东亚棉藓属（Plagiothecium）的分类学修订及分子系统学研究
|
摘要
棉藓属(Plagiothecium Bruch&Schimp.)是棉藓科的核心属,为温带山地侧蒴藓类中重要的组成部分。尽管目前基于数个形态特征性状的综合可以将其与近缘属区分,但由于该属缺乏独征,对于其是否为一个自然类群仍有争议。东亚地区有大量棉藓属及其近缘属物种分布,然而由于小范围修订造成的片面理解,属内存在诸多物种界定的模糊、不一致甚至相互矛盾之处,也遗留了一定数量仅有模式标本记载的“幽灵种”。
本研究通过经典形态分类学和分子系统学两条主线,1)基于全面的文献检索、160余份模式标本和2000余份地方性区系标本的观察,初步对东亚棉藓属进行重新整理；2)在此基础上选取18个代表性分类单位的54个样本,基于细胞核ITS、gapCp和叶绿体rbcL、rps4-trnS、psaB、trnG、trnL-F等7个分子标记信息,以最大简约法、最大似然法和贝叶斯推论对东亚棉藓属的概念和种间关系进行重构；3)针对属内形态界限较为模糊的圆条棉藓(P. cavifolium (Brid.) Z. Iwats.)-垂蒴棉藓(P. nemorale (Mitt.) A. Jaeger)-长喙棉藓(P. succulentum (Wilson) Lindb.)-P. insigne Cardot complex,选取68个代表性样本,基于细胞核ITS2和叶绿体ndhB、psbB-H、rp12、rpl16、trnG、trnL-F等7个分子标记信息,以最大简约法、最大似然法、贝叶斯推论和部分样本序列的单倍型归纳,对该complex内各单位的分类地位进行重新讨论；4)综合形态学研究及分子系统学研究结果,为东亚棉藓属植物物种多样性及分布提供最新资料。研究结果如下：
1.基于形态学研究,将石氏棉藓(P. shevockii S. He)处理为阔叶棉藓石氏变种(P. platyphyllum var. shevockii (S. He) Q. Zuo&Y. F. Wang);将台湾棉藓直叶变种(P. formosicum var. rectiapex D. K. Li)、扁平棉藓宽叶变种(P. neckeroideum var. niitakayamae (Toyama) Z. Iwats.)和扁平棉藓锡金变种(P. neckeroideum var. sikkimense Renauld&Cardot)处理为扁平棉藓(P. neckeroideum Schimp.)的异名；将狭叶棉藓(P. subulatum Broth.)从棉藓属中排除并处理为柔软明叶藓(Vesicularia flaccida (Sull.&Lesq.) Z. Iwats.)的异名。由于未见典型样本或分类地位不明,暂将圆条棉藓阔叶变种(P. cavifolium var. fallax (Cardot&Ther.) Z. Iwats.)、弯叶棉藓(P. curvifolium Schlieph. ex Limpr.)、P. shinii Sakurai、长喙棉藓和波叶棉藓(P. undulatum (Hedw.) Schimp.)作为东亚棉藓属植物的存疑种。
2.基于三种方法构建的基因树均显示,原形态范畴的棉藓属不是一个单系类群。综合形态学和分子系统学研究结果,建议将牛尾藓属(Struckia Mull. Hal.)处理为棉藓属的异名并将其下物种归入棉藓属内,并将毛尖棉藓(Plagiothecium piliferum (Sw.) Schimp.)保留于棉藓属中,同时参照原牛尾藓属的形态特征对棉藓属的定义进行微调。调整后的棉藓属可视为一个较为自然的类群。
3.综合形态学和分子系统学研究结果,认为光泽棉藓(P. laetum Schimp.)与南半球分布的P. lucidum (Hook. f.&Wilson) Paris为同物异名,根据命名法规,后者应作为光泽棉藓的合法学名；将东亚特有的台湾棉藓(P. formosicum Broth.&Yasuda)处理为光泽棉藓台湾变种(P. lucidum var. formosicum (Broth.&Yasuda) Q. Zuo&Y. F.Wang)。
4.分子系统学研究表明,滇边棉藓(P. handelii Broth.)-圆叶棉藓(P. paleaceum (Mitt.) A. Jaeger)、直叶棉藓(P. euryphyllum (Cardot&Ther.) Z. Iwats.)-钝叶棉藓(P. obtusissimum Broth.)、棉藓(P. denticulatum (Hedw.) Schimp.)-阔叶棉藓石氏变种(P. platyphyllum var. shevockii)、小叶棉藓(P. latebricola Schimp.)-光泽棉藓是四对东亚棉藓属中亲缘关系较近的姐妹分类单位。
5.圆条棉藓、垂蒴棉藓和长喙棉鲜和P. insigne Cardot具有非常密切的亲缘关系,在分子系统学研究中,圆条棉藓和垂蒴棉藓均不呈单系。综合形态、分子证据和地理分布格局,建议维持圆条棉藓和垂蒴棉藓的物种地位,将长喙棉藓处理为圆条棉藓长叶变种(P. cavifolium var. succulentum (Wilson) Q. Zuo&Y. F. Wang),并将P. insigne Cardot降为垂蒴棉藓的异名。圆条棉藓长叶变种的分布可能仅限于欧洲。
综上,本研究确认东亚有棉藓属植物14种2变种分布,并在文中提供了分种检索表以及各物种的描述、分布信息、图版和讨论。本研究共产生3个新组合,2个新地位和6个新异名。
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.
本研究通过经典形态分类学和分子系统学两条主线,1)基于全面的文献检索、160余份模式标本和2000余份地方性区系标本的观察,初步对东亚棉藓属进行重新整理；2)在此基础上选取18个代表性分类单位的54个样本,基于细胞核ITS、gapCp和叶绿体rbcL、rps4-trnS、psaB、trnG、trnL-F等7个分子标记信息,以最大简约法、最大似然法和贝叶斯推论对东亚棉藓属的概念和种间关系进行重构；3)针对属内形态界限较为模糊的圆条棉藓(P. cavifolium (Brid.) Z. Iwats.)-垂蒴棉藓(P. nemorale (Mitt.) A. Jaeger)-长喙棉藓(P. succulentum (Wilson) Lindb.)-P. insigne Cardot complex,选取68个代表性样本,基于细胞核ITS2和叶绿体ndhB、psbB-H、rp12、rpl16、trnG、trnL-F等7个分子标记信息,以最大简约法、最大似然法、贝叶斯推论和部分样本序列的单倍型归纳,对该complex内各单位的分类地位进行重新讨论；4)综合形态学研究及分子系统学研究结果,为东亚棉藓属植物物种多样性及分布提供最新资料。研究结果如下：
1.基于形态学研究,将石氏棉藓(P. shevockii S. He)处理为阔叶棉藓石氏变种(P. platyphyllum var. shevockii (S. He) Q. Zuo&Y. F. Wang);将台湾棉藓直叶变种(P. formosicum var. rectiapex D. K. Li)、扁平棉藓宽叶变种(P. neckeroideum var. niitakayamae (Toyama) Z. Iwats.)和扁平棉藓锡金变种(P. neckeroideum var. sikkimense Renauld&Cardot)处理为扁平棉藓(P. neckeroideum Schimp.)的异名；将狭叶棉藓(P. subulatum Broth.)从棉藓属中排除并处理为柔软明叶藓(Vesicularia flaccida (Sull.&Lesq.) Z. Iwats.)的异名。由于未见典型样本或分类地位不明,暂将圆条棉藓阔叶变种(P. cavifolium var. fallax (Cardot&Ther.) Z. Iwats.)、弯叶棉藓(P. curvifolium Schlieph. ex Limpr.)、P. shinii Sakurai、长喙棉藓和波叶棉藓(P. undulatum (Hedw.) Schimp.)作为东亚棉藓属植物的存疑种。
2.基于三种方法构建的基因树均显示,原形态范畴的棉藓属不是一个单系类群。综合形态学和分子系统学研究结果,建议将牛尾藓属(Struckia Mull. Hal.)处理为棉藓属的异名并将其下物种归入棉藓属内,并将毛尖棉藓(Plagiothecium piliferum (Sw.) Schimp.)保留于棉藓属中,同时参照原牛尾藓属的形态特征对棉藓属的定义进行微调。调整后的棉藓属可视为一个较为自然的类群。
3.综合形态学和分子系统学研究结果,认为光泽棉藓(P. laetum Schimp.)与南半球分布的P. lucidum (Hook. f.&Wilson) Paris为同物异名,根据命名法规,后者应作为光泽棉藓的合法学名；将东亚特有的台湾棉藓(P. formosicum Broth.&Yasuda)处理为光泽棉藓台湾变种(P. lucidum var. formosicum (Broth.&Yasuda) Q. Zuo&Y. F.Wang)。
4.分子系统学研究表明,滇边棉藓(P. handelii Broth.)-圆叶棉藓(P. paleaceum (Mitt.) A. Jaeger)、直叶棉藓(P. euryphyllum (Cardot&Ther.) Z. Iwats.)-钝叶棉藓(P. obtusissimum Broth.)、棉藓(P. denticulatum (Hedw.) Schimp.)-阔叶棉藓石氏变种(P. platyphyllum var. shevockii)、小叶棉藓(P. latebricola Schimp.)-光泽棉藓是四对东亚棉藓属中亲缘关系较近的姐妹分类单位。
5.圆条棉藓、垂蒴棉藓和长喙棉鲜和P. insigne Cardot具有非常密切的亲缘关系,在分子系统学研究中,圆条棉藓和垂蒴棉藓均不呈单系。综合形态、分子证据和地理分布格局,建议维持圆条棉藓和垂蒴棉藓的物种地位,将长喙棉藓处理为圆条棉藓长叶变种(P. cavifolium var. succulentum (Wilson) Q. Zuo&Y. F. Wang),并将P. insigne Cardot降为垂蒴棉藓的异名。圆条棉藓长叶变种的分布可能仅限于欧洲。
综上,本研究确认东亚有棉藓属植物14种2变种分布,并在文中提供了分种检索表以及各物种的描述、分布信息、图版和讨论。本研究共产生3个新组合,2个新地位和6个新异名。
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.
引文