Adalia bipunctata is a well-known predaceous ladybird distributed in Europe, Central Asia and North America. This species has not been recorded in Japan. Recently, we found this species in the Osaka Bay area in central Japan, and assume that it was imported with goods such as timber by ships. We studied the life history and the distribution in the Osaka Bay area since the initial discovery. The larvae and adults preyed on aphids (mainly, Periphyllus viridis) on trees such as Acer buergerianum and Rhaphiolepis umbellata. The over-wintered adults appeared in March and laid eggs. The adults emerged in spring, and were in the rolled leaves throughout the rest of the year. Thus, in Japan this ladybird is univoltine with long inactivity in adult. The life history of Japanese population of A. bipunctata differs considerably from other areas where populations are multivoltine. The developmental threshold was estimated to be 6.3°C and the sum of effective temperatures was 322.6 day-degrees for the period from egg to adult emergence. Predation on prepupae of A. bipunctata by the larvae of native species such as Harmonia axyridis was observed occasionally.
The morphology of two Salvelinema Trofimenko, 1962 species, S. salmonicola (Ishii, 1916) and S. walkeri (F.kbaum, 1935), swimbladder nematodes of salmonids, was studied in detail, including scanning electron microscopy (SEM), on the basis of newly collected materials from Oncorhynchus masou, О. mykiss and Salvelinus malma from Japan and from Oncorhynchus ciarki, О. kisulch and O. nerka from North America (Vancouver Island, B.C., Canada and Gulf of Alaska). Both nematode species proved to be morphologically very similar, differing substantially in the numbers and arrangements of egg filaments. Deirids were described for the first time for Salvelinema. Salvelinema iwana (Fujita, 1928), S. amemasu (Fujita, 1939), S. kosugii (Fujita, 1939), S. oncorhynchi (Fujita, 1939) and S. salvelini (Fujita, 1939) (= S. ishii (Fujita, 1941)) were synonymised with S. salmonicola. Comephoronema Layman, 1933 is re-erected as a valid genus related to Salvelinema.
We encountered two cases of infection with large female nematodes of the genus Philometra Costa, 1845 in the body cavity of a map puffer Arothron mappa (Lesson) caught off Okinawa, Japan, and a blackspotted puffer Arothron nigropunctatus (Bloch et Schneider) caught off Queensland, Australia, both reared in aquariums in Japan. No morphological difference was observed between the nematodes from A. mappa and A. nigropunctatus. We identified the nematodes as Philometra pellucida (Jägerskiöld, 1893) based on their morphology. The sequences of the nematodes from both hosts were identical to each other (1,643 bp) and formed a clade with other 17 nematodes belonging to the genera Philometra and Philometroides Yamaguti, 1935 with high bootstrap value (bp = 100). It is the first time that the genetic data on P. pellucida are provided. Philometra robusta Moravec, Möller et Heeger, 1992 is synonymised with the former species.
Morphological data and molecular analyses are used to describe the taxonomy of philometrid nematodes of the genus Philometra Costa, 1845, found in the gonads of marine fishes in Japan. A new Philometra species, P. sawara sp. n., is described based on male and female specimens collected from the gonads of Scomberomorus niphonius (Cuvier) (Japanese Spanish mackerel). Two additional species, Philometra nemipteri Luo, 2001 and Philometra sciaenae Yamaguti, 1941, are confirmed as valid species and are redescribed based on specimens collected from the gonads of Nemipterus virgatus (Houttuyn) (golden threadfin bream) and Pennahia argentata (Houttuyn) (silver croaker), respectively. Male P. nemipteri are first reported and described in this study. Redescriptions of female P. nemipteri and male and female P. sciaenae were also necessary based on our morphological observations. A molecular comparison of the internal transcribed spacer 2 (ITS2) region of the ribosomal DNA between P. sawara, P. nemipteri, P. sciaenae, and previously reported philometrid nematodes from the genus Philometra and Philometroides Yamaguti, 1935 supports the conclusion that the three Philometra species in the current study are independent. An ITS2-derived neighbour-joining tree, consisting of both the current specimens and previously described Philometra and Philometroides species, is also presented.
Gangesia parasiluri Yamaguti, 1934 (Cestoda: Proteocephalidae) is redescribed on the basis of adults obtained from the intestine of Silurus asotus Linnaeus (Teleostei: Siluridae) from Lake Suwa, Nagano Prefecture, central Japan. Its life cycle was studied in the field and laboratory. Rostellar hooks of the adults showed a wide variation in number, ranging from 35 to up to 57. Plerocercoids were found in the rectum of Chaenogobius urotaenia (Hilgendorf) and Rhinogobius brunneus (Temminck et Schlegel) (Teleostei: Gobiidae) from the same lake. Procercoids were formed in the haemocoel of Mesocyclops leuckarti (Claus) (Copepoda: Cyclopidae) 7 days post infection at 21-25°C. They developed into plerocercoids in the intestine of Pseudorasbora puntila pumila Miyadi (Teleostei: Cyprinidae), R. brunneus and S. asotus. Plerocercoids from naturally and experimentally infected fishes were fed to S. asotus, from which immature worms were recovered. It is considered that the life cycle involves three hosts: a copepod as the intermediate host in which procercoids are formed, small fish as paratenic hosts which retain plerocercoids and transport them into S. asotus, and S. asotus as the definitive host in which adults develop. Rostellar hooks of the adults were much fewer, much larger and arranged in fewer circles than those of the plerocercoids. It is suggested that the former are newly formed and replace the latter in an early stage of development of plerocercoids into adults in 5. asotus.
Salmincola markewitschi Shedko et Shedko, 2002 (Copepoda: Lernaeopodidae) is an ectoparasitic copepod mainly infecting the buccal cavities of white-spotted charr Salvelinus leucomaenis (Pallas) (Salmonidae). This species has only been recorded from Northeast Asia, where a morphologically similar congener Salmincola carpionis (Krøyer, 1837) is also distributed, using the same host species. These copepods are hard to distinguish from each other because of their similarities. We thus examined the newly collected specimens morphologically and genetically from five populations of white-spotted charr in Japan. Most of the specimens were morphologically consistent with S. markewitschi but showed great variations in the numbers of spines on the exopods of the antennae, shape of the maxilliped myxal palps, and the bulla diameter. Consequently, some specimens shared characteristics with S. carpionis. In addition to the mophological continuities, genetic analyses of 28S rDNA and COI mitochondrial DNA confirmed that all specimens belong to a single species. Further taxonomic revisions are required to draw conclusions of whether S. markewitschi is a valid species different from S. carpionis, by collecting samples from across their wide distributional ranges, such as Europe, North America, and Northeast Asia. A key to identification of species of Salmincola Wilson, 1915 occurring in Japan is also provided.
Gravid females of two species of philometrid nematodes (Philometridae) were collected from marine perciform fishes in Japanese waters, mainly from the southern Sea of Japan. Based on light microscopy and scanning electron microscopy examinations, the previously described but poorly known species Philometra cryptocentri Yamaguti, 1961 is redescribed from specimens recovered from the abdominal cavity of Acanthogobius flavimanus (Temminck et Schlegel), Pterogobius elapoides (Günther) and P. zonoleucus Jordan et Snyder (all Gobiidae) (all new host records); the number (14) and arrangement of cephalic papillae in this species are described for the first time. The new species, Philometroides branchiostegi sp. n. from head tissues of Branchiostegus japonicus (Houttuyn) (Malacanthidae), based on a single specimen, is mainly characterized by the embossment of the entire body except for the cephalic end, presence of four submedian pairs of large cephalic papillae of external circle and two small lateral single papillae of internal circle, pair of large papilla-like caudal projections, the oesophagus with a distinct anterior inflation, by a markedly small body (length about 18 mm) and the larvae 306-465 µm long.