Most tortoise beetles, belonging to the subfamily Cassidinae (Coleoptera: Chrysomelidae), possess distinctive explanate margins, comprising elongations of the pronotum and elytra outer margins. These margins flatten against the ground, serving as a unique defensive mechanism against predators. To understand the developmental and evolutionary origins of explanate margins, we examined the development of the pronotal part of these structures in two tortoise beetle species: Thlaspida biramosa (Boheman) (tribe Cassidini) and Laccoptera nepalensis (Boheman) (tribe Aspidimorphini). Although final (fifth) instar larvae of both species exhibited no external prothoracic structures associated with explanate margins, pupae possessed a plate-shaped structure projecting anterolaterally on their pronotum. This plate-shaped structure was identified as the pupal primordium of the pronotal explanate margin, as the explanate margin emerged from inside the structure during eclosion. In prepupae of T. biramosa, the primordial tissue exhibited three region-specific folding and furrowing patterns, beneath larval cuticles. These epithelial structures expanded within minutes at the onset of pupation, resulting in pupal primordial formation. Thus, pronotal explanate margins originate from pronotal epithelia, with the furrowing and folding patterns of the epithelia shaping pupal and even adult pronotal explanate margins. The presence of morphologically similar pupal pronotal projections in various Cassidinae suggests that the development of pronotal explanate margins is likely common in these beetles.

Extreme temperatures are a major threat to the survival of ectotherms such as amphibians. The tree frogs belonging to the genus Buergeria have accomplished a latitudinal distribution and a wide range of thermal adaptations. In particular, Buergeria japonica, referred to as the “hot spring frog”, has been reported to tolerate extremely high temperatures. However, it is unclear how the heat tolerance and metamorphic strategies of this species vary among populations at different temperatures. We therefore conducted long-term heat tolerance experiments on multiple populations of B. japonica tadpoles and their congenic species to determine their survivability and development speed. We observed heat tolerance differences between B. japonica/Buergeria choui and Buergeria buergeri. Buergeria japonica exhibited the highest tolerance among all species, and the Seranma hot spring population showed the highest survival rate and accelerated development speed. However, at temperatures higher than 35°C, they could not survive until the completion of metamorphosis, contrary to previous field observations. Our behavioral experiment showed attenuation of the high temperature preference of B. japonica tadpoles associated with developmental stages, suggesting that they can tolerate extreme temperatures for a limited time window during their development until metamorphosis.

Pigment-based coloration is prevalent in animals, but its expression greatly varies across species, populations, and even among individuals in the same populations. Some animals are highly pigmented and thus have conspicuous coloration, whereas others are modestly pigmented and thus have drab coloration. A possible explanation for the variety in pigmentation is a resource-based tradeoff, in which resources invested in pigmentation are unavailable for other functional traits, and thus animals that need to invest in the latter have limited resources to invest in pigmentation. Resource-based tradeoff is plausible in theory, but direct tests are scarce, partially because of many components of pigment-based coloration (i.e., multiple pigments, integument microstructure, and stains) that affect coloration, preventing the use of coloration as an index of pigmentation. Here, using the barn swallow, Hirundo rustica, we examined the relationship between pheomelanin pigmentation in reddish throat patch (a precopulatory sexual trait) and total sperm length (a postcopulatory sexual trait), with particular attention to glutathione as the common resource. We predicted that pheomelanin, which is the predominant pigment in the reddish throat patch, should be negatively related to total sperm length, and that both sexual traits should be further negatively related to the amount of glutathione. As predicted, we found a negative relationship between pheomelanin pigmentation and total sperm length. However, the amount of glutathione in the blood showed no detectable relationship to them. The tradeoff between pheomelanin pigmentation and sperm size, as inferred from the current and previous results, might not be a simple glutathione-based tradeoff.

The TGF-β signaling pathway plays an important role in wound healing and immune response. In this study, a TGF-β type I receptor (TGF-βRI) homolog was cloned and characterized from freshwater mussel Hyriopsis cumingii. The full-length cDNA of the TGF-β RI gene was 2017 bp, with a 1554 bp open reading frame (ORF), and encoded 517 amino acids. The predictive analysis further identified distinct regions within the TGF-βRI protein: a signal peptide, a membrane outer region, a transmembrane region, and an intracellular region. Real-time quantitative PCR results showed that the TGF-β RI gene was expressed in all tissues of healthy mussels. The transcripts of TGF-β RI in hemocytes and hepatopancreas were significantly up-regulated at different periods after stimulation with Aeromonas hydrophila and peptidoglycan (PGN) (P < 0.05). The mRNA expression of TGF-β RI progressively increased from day 1 to day 10 after trauma (P < 0.05), and it returned to the initial level by day 15. The expression levels of TGF-β , Smad5, MMP1/19, and TIMP1/2, but not Smad3/4, were significantly up-regulated at different time points after trauma. However, the expression levels of TGF-β , MMP1/19, and TIMP2 were decreased after treatment with the inhibitor SB431542. Furthermore, the recombinant TGF-βRI proteins were expressed in vitro and existed in the form of inclusion bodies. Western blotting results showed that TGF-βRI proteins were expressed constitutively in various tissues of mussels, and their expression was up-regulated after trauma, which was consistent with the mRNA expression trend. These results indicate that TGF-β RI is involved in the process of wound repair and immune response.

Left–right asymmetry in paired organs is well documented across various species, including the claws of fiddler crabs and snail-eating snakes' dentition. However, the mechanisms underlying these asymmetries remain largely elusive. This study investigates Doubledaya bucculenta (Coleoptera: Erotylidae), a lizard beetle species known for pronounced left-sided asymmetry in adult female mandible and gena. Given that insect mouthparts comprise multiple functionally significant appendages, we aimed to clarify the degree of asymmetry extending beyond the mandibles and genae. Phenotypic morphology was assessed through trait measurement and asymmetry index calculations. Our detailed morphometric analyses revealed left-longer asymmetry not only in mandibles and genae but also in maxillae and labium. Notably, the degree of asymmetry in other mouthparts was generally less pronounced compared to that in outer mandibles, suggesting a potential influence of left mandible development on other mouthparts. Additionally, male mandibles exhibited region-specific asymmetry, potentially indicative of constrained evolutionary adaptations. This study enhances a comprehensive understanding of adult phenotype morphology and offers insights into the developmental basis of asymmetrical mouthparts.

We investigated geographic, genetic, and morphological variations in the intertidal limpet Lottia dorsuosa, a species with a broad distribution across Japan. A total of 98 specimens were obtained from 36 locations spanning the entire Japanese Archipelago, encompassing both the northern and southern regions. Examination of mitochondrial COI sequences revealed a distinct geographic genetic structure, delineating three prominent clades: (1) the Kuroshio Current, (2) the Tsushima Current, and (3) the Ryukyu-China groups. The observed geographical structuring between the Pacific and Sea of Japan side mirror patterns was noted in previously studied species, such as Turbo sazae and Batillaria attramentaria. Within L. dorsuosa, the Kuroshio Current group exhibited a substantial genetic distance, reaching a maximum of 12.35%, when compared to the more closely linked Tsushima Current and Ryukyu-China groups. Compared to other groups, the Ryukyu and China groups represented relatively recent differentiations, and the former group is currently facing a heightened risk of extinction owing to its sparse population density. The emergence of intraspecific geographic structures is likely attributable to the comparatively brief planktonic larval stage, which is a common characteristic of patellogastropod limpets.

Microfocus X-ray computed tomography (micro-CT) is expected to be utilized in the taxonomy of macroturbellarians that require histological technique(s) for identification, allowing nondestructive observation of the internal structures of specimens in a short time. With micro-CT, we observed a polyclad flatworm, Paraplanocera oligoglena (Schmarda, 1859), in this study. In the CT images, the main reproductive organs in the polyclad specimen were well observed, but some diagnostic characters were unclear or undetectable. We also prepared histological sections from the CT-scanned specimen. The histological sections were still observable and we could confirm the structures that were indistinct in the CT images; however, dye-affinity of tissues was slightly altered compared with those in usual sections. Integrating information from micro-CT images and subsequent histological observations, we successfully generated a 3D model of the reproductive organs of the polyclad. Our results suggest that the micro-CT imaging, as of the current resolution, would not completely replace the traditional histological technique; instead, these two techniques need to complement each other for a better understanding of the morphology that underpins the polyclad systematics.

We identified two gall-inducing wasp species infesting eucalypts leaves, including an undescribed species, Ophelimus cracens sp. nov., and Epichrysocharis burwelli, which is a new record for Taiwan. The major hosts of O. cracens were Eucalyptus grandis, Eu. urophylla, and Eu. camaldulensis (Myrtaceae). We observed failed galls of O. cracens at an early stage on Eu. amplifolia and Corymbia maculata. All O. cracens adults discovered on infected leaves were females, and four parasitoid species were identified in samples collected from two cities, three counties, and four municipalities across Taiwan. Epichrysocharis burwelli was exclusively found on C. citriodora in Hsinchu, Nantou, and Tainan Cities. This marks the first record of Ep. burwelli in Asia, accompanied by the identification of one parasitoid species. The adult longevity of adults which emerged from their major hosts, when provided with honey-water solution, was 5.5 days for O. cracens and 5.7 days for Ep. burwelli. Recognizing the potential damage by these wasps on Eucalyptus production areas in the absence of parasitoids, further investigations of their biology and control are warranted.