Based on morphological and molecular evidence, three new earthworm species of the genera Amynthas Kinberg, 1867 and Metaphire Sims and Easton, 1972 from Leshan City of southwest China's Sichuan Province were identified in this study. They are named Amynthas agenesis sp. nov., Metaphire jinhensis sp. nov., and M. ebianensis sp. nov. All three new species have a large size (the dimensions of the adult body are more than 200 mm × 10 mm) and three pairs of spermathecal pores in 6/7–8/9. Although these three new species are morphologically somewhat similar to the other species in the same group, they are distinguishable in several morphological characteristics. Metaphire jinhensis sp. nov. has paired and bunchy ovaries that are attached to septa 12/13. Metaphire ebianensis sp. nov. has large and well-developed prostate glands, and each of its seminal vesicles has a dorsal lobe. Amynthas agenesis sp. nov. has accessory glands in spermathecae, prostate, and intestinal caeca regions. The maximum likelihood tree was constructed based on the mitochondrial cytochrome c oxidase subunit I gene, and it showed that the three new species are clustered on different branches. Besides, phylogenetic trees also suggested that the genera Amynthas and Metaphire did not evolve separately within their respective taxa and thus were not monophyletic. This study provides a detailed taxonomic characterization of three new species and helps to better understand the species diversity of earthworms, which is urgently needed to ensure the ecological stability of wild earthworms.

Phenotypic plasticity, the ability of organisms to change their phenotype depending on external stimuli, enables their survival in fluctuating environments. An extreme example is polyphenism, in which a single genotype produces discrete phenotypes in response to external cues. However, under persistent environmental conditions, natural selection would favor reduced plasticity. This study focused on the loss of reproductive polyphenism and revealed the underlying mechanism in the pea aphid Acyrthosiphon pisum. Although most populations exhibit reproductive polyphenism, known as cyclical parthenogenesis, with a seasonal shift between parthenogenesis and sexual reproduction, some exhibit obligate parthenogenesis. To investigate the potential role of changes in the environmental sensitivity of the juvenile hormone (JH) pathway during this evolutionary shift, we analyzed the expression of genes involved in JH synthesis and degradation. We found that five of seven JH-related genes exhibited photoperiodic responses in one cyclical-parthenogenetic strain, whereas none of them responded to photoperiod in the two obligate-parthenogenetic strains. Notably, CYP15A and JHEH genes, which are involved in the final step of JH synthesis and in the initiation of JH degradation, respectively, showed strong photoperiodic responses in the cyclical-parthenogenetic strain but showed no responses in the obligate-parthenogenetic strains. Acetone treatment induces male production in obligate-parthenogenetic strains, suggesting that the developmental pathway for male production remains functional in these strains. These results suggest that the loss of the photoperiodic response in both JH synthesis and degradation pathways is a key mechanism underlying the elimination of the sexual phase, resulting in the loss of reproductive polyphenism in aphids.

Cephalopods, as prey for predators of various taxa, frequently experience arm loss. Arm loss in octopods may arise not only from predation pressure but also species-specific reproductive ecology. Therefore, investigating the occurrence of arm loss may provide insights into various aspects of octopods' reproductive ecology. In this study, we explored the seasonal and sexual differences in arm loss occurrences in two small octopus species, the Japanese pygmy octopus, Octopus parvus, and the Japanese blue-lined octopus, Hapalochlaena cf. fasciata. Notably, O. parvus exhibited a higher arm loss rate compared with previously studied species, potentially attributable to its relatively small size and sublethal predation by large crabs sharing the species' intertidal habitat. Regarding H. cf. fasciata, arm loss in males and females tended to increase toward the spawning season, with males experiencing a more rapid increase. The smaller size of males and arm loss due to male–male conflict related to reproduction and sexual cannibalism during copulation are likely contributing factors. Additionally, the impact of arm loss on egg retention and protective measures may prompt females to adopt behaviors minimizing the risk of arm loss.

The Japanese serow, Capricornis crispus, is a species endemic to Japan, residing in the mountainous forests of Honshu, Shikoku, and Kyushu. Gunma Prefecture, situated in central Honshu, is one of its habitats. To evaluate the genetic diversity and interrelationships among local populations in Gunma Prefecture, we examined the mitochondrial DNA control region sequences of 364 individuals. Our analysis, using all accessible Japanese serow sequences, revealed that they can be broadly categorized into four clades, labeled I to VI. Within Gunma Prefecture, we identified 15 distinct haplotypes, which can be classified into three haplogroups: G1, G2, and G3. G1, included in clade I, is associated with those reported in northeastern Honshu. G2, which forms clade IV on its own, is predominantly endemic to Gunma Prefecture, with a frequency of 90% in Showa Village at the western base of Mt. Akagi. In contrast, G3, included in clade V, forms a sister group to the haplotype discovered in the Japanese Alps. The haplotype composition exhibited a stark contrast between the regions on the west and east sides of the Kanto Plain, indicating that the Kanto Plain serves as a dividing line for Japanese serow populations. In Tsumagoi Village, 134 out of 144 animals shared the same haplotype, resulting in extremely low haplotype diversity, as indicated by a significant negative value in neutrality tests. This finding aligns with the observed rapid increase in serow in Tsumagoi.

The metridioid enthemonaean sea-anemone family Gonactiniidae Carlgren, 1893 is characterized by having one of the simplest morphologies among the Actiniaria. It currently includes two monotypic genera, each consisting of a species described in the 19th century from the Atlantic, although additional specimens have also been reported from the Mediterranean and South Pacific. In this study, we discovered a new species of gonactiniid anemone from Kumano-Nada, off the Pacific coast of Japan. This is the first record of this family from the North Pacific. According to our phylogenetic analyses, this anemone is the sister group to the other two genera of Gonactiniidae, Gonactinia Sars, 1851 and Protanthea Carlgren, 1891. Accordingly, we establish a new genus for this new species. Additionally, we discuss the simplification of body form in this lineage of sea anemones based on the discovery of this new species, which exhibits an intermediate morphology between the other gonactiniids and non-gonactiniid actiniarians.