Suetsugu Kenji, Sueyoshi Masahiro
Department of Biology, Graduate School of Science, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe, 657-8501, Japan.
Forest Zoology Group, Kyushu Research Center, Forestry and Forest Products Research Institute, 4-11-16 Kurokami, Kumamoto, 860-0862, Japan.
J Plant Res. 2018 May;131(3):497-503. doi: 10.1007/s10265-017-1007-4. Epub 2018 Jan 10.
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.
单子叶植物蜘蛛抱蛋属包含有根状茎的多年生植物，分布于亚洲热带至暖温带地区。几乎所有物种的传粉者都鲜为人知，这可能是因为蜘蛛抱蛋属植物的花不显眼。然而，其独特的花形态表明是生物传粉，因为花粉粒藏在每朵花的柱头之下。人们怀疑蜘蛛抱蛋有非常特殊的传粉生态。到目前为止，怀疑其传粉者有软体动物、甲壳类动物或弹尾虫。然而，最近一项研究表明，在日本南部黑岛（蜘蛛抱蛋的自然栖息地），蜘蛛抱蛋主要由蕈蚊传粉。在此，我们调查了日本中部滋贺县（引入种群所在地）蜘蛛抱蛋的传粉生态，以揭示蕈蚊是否也是引入种群的主要传粉者。我们的研究证实了在所调查的传粉过程中有蕈蚊传粉。此外，黑岛和滋贺县的主要传粉者（即四氏柯氏蕈蚊和某种球角蕈蚊）是相同的。因此，蜘蛛抱蛋主要依靠一个狭窄分类群的蕈蚊进行传粉。相比之下，尽管在自然条件下结实率相对较高，但我们未能记录到任何陆生端足目动物访问蜘蛛抱蛋的花。这一事实将反驳先前研究提出的端足目动物传粉假说。我们认为，蜘蛛抱蛋通过真菌拟态被蕈蚊传粉，这是由于它与蘑菇子实体表面相似且有强烈的麝香味。
