Subgenus Cyclobalanopsis Research Articles

Correlation between the shoot‐cutting behavior of the acorn weevil and the reproductive traits of host fagaceous trees

AbstractMany fagaceous species mature acorns during the second autumn after flowering and are called “2‐year species.” In 2‐year species of subgenus Cyclobalanopsis (genus Quercus), alternate bearing (2‐year seed production cycle) is prominent, but this has not been reported for other 2‐year species in the genera of Lithocarpus and Castanopsis. We tested the hypothesis that the difference in reproduction of 2‐year species is linked to the weevil, Mechoris ursulus. After ovipositing on acorns, this insect cuts the shoots to which the acorns are attached. We examined the host preference of M. ursulus and reproductive traits of fagaceous 2‐year species. Percentage infestation was remarkably high in the subgenus Cyclobalanopsis, whereas Lithocarpus and Castanopsis species suffered almost no damage. Furthermore, unlike Lithocarpus and Castanopsis, most of the acorn‐producing shoots in subgenus Cyclobalanopsis had no current‐year shoots. The clear relationship suggests that alternate bearing in subgenus Cyclobalanopsis is an adaptation to the shoot‐cutting behavior of M. ursulus.

A consistent species richness–climate relationship for oaks across the Northern Hemisphere

AbstractAimAlthough the effects of climate on species richness are known, regional processes may lead to different species richness–climate relationships across continents resulting in species richness anomalies, especially for tropical groups. Phylogenetic niche conservatism may also influence species richness–climate relationships of different lineages. Here, we tested whether regional effects also exist for temperate lineages using the genus Quercus.LocationNorthern Hemisphere.Time periodPresent day.Major taxa studiedQuercus (Fagaceae).MethodsWe used a dated phylogeny and distribution data for Quercus to evaluate its global species richness patterns and phylogenetic niche conservatism. To evaluate the consistency in species richness–climate relationships across continents of the genus Quercus as a whole and the temperate subgenus Quercus, we conducted analyses of covariance with continent as the categorical variable and climate variables as the covariate. We calibrated four widely used models using the global data or data from each continent separately and evaluated the predictive power of each model for different continents using the root mean squared error.ResultsThe relationships between species richness and climate were not significantly different among continents for both the genus Quercus as a whole and the subgenus Quercus. Unlike the models based on European data, those based on North American and eastern Asian data predicted both the global species richness and the richness in other continents. The species richness of a subtropical subgenus Cyclobalanopsis was most influenced by water availability, while that of a temperate subgenus Quercus was most influenced by environmental temperature.Main conclusionsIn contrast to the subtropical subgenus Cyclobalanopsis, our results showed a consistent richness–climate relationship and absence of regional effects on species richness across continents for the temperate subgenus Quercus, likely suggesting that the species richness of temperate lineages, for example subgenus Quercus, may have reached equilibrium with the contemporary climate in the Northern Hemisphere.

First record of Erysiphe quercicola (Ascomycota: Erysiphales) on species of Quercus subgenus Cyclobalanopsis (evergreen oaks, Fagaceae)

During the DNA sequence analyses of specimens on Quercus subgenus Cyclobalanopsis deposited as Erysiphe gracilis or Cystotheca wrightii, some specimens exhibited DNA sequences that are different from the sequences of the two species. Based on BLAST search and morphological observations, the true causal agent was identified as E. quercicola. This is the first record of E. quercicola on species of subgenus Cyclobalanopsis. Previous studies revealed that E. quercicola is plurivorous infecting a wide range of tropical fruit trees and woody plants. Further studies are needed to address the question as to why only E. quercicola infect species of subgenus Cyclobalanopsis.

Introgression Threatens the Genetic Diversity of Quercus austrocochinchinensis (Fagaceae), an Endangered Oak: A Case Inferred by Molecular Markers.

Natural introgression can cause negative effects where rare species experience genetic assimilation and invade by their abundant congeners. Quercus austrocochinchinensis and Q. kerrii (subgenus Cyclobalanopsis) are a pair of closely related species in the Indo-China area. Morphological intermediates of the two species have been reported in this region. In this study, we used AFLP, SSR and two key leaf morphological diagnostic traits to study the two Q. austrocochinchinensis populations, two pure Q. kerrii and two putative hybrid populations in China. Rates of individual admixture were examined using the Bayesian clustering programs STRUCTURE and NewHybrids, with no a priori species assignment. In total, we obtained 151 SSR alleles and 781 polymorphic loci of AFLP markers. Population differentiation inferred by SSR and AFLP was incoherent with recognized species boundaries. Bayesian admixture analyses and principal coordinate analysis identified more hybrids and backcrossed individuals than morphological intermediates in the populations. SSR inferred a wide genetic assimilation in Q. austrocochinchinensis, except for subpopulation D2 in the core area of Xi-Shuang-Ban-Na Nature Reserve (XSBN). However, AFLP recognized more Q. austrocochinchinensis purebreds than SSR. Analysis using NewHybrids on AFLP data indicated that these hybridized individuals were few F2 and predominantly backcrosses with both parental species. All these evidences indicate the formation of a hybrid swarm at XSBN where the two species co-exist. Both AFLP and SSR recognized that the core protected area of XSBN (D2) has a high percentage of Q. austrocochinchinensis purebreds and a unique germplasm. The Hainan population and the other subpopulations of XSBN of the species might have lost their genetic integrity. Our results revealed a clear genetic differentiation in the populations and subpopulations of Q. austrocochinchinensis and ongoing introgression between Q. austrocochinchinensis and Q. kerrii at the disturbed contact areas. Combining the results from genetic and morphological analyses, the conservation of subpopulation D2 should be prioritized. Conservation and restoration of the integrity of tropical ravine rainforest is an important long-term goal for the successful conservation of Q. austrocochinchinensis. The fine-scale landscape might play an essential role in shaping the spatial patterns of hybridization. Further studies are needed to evaluate these patterns and dynamics.

De novo transcriptome assembly and development of SSR markers of oaks Quercus austrocochinchinensis and Q. kerrii (Fagaceae)

The commonly found oak species Quercus kerrii and the rare species Quercus austrocochinchinensis (subgenus Cyclobalanopsis) are genetically close and found in sympatry in Indo-China with morphological evidences of hybridization. The two species provide an opportunity to investigate the mechanism of speciation and to study how species integrity is maintained in the subgenus Cyclobalanopsis. However, the genomic resources are lacking in Cyclobalanopsis to produce enough molecular markers. We performed RNA-seq on Q. austrocochinchinensis and Q. kerrii by pooling tissues of new and old leaves, roots, and stems. A total of 14,247,444/12,900,500 (Q. austrocochinchinensis/Q. kerrii) clean reads were obtained from 2 × 300 bp Illumina MiSeq sequencing platform. De novo assembly produced 79,312/81,921 contigs representing 49,845/50,767 unigenes. The Ka/Ks estimation and following enrichment analysis identified 24 genes. Most of them were related to biosynthesis and growth, which may be involved in the process of speciation. 5196/5021 primer pairs were successfully designated from 13,762/13,430 putative loci with microsatellite repeats. We selectively screened 215 polymorphic simple sequence repeat (SSR) loci according to the list of 29,893 pairwise orthologous genes predicted by a reciprocal best hits algorithm. From the 215 loci, we selected 102 well-amplified SSR primers for polymorphic SSR locus analysis. We found 18 highly polymorphic loci and suitable for population genetic analysis, with 10 loci that had a diagnostic power that may be useful in studying hybridization. Finally, in silico PCR was performed using two Fagaceae species Quercus robur and Castanea mollissima. Our study provides a set of useful SSR markers and can enable further functional and comparative genomic research on the Quercus subgenus Cyclobalanopsis.

Eight new species of Cycloneuroterus Melika & Tang gallwasps from Taiwan and mainland China (Hymenoptera: Cynipidae: Cynipini).

Eight new species of cynipid gallwasps, Cycloneuroterus abei Melika & Tang, C. ergei Tang & Melika, C. gilvus Melika & Tang, C. globosus Melika & Tang, C. jianwui Tang & Melika, C. lohsei Melika & Tang, C. tumiclavus Tang & Melika, C. uraianus Tang & Melika, from Taiwan and mainland China are described. Descriptions, diagnoses, biology, and host associations for the new species and a key to all Cycloneuroterus species are given. All taxa are supported by morphological and molecular data. Seven newly described species induce galls on Quercus subgenus Cyclobalanopsis, while one, C. uraianus, induces galls on Castanopsis. This is the first Cycloneuroterus species known to associate with Castanopsis.

A New Species of Dryocosmus Giraud (Hymenoptera: Cynipidae: Cynipini) in Japan and Korea—First Record of Eastern Palearctic Dryocosmus Species Showing Alternation of Generations on Section Cerris Oaks

Dryocosmus kunugiphagus Ide and Abe, n. sp. associated with a section Cerris oak, Quercus acutissima Carruth., is described in Japan and Korea. Although section Cerris oaks are the main host plants of Western Palearctic species of Dryocosmus Giraud, hitherto known Eastern Palearctic ones exhibit host specificity with plants of the genus Castanea Mill. and the subgenus Cyclobalanopsis (Oerst.) of the genus Quercus L. Therefore, the present study served as the first record of a Dryocosmus species being associated with section Cerris oaks in the Eastern Palearctic region. The species was previously identified as Spathegaster sp., Andricus inflator Hartig, and Neuroterus boni-henrici Dettmer in Japan; however, examination of adults that emerged from galls resulted in the description of a new Dryocosmus species. Collection and emergence dates indicated the occurrence of a prolonged diapause in the asexual generation of D. kunugiphagus.

The first fossil record of ring-cupped oak (Quercus L. subgenus Cyclobalanopsis (Oersted) Schneider) in Tibet and its paleoenvironmental implications

Some taxa are good indicators of particular climates because their distribution is determined by specific temperature or precipitation requirements. Ring-cupped oaks (Quercus L. subgenus Cyclobalanopsis (Oersted) Schneider) are mainly distributed in tropical and subtropical climates in southeastern and eastern Asia. Recently, we collected many leaf fossils of ring-cupped oaks from the Upper Miocene Lawula Formation of eastern Tibet at an elevation of 3910m. No modern species of ring-cupped oaks could survive at such a high elevation under current climate conditions. Based on detailed morphological comparisons with extant and fossil species, we propose a new species, Quercus tibetensis H. Xu, T. Su et Z.K. Zhou sp. nov., representing the first fossil record of ring-cupped oaks in Tibet. We investigated the climate requirements of the nearest living relatives (NLRs) of Q. tibetensis, and the ranges of mean annual temperature (MAT) and mean annual precipitation (MAP) are 7.9°C to 21.7°C, and 733.0mm to 2536.8mm, respectively, compared with the current climate at the fossil site with MAT of 4.4°C and MAP of 516.5mm. The NLRs of Q. tibetensis are distributed at elevations from 70m to 3000m, much lower than the fossil locality (3910m). The altitudinal difference of the fossil site is 161m to 3091m between the late Miocene and today, even considering the warmer global climate during the late Miocene. Our results indicate that the climate conditions at the fossil site during the late Miocene were warmer and more humid than the current climate. Meanwhile, this new fossil finding corroborates results from previous studies that the southeastern part of the Qinghai–Tibetan Plateau experienced continued uplift since the late Miocene.

Habitat-linked temperature requirements for fruit germination in Quercus species: A comparative study of Quercus subgenus Cyclobalanopsis (Asian evergreen oaks) and Quercus subgenus Quercus

The genus Quercus contains two subgenera with distinct geographic and habitat ranges. Generally, subgenus Quercus has the wider habitat range spanning subtropical to temperate regions across the Northern Hemisphere, whereas subgenus Cyclobalanopsis mainly occurs in subtropical and tropical Asia. Particularly for subgenus Cyclobalanopsis, germination patterns and behaviour, and how they relate to climate are unknown. In this study we investigated the germination responses of 6 species from subgenus Cyclobalanopsis and 9 species from subgenus Quercus to different temperatures and tested for associations between germination requirements and habitat range. Species from subgenus Cyclobalanopsis from subtropical and tropical habitats (average overwinter monthly temperature≥8°C) germinated poorly at 15°C and reached high germination percentages at 25°C. Irrespective of the taxa, species living in a wide habitat range (average overwinter temperature range −8 to 23°C) reached high germination percentages at 15–25°C. Across all the species, time to 50% germination was not related to fruit traits but was significantly associated with phylogeny: subgenus Cyclobalanopsis fruits germinated more slowly than those of subgenus Quercus at all temperatures tested. Across species, sensitivity to lower germination temperatures was correlated with the highest temperature in their habitat after fruit dispersal. This study demonstrates a link between germination requirements and divergent distribution patterns between the two subgenera.

Quercus (subg. Cyclobalanopsis) leaf and cupule species in the late Miocene of eastern China and their paleoclimatic significance

The fossil record of Quercus subgenus Cyclobalanopsis can be traced back to the Late Eocene of eastern Asia based on fossil foliage and acorns. We refer new occurrences of leaf and acorn fossils from the upper Miocene of Tiantai, eastern Zhejiang, China, to two new species, Quercus paraglauca sp. nov. and Quercus heterobracteolata sp. nov.. Q. heterobracteolata represents the earliest confirmed fossil acorn of the subgenus Cyclobalanopsis in China. A review of other occurrences reported in the literature reveals that the divergence of subgenus Cyclobalanopsis occurred not later than the Eocene, and in the Miocene Cyclobalanopsis was already widely distributed. Comparisons of cuticular structure between Q. paraglauca and its nearest living relative species (NLR) Q. glauca suggest that: 1) atmospheric CO2 concentration in the late Miocene was ca. 400ppmv, i.e. higher than the present natural CO2 concentration, eliminating the industrial influence; 2) the Q. glauca trichome base density is sensitive to the environmental changes; and 3) the late Miocene climate of Zhejiang (eastern China) was warmer and more humid than today.

A new genus of cynipid inquiline, Lithosaphonecrus Tang, Melika & Bozsó (Hymenoptera: Cynipidae: Synergini), with description of four new species from Taiwan and China

The cynipid inquilines genus Saphonecrus is known to be a polyphyletic group with distinct lineages. One lineage is associated with Synophrus in the Western Palaearctic on section Cerris oaks. Another involves the type species of Saphonecrus, S. connatus, and represents a distinct and probably early-diverging lineage with a Palaearctic distribution on white oaks. The third main lineage is predominantly Asian, and associated with Quercus subgenus Cyclobalanopsis and Quercus section Cerris and the oak-related Fagaceae including Lithocarpus. This third lineage shows large diversity, and includes the genus Ufo, the European lineage of S. undulatus and S. haimi, and the herein described new genus, Lithosaphonecrus Tang, Melika & Bozsó, known from Taiwan and China, with four new species: L. formosanus Melika & Tang, L. dakengi Tang & Pujade-Villar, L. huisuni Tang, Bozsó & Melika and L. yunnani Tang, Bozsó & Melika. All the four described species are associated only with Lithocarpus. Descriptions, diagnoses, biology, and host associations for the new genus and species are given, as well as a key to species and cynipid inquilines genera. All taxa are supported by morphological and molecular data.

Leaf epidermal features ofQuercussubgenusCyclobalanopsis(Fagaceae) and their systematic significance

Leaf epidermal features are important taxonomic features in Quercus. We studied leaf epidermal features of 91 species and one forma of Quercus subgenus Cyclobalanopsis using light and scanning electron microscopy. Trichome terminology in oaks was assessed and clarified, aiming to score the epidermal features accurately for genus-wide comparison. Nine trichome types, anomocytic and cyclocytic stomatal apparatus, smooth layer and platelet epicuticular wax flakes, and two trichome base types were found in subgenus Cyclobalanopsis. The epidermal features revealed three main groups in subgenus Cyclobalanopsis. The epidermal features of Quercus s.l. were uniform, supporting recognition of Cyclobalanopsis as a subgenus of Quercus rather than as a separate genus. Most leaf epidermal features show a mosaic pattern, although their numerous variations offered valuable resources for species identification. The leaf epidermal features that can be used for identification of Quercus leaves are also discussed and summarized. © 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 176, 224–260.

Multiple nuclear genes stabilize the phylogenetic backbone of the genus Quercus

Phylogenetic relationships among 108 oak species (genus Quercus L.) were inferred using DNA sequences of six nuclear genes selected from the existing genomic resources of the genus. Previous phylogenetic reconstructions based on traditional molecular markers are inconclusive at the deeper nodes. Overall, weak phylogenetic signals were obtained for each individual gene analysis, but stronger signals were obtained when gene sequences were concatenated. Our data support the recognition of six major intrageneric groups Cyclobalanopsis, Cerris, Ilex, Quercus, Lobatae and Protobalanus. Our analyses provide resolution at deeper nodes but with moderate support and a more robust infrageneric classification within the two major clades, the ‘Old World Oaks’ (Cyclobalanopsis, Cerris, Ilex) and ‘New World Oaks’ (Quercus, Lobatae, Protobalanus). However, depending on outgroup choice, our analysis yielded two alternative placements of the Cyclobalanopsis clade within the genus Quercus. When Castanea Mill. was chosen as outgroup, our data suggested that the genus Quercus comprised two clades corresponding to two subgenera as traditionally recognized by Camus: subgenus Euquercus Hickel and Camus and subgenus Cyclobalanopsis Øersted (Schneider). However, when Notholithocarpus Manos, Cannon and S. Oh was chosen as an outgroup subgenus Cyclobalanopsis clustered with Cerris and Ilex groups to form the Old World clade. To assess the placement of the root, we complemented our dataset with published data of ITS and CRC sequences. Based on the concatenated eight gene sequences, the most likely root position is at the split between the ‘Old World Oaks’ and the ‘New World Oaks’, which is one of the alternative positions suggested by our six gene analysis. Using a dating approach, we inferred an Eocene age for the primary divergences in Quercus and a root age of about 50–55 Ma, which agrees with palaeobotanical evidence. Finally, irrespective of the outgroup choice, our data boost the topology within the New World clade, where (Protobalanus + Quercus) is a sister clade of Lobatae. Inferred divergence ages within this clade and the Cerris–Ilex clade are generally younger than could be expected from the fossil record, indicating that morphological differentiation pre-dates genetic isolation in this clade.

The geographical distribution and differentiation of Chinese beech forests and the association with Quercus

AbstractQuestionsHow do Chinese beech forests differ in species composition and environmental requirements? What are the environmental determinants for the distribution of Chinese beech forests? What is the interspecific relationship among the Fagus species and with Quercus in the communities?LocationThe natural range of four Chinese Fagus species, including subtropical mainland China and Taiwan Island.MethodsBeech forests were sampled in 28 mountains. Community clustering and canonical correspondence analysis was applied to visualize species composition differences of the community types, and divergent environmental requirements of different Fagus species. The niche overlap among different Fagus species and with different subgroups of Quercus was measured. Based on generalized linear models, hierarchical variation partitioning was applied to estimate the contributions of climatic and topographic variables to the spatial variation in the abundance of different Fagus and Quercus species.Results(1) Among the Chinese beech forests dominated by four Fagus species, F. engleriana communities and F. hayatae communities are closer in species composition, as are the F. lucida communities and F. longipetiolata communities. (2) F. longipetiolata has the weakest and F. engleriana the strongest tolerance to freezing. The mainland F. hayatae, F. lucida and the island F. hayatae communities differ prominently along a humidity gradient from dry to wet. The spatial variation of abundance of all Fagus species is primarily related to precipitation seasonality, while the distributions of Quercus species are more sensitive to topographic feature at local scale. (3) The niche overlaps among the Fagus species are low at community level. F. engleriana and F. lucida have higher dominances in the communities than F. hayatae and F. longipetiolata. Quercus species are common components of beech forests in mainland China, but only Quercus subgenus Cyclobalanopsis species occur in F. hayatae communities in Taiwan Island. Different Fagus species have different associations with Quercus species in subgenus Quercus or Cyclobalanopsis.ConclusionsThe distribution of beech forests in China is primarily related to the precipitation seasonality of the monsoon climate, and differentiated on both temperature and moisture gradients. Within species ranges, the presence of oak in the beech forest is significantly regulated by topography.

Genetic admixing of two evergreen oaks, Quercus acuta and Q. sessilifolia (subgenus Cyclobalanopsis), is the result of interspecific introgressive hybridization

In forests worldwide, Quercus is a major genus; however, the boundaries between the constituent species are relatively weak, and hybridization is reported frequently. In this study, we examined Quercus acuta and Quercus sessilifolia (subgenus Cyclobalanopsis), which have a putative hybrid—Q. x takaoyamensis. We investigated leaf morphological traits and microsatellites of Q. acuta and Q. sessilifolia in the area where the two species are both found. Although the leaf traits overlapped, the two species could be distinguished morphologically as demonstrated by principal component analysis based on a range of these traits. They were also genetically differentiated, with F ST = 0.104. However, they shared most of the alleles at all eight loci examined, and considerable genetic admixing was detected. Admixture analysis demonstrated that Q. acuta and Q. sessilifolia, respectively, contained 11 and 24 % of individuals with a probability of less than 0.9 of being correctly assigned to their species. Model-based testing showed that this admixing was created by not only shared ancestral polymorphism but also by hybridization. Effective population size and migration rate were estimated using the coalescent approach. We estimated 8.843 and 71.98 effective numbers of migrants per generation to Q. acuta and Q. sessilifolia, respectively. Theoretically, one to ten migrants per generation are required to prevent complete genetic differentiation. Based on the results of this study, it appears that genetic admixing, with sharing of most alleles, is probably common in the two species and is maintained by interspecific introgressive hybridization.

Evolutionary history influences the effects of water–energy dynamics on oak diversity in Asia

AbstractAimWater–energy dynamics are often correlated with geographical patterns of terrestrial plant richness. However, the relative importance of water and energy on species richness is still being debated. Some studies suggest a transition in the relative importance of water and energy along a latitudinal gradient, i.e. that water is the most important factor at low latitudes, whereas energy is the leading factor at high latitudes. The generality of this transition is yet to be established and is the focus of the current study. In particular, we examine whether differences in the evolutionary histories of two subgenera of Asian oaks influence the derived models of water–energy dynamics.LocationAsia (70–140° E; 10–60° N).MethodsWe performed geographically weighted regressions to quantify geographical variation in the relative importance of water and energy on the species richness of Asian oaks (Quercus L.). We also evaluated how evolutionary history influences the relative importance of water and energy in determining species richness, by comparing patterns in the two oak subgenera: Quercus subg. Quercus and Quercus subg. Cyclobalanopsis. In particular, we assessed how the ancestral climatic niche of these two subgenera (i.e. subgenus Quercus of temperate origin versus subgenus Cyclobalanopsis of tropical origin) relates to the relative importance of water and energy on contemporary diversity patterns.ResultsWe found no geographical transition line in the relative importance of water and energy along the latitudinal gradient studied. Instead, we found that the importance of energy relative to water on the species richness of subgenus Quercus increased from mid‐latitudes (warm temperate regions) towards both tropical and boreal regions: this pattern might reflect that this subgenus originated in the temperate region. In contrast, the importance of both water and energy on the species richness of the tropical subgenus Cyclobalanopsis increased from tropical to boreal regions, probably due to a lack of adaptation to winter coldness.Main conclusionsOur results suggest that differences in the evolutionary history – specifically the ancestral climatic niche – of the two subgenera of oaks influence the effects of water–energy dynamics on species richness along a latitudinal gradient through niche conservatism.

A new genus of oak gallwasp, Cyclocynips Melika, Tang & Sinclair (Hymenoptera: Cynipidae: Cynipini), with descriptions of two new species from Taiwan.

A new genus of cynipid oak gallwasp-Cyclocynips Melika, Tang, & Sinclair (Hymenoptera: Cynipidae: Cynipini), with two new species--C. uberis and C. tumorvirgae--reared from galls on oaks of the Quercus subgenus Cyclobalanopsis is described from Taiwan. Descriptions of asexual generation adults and their diagnostic characters are presented. The likelihood of yet undiscovered sexual generations and the evolution of host-plant associations in these species are discussed.

Description of Two New Species of Dryocosmus (Hymenoptera: Cynipidae: Cynipini) Inducing Galls on the Strictly Asian Subgenus Cyclobalanopsis of the Genus Quercus, with a Key to Species of Dryocosmus in East Asia

ABSTBACT Two new species of Dryocosmus (Hymenoptera: Cynipidae: Cynipini), D. sefuriensis Ide, Wachi et Abe, sp. nov. and D. sakureiensis Ide, Wachi et Abe, sp. nov., are described from Japan. A key to species of Dryocosmus in East Asia is given. Although the members of Dryocosmus have been known to induce galls on the subgenus Quercus of the genus Quercus and the genera Castanea, Castanopsis, Chrysolepis, and Lithocarpus of Fagaceae, this is the first record of this gall wasp genus from the strictly Asian subgenus Cyclobalanopsis of the genus Quercus. The discovery of two new species of Dryocosmus associated with Q. (C.) acuta suggests the exceptionally diverse host range of Dryocosmus and the species richness of Cynipini on this plant subgenus in Asia.

Two‐year cycles of synchronous acorn and leaf production in biennial‐fruiting evergreen oaks of subgenus Cyclobalanopsis (Quercus, Fagaceae)

AbstractMany masting species switch resources between vegetative growth and reproduction in mast and non‐mast years. Although masting of oak species is well known, there have been few investigations of the relationship between vegetative growth and reproduction based on long‐term monitoring data, especially in evergreen oaks of subgenus Cyclobalanopsis. We investigated annual variations over 13 years in acorn and leaf production of three evergreen oak species in subgenus Cyclobalanopsis, genus Quercus (Fagaceae)—Q. acuta, Q. salicina and Q. sessilifolia—in western Japan. In these species, the maturation of acorns occurs in the second autumn after flowering, which is known as a biennial‐fruiting habit. We found a pattern of acorn production and masting in alternate years that was synchronized in all three species. Masting was not correlated with temperature and precipitation. Annual leaf‐fall also showed 2‐year cycle in the three oak species; peak years were synchronized between species and peak leaf‐fall alternated with acorn production in all three species. Furthermore, there was a significant negative correlation between acorn and leaf production in all three species. Data showing 2‐year cycles of acorn and leaf production and the negative correlation between them supports the hypothesis of resource switching between vegetative growth and reproduction. The 2‐year cycle might be the basic, intrinsic rhythm of resource allocation in biennial‐fruiting Cyclobalanopsis species.

Three New Species and a New Record of Cycloneuroterus (Hymenoptera: Cynipidae: Cynipini) Inducing Galls on Cyclobalanopsis in Japan

Abstract The following three new species of Cycloneuroterus Melika et Tang (Hymenoptera: Cynipidae: Cynipini) from Japan are described: C. akagashiphilus from Quercus (Cyclobalanopsis) acuta and C. hisashii and C. arakashiphagus from Q. (C.) glauca. Quercus (C.) acuta is recorded as a host plant of Cynipini for the first time. Cycloneuroterus fortuitusus Tang et Melika, previously known from Taiwan, is newly recorded for Japan. A key to all eight recognized species of Cycloneuroterus is provided. The hitherto known five species of Cycloneuroterus were recorded in Taiwan only and four of them induce galls on the strictly Asian subgenus Cyclobalanopsis. Therefore, the discovery of the three new species of Cycloneuroterus in Japan confirms the close association between Cycloneuroterus and Cyclobalanopsis, and suggests the existence of the potentially diverse cynipid fauna on this subgenus in Asia. More extensive sampling is expected to reveal the species richness in the Cynipini in the region.