. In live specimens, muscles hold the dorsal body wall in a W-shape (three ridges and two troughs). Body shape actively changes by contracting and elongating when alive. Ring furrow and side furrow are present. Ventral mouth present, oval-shaped, just anterior to ring furrow. Glandular network present over ventral surface, starting near anterior tip of body and ending just in front of ring furrow. Internally, body wall with epidermis, circular and longitudinal muscles, parenchyma and gastrodermis present. Oocytes present within intestine. Statocyst situated near anterior tip of body, just inside side furrow. Description of juvenile. Based on paratype. Similar to female, but differs as follows: body 1.1 cm in length pale orange in color dorsal body surface in live specimen smooth, lacking longitudinal ridges and troughs, similar to that of X. bocki gametes not observed. Ventral glandular network not detected externally, but observed with microCT imaging. Genetic information. Whole mitochondrial genome sequences (15,244 bp in holotype 15,249 bp in paratype) and partial Histone H3 gene sequences (346 bp in holotype 413 bp in paratype) were determined and deposited as INSD accession numbers LC228486, LC228485, LC228579 and LC228578, respectively. Remarks. The same species name presented in Nakano et al. (2017) [1] is nomen nudum as the publication does not meet the requirement of the amendment of Article 8.5.3 of the Code [2]. The present erratum fully meets the amended provisions of the Code, and thus this work makes the specific name japonica in the combination of Xenoturbella japonica available. Acknowledgements The authors would like to thank Takafumi Nakano for discussions concerning this erratum.
  • Hiroaki Nakano, Hideyuki Miyazawa, Akiteru Maeno, Toshihiko Shiroishi, Keiichi Kakui, Ryo Koyanagi, Miyuki Kanda, Noriyuki Satoh, Akihito Omori, Hisanori Kohtsuka
    BMC EVOLUTIONARY BIOLOGY 17 (1) 245  1471-2148 2017/12 [Refereed][Not invited]
    Background: Xenoturbella is a group of marine benthic animals lacking an anus and a centralized nervous system. Molecular phylogenetic analyses group the animal together with the Acoelomorpha, forming the Xenacoelomorpha. This group has been suggested to be either a sister group to the Nephrozoa or a deuterostome, and therefore it may provide important insights into origins of bilaterian traits such as an anus, the nephron, feeding larvae and centralized nervous systems. However, only five Xenoturbella species have been reported and the evolutionary history of xenoturbellids and Xenacoelomorpha remains obscure. Results: Here we describe a new Xenoturbella species from the western Pacific Ocean, and report a new xenoturbellid structure - the frontal pore. Non-destructive microCT was used to investigate the internal morphology of this soft-bodied animal. This revealed the presence of a frontal pore that is continuous with the ventral glandular network and which exhibits similarities with the frontal organ in acoelomorphs. Conclusions: Our results suggest that large size, oval mouth, frontal pore and ventral glandular network may be ancestral features for Xenoturbella. Further studies will clarify the evolutionary relationship of the frontal pore and ventral glandular network of xenoturbellids and the acoelomorph frontal organ. One of the habitats of the newly identified species is easily accessible from a marine station and so this species promises to be valuable for research on bilaterian and deuterostome evolution.
  • Daisuke Shimada, Atsushi C. Suzuki, Megumu Tsujimoto, Satoshi Imura, Keiichi Kakui
    Species Diversity 22 (2) 151 - 159 1342-1670 2017/12/01 [Refereed][Not invited]
    A new species of free-living marine nematode, Oncholaimus langhovdensis sp. nov., is described from the intertidal zone of Langhovde (near Syowa Station), Dronning Maud Land, East Antarctica. It closely resembles 11 congeners in the conico-cylindrical tail shape present in males and amphid and excretory pore positions, short spicules, and Demanian system structure present in females. However, it mainly differs from these congeners in body size, de Man's ratios, tail length and shape, and Demanian system structure present in females. Oncholaimus langhovdensis sp. nov. also resembles four congeners known only by females, but it can be distinguished from them based on the tail length and uvette position. In addition to O. langhovdensis sp. nov., two undescribed species (Tripyloididae gen. sp. and Axonolaimidae gen. sp.) and four unidentified species (Sphaerolaimus sp., Oncholaimidae gen. sp., Comesomatidae gen. sp., and Chromadorida fam. gen. sp.) were found from the same locality.
  • Yuki Tanabe, Ryota Hayashi, Shinri Tomioka, Keiichi Kakui
    ZOOTAXA 4353 (1) 146 - 160 1175-5326 2017/11 [Refereed][Not invited]
    We describe Hexapleomera urashima sp. nov. from the carapaces of loggerhead sea turtles (Caretta caretta) on Yakushima Island, southwestern Japan, the primary nesting site for the North Pacific population of this turtle. Hexapleomera urashima closely resembles H. edgari Bamber collected from Australian loggerheads (South Pacific population), sharing a uropod with four articles and maxillipedal endites with distal spiniform setae, but differs in having the maxillipedal coxa with two simple setae, the maxillipedal endite with two tiny dorsosubdistal and two distal spiniform setae, the labial palp fused to the outer lobe of the labium, and the basal article of pleopod 3 without inner setae. Several characters (e.g., size or presence/absence of a dorsal triangular process on the male fixed finger; number of inner setae on the pleopodal endopod), assumed to be diagnostic for species in Hexapleomera, actually vary within H. urashima, indicating that reassessment of species diagnoses is warranted. Hexapleomera urashima showed two COI haplotypes differing by one substitution, but separated from representatives of four other genera by 32.2-48.4% K2P distance. Indices of saturation substitution indicated that COI is not useful for phylogeny reconstruction within Tanaididae.
  • Keiichi Kakui, Chizue Hiruta
    ZOOLOGICAL LETTERS 3 2056-306X 2017/11 [Refereed][Not invited]
    Background: Animals in diverse aquatic groups construct tubes using mucus and filaments, and the acquisition of this capability has likely played an important role in the evolution and diversification of small benthic animals. Tanaidacea is a crustacean order that includes tube-constructing species, most of which belong to Tanaidoidea and Paratanaoidea, with a few in Kalliapseudidae (Apseudoidea). Two previously reported systems used in tube construction are the thoracic-gland system, with secretory glands in thoracic segments (pereonites), and the pereopodal-gland system, with glands in pereopods. Results: Parapseudidae (Apseudoidea) also includes a tube-constructing species, Parapseudes algicola (Shiino, 1952), which lacks large secretory glands in all pereonites and pereopods, but has a pair of acinar glands in the pleotelson, lateral to the gut. Each gland connects to the gut via a short duct, and thence to the exterior via the anal opening. Secretions released from these glands are used to construct tubes, and contain acidic and neutral mucopolysaccharides. Conclusion: We report in P. algicola a third, novel secretory system, here termed the pleotelsonal-gland system, used for tube construction in Tanaidacea. It is similar to the secretory system in some "thalassinidean" decapods; both systems have secretory glands connecting to the gut and thence to the anal opening as the outlet; however, these gland systems likely evolved independently. Recent discoveries of novel secretory systems for tube construction in Tanaidacea suggest that information from smaller, less well-known groups will be necessary to understand how acquisitions of tube-constructing capability affected diversification in animals.
  • Badamdorj Bayartogtokh, Satoshi Shimano, Wataru Hagino, Keiichi Kakui, Shimpei F. Hiruta, Sri Hartini
    International Journal of Acarology 43 (6) 444 - 449 0164-7954 2017/08/18 [Refereed][Not invited]
    Herein, the supplementary description of adults of Eremaeozetes octomaculatu along with illustrations is provided, which is recorded for the first time from Indonesia. Eremaeozetes octomaculatus is an Oriental and Oceanian species, currently known from the Western Samoa Island of Polynesia, Luzon and Mindanao Islands of the Philippines, Okinawa Island in the Ryukyu Archipelago of Japan, and recently we found it in the Java Island of Indonesia. This species appears to be primarily an inhabitant of tropical forests, and it prefers mosses and fungi growing on stones, tree trunks, as well as forest floors and decomposed plant debris. Data of analysis on 28S D3 gene sequence of this species is provided. Comparison of the E. octomaculatus sequence with other oribatid mites 28S D3 sequences identifies that Scapheremaeus is the closest relative to E. octomaculatus with regard to the species included in this analysis, but the relationship was supported by week bootstrap value.
  • Keiichi Kakui, Daisuke Shimada
    ZOOTAXA 4282 (2) 324 - 336 1175-5326 2017/06 [Refereed][Not invited]
    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.
  • Keiichi Kakui, Yoshinobu Hayakawa, Haruo Katakura
    ZOOLOGICAL SCIENCE 34 (2) 129 - 136 0289-0003 2017/04 [Refereed][Not invited]
    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 (F-0) that arises from mancae that are released in autumn, overwinters, reproduces the following spring, and then disappears. The overwintering group produces mancae (F-1) that reach maturity and themselves reproduce within six weeks after release; the F-1 mancae give rise to an F-2 and possibly an F-3 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 degrees 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.
  • Habitat of a tanaidacean Apseudes nipponicus Shiino, 1937
    Kakui K, Suzuki A, Nakano H, Kohtsuka H
    Bulletin of the Kitakyushu Museum of Natural History and Human History Series A (Natural History) 15 1 - 3 2017/03 [Refereed][Not invited]
  • Tomoyuki Komai, Ivan Marin, Keiichi Kakui
    ZOOTAXA 4226 (1) 93 - 102 1175-5326 2017/01 [Refereed][Not invited]
    A poorly known abyssal squat lobster, Munidopsis petalorhyncha Baba, 2005 [= Munidopsis subsquamosa latimana Birstein & Zarenkov, 1970], is redescribed on the basis of the holotype from the Kuril Trench at depths of 5060-5130 m and two recently collected specimens from off Japan at depths of 5353-5382 m. Examination of those specimens enabled us to reassess diagnostic characters of the species. Munidopsis petalorhyncha appears closest to M. thieli Trkay, 1975, known from abyssal plain of the eastern Atlantic, but the spinulose lateral margins of the rostrum, the presence of a distinct lateral eye spine, the presence of a distomesial spine on article 3 of the antennal peduncle and spinose ventral (flexor) margins of meri of pereopods 2-4 distinguish M. petalorhyncha from M. thieli.
  • Naoto Jimi, Megumu Tsujimoto, Kentaro Watanabe, Keiichi Kakui, Hiroshi Kajihara
    ZOOTAXA 4221 (4) 477 - 485 1175-5326 2017/01 [Refereed][Not invited]
    A new species of polychaete, Flabegraviera fujiae sp. nov., is described and the first report of F. mundata (Gravier, 1906) from the shallow water around Syowa Station, Antarctica, is presented. Flabegraviera fujiae sp. nov. resembles F. profunda Salazar-Vallejo, 2012 but is discriminated from the latter by having eyes and an exposed cephalic cage. The specimen of F. mundata was collected from a depth of 8 m, providing the shallowest record of this species to date.
  • Review of the taxonomy, diversity, ecology, and other biological aspects of Order Tanaidacea from Japan and surrounding waters
    Kakui K
    In: Motokawa M, Kajihara H (Eds) Species Diversity of Animals in Japan, Springer 603 - 627 2016/12 [Refereed][Invited]
  • An overview of recent marine-biodiversity research in Japan
    Kajihara H, Kakui K
    In: Motokawa M, Kajihara H (Eds) Species Diversity of Animals in Japan, Springer 25 - 45 2016/12 [Refereed][Invited]
  • Yukiko Narahara-Nakano, Keiichi Kakui, Ko Tomikawa
    ZOOTAXA 4200 (2) 335 - 339 1175-5326 2016/11 [Refereed][Not invited]
  • Shinri Tomioka, Tomohiko Kondoh, Waka Sato-Okoshi, Katsutoshi Ito, Keiichi Kakui, Hiroshi Kajihara
    ZOOLOGICAL SCIENCE 33 (5) 545 - 554 0289-0003 2016/10 [Refereed][Not invited]
    Capitella teleta Blake et al., 2009 is an opportunistic capitellid originally described from Massachusetts (USA), but also reported from the Mediterranean, NW Atlantic, and North Pacific, including Japan. This putatively wide distribution had not been tested with DNA sequence data; intraspecific variation in morphological characters diagnostic for the species had not been assessed with specimens from non-type localities, and the species status of the Japanese population(s) was uncertain. We examined the morphology and mitochondrial COI (cytochrome c oxidase subunit I) gene sequences of Capitella specimens from two localities (Ainan and Gamo) in Japan. Specimens from Ainan and Gamo differed from C. teleta from Massachusetts in methyl-green staining pattern, shape of the genital spines, and shape of the capillary chaetae; we concluded that these characters vary intraspecifically. Species delimitation analyses of COI sequences suggested that worms from Ainan and Massachusetts represent C. teleta; these populations share a COI haplotype. The specimens from Gamo may represent a distinct species and comprise a sister group to C. teleta s. str.; we refer to the Gamo population as Capitella aff. teleta. The average Kimura 2-parameter (K2P) distance between C. teleta s. str. and C. aff. teleta was 3.7%. The COI data indicate that C. teleta actually occurs in both the NW Atlantic and NW Pacific. Given the short planktonic larval duration of C. teleta, this broad distribution may have resulted from anthropogenic dispersal.
  • Shimpei F. Hiruta, Keiichi Kakui
    ZOOTAXA 4169 (3) 515 - 539 1175-5326 2016/09 [Refereed][Not invited]
    We describe three new species of brackish-water ostracods representing two genera in the ostracod tribe Thalassocypridini from mangrove forests in the Ryukyu Islands, subtropical southwestern Japan, and provide their barcoding sequences for the mitochondrial cytochrome c oxidase subunit I (COI) gene. Mangalocypria ryukyuensis sp. nov. was found on Okinawa Island. We also found a Mangalocypria population on Ishigaki Island that was morphologically identical to M. ryukyuensis on Okinawa, but an individual differed by 4.7% in COI sequence (K2P distance) from an individual from Okinawa. This is the first record for Japan of a species in Mangalocypria. Paracypria longiseta sp. nov., obtained from Okinawa Island, is similar to Pontoparta hartmanni. Paracypria plumosa sp. nov. from Ishigaki Island is similar to Pa. adnata described from Yakushima Island, Japan. The COI genetic distance between individuals of Pa. longiseta and Pa. plumosa was roughly as large as that between either of these species and individuals in the Mangalocypria populations. Our study underscores that genera in Thalassocypridini may not represent natural groups, and that this tribe needs taxonomic revision.
  • Kakui K
    Cancer 25 131 - 136 2016/08 [Not refereed][Invited]
  • Craig R. McClain, James P. Barry, Douglas Eernisse, Tammy Horton, Jenna Judge, Keiichi Kakui, Chris Mah, Anders Waren
    ECOLOGY 97 (4) 885 - 898 0012-9658 2016/04 [Refereed][Not invited]
    Energy availability has long been recognized as a predictor of community structure, and changes in both terrestrial and marine productivity under climate change necessitate a deeper understanding of this relationship. The productivity-diversity relationship (PDR) is well explored in both empirical and theoretical work in ecology, but numerous questions remain. Here, we test four different theories for PDRs (More-Individuals Hypothesis, Resource-Ratio Theory, More Specialization Theory, and the Connectivity-Diversity Hypothesis) with experimental deep-sea wood falls. We manipulated productivity by altering wood-fall sizes and measured responses after 5 and 7 years. In November 2006, 32 Acacia sp. logs were deployed at 3203 m in the Northeast Pacific Ocean (Station Deadwood: 36.154098 degrees N, 122.40852 degrees W). Overall, we found a significant increase in diversity with increased wood-fall size for these communities. Increases in diversity with wood-fall size occurred because of the addition of rare species and increases of overall abundance, although individual species responses varied. We also found that limited dispersal helped maintain the positive PDR relationship. Our experiment suggests that multiple interacting mechanisms influence PDRs.
  • Tomonari Kaji, Keiichi Kakui, Naoyuki Miyazaki, Kazuyoshi Murata, A. Richard Palmer
    FRONTIERS IN ZOOLOGY 13 1742-9994 2016/03 [Refereed][Not invited]
    Background: The study of morphology is experiencing a renaissance due to rapid improvements in technologies for 3D visualization of complex internal and external structures. But 3D visualization of the internal structure of mesoscale objects - those in the 10-1000 mu m range - remains problematic. They are too small for microCT, many lack suitable specific fluorescent markers for confocal microscopy, or they require labor-intensive stacking and smoothing of individual TEM images. Here we illustrate the first comprehensive morphological description of a complete mesoscale biological system at nanoscopic resolution using ultra-modern technology for 3D visualization - serial block-face scanning electron microscopy (SBF-SEM). The SBF-SEM machine combines an in-chamber ultramicrotome, which creates a serial array of exposed surfaces, with an SEM that images each surface as it is exposed. The serial images are then stacked automatically by 3D reconstruction software. We used SBF-SEM to study the spinneret (thread-producing) system of a small, tube-dwelling crustacean that weaves tubes of silk. Thread-producing ability is critical for the survival of many small-bodied animals but the basic morphology of these systems remains mysterious due to the limits of traditional microscopy. Results: SBF-SEM allowed us to describe - in full 3D - well-resolved components (glands, ducts, pores, and associated nerves and muscles) of the spinneret system in the thoracic legs and body segments of Sinelobus sp. (Crustacea, Peracarida, Tanaidacea), a tube-building tanaid only 2 mm in body length. The 3D reconstruction by SBF-SEM revealed at nanoscale resolution a unique structure to the gland and duct systems: In each of three thread-producing thoracic segments, two separate ducts, derived from two separate glands located in the body, run through the entire leg and merge at the leg tip just before the spinneret pore opening. We also resolved nerves connecting to individual setae, spines and pores on the walking legs, and individual muscles within each leg segment. Conclusions: Our results significantly expand our understanding of the diversity of spinneret systems in the Crustacea by providing the first well-resolved view of spinneret components in the peracarid crustacean order, Tanaidacea. More significantly, our results reveal the great power of SBF-SEM technology for comprehensive studies of the morphology of microscopic animals.
  • Keiichi Kakui
    SYSTEMATIC PARASITOLOGY 93 (1) 57 - 68 0165-5752 2016/01 [Refereed][Not invited]
    Two new species of nicothoid copepod are described. Rhizorhina ohtsukai n. sp. found on a leptocheliid (Leptochelia sp.) collected at depths of 151-136 m in the North Pacific Ocean is most similar to Rhizorhina aesthetes Boxshall & Harrison, 1988 but can be distinguished by the possession of a narrower body with a rounded anterior end, and in the position of the gonopores. Rhizorhina soyoae n. sp. found on an apseudid (Fageapseudes sp.) collected at depths of 1,595-1,557 m in East China Sea most closely resembles Rhizorhina tanaidaceae Gotto, 1984 but differs in having a narrower body with a rounded anterior end. Partial nucleotide sequences of the cytochrome c oxidase subunit I (COI) gene were obtained from the two copepods in order to enable future barcoding. A phylogenetic reconstruction based on the 18S rRNA gene placed the copepods within the Siphonostomatoida Burmeister, 1835, with the nicothoid Choniosphaera maenadis (Bloch & Gallien, 1933), and separate from the Rhizorhina spp. clade, suggesting that the family Nicothoidae Dana, 1849 is not monophyletic. This is the third report of copepods parasitic on tanaidacean crustaceans.
  • Hiroshi Kajihara, Keiichi Kakui, Hiroshi Yamasaki, Shimpei F. Hiruta
    ZOOLOGICAL SCIENCE 32 (6) 596 - 604 0289-0003 2015/12 [Refereed][Not invited]
    Based on specimens collected subtidally (similar to 10 m in depth) in Tomioka Bay, Japan, we describe the palaeonemertean Tubulanus tamias sp. nov., which differs from all its congeners in body coloration. In molecular phylogenetic analyses based on partial sequences of the nuclear 18S and 28S rRNA genes and histone H3, as well as the mitochondrial 16S rRNA and cytochrome c oxidase subunit I genes, among selected palaeonemerteans, T. tamias nested with part of the congeners in Tubulanus, while the genus as currently diagnosed appears to be non-monophyletic. Molecular cloning detected polymorphism in 28S rDNA sequences in a single individual of T. tamias, indicating incomplete concerted evolution of multiple copies. Tubulanus tamias is peculiar among tubulanids in having 9-10 pigment-cup eyes in the epidermis on either side of the head anterior to the cerebral sensory organs, and remarkably there are two types of eyes. The anterior 8-9 pairs of eyes, becoming larger from anterior to posterior, are completely embedded in the epidermis and proximally abutting the basement membrane; each pigment cup contains bundle of up to seven, rod-shaped structure that resemble a rhabdomeric photoreceptor cell. In contrast, the posterior-most pair of eyes, larger than most of the anterior ones, have an optical cavity filled with long cilia and opening to the exterior, thus appearing to have ciliary-type photoreceptor cells. The size and arrangement of the eyes indicate that the posterior-most pair of eyes are the remnant of the larval (or juvenile) eyes.
  • Uyeno D, Kakui K
    Species Diversity 20 (2) 153 - 158 2015/11 [Refereed][Not invited]
  • Hiroaki Nakano, Keiichi Kakui, Hiroshi Kajihara, Michitaka Shimomura, Naoto Jimi, Shinri Tomioka, Hayate Tanaka, Hiroshi Yamasaki, Masaatsu Tanaka, Takato Izumi, Masanori Okanishi, Yutaro Yamada, Hideo Shinagawa, Toshihiko Sato, Yasutaka Tsuchiya, Akihito Omori, Mamoru Sekifuji, Hisanori Kohtsuka
    REGIONAL STUDIES IN MARINE SCIENCE 2 77 - 81 2352-4855 2015/11 [Refereed][Not invited]
    JAMBIO, Japanese Association for Marine Biology, has been organizing JAMBIO Coastal Organism Joint Surveys at Shimoda Marine Research Center, University of Tsukuba, and Misaki Marine Biological Station, the University of Tokyo. The aims of the Surveys are to uncover the benthic marine fauna of the coastal areas in and around Sagami Bay, and to form a collaborative network between marine biologists across Japan. We have so far performed six surveys, with over 100 participants in total, using common equipment such as dredges, bottom mud samplers, and epibenthic sleds. Even in Sagami Bay, one of the most intensively studied marine environments in the world, we have succeeded in collecting about 50 probable undescribed species. Other species were collected for the first time from Sagami Bay or found from previously unreported depth. The Surveys could be useful for ecological and environmental studies as well. We plan to continue the JAMBIO Coastal Organism Joint Surveys to further reveal the rich biodiversity within and around Sagami Bay and to accelerate nationwide research collaborations. We also hope to expand the Surveys to include plants and protists, and to perform them at other areas in Japan. Through the Surveys, we aim to develop new cross-disciplinary research areas and to record the long-term transition of biota along the Japanese coast. (C) 2015 Elsevier B.V. All rights reserved.
  • Keiichi Kakui, Tohru Naruse
    ZOOTAXA 3995 (1) 138 - 148 1175-5326 2015/08 [Refereed][Not invited]
    We describe Indoapseudes bamberi sp. nov., based on a specimen from Funaura Bay, Iriomote Island, Japan. This species can be distinguished from its five congeners by having the combination of the antenna with a squama and pereopods 1 and 2 with one dorsal spine on the basis. We also determined part of the nucleotide sequence for the cytochrome c oxidase subunit I (COI) gene in I. bamberi, and present a key to Indoapseudes species.
  • Shimada D, Kakui K
    Nematological Research 45 (1) 13 - 18 2015/07 [Refereed][Not invited]
  • Kajihara H, Tomioka S, Kakui K, Iseto T
    Species Diversity 20 83 - 88 2015/05 [Refereed][Not invited]
  • Kakui K, Kohtsuka H
    Species Diversity 20 45 - 58 2015/05 [Refereed][Not invited]
  • First report of Zeuxo sp. (Crustacea: Tanaidacea) as prey for the forktongue goby, Chaenogobius annularis Gill, 1859. [in Japanese with English abstract]
    Kakui K
    Rishiri Studies 34 1 - 6 2015/03 [Not refereed][Not invited]
  • A novel transmission pathway: first report of a larval trematode in a tanaidacean crustacean.
    Kakui K
    Fauna Ryukyuana 17 13 - 22 2014/12 [Refereed][Not invited]
  • Northernmost records of Antedon serrata A. H. Clark from Hokkaido. [in Japanese with English abstract]
    Kohtsuka H, Kakui K, Kajihara H
    Bulletin of the Biogeographical Society of Japan 69 185 - 188 2014/12 [Refereed][Not invited]
  • タナイスの糸.
    うみうし通信 84 2 - 3 2014/09 [Not refereed][Invited]
  • Keiichi Kakui, Chizue Hiruta
    JOURNAL OF MORPHOLOGY 275 (9) 1041 - 1052 0362-2525 2014/09 [Refereed][Not invited]
    Among arthropods, various insects, spiders, and crustaceans produce thread. The crustacean Tanaidacea include species that use thread mainly to construct dwelling tubes. While thread production was previously known only in Tanaoidea and Paratanaoidea, it was recently discovered in two species in Kalliapseudidae (Apseudoidea), although information on the morphology of the thread-producing system was lacking. Using histology, light and scanning electron microscopy, we found that the kalliapseudid Phoxokalliapseudes tomiokaensiscomb. nov. lacks the sort of glandular structures associated with thread production in the pereonites, but has these structures in pereopods 1-6. We observed four types of glandular systems defined by the types and distribution of glands they contain: Type A (pereopod 1), Type B (pereopods 2 and 3), Type C (pereopods 4 and 5), and Type D (pereopod 6). All types have small rosette glands and lobed glands; Type A additionally has large rosette glands. The inferred thread-producing apparatus in P. tomiokaensis is very different from that in Tanaoidea and Paratanaoidea, suggesting that kalliapseudids evolved thread production independently from the latter two groups. J. Morphol. 275:1041-1052, 2014. (c) 2014 Wiley Periodicals, Inc.
  • Tanaidaceans from Rishiri Island [in Japanese with English Abstract].
    Kakui K, Tomioka S, Yamasaki H
    Rishiri Studies 33 7 - 12 2014/03 [Not refereed][Not invited]
  • Kakui K, Yamasaki H
    Species Diversity 2013 (18) 2 - 245-254 2013/12 [Refereed][Not invited]
  • Keiichi Kakui, Saowapa Angsupanich
    ZOOTAXA 3736 (4) 345 - 367 1175-5326 2013/11 [Refereed][Not invited]
    We describe Halmyrapseudes gutui sp. nov. from a mangrove area on Lidee Island, southern Thailand. This species closely resembles H. cooperi, H. killaiyensis, and H. thaumastocheles, but differs in having the lacinia mobilis with three teeth, and the pereopod 1 carpus with 0,1 or 1,1 ventral simple setae proximal to each spiniform seta. We redescribed and synonymized two species of questionable affiliation, Apseudes cooperi and A. digitalis, placing them in Halmyrapseudes, and partly redescribed Halmyrapseudes killaiyensis. Halmyrapseudes and Pseudohalmyrapseudes have disjunct distributions. Halmyrapseudes is similar in distribution to two freshwater fish taxa whose distributions are considered to reflect the breakup of Gondwana and subsequent continental drift. Pseudohalmyrapseudes occurs around Australia, and its distribution seems to be separated from that of Halmyrapseudes by Wallace's Line or Huxley's Line, which are distributional barriers for both terrestrial organisms and an amphidromous shrimp. The adjacent distributions and morphological similarities suggest that Halmyrapseudes and Pseudohalmyrapseudes are sister taxa.
  • Keiichi Kakui, Chizue Hiruta
    NATURWISSENSCHAFTEN 100 (9) 891 - 894 0028-1042 2013/09 [Refereed][Not invited]
    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.
  • New record of Cardiodectes medusaeus (Wilson, 1908) (Copepoda: Siphonostomatoida: Pennellidae) from a stranded pearly lanternfish, Myctophum nitidulum Garman (Myctophiformes: Myctophidae) from the Ryukyu Islands, southern Japan. [in Japanese]
    Uyeno D, Kakui K, Nagasawa K
    The Biological Magazine Okinawa 51 67 - 72 2013/05 [Refereed][Not invited]
  • 第166回農林交流センターワークショップ「分子系統学の理論と実習」体験記.
    日本進化学会ニュース 14 (1) 23 - 25 2013/03 [Not refereed][Invited]
  • Shimada D, Kakui K, Kajihara H
    Species Diversity 17 (2) 221 - 226 2012/12 [Refereed][Not invited]
  • A new species of Stegidotea Poore, 1985 (Isopoda: Chaetillidae) from Japan.
    Shimomura M, Kakui K
    Crustaceana Monographs 17 303 - 314 2012/09 [Refereed][Invited]
  • Keiichi Kakui, Saowapa Angsupanich
    RAFFLES BULLETIN OF ZOOLOGY 60 (2) 421 - 432 0217-2445 2012/08 [Refereed][Not invited]
    We establish the new genus Birdotanais, based on the new species B. songkhlaensis collected from brackish Songkhla Lagoon in Thailand. Birdotanais shows close similarity to members of Families Nototanaidae and Tanaissuidae; we place it in former based on the type species having black eyes and the mandibular molar bearing a broad masticatory region. Birdotanais differs from confamilial genera in having an oval pleopodal endopod with one mid-inner plumose seta, and a nearly straight dactylus-unguis bearing a tiny unguis, on pereopods 4-6. We present a key to genera in Families Nototanaidae and Tanaissuidae.
  • Keiichi Kakui, Norio Kobayashi, Hiroshi Kajihara
    JOURNAL OF CRUSTACEAN BIOLOGY 32 (1) 127 - 139 0278-0372 2012/02 [Refereed][Not invited]
    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.
  • Keiichi Kakui, Toru Katoh, Shimpei F. Hiruta, Norio Kobayashi, Hiroshi Kajihara
    ZOOLOGICAL SCIENCE 28 (10) 749 - 757 0289-0003 2011/10 [Refereed][Not invited]
    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.
  • Michitaka Shimomura, Keiichi Kakui
    CRUSTACEANA 84 (5-6) 543 - 551 0011-216X 2011/05 [Refereed][Not invited]
    A new ingolfiellid amphipod. Ingolfiella ogasawarensis n. sp. is described from shallow water off the Ogasawara Islands, southern Japan. The new species differs from its congeners primarily by having a moderately thick body; pereionites 2-7, pleonites 1-3, and urosomites 1-3 each bearing a pair of dorsal setae; a broad dorsal crest on the basis of gnathopod 1; 6 minute teeth, 1 long stout palmar angle spine, 1 short stout seta, and 8 slender simple setae on the ventral margin of the carpus of gnathopocl 2; propodi of pereiopods 3 and 4 longer than the carpi; uropod 1 shorter than uropod 2; and the first spine on the inner ramus of uropod 1 larger than the following three spines.
  • Pseudosphyrapus cuspidiger sp. nov. from the Nansei Islands, Japan, with a supplementary description of Kudinopasternakia balanorostrata Kakui, Kajihara and Mawatari, 2007 (Crustacea: Tanaidacea: Apseudomorpha: Sphyrapodidae).
    Kakui K, Kajihara H
    Bulletin of the National Museum of Nature and Science Suppl 5 53 - 70 2011/02 [Refereed][Not invited]
  • Hiruta SF, Kakui K
    TAXA, Proceedings of the Japanese Society of Systematic Zoology 日本動物分類学会 29 19 - 30 1342-2367 2010/08 [Refereed][Not invited]
    Personal computers (PCs) are now indispensable to any field of study, and it is important to master efficient ways to compose documents, analyze data, and manage literature. This is especially true of illustrations, which take much time and repeated editing prior to use in publications, posters, presentations, and so on. Although some reports exist on techniques for making digital illustrations there has been rapid progress in the development of new PC hardware and software, so that some types of previously intractable digital graphical processing methods are now feasible and even routine. ...
  • Ko Tomikawa, Keiichi Kakui, Hiroshi Yamasaki
    ZOOLOGICAL SCIENCE 27 (7) 615 - 626 0289-0003 2010/07 [Refereed][Not invited]
    A new melitoid Amphipoda, Psammogammarus mawatarii, is described from Kuchinoerabu Island, Kagoshima Prefecture, Japan. This is the first record of the genus from Asia. The new species is morphologically similar to P. garthi, but differs from the latter in the following features: 1) lateral cephalic lobe of head not strongly produced; 2) head lacking antennal sinus; and 3) posteroventral corner of epimeral plate 3 rounded. Morphology of maxillae 1 and 2, and mandible, and gut contents (harpacticoid Copepoda) of P. mawatarii indicate that the feeding type of the species seems to be, at least facultatively, carnivorous.
  • Keiichi Kakui, Hiroshi Kajihara, Shunsuke F. Mawatari
    ZOOKEYS 33 (33) 1 - 17 1313-2989 2010 [Refereed][Not invited]
    The new species Nesotanais ryukyuensis sp. n. is described from Japan. Nesotanais ryukyuensis most closely resembles N. rugula Bamber, Bird & Angsupanich, 2003, but can be distinguished by the length of simple seta on maxillipedal basis and the shape of cheliped in male. A key to species of the genus Nesotanais is given. The male chelipeds of N. rugula are redescribed. The serial ridges on the inner surface of the chelipedal propodus and dactylus in Nesotanais ryukyuensis and N. rugula are likely to be stridulating ridges that might produce sound.
  • Keiichi Kakui, Hiroshi Kajihara, Shunsuke F. Mawatari
    ZOOTAXA 1563 (1563) 37 - 54 1175-5326 2007/08 [Refereed][Not invited]
    Two new species, Kudinopasternakia balanorostrata and Pseudosphyrapus quintolongus are described from Japan. Kudinopasternakia balanorostrata is characterized by an acorn-shaped rostrum. It most closely resembles K. siegi (Viskup & Heard, 1989), but can be distinguished by the shape of the rostrum, the number of setae on article 2 of the mandibular palp, and the setation on the outer lobe of the fixed endite of the maxilla. Pseudosphyrapus quintolongus is characterized by an unusually large lateral process on pleonite 5, which distinguishes it from all other species in the genus. Keys to species of Kudinopasternakia and Pseudosphyrapus are given.

Awards & Honors

  • 2012/10 日本動物学会 平成24年度川口賞(川口四郎基金による若手研究者国際会議渡航補助)
    受賞者: 角井敬知

Research Grants & Projects

  • 海の底から泳ぎ出す:小型底生甲殻類による泳ぐ矮雄の獲得と進化史
    Date (from‐to) : 2019/04 -2022/03 
    Author : 角井敬知
  • 南西諸島における汽水性タナイス目甲殻類の多様性と進化史
    Date (from‐to) : 2018/09 -2020/08 
    Author : 角井敬知
  • 微小水生甲殻類タナイス目の性表現と生殖様式に関する研究
    Date (from‐to) : 2018/07 -2019/03 
    Author : 角井敬知
  • 深海性タナイス目甲殻類の分類学的研究
    Date (from‐to) : 2018/04 -2019/03 
    Author : 角井敬知
  • 底生動物による海藻葉上固着生活獲得までの進化史の解明
    Date (from‐to) : 2016/04 -2019/03 
    Author : 角井敬知
  • 八重山周辺海域に分布する小型甲殻類相のデータベース構築:1.内湾環境
    Date (from‐to) : 2016/04 -2017/03 
    Author : 上野大輔, 下村通誉, 角井敬知
  • 汽水生小型甲殻類ネソタナイスの分類学的・生殖生物学的研究
    Date (from‐to) : 2015/04 -2016/03 
    Author : 角井敬知
  • タナイス目で見つかった,軟甲綱で初となる自家受精種の総合的研究
    公益財団法人日本科学協会:平成26年度笹川科学研究助成 学術研究部門
    Date (from‐to) : 2014/04 -2015/03 
    Author : 角井敬知
  • 死サンゴ片堆積場(ガレ場)における小型無脊椎動物の多様性調査
    Date (from‐to) : 2014/04 -2015/03 
    Author : 角井敬知
  • うみさわ会(若手海洋生物研究者フィールドワークショップ)
    Date (from‐to) : 2014/04 -2015/03 
    Author : 山崎博史, 角井敬知
  • タナイス目甲殻類の系統進化学的研究-出糸能力獲得の起源について-
    Date (from‐to) : 2012/04 -2014/03 
    Author : 角井敬知
  • タナイス目甲殻類の多様性を生み出した“脚型”の進化史の解明
    Date (from‐to) : 2010/04 -2012/03 
    Author : 角井敬知

Educational Activities

Teaching Experience

  • Methods in Biodiversity Studies
    開講年度 : 2018
    課程区分 : 修士課程
    開講学部 : 理学院
    キーワード : 生物多様性,分類,系統,古生物,進化発生学,動物,植物,海藻,原生生物,系統地理学
  • Special Lecture in Biology I
    開講年度 : 2018
    課程区分 : 学士課程
    開講学部 : 理学部
    キーワード : 寄生 水族寄生虫 カイアシ類 宿主動物
  • Laboratory Course in Marine Biology I
    開講年度 : 2018
    課程区分 : 学士課程
    開講学部 : 理学部
    キーワード : 分類学 解剖学 海産無脊椎動物学
  • Laboratory Course in Systematic Zoology
    開講年度 : 2018
    課程区分 : 学士課程
    開講学部 : 理学部
    キーワード : 分類学 系統学

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