Zoological Science

Tardigrades in the genus Milnesium have complex double claws on each leg, which consist of two slender primary branches and two basal secondary branches. The latter usually have two or three hooks. For more than a century, taxonomists have had great difficulties evaluating the claw variation in species identification in Milnesium. This review explains the complicated story and proposes a new notation system for Milnesium claw configuration with a discussion about anterior-posterior axes on tardigrade legs.

We satellite-tracked the eastern buzzard (Buteo japonicus) wintering in Japan to delineate both northward and southward migration routes, destinations, and stopover behavior. Twenty-two buzzards were captured and fitted with functional platform transmitter terminals. For these buzzards that departed from the capture sites, we observed a total of 65 northward migrations during 2008–2016 and a total of 55 southward migrations during 2008–2015. In spring, the eastern buzzards migrated eastward along the Seto Inland Sea in the Chugoku region or further inland. In eastern Honshu, they followed two different routes. One was to Hokkaido via the Tsugaru Peninsula from central or northern central Honshu northward along the side of the Sea of Japan in northern Honshu. The other was to Hokkaido via the Shimokita Peninsula, mainly from the Pacific Ocean side of northern Honshu, moving eastward through central Honshu. Of the 17 birds tracked, 10 summered in Sakhalin, three in Hokkaido, three in northern Honshu, and one unknown. In autumn, the buzzards retraced their northward migration routes. Of the 14 birds that were tracked the entire southward migration, 13 (92%) returned to their respective capture sites. One juvenile wintered in an area different from the capture site. Our study contributes to a deeper understanding of the distribution of breeding and wintering grounds and the migration routes of B. japonicus. In addition, the information on migration obtained in this study can contribute toward appropriate environmental impact assessment for wind power facilities in Japan.

Hybridization induced by human activities, such as crossbreeding between invasive and native species, can adversely affect the natural biodiversity of an ecosystem. In Japan, the endemic turtle species Mauremys japonica is known to hybridize with the alien species Mauremys reevesii, and putative hybrids have been encountered in the wild. If M. japonica × M. reevesii hybrids can readily crossbreed with M. japonica, the hybridization with M. reevesii could lead to the extinction of pure M. japonica populations. However, information on the reproductive ability of M. japonica × M. reevesii hybrids is limited. In this study, we collected wild-caught hybrids from across western Japan to assess their reproductive ability. We investigated the nesting season timing, clutch size, embryonic development, hatching success, and sperm viability. The results showed that female hybrids nested during the same months as the parental species and had similar clutch sizes and hatching success. No embryonic development abnormalities were detected, and viable sperm were observed in all hybrid male semen samples. In conclusion, the fertility of M. japonica × M. reevesii hybrids appears to be similar to the fertilities of the parental species, posing a potential challenge for M. japonica conservation.

We conducted a quantitative dietary analysis of the Japanese dormouse (Glirulus japonicus) using fecal samples collected in the subalpine zone of the Yatsugatake Mountains, central Japan. Dormouse diets were dominated by insects (69.2%) in summer and both fruit (43.0%) and insects (33.4%) in autumn. Leaves accounted for a small proportion of the diet in all seasons. Dormice may be reliant on insects because fruits are scant in summer, and on fruits to accumulate body fat in autumn before hibernation.

Obscure puffer, Takifugu obscurus, is an important aquaculture species in China, but the disease problem of this species seriously affects its production and causes huge economic losses. In order to reveal the molecular mechanism of disease resistance, polyinosinic-polycytidylic acid [poly(I:C)] was used to stimulate obscure puffer. At 0, 12, and 48 h (named To0, To12, and To48) after poly(I:C) challenge, the kidneys from obscure puffer were collected for transcriptome sequencing. A total of 54,816 transcripts was generated. Pairwise comparison of the sequencing libraries of tissue samples at these three time points revealed that the number of differentially expressed genes (DEGs) at To12 vs To0, To48 vs To0, and To48 vs To12 were 2039, 776, and 2579, respectively. Gene Ontology (GO) function classification analysis revealed that some DEGs were annotated to GO items for membrane, biological process, molecular function, and metabolic process. Kyoto Encyclopedia of Genes and Genomes pathway (KEGG) analysis of DEGs demonstrated that they mainly presented in immune-related pathways, such as Toll-like receptor signaling pathway, Retinoic acid-inducible gene-I-like receptor signaling pathway and NOD-like receptor signaling pathway. Then, eight genes were randomly selected from immune-related genes for real-time quantitative reverse transcription PCR verification (RT-qPCR), and 22 key immune DEGs were used to construct network functions. This study has obtained a large number of information resources about the transcriptome of obscure puffer, which can provide references for further research on the anti-virus response of obscure puffer.

A new species of Dalyelliidae, Gieysztoria pellucida Wang and You, is described based on material collected in southern China through an integrative approach combining morphological, histological, and molecular (18S and 28S rDNA) data. Gieysztoria pellucida sp. nov. is morphologically characterized by a fan-shaped (about 270° when pressed) stylet, consisting of 13 similar distal spines and a broad girdle without fenestrae region. This stylet is distinct from that of any other similar species in the Aequales group to which this species belongs. In addition, specimens identifiable as Gieysztoria garudae Van Steenkiste, Van Mulken, and Artois, 2012 were discovered from the same location as G. pellucida sp. nov. Gieysztoria garudae has previously been known only from India; the present study thus represents the first record of the species from China.

I report digenean metacercariae from Staurozoa, which were not previously known as digenean hosts. The host species, Haliclystus tenuis Kishinouye, 1910, was collected from algae in Oshoro Bay, Hokkaido, Japan, and contained metacercariae in the mesoglea. The metacercariae were encysted; cysts were oval, 93 µm long by 64 µm wide in one live individual. For the digenean, I generated partial sequences for the 18S rRNA (1585 bp) and 28S rRNA (1672 bp) genes, and the region spanning the 3′ end of the cytochrome c oxidase subunit gene and the 5′ end of the 16S rRNA gene, including the threonine tRNA gene (868 bp in total). Phylogenetic reconstructions based on combined 18S + 28S datasets showed the digenean to belong in Opecoelidae, members of which utilize marine or freshwater teleost fishes as definitive hosts, and placed it in Plagioporinae (sensu lato) clade C within Opecoelidae.

A new species of pachychilid freshwater gastropod, Sulcospira elonga sp. nov., is described from Guangxi Zhuang Autonomous Region, China, based on morphological and molecular evidence. The new species is distinguished from its congeners by a combination of characters, including eight to 11 whorls, spiral lirae and axial ribs present, the shell width is about 1.4–1.6 times the maximum width except for the body whorl, and stomach with outer and inner crescentic pads connected to each other.