Amami-Oshima Island Research Articles

Pentalagus furnessi food plants at two sites on the western Amami-Oshima Island, Japan

<i>Pentalagus furnessi</i> food plants at two sites on the western Amami-Oshima Island, Japan

Description of the second species of Synhalcurias Carlgren, 1914, Synhalcurias kahakui sp. nov. (Actiniaria: Actinernidae) with redescription of S. elegans (Wassilieff, 1908).

We describe a new sea anemone species, Synhalcurias kahakui sp. nov., from specimens collected off Otouto-jima and Amami-oshima islands in July 2016 and May 2019. respectively. These sea anemones were identified as belonging to family Actinernidae due to their many endocoelic perfect mesenteries and identified as belonging to the genus Synhalcurias Carlgren, 1914 because they have an oral disc without any developed lobes. Though this genus presently accommodates only one species, Synhalcurias elegans (Wassilieff, 1908), our specimens are smaller than the aforementioned species, have fewer mesenteries, lack nematocyst batteries on the column, and have two types of microbasic p-mastigophores on the mesenterial filaments. These specimens are described as Synhalcurias kahakui sp. nov. In view of the new species, the diagnosis of genus Synhalcurias is revised. In addition, we redescribe S. elegans based on newly specimens collected from Japan.

Relationships between clear cutting history and/or microtopography and species diversity in the laurel forest of amami-oshima island, a world natural heritage candidate, kagoshima, japan ―kagoshima university satsunan islands forest ecosystem research group―

relationships between clear cutting history and/or microtopography and species diversity in the laurel forest of amami-oshima island, a world natural heritage candidate, kagoshima, japan ―kagoshima university satsunan islands forest ecosystem research group―

A New Species of Sea Whip Gorgonian-Associated Zoantharian (Cnidaria: Anthozoa: Hexacorallia: Parazoanthidae) from the Ryukyu Islands, Japan, with Subgeneric Subdivision of Genus Umimayanthus.

Symbioses between invertebrates are common in the ocean although usually the diversity and specificity of their interactions are not well understood. Parazoanthidae (Cnidaria: Anthozoa: Zoantharia) is one of the most diverse zoantharian families in terms of numbers of genera and species. Species in this family are commonly associated with various other invertebrates that they utilize as their substrate. Previous studies have re-organized the taxonomy of Parazoanthidae and revealed a strong specificity between many parazoanthid species and genera and their substrates. However, our understanding of the species diversity of Parazoanthidae is far from complete, as parazoanthids are often overlooked in sampling surveys. In this study, we establish three subgenera under the genus Umimayanthus Montenegro, Sinniger, and Reimer, 2015; the nominotypical Umimayanthus, Paraumimayanthus subgen nov., and Gorgoniazoanthus subgen. nov., based on the finding of a new species, Umimayanthus (Gorgoniazoanthus) kanabou sp. nov., associated with the sea-whip gorgonian Ellisella sp. from approximately 30 m depth in shallow mesophotic coral reef communities in Oura Bay on Okinawajima Island and in Oshima Strait near Amami-Oshima Island, in the Ryukyu Islands, southern Japan. We additionally report on gastropods and crustaceans observed in association with U. kanabou, and these species are thought to potentially prey upon the zoantharians or on gorgonian polyps. Umimayanthus kanabou is phylogenetically closely related to congeneric sponge-associated Umimayanthus spp., further supporting the recent hypothesis that substrate preferences may change during the evolutionary history of zoantharians.

Genetic lineage of the Amami islanders inferred from classical genetic markers

The genetic structure of the people of mainland Japan and Okinawa has been gradually unveiled in recent years. However, previous anthropological studies dealing with people in the Amami islands, located between mainland Japan and Okinawa, were less informative because of the lack of genetic data. In this study, we collected DNAs from 104 subjects in two of the Amami islands, Amami-Oshima island and Kikai island. We analyzed the D-loop region of mtDNA, four Y-STRs, and four autosomal nonsynonymous SNPs to clarify the Amami islanders' genetic structure compared with peoples in Okinawa, mainland Japan, and other regions of East Asia. We found that the Amami islanders showed a genetically intermediate position between mainland Japan and Okinawa in mtDNA and Y-STR. However, the frequencies of several autosomal SNPs in the Amami islanders indicated a significant difference from mainland Japanese, which may be because of the gene flow from Okinawa but not natural selection. Moreover, extremely high or low frequencies of several alleles implied a founder effect in Kikai islanders. Note that there is room for the interpretation of the results because of the small sample size and number of alleles in the present study. Geographically broad and detailed samplings and genome-wide analyses are awaited.

Gilpinia hakonensis and similar species in Japan and ovipositors of five European Gilpinia species (Hymenoptera, Diprionidae).

The following three Japanese conifer sawflies are described or redescribed with figures of the ovipositors and male genitalia: Gilpinia hakonensis (Matsumura, 1912) from Honshu and Kyushu, Japan and Korea, G. amamiana Okutani, 1965, from Amami Oshima Island and Tokunoshima Island, Japan and G. okinawa sp. nov. from Okinawa Island, Japan. These three species are very similar and belong to the G. socia group. The lectotype for Lophyrus hakonensis Matsumura, 1912 is designated. The males of G. hakonensis and G. amamiana are described for the first time. Gilpinia fukudai (Togashi, 1964) from Honshu, Japan, is a new synonym of G. hakonensis. The host plant of G. hakonensis is Pinus densiflora Siebold et Zucc. Gilpinia amamiana is newly recorded from Tokunoshima Island. For comparison, ovipositors of five European species of the G. socia group, G. abieticola (Dalla Torre, 1894), G. frutetorum (Fabricius, 1793), G. laricis (Jurine, 1807), G. socia (Klug, 1812) and G. variegata (Hartig, 1834), are described and figured. The ovipositors of G. frutetorum, G. laricis and G. variegata are figured for the first time. Gilpinia laricis is newly recorded from Bulgaria.

Effects of topography and anthropogenic alterations in forest environments on the breeding use by two endangered frog species in Amami-Oshima Island

ABSTRACT Amphibians are among the most threatened taxa in the world. Anthropogenic habitat alteration is possibly the most important driver of their population decline and can occur through many different factors. To develop effective conservation measures when multiple factors are involved, we need to know the relative impact of each factor. I aimed to reveal breeding site choice by two endangered frog species (Babina subaspera and Odorrana splendida) in the subtropical forests of Amami-Oshima Island, where multiple anthropogenic factors are expected to have effects on the forest environment. I analyzed the breeding use by the two species with nine topographic and three anthropogenic (forest age, forest road density, and density of invasive mongoose) variables, using random forest analysis. The critical variable for determining the breeding use by B. subaspera was the size of upstream contributing area (UCA), followed by topographic wetness index (TWI) and altitude, while that for O. splendida was altitude, followed by UCA, and TWI. The importance of anthropogenic variables was less than that of topographic variables and was greatest for forest age and lowest for mongoose density. Forest sites less than 40 years old, with more roads within a 500 m buffer, and with a higher mongoose density showed a low probability of the frog’s presence. The peculiar topographical requirements of the two frog species for breeding may be the reason for the relatively small impact of anthropogenic variables compared to topographic variables.

Molecular epidemiology of Leptospira spp. among wild mammals and a dog in Amami Oshima Island, Japan.

Leptospirosis is a worldwide zoonosis caused by the pathogenic Leptospira spp. Canine and human leptospirosis sometimes occur on Amami Oshima Island, located in the Nansei Archipelago, southwestern Japan; however, information on the causative Leptospira spp. on this island is quite limited. This study aimed to investigate the molecular and serological characteristics of Leptospira spp. isolated from wild animals and a dog in Amami Oshima Island. We obtained seven Leptospira strains by culturing kidney tissues of wild animals, such as black rats (2), wild boars (3), and rabbit (1) as well as blood from a symptomatic dog. Using flaB sequencing and microscopic agglutination test with antisera for 18 serovars, the isolates were identified as Leptospira borgpetersenii serogroups Javanica (black rat), L. interrogans serogroup Australis (black rat and dog), and L. interrogans serogroup Hebdomadis (wild boar and rabbit). The sequence type (ST) of L. borgpetersenii serogroup Javanica was determined to be ST143 via multilocus sequence typing (MLST) using seven housekeeping genes. For L. interrogans, MLST and multiple-locus variable-tandem repeat analysis (MLVA) revealed identical ST and MLVA types in rat and canine isolates, whereas two STs and MLVA types were identified in wild boar isolates. The STs and MLVA types of rabbit and one of the wild boars were identical. Bacterial culture and flaB-nested polymerase chain reaction demonstrated a high rate of Leptospira infection in wild boars (58.3%, 7/12), whereas Leptospira spp. were detected in 4.8% of black rats (2/42). This study revealed diverse Leptospira genotype and serotype maintenance in wild mammals on Amami Oshima Island. MLST and MLVA indicated that black rats were a source of canine infection. Wild boars carry L. interrogans and are considered an important maintenance host because antibodies against serogroup Hebdomadis were detected in human and canine leptospirosis patients on this island.

Invertebrates found on floating Sargassum horneri (Fucales, Sargassaceae) under the Kuroshio Current in the Pacific Ocean

ABSTRACT The ecology and biogeography of the invertebrate epifauna related to floating Sargassum in the East China Sea were studied. Floating algal rafts composed of only Sargassum horneri (Turner) C. Agardh were collected in the East China Sea in March 2012 when the rafts were distributed not only on the continental shelf but also, unusually, south and east of the Kuroshio Current in the Pacific Ocean. In total, 71 samples collected at 11 stations were studied. Of the 11 invertebrate taxa recognized, harpacticoid copepods were most abundant, followed by malacostracans, and cirripedes. The densities of these three taxa were higher than those of other invertebrates. The number of invertebrate taxa was not correlated with the algal wet weight. There were more invertebrate taxa in the coastal area around Amami-Oshima Island than in other areas. The trajectories of drifting buoys indicated that the algal rafts collected in this area floated longer than those in other areas, allowing the colonization of invertebrates from the surrounding water.

Consideration of Statistics and Cross-reactivity Rate of Contact Dermatitis Due to &lt;i&gt;Rhus succedanea&lt;/i&gt; L and Mango in Amami-Oshima Island

Consideration of Statistics and Cross-reactivity Rate of Contact Dermatitis Due to &lt;i&gt;Rhus succedanea&lt;/i&gt; L and Mango in Amami-Oshima Island

Report on a Preliminary Test of Roadkill Observation System in Amami-Oshima Island, Japan

Report on a Preliminary Test of Roadkill Observation System in Amami-Oshima Island, Japan

Tree cavity abundance and formation in subtropical evergreen broad-leaved forests on Amami Oshima Island, Japan: Implications for conservation of cavity-using species

Tree cavity abundance and formation in subtropical evergreen broad-leaved forests on Amami Oshima Island, Japan: Implications for conservation of cavity-using species

Community-Based Portable Reefs to Promote Mangrove Vegetation Growth: Bridging between Ecological and Engineering Principles.

Despite all efforts and massive investments, the restoration of mangroves has not always been successful. One critical reason for this failure is the vulnerability of young mangroves, which cannot grow because of hydrodynamic disturbances in the shallow coastal water. For a comprehensive study bridging ecological and engineering principles, a portable community-based reef is proposed to shield mangroves from waves during the early stages of their growth. A series of field observations were conducted on Amami Oshima Island (Japan), to observe the growth of young mangroves and their survival rate under moderate wave conditions. The evolution of young mangroves was also observed in the laboratory under a controlled indoor environment. At the research site, it was confirmed that, after six months of germination, young mangroves could withstand normal high waves. Laboratory-grown plants were lower in height and had fewer leaves compared with the native mangroves on Amami. Based on these results, an economical reef system was designed. For this purpose, the Ahrens formula for the design of a low-crested reef breakwater was revisited. The results showed that a 50-cm-high reef constructed with 15-kg stones can protect mangroves that are a few months old and effectively promote early mangrove growth.

Geomorphological and geological features of Akina beach, the enshring site of the Hirasemankai festival, Amami-Oshima Island, Kagoshima Prefecture, southwest Japan

Geomorphological and geological features of Akina beach, the enshring site of the Hirasemankai festival, Amami-Oshima Island, Kagoshima Prefecture, southwest Japan

First specimen-based records of six fish species from Amami-oshima island, Ryukyu Islands, Japan

First specimen-based records of six fish species from Amami-oshima island, Ryukyu Islands, Japan

Species composition and mitochondrial molecular phylogeny of &lt;i&gt;Acropora&lt;/i&gt; corals in Funakoshi, Amami-Oshima Island, Japan: A proposal for its new taxonomic grouping

Species composition and mitochondrial molecular phylogeny of &lt;i&gt;Acropora&lt;/i&gt; corals in Funakoshi, Amami-Oshima Island, Japan: A proposal for its new taxonomic grouping

Phylogeography of a widespread Palaearctic forest bird species: The White‐backed Woodpecker (Aves, Picidae)

AbstractWe use multilocus molecular data and species distribution modelling to investigate the phylogenetics and the phylogeography of the White‐backed Woodpecker (Dendrocopos leucotos), a bird species widely distributed over the entire Palaearctic. Our phylogenetic results reveal three well‐supported clades within D. leucotos: the Chinese endemic subspecies (tangi, insularis), the northerly distributed subspecies (leucotos, uralensis) and the four poorly genetically differentiated Japanese subspecies (subcirris, stejnegeri, namiyei, owstoni), and the south‐western Palaearctic lilfordi subspecies. According to our results, the Amami Woodpecker, endemic to Amami Oshima Island (Ryukyu archipelago, Japan) sometimes treated as full species Dendrocopos owstoni, does not deserve a species‐level status. Based on the mitochondrial phylogeographic results, the Japanese archipelago was recently colonized only once by D. leucotos from eastern Eurasia. Our results suggest a split between the leucotos and lilfordi lineages that dates back to mid‐Pleistocene (around 0.6 Mya) with likely no gene flow between these two subspecies since then. Our results thus do not support a phylogeographic pattern in which Central Europe and Northern Europe were recolonized from one or several southern glacial refugia where lilfordi populations persisted through several Pleistocene glacial periods. Spatial variation in mitochondrial diversity across leucotos/uralensis populations and niche ecological modelling suggest a possible eastward population expansion from a unique glacial refugium likely located in Central Europe. Molecular species delimitation methods, gene flow analyses and differences in adult and juvenile plumage indicate that the lilfordi subspecies may warrant to be ranked as a valid phylogenetic species. Further studies are nevertheless needed in the Balkans, where leucotos and lilfordi came recently into contact to measure the effectiveness of reproductive barriers and gene flow.

Habitat preference, movements and growth of giant mottled eels, Anguilla marmorata, in a small subtropical Amami-Oshima Island river.

Although anguillid eel populations have decreased remarkably in recent decades, few detailed ecological studies have been conducted on tropical eels such as the giant mottled eel whose range extends across the whole Indo-Pacific. This species was studied throughout the entire 0.5 km mainstem reaches of Oganeku River on the subtropical Amami-Oshima Island of Japan over a two-year period using four sampling periods to understand its habitat preference, early life-stage dispersal process, movements, and annual growth using a mark-recapture experiment conducted with quantitative electrofishing. A total of 396 juvenile growth-phase A. marmorata eels were caught and tagged, with 48 individuals being recaptured at least once. Their density irrespective of size of eels was most strongly determined by distance from the river mouth, followed by riverbank type according to random forest models. Eel density decreased with increasing distance from the freshwater tidal limit located about 100–150 m from the river mouth. Eels preferred vegetated riverbanks, while they avoided those of concrete and sand. The density of small eels (total length: TL < 240 mm) was also associated with depth and velocity, with small eels tending to prefer riffle or run habitats. In contrast, large eels (TL ≥ 240 mm) were found in habitats of any depth and velocity. The TL of eels had a minimum peak at around the tidal limit, and it increased with increasing distance from the tidal limit. The observed density and size gradients of eels in relation to the distance from the river mouth suggested that A. marmorata initially recruited to freshwater tidal limit areas and then dispersed in both downstream and upstream directions. The growth rate of eels varied greatly among individuals that were at large for various periods of time and ranged from 0 to 163.2 mm/year (mean ± SD of 31.8 ± 31.0 mm/year). Of the recaptured eels, 52.1% were recaptured in a section that was different from the original capture section, and their mean ± SD distance travelled was 46.5 ± 72.5 m (median = 20 m). 47.9% of the eels were recaptured from the original section of capture (i.e., <10 m distances travelled), suggesting that they had strong fidelity to specific habitats with limited movements. The distance travelled of eels that had moved was greater for small eels (range = 10–380 m; mean ± SD = 84.4 ± 121.9 m) than large individuals (range = 10–120 m; mean ± SD = 30.9 ± 31.0 m), which indicates that the mobility of the eels declines as they grow. This is the first clear detailed documentation of the spatial distribution, growth, and movements of tropical eels in a small river system in relation to environmental conditions that provides an example of how future studies can be conducted in other areas to understand how conservation efforts can be most efficiently targeted for maximum success.

Analysis of fecal samples from Amami rabbits (Pentalagus furnessi) indicates low levels of antimicrobial resistance in Escherichia coli

In recent years, antimicrobial-resistant bacteria have been isolated from different wildlife species that have not been exposed to antibiotics. Antimicrobial resistance profile analysis of wildlife-derived Escherichia coli is one of the ways to obtain information about changes in wildlife habitats. The Amami rabbit (Pentalagus furnessi) is one of the Japanese endemic wildlife species that requires conservation due to its declining population. However, detailed information on its ecology, including habitat, is unclear. We conducted antimicrobial susceptibility testing (broth microdilution assay) of 12 antimicrobials on 135 E. coli strains isolated from the feces of free-living Amami rabbits, collected between 2017 and 2020. No antimicrobial-resistant E. coli were isolated from any sample, indicating that antimicrobial-resistant E. coli were not widely distributed in the Amami rabbit population. In addition, these results suggested that the habitat of Amami rabbits may not be contaminated with antimicrobials derived from humans, Japanese livestock, and wildlife that come in contact with the rabbits. This is the first study to examine the antimicrobial resistance of bacterial isolates from the Amami rabbits for a multi-year period. In order to observe changes in wildlife habitats on the Amami-Oshima Island, inhabited by many rare species including Amami rabbits, continued surveillance of antimicrobial-resistant E. coli in wildlife is necessary.

Acoustic Detection of an Unknown Bat Species in Okinawa

Pipistrelles of the genus Hypsugo are among the rarest bats in Japan, known from a handful of records. In June 2018, a sequence of echolocation calls apparently by a bat of this genus was recorded by an automatic ultrasound recorder on the island of Okinawa. The calls closely resemble H. pulveratus, a Chinese species never before recorded in Japan, and H. alaschanicus, a very rare species in Japan. They also resemble calls of Hypsugo sp. bats from a small population recently discovered on nearby Amami-Oshima Island. The extreme rarity in our recordings, combined with lack of detection in Okinawa by other surveys, suggests that the individual was a vagrant. However, given the cryptic nature of the species on Amami, it remains possible that there is a small and likely endangered resident population, underlining the need for further bat surveys on Okinawa and other Nansei Islands.