A Revision Of Plagiothecium(Plagiotheciaceae) In East Asia Based On Morphological And Molecular Data

Plagiothecium Bruch&Schimp., the core genus of Plagiotheciaceae, is one of the most important members of temperate pleurocarpous mosses. Although it can be discriminated from several putative sibling genera by a series of diagnostic morphological character states, Plagiothecium is actually a genus without autapomorphy. Thus, the monophyly of the genus is still doubted. The vast land of East Asia harbors a large proportion of species in Plagiothecium and its putative sibling genera However, although some regional revisions have been accomplished, a comprehensive understanding of the species diversity of East Asian Plagiothecium is lacking. There is still much ambiguity or even contradiction about the concept of some taxa. Besides, some "ghost species" have never been studied again after they were described.Based on comprehensive evidences from morphological and molecular phylogenetic studies, the objective of this dissertation is:1) Revise Plagiothecium in East Asia through extensive review of relevant literatures and detailed observation of about160type specimens and over2000general specimens;2) Reconstruct the relationship among Plagiothecium species as well as the relationship among Plagiothecium and its putative sibling genera based on information from7DNA loci (nuclear ITS, gapCp, and chloroplast rbcL, rps4-trnS, psaB, trnQ trnL-F) of18representative taxa (54samples) with maximum parsimony analysis (MP), maximum likelihood analysis (ML) and Bayesian inference (BI);3) Reconstruct the relationship among the taxa of P. cavifolium-P. nemorale-P. succulentum-P. insigne complex based on information from7DNA loci (nuclear ITS2, and chloroplast ndhB, rpl2, rp/16, psbB-H, trnQ trnL-F) of68representative samples with MP analysis, ML analysis, BI and haplotype data.5) Provide the updated information about species diversity and geographic distribution of Plagiothecium in East Asia. The main results are as follows:1. Based on morphological evidences,1) P. shevockii S. He is treated as P. platyphyllum var. shevockii (S. He) Q Zuo&Y. F. Wang;2) P. formosicum var. rectiapex D K. Li, P. neckeroideum var. niitakayamae (Toyama) Z. Iwats. and P. neckeroideum var. sikkimense Renauld&Cardot are synonymized to P. neckeroideum Schimp.;3) P. subulatum Broth. is excluded from Plagiothecium and reduced to a synonym of Vesicularia flaccida (Sull.&Lesq.) Z. Iwats.;4) P. cavifolium var.fallax (Cardot&Ther.) Z. Iwats., P. curvifolium Schlieph. ex Limpr., P. shinii Sakurai, P. succulentum and P. undulatum (Hedw.) Schimp. are treated as dubious taxa due to the uncertainty of taxonomic status or the lack of typical voucher specimens in East Asia.2. The gene trees from MP, ML and BI analyses are almost congruent. The morphological circumscribed Plagiothecium is resolved non-monophyletic in all the analyses. According to both morphological and molecular evidences, Struckia is reduced to a synonym of Plagiothecium, and we suggest that P. piliferum (Sw.) Schimp. is retained in Plagiothecium until further evidence is available. The concept of Plagiothecium is slightly amended, and the redefined Plagiothecium is considered as a natural group.3. Both morphological and molecular evidences revealed that P. laetum Schimp. and P. lucidum (Hook. f.&Wilson) Paris, a species distributed in the Southern Hemisphere, are synonymous. Due to the fact that P. lucidum is the older name, P. laetum is synonymized to it. P. formosicum Broth.&Yasuda, a species endemic to East Asia, is treated as a variety of the widespread P. lucidum.4. It is suggested by molecular evidences that P. handelii-P. paleaceum, P. euryphyllum-P. obtusissimum, P. denticulatum-P. platyphyllum var. shevockii, P. latebricola-P. lucidum are four pairs of sister groups among East Asian Plagiothecium species.5. P. cavifolium, P. nemorale, P.succulentum and P. insigne are extremely close related taxa morphologically and phylogenetically. Both P. cavifolium and P. nemorale are resolved non-monophyletic in all the phylogenetic analyses. According to morphological and molecular evidences as well as their geographic range, we suggest that P. cavifolium and P. nemorale are retained as species. P. succulentum, whose geographic range is probably restricted in Europe, is treated as a variety of P. cavifolium. P. insigne is reduced to a synonym of P. nemorale.In conclusion,14species and2variety of Plagiothecium are recognized in East Asia, and a key to species as well as their descriptions, illustrations, and notes are provided. Three new combinations, two new status and six new synonyms are proposed in this study.