Plant Diversity ›› 2022, Vol. 44 ›› Issue (02): 191-200.DOI: 10.1016/j.pld.2021.07.001

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Diversity and species-specificity of brood pollination of leafflower trees (Phyllanthaceae: Glochidion) by leafflower moths (Lepidoptera: Epicephala) in tropical Southeast Asia (Cambodia)

Pisal Chheanga,b,c, David H. Hembryd, Gang Yaoe, Shi-Xiao Luoa   

  1. a Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China;
    b University of Chinese Academy of Sciences, Yuquanlu, 19A, Beijing, 100049, China;
    c National Authority for Preah Vihear, Choam Khsant, 13403, Cambodia;
    d Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721, USA;
    e South China Limestone Plants Research Centre, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, 510642, China
  • Received:2021-01-26 Revised:2021-06-18 Online:2022-04-25 Published:2022-04-24
  • Contact: Shi-Xiao Luo,
  • Supported by:
    We express our deep thanks to Mr. Khou Eanghourt for his advice and facilitation of fieldwork. We also thank Mr. Nung Mao, Pisal Chheang's family, and many friends for their kind assistance with the field and laboratory work, and Peter van Welzen for discussing the identification of Cambodian Glochidion with us. We also thank the Ministry of Environment (Cambodia), Preah Vihear Heritage Site, Phnom Kulen National Park, Bokor National Park, Kirirom National Park, and Ream National Park for allowing us access to field sites and permission to conduct fieldwork. This project was supported by the National Natural Science Foundation of China (grants no. 31170217 and 31370268 to S.-X. Luo), and the Chinese Academy of Sciences’ “The Belt and Road” Master Fellowship Programme for providing P. Chheang a fully funded master's scholarship.

Abstract: Glochidion (Phyllanthaceae; leafflower trees) is a genus of trees which is widely reported to be pollinated by leafflower moths (Gracillariidae: Epicephala) in temperate and subtropical Asia, Australia, and the Pacific islands. However, the pollination ecology of Glochidion is not well described from tropical Asia, the region where it is most species-rich at both local (≤9 spp.) and regional (~200 spp.) scales. Here we report investigations of pollination biology and species-specificity of five Glochidion species in tropical Southeast Asia (Cambodia). Through nocturnal observations and fruit dissections, we find that at least three and likely five Glochidion species in Cambodia are pollinated by seed-parasitic leafflower moths. We find no evidence that any of these leafflower moths are non-mutualistic parasites, despite known examples of such parasites of this mutualism elsewhere in Asia. While the presence of a single larva in a fruit results in only a fraction of seeds being consumed, the presence of more than one larva per fruit—a frequent occurrence in some species—can result in almost all seeds within the fruit being infested. Multilocus phylogenetic analysis indicates that there are five different minimally monophyletic leafflower moth clades, each of which pollinates a unique Glochidion host species. Our results indicate that in its center of diversity in tropical Asia this system is an obligate pollination mutualism as previously described at the global margins of its distribution. These findings provide insights into the processes that generate and maintain biodiversity and maintain mutualism stability in plant–insect interactions in this biodiversity hotspot.

Key words: Glochidion, Epicephala, Obligate pollination mutualism, Leafflower–leafflower moth, Phyllanthaceae, Southeast Asia