Kunihiko Izawa

Some new and known species of Hatschekiidae (Copepoda, Siphonostomatoida) parasitic on Japanese actinopterygian fishes belonging to Ophidiiformes, Beryciformes and Scorpaeniformes, with discussion on the female genital system and the insemination mode in Siphonostomatoida*

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.

Some new and known species of the Lernanthropidae (Copepoda, Siphonostomatoida) parasitic on the branchial lamellae of Japanese actinopterygian fishes, with revision of two known species of the family and discussion on the insemination mode in the Siphonostomatoida*

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.

Five New Species of Eudactylina Van Beneden, 1853 (Copepoda, Siphonostomatoida, Eudactylinidae) Parasitic on Japanese Elasmobranchs

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 (Muller & Henle, 1841) and Taeniura meyeni Muller & 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 1st endopodal segment of the male leg 2 are discussed.

Pseudohatschekiidae, a new family for Pseudohatschekia branchiostegi Yamaguti, 1939 (Crustacea: Copepoda: Siphonostomatoida) from Branchiostegus spp. (Teleostei: Perciformes: Malacanthidae) in Japanese waters, with descriptions of the early developmental stages of P. branchiostegi

The siphonostomatoid copepod Pseudohatschekia branchiostegi Yamaguti, 1939 is redescribed in detail based on specimens of both sexes collected from the gill filaments of three species of Branchiostegus Rafinesque (Teleostei: Malacanthidae) captured in Japanese waters. Descriptions of two naupliar stages and the infective copepodid stage of P. branchiostegi are also provided for the first time, and P. mebaru Yamaguti, 1939 is recognised herein as a junior synonym of P. branchiostegi. The latter copepod species represents a new family, the Pseudohatschekiidae fam. nov., of the Siphonostomatoida characterised by the following apomorphies: (a) two free pedigerous somites present between the cephalothorax and the genital complex; (b) a chelate antenna bearing two digitate processes and a thin cuticular covering; (c) a unilobate maxillule, with the palp completely fused to the endite and represented by a surface seta; (d) a rounded process furnished with pectinate membranes on the apex of the maxillary basis; (e) 2-segmented rami on legs 1–3; and (f) the absence of leg 4. It is also now evident that P. branchiostegi is a relatively common and abundant parasite of Branchiostegus spp. in the Far East.

Descriptions of postembryonic developmental stages prior to adult of Hatschekia multibarbatae Izawa, 2015 (Copepoda, Siphonostomatoida, Hatschekiidae)

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.

Descriptions of the postembryonic developmental stages of Hatschekia bifurcataYamaguti & Yamasu, 1959 (Copepoda, Siphonostomatoida, Hatschekiidae)

A series of descriptions of postembryonic developmental stages of Hatschekia bifurcataYamaguti & Yamasu, 1959 is presented based on free-living larvae reared from eggs detached from ovigerous females recovered from the branchial lamellae of Aulacocephalus temminckiBleeker, 1855, as well as on copepodids I-VI from A. temminckiand Diploprion bifasciatumCuvier, 1828 (Pisces, Perciformes, Serranidae). The number of naupliar stages preceding the infective copepodid I is three in this species as in H. multibarbataeIzawa, 2015. A diagnostic feature of the species, a hook-like ventral process on the fourth antennular segment of the female, is regarded as an enlarged seta and was found to appear after copepodid V. A correction in the previously given setation of leg 2 and a complemental description of the antennule of the adult female are made. The male of this species is herein described for the first time. The sexes become distinct at copepodid III, and then growth curves of both sexes diverge stage by stage, as in H. multibarbatae. Aulacocephalus temminckiis reported as a new host species for H. bifurcata.

Redescription of adults and description of developmental stages of Trebius shiinoi Nagasawa, Tanaka & Benz, 1998 (Copepoda, Siphonostomatoida, Trebiidae) from the Japanese angelshark, Squatina japonica Bleeker, 1858

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.

Resurrection and redescription of Hatschekia cylindrica Shiino, 1957 (Copepoda, Siphonostomatoida, Hatschekiidae), with description of its developmental stages

Hatschekia cylindrica Shiino, 1957 is resurrected and redescribed based on newly obtained specimens, and all developmental stages except copepodid II are described based on free-living larvae reared from eggs detached from ovigerous females, as well as on both sexes of copepodids III-V recovered together with adults from Pseudolabrus sieboldi Mabuti & Nakabo, 1997 (Pisces, Labridae). There are three naupliar stages preceding the infective copepodid I and the sexes are distinct after copepodid III, as in the two other species of Hatschekia studied thus far in this respect.

Some new and known species of Lernanthropidae (Copepoda, Siphonostomatoida) parasitic on Japanese actinopterygian fishes, with a revision of two known species of the family

Six species of Lernanthropidae parasitic on the branchial lamellae of Japanese actinopterygian fishes are (re-)described. They are: Lernanthropinus maajii sp. nov. from Trachurus japonicus (Temminck & Schlegel, 1844) (Carangidae), L. sphyraenae (Yamaguti & Yamasu, 1959) from Sphyraena pinguis Gunther, 1874 and S. japonica Bloch & Schneider, 1801 (Sphyraenidae), Lernanthropsis mugilii (Shishido, 1898) from Mugil cephalus Linnaeus, 1758 (Mugilidae), Lernanthropus seriolii Shishido, 1898 from Seriola lalandi Valenciennes, 1833 (Carangidae), Sagum brotulae sp. nov. from Brotula multibarbata Temminck & Schlegel, 1846 (Ophididae), and S. epinepheli (Yamaguti & Yamasu, 1960) from Epinephelus akaara (Temminck & Schlegel, 1842) (Serranidae). Lernanthropinus holiulini sp. nov. and Sagum pillaisebastiani sp. nov. are herein established for Ho et al.’s (2008) Lernanthropinus sphyraenae and Pillai & Sebastian’s (1967) Sagum epinepheli , respectively.

Redescription of five known species of Hatschekia Poche, 1902 (Copepoda, Siphonostomatoida, Hatschekiidae) parasitic on Japanese tetraodontiform fishes, with discussion on sexually dimorphic features in the genus

Five known species of Hatschekia Poche, 1902, parasitic on the branchial lamellae of Japanese tetraodontiform fishes, are redescribed. They are H. monacanthi Yamaguti, 1939, H. bibullae Uyeno & Nagasawa, 2010, H. kuroshioensis Uyeno & Nagasawa, 2010, H. ostracii Yamaguti, 1953, and H. legouili Nunes-Ruivo, 1954. The males of H . bibullae and H. legouili , free-living larval stages of H. bibullae reared from eggs, the copepodid IV female of H. kuroshioensis , and both sexes of copepodids III-V of H. legouili are described for the first time. The antenna, the postantennal process, the length of the caudal ramus, and the ornamentation of the dorsal shield of the cephalothorax, if present, are sexually dimorphic within the genus. By showing these sexually dimorphic features of the male, it is inferred that both sexes of copepodid II-IV and copepodid V male, have attributes of the male.