Study On The Taxonomy Of The Family Bryaceae (musci) In North Region Of China

The family Bryaceae is a large acrocarpous moss family with diplolepidous-alternate peristome, about 14 genera and more than 800 species have been reported in the world. The majority of the species are cosmopolitan, except only a few limited to tropical and subtropical regions. It has the distribution from plain including residential areas and roadsides to high-altitude areas, also in the tundra zone and in the arid desert areas. According to the statistics in"Flora Bryophytorum Sinicorum", about 11genera (including Pohlia Hedw.), 102 species and 4 varieties of Bryaceae are considered to be taxonomically valid in China. The study of Bryaceae beginning in the early 19th century, the deep research was carried out by Brotherus, Andrews, Dixon, Nyholm, Ochi, Spence and so on. With regard to the study of Bryaceae, it has not a unified taxonomic standard. According to the situation and problems of the research, we have put emphasis mainly on some problems about Bryaceae in North region of China as follows:1. About 8 genera, 54 species and 2 varieties of Bryaceae in North region of China are accepted in this investigation based on documents, collections and identification of specimens from some herbaria (HBNU, PE, HKAS, HSNU and so on). 1 species (Bryum amblyodon C. Muell.) is recorded new to China. 41 species and 1 varieties are new record to a few provinces in North region of China, among them, Brachymenium longicolle Thér., B. muricola Broth., B. sinense Card., Bryum bornholmense Winkelm. & Ruthe., B. leptocaulon Card., B. longisetum C. Muell.and Pohlia crudoides (Sull. et Lesq.) Broth. var. revolvens (Card.) Ochi are the first recorded in North region of China.2. The detail descriptions of general morphological characters about gametophyte and sporophyte of Bryaceae are achieved based on the observation to the characteristics of anatomy under the Light microscope (LM). Figures and pictures of some characters are given in this discussion.3. Capsules of 27 species and spores of 21 species of Bryaceae in North region of China have been observed under LM and Scanning electron microscope (SEM). The results show that most exostome teeth of 27 species are lanceolate, but subulate in Brachymenium and Plagiobryum. In dry state, four types have been observed about the orientation of exostome teeth: (1) nearly erect. The exostome teeth of most species of Bryum, Anomobryum gemmigerum, Rhodobryum ontariense and Leptobryum pyriforme belong to this type; (2) erect-incurved. Two species of Brachymenium are entitled to this type; (3) curved-arcuate, with the tips inserted between the endostome teeth. This type occurs in Plagiobryum, Bryum apiculatum, B. longisetum, Pohlia cruda, P. nutans. (4) reflexed. Bryum cellulare, Pohlia elongate, P. longicollis fall into this type. The differentiations of ornamentation in the outer surface of exostome tooth also exist among these genera. Therefore, these features can look as accessorial features in separating different genera.Spores of 21 species of Bryaceae all have the katalept, but the shape of katalept are different in these species, the external ornamention of sporoderm exist in all 21 species, but the type and tiny structure of surface varied among these species. So this character is also ill-suited in dividing different genera. But it is a stability standard in separating some species.4. Gemmaes of 15 species of Bryaceae in North region of China have been observed under LM and SEM. The results indicate the difference is obvious and it can be look as a steady character in identifying specimens. There are different morphological characters in a different developmental stage, which bring out certain difficulty in systematic taxonomy.5. Based on the cladistic principles, Ditrichum pusillum as outgroup and 21 species of Bryaceae as the ingroup and the phylogenetic analysis is carried out. Maximum parsimony analyses (MP) and neighbour-joining analyses (NJ) are used to set up the phylogenetic trees. The results from two methods indicate the phylogenetic tree is divided into two parts. So we agree with Ochi in dividing Bryaceae into two subfamilies, but Anomobryum and Rhodobryum which are merged with Bryum are treated as separate genera here.6. Description, habitat and distribution are given to every species, key to subfamilys, genera and species of Bryaceae in North region of China are provided in the study.7. Based on the statistics of distribution of every species in areas of North region of China, the results show species of Brayceae are abundance in Shanxi, Henan, Hebei and Xinjiang.According to Chen and Wu, three areas of China and four other areas in the worldwide bryological regions are compared with each other using clustering method. The results reveal the bryological elements of North China region and Central China region are similar to Japan, the North temperate elements are dominant, Northeastern China region and Menggu-Xinjiang region are close to Europe, North America and Russia, the bryophyta are mainly Pan-arctic elements.