Izawa Marine Biological Laboratory

Tsu-shi, Japan

Izawa Marine Biological Laboratory

Tsu-shi, Japan

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A redescription of Trebius shiinoi Nagasawa, Tanaka & Benz, 1998 and descriptions of its developmental stages, nauplius I and II, copepodid I, II (female), III (female), IV (female) and V (male) are presented based on specimens obtained from the Japanese angelshark, Squatina japonica Bleeker, 1858, captured at Seto and Kushimoto, Wakayama Prefecture, Japan, in 1971-1972. The family is the second representative of the Siphonostomatoida known to have nauplii with spatulate balancers, next to Caligidae. However, T. shiinoi also differs significantly from caligids in lacking a chalimus phase in its life cycle. The postnaupliar development of the species involves a single morphological leap, which takes place through a moult from copepodid II to III, and then development proceeds linearly up to the adult. The majority of the copepodids I found appear to have already been grasped by an adult male each (precopulatory mate guarding). Copepodid II exhibits sexual activity by the possession of a spermatophore receptacle in the female. Copepodids after copepodid III are caligiform, having marginal membranes on the cephalothrax, as in the adult. Copulation takes place at least in copepodid III and/or IV, and the spermatozoa discharged are stored in the genital antra to later fertilize the ova in the adult. Judging from the fact that in the adult female a spermatophore receptacle is absent, it is deducible that no copulation is taking place in the adult stage. This reproductive process is unique in the Copepoda. © 2013 Koninklijke Brill NV, Leiden.


Five new species of the genus Eudactylina are described based on specimens recovered from the branchial lamellae of six species of Japanese elasmobranchs. These are E. musteli nov. sp. from Mustelus griseus Pietschmann, 1908 (Triakidae), E. squatini nov. sp. from Squatina japonica Bleeker, 1858 (Squatinidae), E. dasyati nov. sp. from Dasyatis akajei (Müller & Henle, 1841) and Taeniura meyeni Müller & Henle, 1841 (Dasyatidae), E. taeniuri nov. sp. from T. meyeni, and E. gymnuri nov. sp. from Gymnura japonica (Temminck & Schlegel, 1850) (Gymnuridae). The males of four new species and the copepodid stages IV and V of E. gimnuri nov. sp. are described. Segment formation of the abdomen in the late copepodid stages of this genus and a peculiar process of the 1 st endopodal segment of the male leg 2 are discussed. © 2011 BRILL.


A series of descriptions of postembryonic developmental stages prior to the adult of Hatschekia multibarbatae Izawa, 2015 is presented based on free-living larvae reared from eggs detached from ovigerous females, as well as on copepodids I-V recovered together with adults from Brotula multibarbata Temminck & Schlegel, 1846 (Pisces, Ophidiiformes, Ophidiidae). The number of naupliar stages preceding the infective copepodid I is three in this species. The postnaupliar development proceeds linearly, up to the adult. © Koninklijke Brill NV, Leiden, 2015.


Five naupliar stages and the infective copopodid stage of Eudactylina dasiati Izawa, 2011, Dangoka japonica Izawa, 2011, and an unidentified eudactylinid species are described based on free-living larvae reared from eggs detached from ovigerous females, which were recovered from the branchial lamellae of Japanese elasmobranchs, Dasyatis akajei (Müller Henle, 1841) (Dasyatidae), Rhinobatos schlegelii Müller & Henle, 1841 (Rhinobatidae), and Alopias vulpine (Bonnaterre, 1788) (Alopiidae), respectively. These species of Eudactylinidae, along with Gangliopus pyriformis Gerstaecker, 1854 (Pandaridae) are the only Siphonostomatoida known to have five naupliar stages prior to the infective copepodid I. Naupliar morphology and the antennular segmentation in the Siphonostomatoida are discussed. Siphonostomatoid nauplii may possess six caudal elements and limb buds of the maxillae, maxillipeds, and two legs, but not maxillules. In the Siphonostomatoida, the naked first antennular segment of the nauplius may be retained to the adult stage. © 2012 Koninklijke Brill NV, Leiden.


Nine species of Hatschekiidae are (re-)described from Japanese actinopterygian fishes belonging to Ophidiiformes, Beryciformes and Scorpaeniformes. They are Hatschekia anomalis sp. Nov., Hatschekia bifurcata Yamaguti & Yamasu, 1959, H. couardi Nunes-Ruivo, 1954, H. fusiformis Shiino, 1957, H. Hoplobrotulae sp. Nov., H. multibarbatae sp. Nov., H. tenuis (Heller, 1865), Prohatschekia awatati (Yamaguti, 1939), and P. Neobythitesi sp. Nov. The first species is recovered from an unusual site of the host. In H. couardi and P. awatati the males are described for the first time and the possession of the naked first antennular segment is confirmed in both sexes of these species. The Hatschekiidae have paired seminal receptacles in the female and adopt the eudactylinid type of insemination mode, though exhibiting variation of the insemination procedure. It can be concluded that the insemination modes link up with the female genital system in the Siphonostomatoida. © 2015 Koninklijke Brill NV, Leiden.


Free-living stages, comprising two naupliar stages and the infective copepodid I, of the parasitic copepod Lernanthropinus labracoglossae Izawa, 2014 are described. The larvae were reared from eggs detached from an ovigerous female, recovered from the branchial lamellae of the Japanese actinopterygian fish Labracoglossa argentiventris Peter, 1866 (Kyphosidae). The number of naupliar stages prior to copepodopid I in the Lernanthropidae is the same as in the Caligidae, Pseudohatschekidae and Trebiidae. The copepodid I of the species has a frontal filament, as do representatives of the Caligidae, Pandaridae and Trebiidae. However, this is regarded as a vestigial feature in the last two families. Copepodid I of L. labracoglossae has a 6-segmented antennule, including the naked first segment, as do the first copepodids of eudactylinid copepods. © Koninklijke Brill NV, Leiden, 2014.


Five naupliar stages and the infective copepodid stage of the parasitic copepod, Gangliopus pyriformis Gerstaecker, 1854 are described based on free-living larvae reared from eggs detached from ovigerous females infecting the branchial lamellae of the thresher shark, Alopias vulpinus (Bontarr, 1788). Among Siphonostomatoida parasitic on fish, G. pyriformis is the first representative known to have five, and not three or fewer naupliar stages in its life cycle. The infective copepodid bears a resemblance to the encysted copepodid 1 of Amaterasia amanoiwatoi Izawa, 2008. © 2010 Koninklijke Brill NV, Leiden.


Eight species of pandarid copepods are redescribed based on specimens recovered from six species of Japanese elasmobranchs. These are Pandarus cranchii Leach, 1819, P. smithii Rathbun, 1886, Gangliopus pyriformis Gerstaecker, 1854, Pseudopandarus gracilis Kirtisinghe, 1950, Dinemoura latifolia (Steenstrup & Lütken, 1861), Echthrogaleus coleoptratus (Guérin-Méneville, 1837), E. denticulatus Smith, 1874, and Nesippus orientalis Heller, 1868. In P. cranchii, both sexes of copepodid IV and V are described, one of them retains the frontal filament. The postnaupliar juveniles preceding the adult are referred to here as copepodid stages instead of chalimus. The presence of the postantennal process was verified in all species here dealt with, though it is replaced by an additional adhesion pad in D. latifolia. The depression, seemingly acting as the sucker, was found in N. orientalis on the female leg 3 basis. © 2010 Brill Academic Publishers.


A genus of parasitic copepods, Achtheinus Wilson, 1908 (Siphonostomatoida, Pandaridae), is resurrected. Although it has been relegated in recent decades to a synonym of Perissopus Steenstrup & Lütken, Achtheinus is distinct from the latter in the dorsal plate system of free pedigers 2-4 and in the shape of the genital complex. The nominal species assigned to this genus are revised and A. oblongus Wilson, 1908, A. dentatus Wilson, 1911, and A. pinguis Wilson, 1912 are redescribed as valid based on museum collections including types deposited in the National Museum of Natural History, Smithsonian Institution, and the Swedish Museum of Natural History, Stockholm, and on newly collected specimens from Japanese sharks. These three congeners are distinct from each other in the relative lengths of the caudal rami and abdomen. Achtheinus japonicus Wilson, 1922, A. parvidens Wilson, 1923, Pholidopus (A.) intermedius Kurtz, 1924, A. galeorhini Yamaguti, 1936, A. platensis Thomsen, 1949, and A. impenderus Shen & Wang, 1958 are all synonyms of A. pinguis. Both sexes of A. oblongus and some copepodid stages of the genus are described for the first time. © Koninklijke Brill NV, Leiden, 2010.


Ten species of Lernanthropidae parasitic on the branchial lamellae of Japanese marine actinopterygian fishes are (re-)described herein. These are: Lernanthropinus carangoides sp. nov., recovered from Carangoides equula (Carangidae), Lernanthropinus labracoglossae sp. nov. from Labracoglossa argentiventris (Kyphosidae), Lernanthropsis mugilii (Shishido, 1898) from Mugil cephalus (Mugilidae), Lernanthropus atrox Heller, 1865 from Pagrus major (Sparidae), Lernanthropus erythrocles sp. nov. from Erythrocles schlegelii (Emmelichthyidae), Lernanthropus incilis Ho, Liu & Lin, 2011 from Evoxymetopon poeyi (Trichiuridae), Lernanthropus seriolae Shishido, 1898 from Seriola lalandi (Carangidae), Lernanthropus talipes Wilson, 1935 from Girella punctata and Kyphosus vaigiensis (Kyphosidae), Sagum paracaesionis sp. nov. from Paracaesio xanthurus (Lutjanidae), and a Lernanthropidae sp. (male) from Parapristopoma trilineatum (Haemulidae). Lernanthropus senegalensis Diebakate & Raibaut, 1996 is transferred to the genus Lernanthropinus. Lernanthropus pristipomoides Kirtisinghe, 1937 is relegated to a junior synonym of L. talipes. The possession of the naked first antennular segment is verified for all lernanthropids herein dealt with, in both sexes. The parabasal flagellum characteristic for the family is regarded as homologous with the postantennal process that is very common among siphonostomatoids parasitic on fishes. Two different modes of insemination exist in the Siphonostomatoida. The Lernanthropidae and Eudactylinidae differ from the Caligidae and Pandalidae in their mode of insemination. © 2014 Koninklijke Brill NV, Leiden.

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