Phylogeny and Taxonomy on Cryptic Species of Forked Ferns of Asia

Zuoying Wei; Zengqiang Xia; Jiangping Shu; Hui Shang; Stephen J Maxwell; Lijun Chen; Xile Zhou; Wang Xi; Bayu Adjie; Quan Yuan; Jianguo Cao; Yuehong Yan

doi:10.3389/fpls.2021.748562

Phylogeny and Taxonomy on Cryptic Species of Forked Ferns of Asia

Front Plant Sci. 2021 Dec 17:12:748562. doi: 10.3389/fpls.2021.748562. eCollection 2021.

Authors

Zuoying Wei^{1

2

3}, Zengqiang Xia^{1

2

4}, Jiangping Shu^{1

5}, Hui Shang², Stephen J Maxwell⁶, Lijun Chen¹, Xile Zhou⁷, Wang Xi², Bayu Adjie⁸, Quan Yuan^{2

3}, Jianguo Cao³, Yuehong Yan^{1

2}

Affiliations

¹ Key Laboratory of National Forestry and Grassland Administration for Orchid Conservation and Utilization, The National Orchid Conservation Center of China and The Orchid Conservation and Research Center of Shenzhen, Shenzhen, China.
² Eastern China Conservation Centre for Wild Endangered Plant Resources, Shanghai Chenshan Botanical Garden, Shanghai, China.
³ College of Life Sciences, Shanghai Normal University, Shanghai, China.
⁴ CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China.
⁵ Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China.
⁶ College of Science and Engineering, James Cook University, Cairns, QLD, Australia.
⁷ Xiangxi Tujia and Miao Autonomous Prefecture Forest Resources Monitoring Center, Jishou, China.
⁸ Research Center for Plants Conservation and Botanic Gardens, National Research and Innovation Agency of Indonesia, Bali, Indonesia.

Abstract

Cryptic species comprise two or more taxa that are grounded under a single name because they are more-or-less indistinguishable morphologically. These species are potentially important for detailed assessments of biodiversity, but there now appear to be many more cryptic species than previously estimated. One taxonomic group likely to contain many cryptic species is Dicranopteris, a genus of forked ferns that occurs commonly along roadsides in Asia. The genus has a complex taxonomical history, and D. linearis has been particularly challenging with many intra-specific taxa dubiously erected to accommodate morphological variation that lacks clear discontinuities. To resolve species boundaries within Dicranopteris, we applied a molecular phylogenetic approach as complementary to morphology. Specifically, we used five chloroplast gene regions (rbcL, atpB, rps4, matK, and trnL-trnF) to generate a well-resolved phylogeny based on 37 samples representing 13 taxa of Dicranopteris, spanning the major distributional area in Asia. The results showed that Dicranopteris consists of ten highly supported clades, and D. linearis is polyphyletic, suggesting cryptic diversity within the species. Further through morphological comparison, we certainly erected Dicranopteris austrosinensis Y.H. Yan & Z.Y. Wei sp. nov. and Dicranopteris baliensis Y.H. Yan & Z.Y. Wei sp. nov. as distinct species and proposed five new combinations. We also inferred that the extant diversity of the genus Dicranopteris may result from relatively recent diversification in the Miocene based on divergence time dating. Overall, our study not only provided additional insights on the Gleicheniaceae tree of life, but also served as a case of integrating molecular and morphological approaches to elucidate cryptic diversity in taxonomically difficult groups.

Keywords: Gleicheniaceae; cryptic diversity; new combination; phylogeny; species delimitation; taxonomy.