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The family Thismiaceae, known as "fairy lanterns" for their urn- or bell-shaped flowers with basally fused tepals, consists of non-photosynthetic flowering monocots mainly in tropical regions, extending into subtropical and temperate areas. Here, we propose a new mycoheterotrophic genus, Relictithismia Suetsugu & Tagane (Thismiaceae), with its monotypic species Relictithismia kimotsukiensis Suetsugu, Yas.Nakam. & Tagane from Kimotsuki Mountains in the Osumi Peninsula, Kagoshima Prefecture, Kyushu Island, southern Japan. Relictithismia resembles Haplothismia Airy Shaw in having a cluster of tuberous roots, a feature previously observed only in this genus within the family Thismiaceae. However, it differs in having solitary flowers (vs. 2-6-flowered pseudo-raceme in Haplothismia), anther thecae largely separated (vs. connate), and the presence of an annulus (vs. absent). Additionally, Relictithismia differs from the geographically overlapping genus Thismia Griff. in its stamen structure and the position of the annulus. In Relictithismia, the stamens lack connectives, and its free filaments arise from the annulus located inside the perianth mouth, while in Thismia, the stamens typically have connate connectives, forming a staminal tube pendulous from the annulus located at the mouth of the floral tube. Our morphological and phylogenetic data indicated that R. kimotsukiensis holds an early-diverging position within the family, situated outside the Old World Thismia clade. This paper offers an extensive description and color photographs of R. kimotsukiensis, complemented by notes on its phylogenetic relationship and evolutionary history., (© 2024. The Author(s).)

Gentiana zollingeri is an annual photosynthetic plant that employs a mycoheterotrophic growth strategy during its underground seedling stage (initial mycoheterotrophy). Notably, the morphological characteristics of its flowering shoots, such as shoot size, leaf size, and leaf color, are highly variable, and it was hypothesized that these variations may be linked to nutritional mode. The morphological characteristics of G. zollingeri individuals were thus investigated alongside environmental factors, 13 C abundance, and diversity of colonizing arbuscular mycorrhizal (AM) fungi. The majority of G. zollingeri flowering individuals were found to exhibit a high affinity for the specific AM fungi that exclusively colonize roots of the mycoheterotrophic seedlings, while other phylogenetically diverse AM fungi could also be detected. The leaves to shoot dry weight ratio (leaf ratio) was negatively correlated with the canopy openness in the habitat, suggesting that leaf development is impeded in sunny conditions. Furthermore, the shoot weight of G. zollingeri was positively correlated with leaf 13 C abundance. Given that 13 C enrichment can provide indirect evidence of mycoheterotrophy in AM plants, the results suggest that the utilization of carbon obtained through mycoheterotrophy, at least during the underground seedling stage, is crucial for G. zollingeri., (© 2023. The Author(s) under exclusive licence to The Botanical Society of Japan.)

Background: Recent advances in immune-checkpoint inhibitors (ICIs) have highlighted the need for effective management of immune-related adverse events (irAEs). This study aimed to conduct a systematic surveillance of real-world development of irAEs for understanding their characteristics and examine the prognostic impact of steroid use for these events., Methods: We retrospectively investigated cancer patients treated with ICIs between 2014 and 2021 and collected information about irAEs throughout their development, management, and clinical outcomes., Results: Overall, 458 patients (45.4%) developed 670 irAEs. The prevalence of irAEs varied by cancer type, but it was increased in regimens with longer treatment durations. Severe irAEs were more common in the nivolumab + ipilimumab and pembrolizumab + axitinib regimens. Patients who received steroids for irAEs at a dosage of < 2 mg/kg had comparable prognosis to those who did not receive steroids; however, patients who received methylprednisolone pulse therapy, primarily for severe pneumonitis and hepatitis, had shorter overall survival than those who did not receive steroids (7.8 versus 23.4 months, p = 0.016). Furthermore, methylprednisolone pulse therapy for irAEs was a poor prognostic factor in multivariate analysis (hazard ratio: 2.19, 95% confidence interval: 1.34-2.86, p < 0.001)., Conclusion: Steroid treatment for irAE does not affect prognosis and should thus be used promptly to control inflammation. However, pulse therapy for severe cases is a poor prognostic factor, and early detection remains the key to managing such irAEs. The irAE characteristics in each regimen should be clarified to establish and provide more sophisticated irAE management, and the current findings will be beneficial to this goal., (© 2023. The Author(s) under exclusive licence to Japan Society of Clinical Oncology.)

The systematics of the Old World Spiranthes sinensis (Pers.) Ames species complex (Orchidaceae) has been complicated by its wide distribution and morphological variations. Within the species complex, S. australis Lindl. has been generally accepted as the only Spiranthes Rich. species distributed on the Japanese mainland. The present study provides morphological, phylogenetic, and ecological evidence for the recognition of S. hachijoensis Suetsugu as a new species of the S. sinensis species complex on the Japanese mainland. Spiranthes hachijoensis is morphologically similar to S. hongkongensis S.Y. Hu & Barretto and S. nivea T.P. Lin & W.M. Lin, sharing a degenerated rostellum, pollinia without a viscidium, and distinctly trilobed stigma. However, the taxon can be morphologically distinguished from S. hongkongensis by its glabrous rachis, ovaries, and sepals, and from S. nivea by its papillate labellum disc, larger papillate basal labellum callosities, and glabrous rachis, ovaries, and sepals. The autogamy and flowering phenology (i.e., earlier flowering) of S. hachijoensis are most likely responsible for premating isolation from the sympatric S. australis. A MIG-seq-based high-throughput molecular analysis indicated that the genetic difference between S. hachijoensis and its putative sister species S. sinensis is comparable to, or even greater than, the genetic difference between pairs of other species within the S. sinensis species complex. Our multifaceted approach strongly supports the recognition of S. hachijoensis as a morphologically, phenologically, phylogenetically, and ecologically distinct species., (© 2023. The Author(s).)

Due to their reduced morphology, non-photosynthetic plants have been one of the most challenging groups to delimit to species level. The mycoheterotrophic genus Monotropastrum, with the monotypic species M. humile, has been a particularly taxonomically challenging group, owing to its highly reduced vegetative and root morphology. Using integrative species delimitation, we have focused on Japanese Monotropastrum, with a special focus on an unknown taxon with rosy pink petals and sepals. We investigated its flowering phenology, morphology, molecular identity, and associated fungi. Detailed morphological investigation has indicated that it can be distinguished from M. humile by its rosy pink tepals and sepals that are generally more numerous, elliptic, and constantly appressed to the petals throughout its flowering period, and by its obscure root balls that are unified with the surrounding soil, with root tips that hardly protrude. Based on genome-wide single-nucleotide polymorphisms, molecular data has provided clear genetic differentiation between this unknown taxon and M. humile. Monotropastrum humile and this taxon are associated with different Russula lineages, even when they are sympatric. Based on this multifaceted evidence, we describe this unknown taxon as the new species M. kirishimense. Assortative mating resulting from phenological differences has likely contributed to the persistent sympatry between these two species, with distinct mycorrhizal specificity., (© 2022. The Author(s).)

In the original publication of the article, Fig. 2(c) was erroneously identical with Fig. 2(a) and correct version is provided below.

The very high floral diversity of Orchidaceae has often been attributed to the intricate relationships between orchids and their pollinators. In particular, the interaction between long-spurred orchids and hawkmoths has been well-studied. However, several recent studies suggest that pollination is driven by complex factors, including floral syndromes and local pollinator availability. Here, we investigated contributions of thrips to seed production in the presumably hawkmoth-pollinated long-spurred orchid Habenaria radiata, using pollination experiments and floral visitor observations. These experiments and observations showed that H. radiata is pollinated by both hawkmoths and thrips. Thrips intrude into the pollen sac, causing several massulae to be shed onto the stigma of the same flower, which is located just below the pollen sac. The fruit set and seed set of flowers enclosed in mesh bags (which allow thrips in) and in flowers enclosed together with thrips in paper bags, were much higher than in flowers enclosed in paper bags without thrips. This suggests that thrips partially contribute to fruit and seed production in this species. It provides evidence that thrips can contribute to seed production in a long-spurred orchid that is morphologically adapted to lepidopteran visitors. Unlike the compact pollinia of typical orchid species, those of H. radiata are mealy and friable, and thrips can therefore dislodge the pollen grains in small clumps. We suggest that secondary pollination by thrips may be more common than previously recognized in orchids with granular pollinia.

The genus Pyrola includes species with different degree of mycoheterotrophy; some species possess individuals that rely on all carbon through their associations with fungi (full mycoheterotrophy, FM), whereas some species obtain carbon through both fungi and photosynthesis by itself (partial mycoheterotrophy, PM). To investigate how plant functional traits of photosynthesis and reproduction are related to the degree of mycoheterotrophy in the initial stage of the transition from PM to FM, we determined morphological traits in FM (or nearly FM) and PM species in two independent lineages, P. picta and P. japonica complexes. We used herbarium specimens and examined leaf number, leaf area, flower number, and scape length in FM or nearly FM species (P. aphylla and P. subaphylla) and PM species (P. picta s.l. and P. japonica). We found a leaf area reduction in FM (or nearly FM) species in both lineages, suggesting that this is a convergent trait. The number of flowers was not significantly different between FM (or nearly FM) and PM species in both lineages. On the other hand, differences in the variation between FM (or nearly FM) and PM species were found in some traits between the two lineages. The FM (or nearly FM) species in one lineage only possessed rudimentary leaves, whereas that in the other linage possessed a few small, ordinary leaves in addition to those with only rudimentary leaves. The scape length of the FM (or nearly FM) species was significantly longer than that of PM species in one lineage, whereas it was shorter in the other lineage. The different and common variations are divergent and convergent traits, respectively, that could be associated with the transition to FM in Pylora. In addition, shoots of both PM species occasionally lacked ordinary leaves, possibly indicating possession of these shoots is preadaptation for the transition to FM in Pyrola.

The monocot genus Aspidistra comprises rhizomatous perennials that are distributed in tropical to warm temperate regions of Asia. Little is known about the pollinators of almost all the species, probably due to the inconspicuous nature of Aspidistra flowers. Nevertheless, the unusual floral morphology suggests biotic pollination, since pollen grains are hidden under each flower's stigma. Aspidistra elatior has been suspected to have a very peculiar pollination ecology. So far, pollination by mollusks, crustaceans, or collembolans has been suspected. However, a recent study showed that A. elatior is mainly pollinated by species of fungus gnats in Kuroshima Island, southern Japan, which is its natural habitat. Here, we investigated the pollination ecology of A. elatior in Shiga Prefecture, central Japan, which is the introduced population, to reveal whether fungus gnats are also the main pollinator in the introduced population. Our study confirmed fungus gnats pollination in the investigated pollination. Furthermore, the main pollinators (i.e., Cordyla sixi and Bradysia sp.) are the same in both Kuroshima and Shiga Prefecture. Therefore, A. elatior mainly depends on a narrow taxonomic group of fungus gnats for pollination. In contrast, we failed to document any terrestrial amphipods visiting the A. elatior flowers, in spite of a relatively high fruit set in natural conditions. This fact will refute the amphipod pollination hypothesis proposed by previous studies. We consider that A. elatior is pollinated by fungus gnats through fungal mimicry, due to its superficial similarity to mushroom fruiting bodies and strong, musky floral scent.

The evolution of mycoheterotrophy has been accompanied by extreme reductions in plant leaf size and photosynthetic capacity. Partially mycoheterotrophic plants, which obtain carbon from both photosynthesis and their mycorrhizal fungi, include species with leaves of normal size and others that are tiny-leaved. Thus, plant species may lose their leaves in a gradual process of size reduction rather than through a single step mutation. Little is known about how the degree of mycoheterotrophy changes during reductions in leaf size. We compared the degree of mycoheterotrophy among five Japanese Cephalanthera species, four with leaves of normal size (Cephalanthera falcata, Cephalanthera erecta, Cephalanthera longibracteata and Cephalanthera longifolia), one with tiny leaves (Cephalanthera subaphylla), and one albino form of C. falcata (as reference specimens for fully mycoheterotrophic plants). The levels of mycoheterotrophy were determined by stable isotope natural abundance analysis. All Cephalanthera species were relatively enriched in 13 C and 15 N in comparison with surrounding autotrophic plants. Cephalanthera subaphylla was strongly enriched in 13 C and 15 N to levels similar to the albinos. Species with leaves of normal size were significantly less enriched in 13 C than C. subaphylla and the albinos. Thus, C. subaphylla was strongly mycoheterotrophic, obtaining most of its carbon from mycorrhizal fungi even though it has tiny leaves; species with leaves of normal size were partially mycoheterotrophic. Hence, during the evolutionary pathway to full mycoheterotrophy, some plant species appear to have gained strong mycoheterotrophic abilities before completely losing foliage leaves.

Larger inflorescences in reward-producing plants can benefit plants by increasing both pollinator attraction and the duration of visits by individual pollinators. However, ultimately, inflorescence size is determined by the balance between the benefits of large inflorescences and the increased cost of geitonogamy. At present, little is known about the relationship between inflorescence size and fecundity in deceptive plants. Given that pollinators are likely to leave inflorescences lacking rewards quickly, it seems unlikely that longer pollinator visits and the risk of geitonogamy would be strong selective pressures in these species, which indicates that pollinator attraction might be the most important factor influencing their inflorescence size. Here we examined the pollination ecology of the deceptive orchid Cephalanthera falcata in order to clarify the effects of inflorescence size on the fruit set of this non-rewarding species. Field observations of the floral visitors showed that C. falcata is pollinated by the andrenid bee Andrena aburana, whilst pollination experiments demonstrated that this orchid species is neither autogamous nor apogamous, but is strongly pollinator dependent. Three consecutive years of field observations revealed that fruit set was positively correlated with the number of flowers per inflorescence. These results provide strong evidence that the nectarless orchid C. falcata benefits from producing larger inflorescences that attract a greater number of innate pollinators. Large inflorescences may have a greater positive effect on fruit set in deceptive plants because a growing number of studies suggest that fruit set in reward-producing plants is usually unaffected by display size.

Few studies have examined the reproductive ecology of mycoheterotrophic plants, but the existing literature hypothesizes that they adopt a self-pollinating strategy. Although growing evidence indicates that some rewarding mycoheterotrophic plants depend (at least partially) on an insect-mediated pollination system, it remains unclear whether some mycoheterotrophic plants can attract pollinators without nectar or other rewards. Moreover, in a broader evolutionary/ecological context, the question of whether the evolution of mycoheterotrophy induces a shift in pollination pattern is still unknown. Here I present a comparative investigation into the breeding system of two fully mycoheterotrophic orchids, Cymbidium macrorhizon and C. aberrans, and their closest extant relative, the mixotrophic C. lancifolium. Pollination experiments were conducted to determine the breeding system of these plants. In addition, flower visitors that might contribute to pollination were recorded. Flowers at different maturity stages were examined to investigate mechanisms enabling or limiting self-fertilization. While nectarless flowers of C. lancifolium and C. macrorhizon can successfully attract potential pollinator honeybees, all three Cymbidium possess an effective self-pollination system in which the rostellum that physically separates the stigma and pollinia is absent. Because mixotrophic and mycoheterotrophic Cymbidium occupy low-light niches, pollinator foraging would be negatively influenced by low-light intensity. In partial and fully mycoheterotrophic Cymbidium, autogamy would likely be favoured as a reproductive assurance to compensate for pollinator limitation due to their lack of nectar and pollinators' hostile habitat preferences.