九州大学学術情報リポジトリ
Kyushu University Institutional Repository
A taxonomic study of Lithocarpus (Fagaceae) in Vietnam based on molecular phylogeny and
morphological observations
グエン, ヴァン, ゴック
https://doi.org/10.15017/1931742
出版情報：九州大学, 2017, 博士（理学）, 課程博士 バージョン：
権利関係：
（様式３）
氏 名 ： グエン ヴァン ゴック
論 文 名 ：A taxonomic study of Lithocarpus (Fagaceae) in Vietnam based on molecular phylogeny and morphological observations
（分子系統学と形態観察にもとづくベトナム産ブナ科マテバシイ属の分類学的研究） 区 分 ：甲
論 文 内 容 の 要 旨
Lithocarpus is the second largest genus of the family Fagaceae, with approximately 350 species in the world. The centre of species diversity is mainly in continental Southeast Asia, especially in China (123 spp.) and Vietnam (117 spp.). In Vietnam, almost all the species of Lithocarpus were described by French botanists until 1920s and some other were until 1950s.
Since then, the taxonomic inventories of Lithocarpus in Vietnam were disrupted until recently.
Therefore, updating our taxonomic knowledge on the species of Lithocarpus using new collections and new techniques such as phylogenetic analysis based on DNA markers are required.
In this dissertation, our morphological observations and molecular phylogenetic analyses based on both classic DNA sequencing of two cpDNA (rbcL and matK) and one nrDNA (ITS) regions and multiplexed inter-simple sequence repeat genotyping by sequencing (MIG-seq) were employed to revise three complexes of Lithocarpus in Vietnam: L. elegans complex, L. hancei complex, and L. vestitus complex.
The NJ tree based on MIG-seq data provided the evidence of species delamination.
Among species of the L. elegans complex, L. blaoensis was clustered not with the other species of the L. elegans complex and more close to the L. hancei complex. Three other species previously reduced to or identified as L. elegans were distinct and an additional new species was confirmed. Thus, “L. elegans s. lat.” previously considered as a widespread polymorphic species included at least five distinct species.
In the L. hancei complex, both the MIG-seq tree and a population genetic analysis supported that it includes at least three distinct species. However, there was no diagnostic morphological difference between L. hancei and L. jacksonianus in spite that the two species co-occur in the same habitat of northern Vietnam. The third species L. yersinii distributed in souther Vietnam was morphologically distinct.
In the L. vestitus complex, the MIG-seq tree and morphological observations showed that “L. vestitus s. lat.” previously considered as a widespread polymorphic species included many cryptic species. As a result, we recognized 13 distinct species including three new species.
Through our study, nine new species are recognized and described: L. bidoupensis, sp.
nov., L. chinhii, sp. nov., L. dahuoaiensis sp. nov., L. hongiaoensis, sp. nov., L.
pseudoannamensis, sp. nov., and L. vuquangensis, sp. nov. from Vietnam, and L. bokorensis, sp.
nov. L. monoromensis, sp. nov., and L. pierreioides, sp. nov. from Cambodia. The photographs, illustrations, DNA barcode sequences, and the description of preliminary conservation status are also provided for the new species. Additionally, eight species are lectotypified in this study.
By applying both molecular and morphological approaches, we could resolve a long-standing problem on the taxonomy of polymorphic species complexes of Lithocarpus in Vietnam.
