Three new interstitial species of the genus Neonesidea (Bairdioidea: Podocopida: Ostracoda) from the infralittoral zone in Japan.

This study is the first to report on interstitial species of the genus Neonesidea: Neonesidea arenalocus sp. nov. from the Pacific coast of central Japan, Neonesidea alyamanai sp. nov. from the Pacific coast of south-western Japan, and Neonesidea alwakasaensis sp. nov. from the Sea of Japan coast of western Japan. All three species share a smaller carapace size than that of the epiphytic Neonesidea species; in particular, the carapace width and valve thickness are significantly less. Furthermore, the terminal claws on the walking legs are more linear than those of the epiphytic Neonesidea species. However, these three new species share a feature in the apical portion of the terminal claw on the males second antennae and asymmetric brush-shaped organs, which are common to this genus. In addition, the results of our field survey indicate that all three new species occur in coarse-grained sediments (coarse sand to pebbles) in the upper infralittoral zone, particularly on Miho-Masaki Beach, which contains an optimum zone for N. arenalocus sp. nov.

Morphological types of male copulatory organs of Bicornucythere bisanensis (Ostracoda, Crustacea) and the description of a new Bicornucythere species.

This study is designed to evaluate the male copulatory organs and carapace size of the inner bay benthic ostracod Bicornucythere bisanensis. The male copulatory organs demonstrate noticeable intraspecific variation in the distal lobe, especially the length of the tip, which shows a gradual variation; whereas the thickness of the distal lobe is conservative within the species. The population from central Japan (Aburatsubo Cove) showed remarkable morphological variations, with four copulatory organ types, each type defined by a combination of four shapes of the right and left distal lobes (Shape R, r, L, and l). While the variety of carapace morphotypes have been previously reported, our findings suggest that one morphotype from western Japan (Misumi-cho) should be treated as a distinct species. Thus, we described it as Bicornucythere misumiensis sp. nov.

Crayfish co-introduced symbiotic ostracod found on native crab in Japan: The first record of epibiont ostracod found a new host.

Ankylocythere sinuosa (Rioja, 1942), a symbiotic ostracod native to North America, was found from the Japanese mitten crab Eriocheir japonica (De Haan, 1835), a species native to Japan, collected from a pond in Shizuoka City, Shizuoka Prefecture, central Japan. Introduced North American crayfish Procambarus clarkii (Girard, 1852), which is a host of A. sinuosa in their native range, inhabits ponds sympatrically with Japanese mitten crabs, and it is thought that the ostracods transferred from the exotic crayfish to the native crabs. In recent years, along with the artificial transportation of crayfish around the world, their symbiotic ostracods also have been found on the body surfaces of exotic crayfish in Europe and Japan. However, no studies have confirmed the infestation of exotic ostracods on native crustaceans in the field. A wide range of developmental stages of A. sinuosa from juveniles to adults were found in Japanese mitten crabs, and mating individuals were also found. This strongly suggests that they can reproduce on the body surface of Japanese mitten crabs. In the future, it will be necessary to strengthen measures against alien species to prevent these exotic symbionts from infestating native ecosystems, and we also need to investigate the exact impact of this symbiont on Japanese mitten crabs.

Two species of the genus Anchistrocheles (Bairdioidea: Ostracoda: Crustacea) from Japan and their developmental characteristics for adaptation to interstitial environments.

A new species and an already known species of the genus Anchistrocheles Brady & Norman, 1889 from the Pacific coast of Japan, are described in detail using scanning electron microscopy of the carapaces and soft-part anatomy of the appendages. The new species, Anchistrocheles hayatotanakai sp. nov., is only the second to be described in the genus Anchistrocheles from Japan, and this study is also the first to describe the appendages of A. yamaguchii Yajima, 1987, previously only known as a fossil from Pleistocene strata of the Atsumi Formation in central Japan. The two species are considered to be closely related because they share many common characters in their appendages, but they are distinguishable from each other based on the male and female copulatory organs, furcal chaetotaxy, brush-shaped organs, number of lateral pore systems, and outlines of the carapaces in dorsal view. Ontogenetic changes of carapace sizes were compared between three interstitial species (Anchistrocheles hayatotanakai sp. nov., A. yamaguchii, and Neonesidea sp. I) and an epifaunal species (N. sp. S). The reduction in carapace width was found to be the primary reason for the reduction in the cross-sectional area and is probably related to the adaptation to interstitial environments. The brush-shaped organs located between the 6th pair of limbs are also shown. This study is the first to report the anatomically precise position of these organs.

Two new species of Bairdiidae (Ostracoda: Crustacea) from the western Pacific coast of Japan.

Herein, two new bairdiid ostracod species in the western Pacific Coast of Japan, namely Neonesidea kamiyai sp. nov. and Bairdoppilata japonica sp. nov. are described. They are the fourth and first species described in their respective genus in Japan within the Recent Bairdiidae. The description of the two new species is based on scanning electron microscopic investigation of carapaces and on the analysis of anatomy and chaetotaxy of appendages. Scanning electron microscopy of the carapace and soft-part anatomy of appendages of the two new species provided the complete species description. An asymmetric brush-shaped organ, with the right part considerably larger than the left part, is found in both species; this characteristic is suggested to be synapomorphic for some taxa in the family Bairdiidae.

Three new species of the genera Loxoconcha and Xestoleberis (Crustacea, Ostracoda, Podocopida) from central and southern Vietnam.

The present study reports three new species of Ostracoda, Loxoconcha damensis sp. nov., Xestoleberis vietnamensis sp. nov. and X. munensis sp. nov., from Phu Quoc Island, southwest Vietnam and Nha Trang Bay, central Vietnam. These species inhabit the coral reefs around isolated islands and can be easily distinguished from other known species based on their morphological differences, mainly in the male copulatory organ. Loxoconcha damensis sp. nov. belongs to Loxoconcha Group A, based on the distributional pattern of their pore system below the eye tubercle. Similarly, based on a combination of morphological types of pore systems, the two new Xestoleberis species belong to Xestoleberis Group A, because these species have two types of pore systems, i.e., sieve-type and lip-type. To the best of our knowledge, this study is the first report on Xestoleberididae and the second on Loxoconchidae from the Recent of Vietnam.

A new interstitial ostracod species of the genus Paracobanocythere from Vietnam, with mitochondrial CO1 sequence data of three Asian species.

This study is a first report of an interstitial ostracod from Southeast Asia. The ostracod species, Paracobanocythere vietnamensis sp. n., was found in the marine interstitial environment of Phu Quoc Island, Vietnam. Thus far, three species of this genus have been described. The morphology of the carapace as well as the appendages of this new species are quite similar to Paracobanocythere hawaiiensis and Paracobanocythere watanabei. However, we found that they could be easily distinguished according to the morphology of the male copulatory organ. Additionally, we estimated the evolutionary distances among these three species based on nucleotide and amino acid sequences of the mitochondrial CO1 gene. Similar morphologies of carapaces and appendages, and relatively small evolutionary distances according to CO1 between Paracobanocythere vietnamensis sp. n. and Paracobanocythere watanabei suggest that these two species are very closely related.

First records of interstitial leptocytherids (Crustacea, Ostracoda): two new species and a redescription of Callistocythere ventricostata Ruan & Hao, 1988 collected from the Okinawa Islands, southern Japan.

Two new and one known species belonging to the genus Callistocythere of the family Leptocytheridae from interstitial environments of the Okinawa Islands are fully described. Callistocythere intermedia sp. nov. is regarded as belonging to the C. japonica group, and Callistocythere ryukyuensis sp. nov. belongs to the C. minor group (these groups were established by Hanai 1957 based on carapace morphology). The redescribed Callistocythere ventricostata Ruan & Hao, 1988 clearly differs from known leptocytherid species in the morphologies of the carapace and the male copulatory organ. The habitats of C. intermedia sp. nov. and C. ryukyuensis sp. nov. are found along the shoreline zone and the mid to high tide levels of the littoral zone, respectively, and C. ventricostata is found from the shoreline to the sub-tidal zone. These species are the first global records of interstitial leptocytherids.

Intraspecific variation in male upper lip morphology of Parapolycope watanabei n. sp. (Crustacea: Ostracoda) and its implications for speciation.

The morphology of non-genitalic structures in males is often associated with mating and courtship, and the evolution of those structures may cause speciation. In the present study, we describe a new species of marine interstitial ostracod from Japan. Morphological comparisons and molecular phylogenetic analysis based on ITS (internal transcribed spacer) 1 and ITS2 sequences revealed intraspecific variation on the male upper lip in the new species. The male upper lip of Parapolycope Klie, 1936 species has been reported to be related to mating behavior, and it likely produces species-specific stimuli for the female. The results of this study suggest that the male upper lip morphology in Parapolycope changed at the early stage of the speciation process.

Three new species of the genus Loxoconcha (Crustacea, Ostracoda, Podocopida) from the Okinawa Islands, southern Japan.

Three new species of Ostracoda, Loxoconcha noharai sp. nov., L. santosi sp. nov. and L. sesokoensis sp. nov., are described from the Okinawa Islands, southern Japan. The two species Loxoconcha noharai sp. nov. and L. santosi sp. nov. live in estuaries, whereas the species L. sesokoensis sp. nov. lives in coral reefs. These species can be easily distinguished from other previously described Loxoconcha species by their morphological differences, mainly in the male copulatory organ, and distribution pattern of their pore systems. In addition, L. sesokoensis sp. nov. is suggested to be phylogenetically apart from any other Loxoconcha species which have been reported so far from Japan and the adjacent seas.

Description and scanning electron microscopic observation of a new species of the genus Polycopetta (Crustacea, Ostracoda, Cladocopina) from an interstitial habitat in Japan.

A new species of the genus Polycopetta Chavtur, 1981, Polycopetta quadrispinata sp. n. is described from the interstitial environment of Mihomasaki Beach in Japan. These observations showed some morphological peculiarities of Polycopetta quadrispinata sp. n. compared with its congeners; Polycopetta monneroni Chavtur, 1979, Polycopetta curva Chavtur, 1979, Polycopetta bransfieldensis (Hartmann, 1987), and Polycopetta pax Kornicker and Harrison-Nelson, 2005. Three characteristics are described for the first time: (1) a seta with serrated tip on the male antennula, (2) the endopodite of the fifth limb consisting of two podomeres, (3) the long spermatozoa in the male posterior body. More detailed observations of the type species are needed in order to update the generic diagnosis.

The lunule of caligid copepods: an evolutionarily novel structure.

Nearly half of the genera of the family Caligidae possess an evolutionarily novel structure called the "lunule" on the ventral surface of the frontal plate. Lunules are paired cup-like suckers that assist in securing attachment of the copepod parasite to its host. Although present in genera such as Caligus and Pseudocaligus, lunules are absent in other caligid genera such as Lepeophtheirus as well as in more primitive caligiforms such as members of the families Trebiidae and Dissonidae. We compared the morphology and development of the anterior margin of the frontal plates between two caligids, Pseudocaligus fugu and Lepeophtheirus sekii, and a more basal caligiform, Dissonus heronensis (a dissonid), using scanning electron, transmission electron, and laser confocal microscopes. Our observations suggest that the lunules originated as a modification of the marginal membranes of the ancestral frontal plates. We also demonstrated the presence of an anlagen cell population for the lunule and marginal membrane in the developing frontal plate. These primordial cells can be detected as early as the first stage of the chalimus phase. Based on these observations, an evolutionary scenario for the lunule is proposed based on cytological evidence. This case study enhances our understanding of "evolutionary novelty," which is a main focus of contemporary evolutionary developmental biology.

Two new species of the interstitial genus Parvocythere (Crustacea, Ostracoda, Cytheroidea) from Japan: an example of morphological variation.

Two new species of the interstitial ostracod genus Parvocythere, Parvocythere gottwaldisp. n. and Parvocythere gracilissp. n., are herein described. Although these two new species are clearly distinguishable by certain morphological differences in elements of the male copulatory organ, and the carapace, they share the following simplified characters of the appendages and male copulatory organ: antennular fourth podomere with no suture; reduced claws on the distal end of antenna; and asymmetric male copulatory organ. The morphological differences among known and new Parvocythere species suggest that the species of this genus can be classified into two groups by the presence/absence of the suture on the antennular fourth podomere. The "Group S" is characterised by the presence of the antennular suture, and all species of this group have a two-clawed antenna and symmetric male copulatory organ, characters which are generally seen in cytheroid ostracods. The species belonging to "Group N" are characterised by the absence of the suture, regarded as a pedomorphic character, show the following characters: two clawed or one clawed antenna, and symmetric or asymmetric male copulatory organ. The morphological variation within Group N includes reductive characters regarded as an adaptation to the narrow spaces of the interstitial environment of a sandy beach. These intrageneric morphological variations of the exclusively interstitial genus Parvocythere suggest the possibilities that Group N might be derived from Group S, and that some adaptive characters to an interstitial environment could have developed after the colonisation of these environments.

A bridge between original and novel states: ontogeny and function of "suction discs" in the Branchiura (Crustacea).

The emergence of novel structures in the course of evolution faces an explanatory problem, leaving the gap from the ancestral structures difficult to bridge. This difficulty is caused by the lack of intermediate stages. Branchiurans are ectoparasitic crustaceans which use a pair of "suction discs" to attach to their host. These structures are modified first maxillae. During ontogeny, the first maxillae transform from a normal cephalic appendage to the specialized suction disc. However, supposedly ancestral branchiurans lack the suction discs in the adults and the first maxilla remains a normal appendage throughout. We describe the muscular arrangements in the developing first maxillae in Argulus coregoni. The suction discs originate as a fusion of the first and second podomeres. The sucker muscles of the suction discs are homologous to the muscles that insert in the second podomere at the early larval stages. The developmental process of the suction disc can be seen as a "recapitulation" of the evolutionary process. We thus show how the first maxilla can maintain not just the biological role but also a functional continuity during the evolution of the novel structure. From this example it is obvious that the intermediate stages of the emerging novelty, if present in the ontogeny, can help solve at least some of the enigmatic appearances of novel structures.

Homology and evolution of the antenna in podocopid ostracods from the perspective of aesthetascs.

Antennal podomere homology has not been well documented in podocopid ostracods. Difficulties associated with describing this homology are compounded by the occurrence of specialised podomeres in both cytheroids and bairdioids. Our research establishes the existence of two kinds of aesthetascs shared among multiple higher taxa. Overgrowth "t-setae" are present in males in Cytheroidea, Cypridocopina and Darwinuloidea, and "aesthetasc yc" is found in both sexes in Cytheroidea and Bairdioidea. Homology of the antennal podomeres among all podocopid superfamilies was determined by using the chaetotaxy of these aesthetascs, leading to a description of evolutionary modifications of the podocopid antenna, which suggests that changes in function of the articulation were prompted by the temporal demands of copulatory behavior in each lineage.

Two new species of Semicytherura (Podocopa: Ostracoda) from Akkeshi Bay, Hokkaido, Japan, with comments on their speciation and related species.

Two new ostracod species, Semicytherura maxima n. sp. and S. ikeyai n. sp., both belonging to the S. henryhowel group of the genus, are described. They were collected from Akkeshi Bay in northeastern Japan, and inhabit the marine sediment surface in places deeper than the intertidal zone. Their distributions in northern Japan seem to be influenced by the cold-water Chishima Current (Oyashio). The geological distribution and species diversity were surveyed for each of the subgroups recognized in the S. henryhowei group. The results suggest that these subgroups split from each other in the NW Pacific by the Early Miocene, and that one of them has spread around the Northern Hemisphere, while the other has remained in the NW Pacific since that time.

The incidence and severity of Henoch-Schönlein purpura nephritis over a 22-year period in Fukushima Prefecture, Japan.

BACKGROUND: Recently, there have been a few reports on the decrease in the incidence of severe Henoch-Schönlein purpura nephritis (HSPN) in Japan. To evaluate the incidence and the severity of HSPN, we examined the epidemiology and clinical manifestations of HSPN in Fukushima Prefecture over a 22-year period. METHODS: We enrolled 61 patients (Group 1) diagnosed with HSPN between 1987 and 1997 and a further 59 patients (Group 2) diagnosed with HSPN between 1998 and 2008. Epidemiology, clinical features, laboratory data, pathological findings, treatment and outcome were retrospectively compared between the two groups. RESULTS: The mean number of patients per 100,000 children per year was 3.5 ± 1.2 in Group 1 and 3.6 ± 0.8 in Group 2. The clinical manifestations and laboratory findings at onset were comparable between Groups 1 and 2. Pathological findings in Group 1 and Group 2 were classified as ISKDC grade IIIa in 16 (26%) and 14 cases (24%), grade IIIb in 26 (43%) and 27 cases (46%), grade IV in 5 (8%) and 6 cases (10%)), grade V in 1 (2%) and 5 cases (8%), and grade VI in 2 (3%) and 2 cases (3%), respectively. There were no inter-group differences in ISKDC classification or rate of crescentic formation. CONCLUSIONS: Our findings suggest that the incidence of HSPN and the severity of HSPN in patients between 1987 and 1997 were similar to those in patients between 1998 and 2008 and that the number of patients with severe HSPN has not decreased.

Origin of the novel chemoreceptor Aesthetasc "Y" in Ostracoda: morphogenetical thresholds and evolutionary innovation.

The morphology and developmental processes of the two types of ostracod chemoreceptors, the Aesthetasc "Y" and the "Grouped setae," were compared. Cypridoidea and Pontocypridoidea, belonging to Cypridocopina, have a large baseball bat-like seta as an autapomorphic character on the second antenna, whereas most ostracod taxa with plesiomorphic characters bear "Grouped setae" consisting of multiple setae on the second antenna. Their budding positions, morphology, and ontogenetic changes were compared, and our deduction is that the Aesthetasc "Y" originated from "Grouped setae-like" organ in the Paleozoic. The morphogenetic processes in the molting period of these chemoreceptors were compared at the cellular level. The observations suggest that the "Grouped setae" are formed by hypodermal cells and share sheath cells corresponding to those of the Aesthetasc "Y" as a common constraint in the molting process of setae. We conclude that modification of the morphogenetic processes in the molting period of the "Grouped setae" gave rise to the Aesthetasc "Y" as a novel organ in the evolutionary pathway of the Ostracoda.

[A study on measles epidemic in Sukagawa area, Fukushima Prefecture from 2002 to 2003].

Measles epidemic occurred in southern part of Fukushima Prefecture from April 2002 to July 2003. Public Iwase hospital in Sukagawa City was the central hospital in the measles epidemic area and 382 patients with measles were admitted to the hospital during the epidemic. Based on clinical records, age distribution, vaccination history, familiar infection and complications were retrospectively investigated. Moreover, the vaccination rates and their calculating methods in the area were compared and the problems on immunization against measles were discussed. As the result, we found that 1) measles epidemic centered on unvaccinated infants, 2) measles was still serious disease with many complications and sometimes fatal, 3) measles was highly infectious and there was no way for prevention except vaccination, 4) the actual condition of measles vaccination was not reflected exactly by the current calculating methods used for the local health reports by the Ministry of Health Labour and Welfare. For the prevention of measles epidemic, it is necessary to know the exact numbers of patients infected with measles and patients deceased due to measles, to calculate precise vaccination rate, and to form the consensus among parents, physicians and administrators to control measles epidemic by the vaccination.