Geographic Variations in the Toxin Profile of the Xanthid Crab Zosimus aeneus in a Single Reef on Ishigaki Island, Okinawa, Japan

Toxic crabs of the family Xanthidae contain saxitoxins (STXs) and/or tetrodotoxin (TTX), but the toxin ratio differs depending on their habitat. In the present study, to clarify within reef variations in the toxin profile of xanthid crabs, we collected specimens of the toxic xanthid crab Zosimus aeneus and their sampling location within a single reef (Yoshihara reef) on Ishigaki Island, Okinawa Prefecture, Japan, in 2018 and 2019. The STXs/TTX content within the appendages and viscera or stomach contents of each specimen was determined by instrumental analyses. Our findings revealed the existence of three zones in Yoshihara reef; one in which many individuals accumulate extremely high concentrations of STXs (northwestern part of the reef; NW zone), another in which individuals generally have small amounts of TTX but little STXs (central part of the reef; CTR zone), and a third in which individuals generally exhibit intermediate characteristics (southeastern part of the reef; SE zone). Furthermore, light microscopic observations of the stomach contents of crab specimens collected from the NW and CTR zones revealed that ascidian spicules of the genus Lissoclinum were dominant in the NW zone, whereas those of the genus Trididemnum were dominant in the CTR zone. Although the toxicity of these ascidians is unknown, Lissoclinum ascidians are considered good candidate source organisms of STXs harbored by toxic xanthid crabs.

A new species of Nogunius Jałoszyński in Japan (Coleoptera: Staphylinidae: Scydmaeninae)

The genus Nogunius Jałoszyński was proposed to accommodate four species distributed exclusively in Japan: N. sokani Jałoszyński (Okinawa Island), N. aogashimanus Jałoszyński (Aogashima, Izu Islands), N. kerri Jałoszyński (Ishigaki Island), and N. fukuuzanus Jałoszyński (Okinawa Island). A female of an undescribed species collected in mainland Japan, on Shikoku, was also recorded. In the present paper we provide evidence that this interesting and apparently very rare genus occurs also on Kyushu. Nogunius sagaensis sp. n. is described, based on a single male collected in Saga Prefecture, NW Kyushu. Diagnostic characters of all nominal species are compared, and a distribution of Nogunius is summarized.

A parasitic insect on a parasitic plant: a new species of the genus Formicoccus Takahashi (Hemiptera, Coccomorpha, Pseudococcidae) from Ishigaki Island, Japan

A new species of the genus Formicoccus Takahashi (Hemiptera, Coccomorpha, Pseudococcidae) collected from the holoparasitic plant Balanophora fungosa J. R. & G. Forst (Balanophoraceae), on Ishigaki Island, Japan, is described as Formicoccus yoshinoi Tanaka, sp. nov. based on the morphology of adult females. This species is similar to F. formicarius (1900) and F. erythrinae Williams, 2004, but differs from them by having fewer than six cerarii, and only one type of ventral oral collar tubular duct distributed on the medial area of the posterior abdominal segments. Keys to the Oriental species of the genus Formicoccus are provided.

How bountiful is the ocean? Participatory valuation of human–nature relationships in Yaeyama Islands, Okinawa, Japan

Valuations of nature are vital for effective conservation planning, and discussions are underway globally on improving the valuation process. Plural valuations of human–nature relationships are the key for better, more inclusive decision-making, which is demonstrated in this research using a case study on human–ocean relationships on Ishigaki Island, a part of the Yaeyama archipelago, Japan. We applied a network analysis to text data obtained from answers on questionnaires with open-ended questions to quantify the importance of values with respect to the pluralities among local people. Therefore, five core elements encompassing the values of the human–ocean relationships on Ishigaki Island were proposed as follows: “Livelihood,” “Attachment and inspiration,” “Local marine culture,” “Respect and fear for nature,” and “Anthropocene environmental problems.” The “Anthropocene environmental problems” element included social and environmental problems caused by various human activities including excessive tourism development, and the data collected through tourism market value analysis implied that past ecosystem service assessments may have over-valued or even triggered this issue. The “Respect and fear for nature” element was found to be important as a potentially unique value in these regions, but this is currently understudied within the literature related to ecosystem services and nature’s contributions to people. This study is among the first works to extract and visualize place-based human–ocean relations in an Asian country. We hope that our methods and findings will be applied to other areas, especially to the local communities of understudied countries and regions, to drive the transformative change of coral reef governance in the Anthropocene.

Gastrodia longiflora (Orchidaceae: Epidendroideae: Gastrodieae), a new mycoheterotrophic species from Ishigaki Island, Ryukyu Islands, Japan

Gastrodia Brown (1810: 330; Gastrodieae, Epidendroideae) is a mycoheterotrophic orchid genus distributed in temperate and tropical regions of Asia, Oceania, Madagascar, and Africa (Cribb et al. 2010, Hsu & Kuo 2010, Suetsugu et al. 2018). It is characterized by fleshy tubers, absence of normal leaves, united sepals and petals and two mealy pollinia without caudicles (Cribb et al. 2010, Hsu & Kuo 2010, Hsu et al. 2012, Suetsugu et al. 2018).

Types of heterogeneities and deformation mechanisms in blueschist rocks: an example from an exhumed subduction complex in Ishigaki Island, Ryukyu Arc

<p>The geological properties of the subduction interface, such as stable metamorphic assemblages and the rheology of shear zone rocks, change with depth. Studies based on seismic and geodetic observations suggest that these changes can be accompanied by differences in seismic styles. In this realm, slow slip events (SSEs) and related tremor signals, grouped as episodic tremor and slip (ETS) events, have been detected down-dip of the subduction megathrust seismogenic zone. A wide range of mechanisms, some invoking rheological heterogeneity, has been proposed to explain ETS occurrence. Given that ETS events accommodate most of the plate interface displacement in a depth range below the seismogenic zone, it is of great interest to understand the rheology of the rock lithologies that are likely to host ETS along the deep subduction interface.</p><p>Here, we present data from an exhumed subduction complex in Ishigaki Island, Ryukyu Arc. In particular, we analyse the Triassic high pressure-low temperature Tomuru metamorphic rocks, which comprise blueschist and greenschist facies metabasites that underwent subduction-related deformation. These rocks offer an important natural laboratory in which to study the characteristics of blueschist deformation structures to infer rheology and, in particular, the role played by heterogeneities in an environment comparable to modern ETS down-dip of the seismogenic zone.</p><p>Through multiscale and multidisciplinary, field- and laboratory-based studies, including quantitative microstructural and image analyses, we focus on two main topics. Firstly, we aim to understand blueschist rheology, by documenting the deformation mechanisms active in blueschist rocks through electron backscatter diffraction (EBSD), in order to quantify intracrystalline deformation and lattice preferred orientation (LPO) development. Secondly, we study the effect of grain size on blueschist foliation development and, ultimately, on blueschist deformation.  Through these analyses, we hope to constrain both subduction interface strength and dominant mineral- scale deformation mechanisms at blueschist conditions.</p>