Cytogeography of<Emphasis Type="Italic"> Ixeris nakazonei</Emphasis> (Asteraceae,Lactuceae) in the Ryukyu Archipelago of Japan and Taiwan

The cytogeographical structures of Ixeris nakazonei, a putative hybrid between I. debilis (6x) and I. repens (2x), were investigated in the Ryukyu Archipelago and Taiwan. In the Ryukyus, I. debilis occurs on Miyakojima Island of the southern Ryukyus and northward, while I. repens occurs on all islands except for Iriomotejima and Yonagunijima Islands. I. nakazonei, comprises six polyploid cytotypes, 3x, 4x, 5x, 6x, 7x and 8x, based on x=8. Four cytotypes from 3x to 6x occur in the central Ryukyus, while four cytotypes from 5x to 8x occur in the southern Ryukyus. The higher polyploids of I. nakazonei tend to be distributed in the more southerly area. Tetraploids of I. nakazonei always co-occur with I. debilis and I. repens, supporting the hybrid origin of this cytotype. Considering the chromosome number, octoploids, which predominate in the southern Ryukyus and Taiwan, may have derived directly from hybridization between I. debilis and I. repens. Odd-numbered polyploids of I. nakazonei, 3x, 5x and 7x, are relatively rare. Their chromosome numbers indicate that triploids and heptaploids are hybrids between the tetraploid of I. nakazonei and I. repens, and between the octoploid of I. nakazonei and I. debilis, respectively. Pentaploids of I. nakazonei in the central and southern Ryukyus are, respectively, hybrids between the tetraploid of I. nakazonei and I. debilis and between the octoploid of I. nakazonei and I. repens, indicating that pentaploids of I. nakazonei have at least two independent origins.     

Origin of Livistona chinensis var. subglobosa (Arecaceae) on the "islet of the gods": Aoshima, Japan

RAPD analysis was performed to discuss the origin of Livistona chinensis var. subglobosa using samples from eight localities, Iriomotejima, Ishigakijima, Okinawa, Yakushima, Tanegashima, Cape Sata, Tsukishima, and Aoshima, in Japan. Random amplified polymorphic DNA (RAPD) markers were obtained using five random primers and analyzed by the unweighted pair group method arithmetic (UPGMA). Data from Iriomotejima clustered with data from Aoshima, suggesting the possibility that seeds or green woods were carried by the tidal current from the southern fields of Iriomotejima to Aoshima.     

Potential speciation of morphotypes in the photosymbiotic ascidian <Emphasis Type="Italic">Didemnum molle</Emphasis> in the Ryukyu Archipelago,Japan

Four morphotypes are recognized in the photosymbiotic ascidian Didemnum molle in the Ryukyu Archipelago: three color morphs (white, dark gray, and brown) of small-type colonies and one large-type colony (white with gray patches). The genetic variation among these four morphotypes was investigated by constructing phylogenetic trees based on a 401-bp fragment of the cytochrome oxidase subunit I (COI) gene of 29 specimens collected from five islands (Okinawajima, Sesokojima, Ikeijima, Kumejima, and Ishigakijima). The results support the monophyly of the genus Didemnum and that of the four morphotypes of D. molle. Moreover, the phylogenetic trees discriminated four clades corresponding to each morphotype. The geographic differences of the sequences were much smaller than the differences among the morphotypes, suggesting that the four morphotypes in D. molle are discrete sibling species. Communicated by Biology Editor Dr Ruth Gates     

Fine-Scale Genetic Structure and Demographic History in the Miyako Islands of the Ryukyu Archipelago

The Ryukyu Archipelago is located in the southwest of the Japanese islands and is composed of dozens of islands, grouped into the Miyako Islands, Yaeyama Islands, and Okinawa Islands. Based on the results of principal component analysis on genome-wide single-nucleotide polymorphisms, genetic differentiation was observed among the island groups of the Ryukyu Archipelago. However, a detailed population structure analysis of the Ryukyu Archipelago has not yet been completed. We obtained genomic DNA samples from 1,240 individuals living in the Miyako Islands, and we genotyped 665,326 single-nucleotide polymorphisms to infer population history within the Miyako Islands, including Miyakojima, Irabu, and Ikema islands. The haplotype-based analysis showed that populations in the Miyako Islands were divided into three subpopulations located on Miyakojima northeast, Miyakojima southwest, and Irabu/Ikema. The results of haplotype sharing and the D statistics analyses showed that the Irabu/Ikema subpopulation received gene flows different from those of the Miyakojima subpopulations, which may be related with the historically attested immigration during the Gusuku period (900 − 500 BP). A coalescent-based demographic inference suggests that the Irabu/Ikema population firstly split away from the ancestral Ryukyu population about 41 generations ago, followed by a split of the Miyako southwest population from the ancestral Ryukyu population (about 16 generations ago), and the differentiation of the ancestral Ryukyu population into two populations (Miyako northeast and Okinawajima populations) about seven generations ago. Such genetic information is useful for explaining the population history of modern Miyako people and must be taken into account when performing disease association studies.     

A taxonomic study of the Rana narina complex, with description of three new species (Amphibia: Ranidae)

A morphometric and electrophoretic survey was conducted to examine taxonomic relationships among eight population samples of the Rana narina complex from the Ryukyu Archipelago of Japan and Taiwan. Five discrete morphotypes are differentiated, and these showed considerable genetic differentiation from each other. From the available information, each of the five morphotypes is judged to represent a species, and three are described as new. Rana utsunomiyaorum sp. nov. and R. supranarina sp. nov. are sympatric in Ishigakijima and Iriomotejima islands of the Yaeyama Group, and differ from the other members by having a shorter hindlimb. Rana utsunomiyaorum is the smallest in the complex, while R. supranarina is the largest. Rana amamiensis sp. nov . occurs on Amamioshima and Tokunoshima islands of the Amami Group and, like R. narina from Okinawajima of the Okinawa Group, has a long hindlimb; it differs from the latter species by having a larger body and relatively small tympanum. These two species differ from R. swinhoana from Taiwan by having a narrower disk on the third finger. A key to known species of the complex is given. Further, syslematics of the R. narina complex within Rana , body size in the two sympatric species, and sexual dimorphism found in this complex are discussed.     

Burmoniscus kitadaitoensis Nunomura, 2009 (Crustacea,Isopoda, Oniscidea) from southern Japan,a junior synonym of B. meeusei (Holthuis, 1947)

Re-examination of the holotype of Burmoniscus kitadaitoensis Nunomura, 2009 from Kitadaitojima Island, southern Japan reveals that this species is a junior synonym of B. meeusei (Holthuis, 1947). Partial regions of mitochondrial COI, 12S and 16S rRNA genes, and nuclear 18S and 28S rRNA genes were detected for species identification in the future.     

A new genus and species of Renaudarctidae (Heterotardigrada: Arthrotardigrada) from Ryukyu Archipelago,Japan

A new armoured marine tardigrade, Nodarctus hallucis gen. et sp. nov., is described from specimens collected from sandy beaches of Haterumajima, Ishigakijima and Okinawajima Islands, Ryukyu Archipelago, Japan. It is a member of the rare family Renaudarctidae, which is characterized by a stocky body with dorsal and ventral plates and stumpy legs with digits, claws and accessory filaments. However, the collected animals have prominent characters that differ from the two known species of the family: subdivided dorsal segmental plates I–III lacking lateral processes, an acute caudal spike, indented sensory plates, short spikes and peculiar papillae on legs I–III, basal spikes of legs IV and only two digits on legs IV. These differences justify the erection of a new genus and species for the animal. Morphological affinities with other marine taxa, the function of the leg papillae and the distribution pattern of the new species are discussed.http://zoobank.org/urn:lsid:zoobank.org:pub:041878AA-B437-45BF-80E3-32591D21D965     

Phylogeny and biogeography of the Anderson's crocodile newt, Echinotriton andersoni (Amphibia: Caudata), as revealed by mitochondrial DNA sequences

The Anderson's crocodile newt, Echinotriton andersoni, is considered a relic and endangered species distributed in the Central Ryukyus. To elucidate phylogenetic relationships and detailed genetic structures among populations, we analyzed variation in the mitochondrial cytochrome b gene. Results strongly support a primary dichotomy between populations from the Amami and Okinawa Island Groups with substantial genetic divergence, favoring a primary divergence between the two island groups. Within the latter, populations from the southern part of Okinawajima Island are shown to be more closely related to those from Tokashikijima Island than to those from the northern and central parts of Okinawajima. The prominent genetic divergence between the two island groups of the Central Ryukyus seems to have initiated in the Miocene, i.e., prior to formation of the strait that has consistently separated these island groups since the Pleistocene. The ancestor of the southern Okinawajima-Tokashikijima is estimated to have migrated from the northern and central parts of Okinawajima into southern Okinawajima at the Pleistocene, and dispersed into Tokashikijima subsequently.     

Morphometric variation in the pusillus group of the genus Rhinolophus (Mammalia: Chiroptera: Rhinolophidae) in East Asia

Based on 203 specimens belonging to the Rhinolophus "pusillus group" (Mammalia: Chiroptera: Rhinolophidae), univariate and multivariate morphometric analyses using 19 characters were performed to assess the confused species taxonomy. The results indicated that R. pusillus (including calidus, parcus, and szechuanus) in the continental region and Hainan Island of China and "R. cornutus" in Japan are morphologically divergent species. Rhinolophus cornutus should be further split into R. cornutus (including orii, pumilus, and miyakonis) in the main islands of Japan, the Amami and Okinawa Group of the central Ryukyu Archipelago, and Miyako Group of the southern Ryukyus; and R. perditus and R. imaizumii from the Yaeyama Group in the southern Ryukyus. Rhinolophus monoceros from Taiwan is morphologically more similar to species in Japan than to R. pusillus. In addition to R. pusillus, another form that is morphologically similar to species in Japan was recognized from Langzhong in Sichuan Province; this may represent an undescribed species, and further examination is necessary to determine its taxonomic status. Specimens from Guang'an in Sichuan Province, China, are also different from the others, and are characterized by the smallest skull size. Although further studies are required, these specimens were tentatively identified as R. subbadius.     

Continuous survey of the distribution of RNA coliphages in Japan

In order to demonstrate the stability and continuity of RNA coliphages (phages) in their natural habitats, we investigated the amount and group types of RNA phages in sewage samples collected continuously from domestic drainage in Japan proper and islands in the seas adjacent to Japan (abbreviated simply as islands, hereafter) over a 5-yr period from 1973 to 1977. It was found that the frequencies of isolation of RNA phages were fairly high and constant. The group types of RNA phages isolated were also stable in the three cities. Choshi, Niigata, and Toyama in Japan proper. The average for the three cities was group II:III = 3:1. The investigation in islands revealed that the frequencies of isolation of RNA phages were fairly high as in the case of the above three cities in Japan proper and the group types of RNA phages isolated were also stable. That is to say, group II phages were predominant on Rishiri Island, Rebun I., Iki I., and Tsushima I., which are located relatively near to mainland Japan, while group III phages were predominant on Amamiohshima I., mainland Okinawa, Ishigakijima I., and Iriomotejima I., which are located south of Kyushu. It can thus be said that the RNA phages in the domestic drainage of Japan proper and islands remained more or less stable over at least the 5-yr period, and an apparent difference in the geographical distribution of RNA phages in Japan exists between Kyushu and Amamiohshima I.     

Phylogeography of the endangered tideland snail Batillaria zonalis in the Japanese and Ryukyu Islands

The phylogeography of the endangered tideland snail Batillaria zonalis in the Japanese and Ryukyu Islands was analyzed on the basis of nucleotide sequences of a mitochondrial gene for cytochrome oxidase c subunit I (COI). Extremely low genetic diversity was found in populations at both the northern and southern boundaries of the geographic distribution of this species in Japan, i.e., Sendai Bay and Iriomotejima Island, respectively, which might be attributed to the population bottleneck due to historical environmental variations and/or the recent foundation of populations in the marginal part of the inhabitable range. Most populations contained unique rare haplotypes, and significant genetic differentiation on the whole was shown, while no clear geographic genetic structure was detected between the Japanese and Ryukyu Islands or over the distribution area of B. zonalis in Japan, with the exception of significant genetic divergences in Ago Bay in the central part of Honshu and the southern part of Okinawajima Island.     

The biogeographical history of Asian keelback snakes of the genus Hebius (Squamata: Colubridae: Natricinae) in the Ryukyu Archipelago,Japan

The islands of the central and southern parts of the Ryukyu Archipelago and Taiwan accommodate suites of allopatric endemics for many terrestrial vertebrates. These subregions, which were isolated as three independent islands since the Late Miocene period, became connected to the continent by the Early Pleistocene land bridge (EPL). Many endemics are considered to have emerged through vicariant events accompanied with the collapse of EPL, but this is not well corroborated. We conducted divergence dating analyses for samples of four allopatric keelback snakes from 20 islands using a published timeframe for natricine snakes. Phylogenetic analyses recognised the existence of eight subclades for the four species. Four of the five subclades in the Central Ryukyus have emerged after the initial isolation of three subregions but before the EPL collapse, indicating iterative divergences within the super‐island and stagnation of diverged entities. In contrast, the Southern Ryukyus was subjected to multiple incursions from both Central Ryukyus and Taiwan, irrespective of the EPL connection. Consequently, among all seven nodes, only two were consistent with the assumption of vicariance. These findings suggest that dispersals and subsequent nonvicariant divergences have contributed to the formation of the current phylogeographical pattern in this continental island chain.     

Isolation and characterization of microsatellite loci in Shortia rotundifolia (Diapensiaceae), an endangered relict plant on the Ryukyu Islands and Taiwan

Ten microsatellite loci were isolated and characterized for Shortia rotundifolia, a relict temperate plant on the subtropical Ryukyu Islands and Taiwan. The number of alleles ranged from 2 to 21. The expected (H _E) and observed (H _O) heterozygosities were 0.027–0.877 and 0.027–0.622, respectively, from 74 individuals on Iriomotejima Island of Ryukyus. One locus exhibited significantly fewer heterozygotes than expected under Hardy–Weinberg equilibrium (P < 0.05). These primers amplifying microsatellites in this species may provide a useful tool for population genetics to establish conservation strategy.     

Bacillus thuringiensis soil populations naturally occurring in the Ryukyus, a subtropic region of Japan

Of 809 soil samples collected from the seven islands of the Ryukyus, Japan, 107 samples (13.2%) contained Bacillus thuringiensis. The frequency of B. thuringiensis among the B. cereus group was 1.1% (235/21842) on the average. The B. thuringiensis soil populations of the Ryukyus consisted of more than 22 H serogroups. The predominant H serotype was the H5ac/21 (serovar canadensis/colmeri), followed by the H3ad (serovar sumiyoshiensis) and H16 (serovar indiana). Geographically, most widely distributed H serogroups were the H16 and H10ac (serovar londrina); the former was recovered from five islands and the latter from three islands. Parasporal inclusions of the isolates were morphologically heterogeneous, roughly grouped into four categories: bipyramidal/cuboidal, spherical/ovoid, irregularly-pointed, and irregular-shaped. About 53% of the isolates formed spherical to ovoid parasporal inclusions. None of the isolates exhibited larvicidal activity against the silkworm, Bombyx mori. Only four isolates belonging to four different serotypes killed larvae of the mosquito, Aedes aegypti. These mosquito-specific isolates all produced spherical parasporal inclusions.     

First record of the filefish,Pervagor nigrolineatus,from Japan

A specimen of the filefish,Pervagor nigrolineatus, was collected from dead coral patches at a depth of 3 m in Zamami-jima, Kerama Islands (26° 14′ N, 127° 19′ E). This species is recorded for the first time from Japan. It has been known to be distributed in the tropical western Pacific from the Philippines to New Guinea (Hutchins, 1986). The present specimen is more similar in scale characters to the Philippine specimens than to the New Guinean ones.     

Phylogeny and phylogeography of the sword-tailed newt,Cynops ensicauda (Amphibia: Caudata), as revealed by nucleotide sequences of mitochondrial DNA

We investigated the phylogenetic relationships and phylogeography among individuals of the endemic newt (Cynops ensicauda) of the Central Ryukyus, Japan based on the mitochondrial cytochrome b gene. The results of phylogenetic analyses showed the presence of remarkable differentiation between assemblages from the Amami and Okinawa Island Groups, supporting the validity of the subspecies C. e. popei described from the latter on morphological grounds. The group of individuals from Okinawa Island Group was further divided into two distinct subgroups unlike the results of previous morphological and allozyme studies. Geographic ranges of these subgroups overlapped in the northern part of Okinawajima Island. The phylogeographic pattern within the Okinawa Island Group suggests an initial division into two geographically isolated population lineages and subsequent secondary sympatry before formation of reproductive isolation. It is also likely that within the Okinawa Island Group emigration occurred from the central and northern parts of Okinawajima Island to its southern part, as well as to several small islets off its western coast. Within the Amami Island Group, recurring restricted gene flow with isolation by distance seems to have occurred around the southwestern region including three islets southwest of Amamioshima Island.     

Discovery of the genus Skidmorella Johnson (Coleoptera: Ptiliidae) in Japan, with descriptions of two new species

The genus Skidmorella Johnson, previously known only from the South Pacific islands, is discovered in Japan. The type species, Skidmorella magnifica Johnson, is confirmed from Japan as the first record of the species other than the type locality. In addition, two new species, Skidmorella amamiana sp. nov. and Skidmorella quadrisulucia sp. nov., are described from the Ryukyus, Japan. Phylogenetic relationships of the genus Skidmorella and its allies are discussed on the basis of their morphological characters.     

First records of tick-borne pathogens, Borrelia, and spotted fever group Rickettsiae in Okinawajima Island, Japan

In early April 2000, tick-borne pathogens were surveyed in the northern area of Okinawajima Island, Okinawa Prefecture, which is the southernmost area of Japan. Borrelia valaisiana, a Lyme disease spirochete, was isolated from a field mouse Mus calori, and unidentified rickettsiae of the spotted fever group were isolated from all stages of Amblyomma testudinarium. These are the first reports of these pathogens on Okinawajima Island.     

Genetic analysis of the endemic island loggerhead shrike, <Emphasis Type="Italic">Lanius ludovicianus anthonyi</Emphasis>

Based on limited research, the island loggerhead shrike, Lanius ludovicianus anthonyi has been considered a distinct subspecies endemic to the northern California Channel Islands. We used mtDNA control region sequences and microsatellite genotyping to compare loggerhead shrikes from the southern California mainland (L. l. gambeli), San Clemente Island (L. l. mearnsi), and the northern islands (L. l. anthonyi). Habitats on the islands are recovering due to the removal of non-native ungulates on the islands, but may be transitioning to habitats less supportive of loggerhead shrikes, so this evaluation comes at a critical time. We utilized 96 museum specimens that were collected over a century to evaluate both spatial and temporal genetic patterns. Analysis of multilocus microsatellite genotypes indicated that historical specimens of loggerhead shrikes (collected between 1897 and 1986) from the two northern islands of Santa Rosa and Santa Cruz are genetically distinct from adjacent mainland and island shrikes. Birds from Santa Catalina Island showed mixed ancestry and did not cluster with the northern island birds. Historical specimens of L. l. mearnsi from San Clemente Island also showed mixed ancestry. Our study provides evidence that a genetically distinct form of loggerhead shrikes, L. l. anthonyi, occurred on the islands of Santa Rosa and Santa Cruz.     

Seasonal changes in populations of three sympatric isopods in a Hong Kong forest

Data on the population dynamics of tropical isopods in general, and those inhabiting forests in particular, are scarce. Consequently, the population dynamics of three sympatric isopods, Burmoniscus ocellatus (Philosciidae), Formosillo raffaelei and Orodillo maculatus (Armadillidae), were studied at two neighbouring sites in a mixed forest in Hong Kong between March 1985 and December 1986. Isopod population densities varied with the species, site and season, with mean densities ranging from 100–150 m^-2. Burmoniscus ocellatus and F. raffaelei had a single recruitment peak per year, while O. maculatus had two. Results of the present study revealed that air temperature was the main factor explaining seasonal variations in population density, while rainfall exerted its effect with a two- to three-week time-lag, depending on the species studied. Approximately 20% of Formosillo raffaelei and O. maculatus sampled were found infected by Rickettsiella bacteria. The possible influence of pathogens, and other biotic factors, on the dynamics of the Hong Kong isopod populations was discussed