A Taxonomic Revision On Macromitrium And Geographical Distribution Analysis

Macromitrium is a rather large pantropical genus of xerophytic epiphytes, belongingto the family Orthotrichaceae, Bryopsida. It is distinguished by the creeping, prostratestems giving rise to branches terminated by sporophytes; the leaves are twisted andcontorted around the branches, mostly with bulging, conic, papillose, or tuberculate cells.Calyptrae are large, mitrate, plicate, naked or hairy. Ovate to cylindric capsules mostlyhave peristomes, which are often reduced and fused, forming a low, single exostomialmembrane.Though China is rich in species of Macromitrium, with58species name recorded,few taxonomic revisions have been published. During our present taxonomic revision onChinese Macromitrium on the basis of more than500specimens including60types inrelation to Chinese Macromitrium, we found four species new to China, nine newsynonyms, and confirmed32species of the genus Macromitrium in China. Thepossibility using four chloroplast genes to identify the species of Chinese Macromitriumwas studied, and the present and potential geographical distribution of ChineseMacromitrium were also analyzed by using ArcGis9.3and Maxent, which werecompared with those of Chinese Orthotrichum. The main results are as follows:1. Macromitrium blumei Nees ex Schw gr., M. cuspidatum Hampe, and M.turgidum Dixonå'ŒMacromitrium gracile (Hook.) Schw gr. are four species new toChinaï¼›Macromitrium taiwanense Nog. is new to the mainland of China.2. Macromitrium courtoisii Broth.&Par., M. melanostomum Par.&Broth., M.subincurvum Card.&Thér., M. cylindrothecium Nog., and M. chungkingense P. C. Chenare five new synonyms of M. tosae Besch.ï¼›Macromitrium heterodictyon Dixon is a newsynonym of M. ousiense Broth.&Par.ï¼›Macromitrium giraldii var. acrophylloides C.Muell., M. handelii Broth. were synonymized with M. cavaleriei Card.&Thér.;Macromitrium japonicum var. makinoi (Brotherus) Noguhi was synonymized with M. japonicum Dozy&Molk., Macromitrium cancellatum Y. X. Xiong is possible a synonymof M. cavaleriei Card.&Thér., but the type of the former was unavailable to us.3. Macromitrium quercicola Broth. was a acceptable species, and M. quercicola var.angustifolium Broth. was treated as a new synonym of M. quercicola Broth..4．Macromitrium fortunatii var. nigrescens Tix. was originally recorded fromVietnam, and hasn’t been found in China, which should be excluded from the moss floraof China.5. We didn’t confirm the distribution of Macromitrium foxworthyi Broth. and M.sulcatum (Hook.) Brid. in China because we had not checked their specimens collectedfrom China. We confirmed the following32species of the genus Macromitrium in China:Macromitrium angustifolium Dozy&Molk., M. blumei Nees ex Schw gr., M.cavaleriei Cardot&Thér., M. clastophyllum Cardot, M. comatum Mitt., M. cuspidatumHampe, M. fasciculare Mitt., M. ferriei Cardot&Thér., M. formosae Cardot, M.fortunatii Cardot&Thér., M. gracile (Hook.) Schw gr., M. gymnostomum Sull.&Lesq.,M. hainanese S. L. Guo&S. He, M. holomitrioides Nog., M. incrustatifolium Robins., M.involutifolium (Hook.&Grev.) Schw gr., M. japonicum Dozy&Molk., M.macrosporum Broth., M. microstomum (Hook.&Grev.) Schw gr., M. moorcroftii (Hook.&Grev.) Schw gr, M. nepalense (Hook. et Grev.) Schw gr., M. ousiense Broth.&Paris,M. prolongatum Mitt., M. quercicola Broth., M. rhacomitrioides Nog., M. schmidii var.macroperichaetialium Guo&Cao, M. taiheizanense Nog., M. taiwanense Nog., M. tosaeBesch., M. tuberculatum Dixon, M. turgidum Dixon, and M. uraiense Nog..6. DNA barcoding is a new technology about species identification. Thirty-eightspecimens, which belong to Macromitrium gymnostomum Sull.&Lesq., M. ousineBroth., M. taiheizanense Nog., M. cavaleriei Card.&Thér., M.japonicum Dozy&Molk.,M. rhacomitrioides Nog., M. microstomum (Hook.&Grev.) Schw gr., and Macrocomatenue subsp sullivantii and Schlotheimia grevilleana were collected from Zhejiang,Fujian, Yunnan, Guangxi and Sichuan Provinces. Their sequences of four chloroplastgenes including trnL, trnG, psbT and rps4were sequenced. Fifteen Baysien phyogenetictrees were made based on the different combinations of the above four chloroplast genes.The species identification rates, the genetic distances between and within species of Macromitrium in the present study were calculated. We found that the combination of thefour chloroplast genes, and three-gene random combinations of the four genes, andtrnL-rps4combination can be applied to identify the species of Macromitrium effectively,all with100%species identification rate. Based on the success amplification andsequencing rate, as well as the phyogentetic relationships among the seven species ofMacromitrium, the combination of trnL-trnG-psbT was recommended for the DNAbarcoding of the genus Macromitrium.7． According to the distribution of29individuals in relation to M. cavalerieiCardot&Thér., M. gymnostomum Sull.&Lesq. and M. japonicum Dozy&Molk. in thephyogentetic trees resulted from four chloroplast genes (trnL, trnG, PsbT, and rps4), wediscussed their morphological variations and characteristics。8. We took131occurrence points of Macromitrium and66occurrences points ofOrthotrichum in China based on field work, relevant literature and museum collections.To predict the potential distribution regions of Macromitrium and Orthotrichum in China,we modeled their geographical distributions by using a maximum entropy algorithmmodeling program (Maxemt3.3.2) based on the presence-only data and19bioclimaticvariables and percent plant coverage. From the prediction we find that ChineseMacromitrium has a high distribution probability in the southeastern and some southernprovinces, with high integrated habitat suitability index in Zhejiang (0.4598), Taiwan(0.4582), Hainan (0.3938), Fujian (0.3313), Chongqing (0.3148), Yunnan (0.3095),Hongkong (0.2942), Hubei (0.2864), Hunan (0.2779) and Guizhou (0.2777), and lowhabitat suitability in northwest, northeast and some north provinces. Compared withMacromitrium, Orthotrichum has high habitat suitability in Yunnan (0.4103), Beijing(0.3437), Liaoning (0.3433), Jilin (0.3204), Guizhou (0.3084), Shanxi (0.3049), Sichuan(0.2792) and Hebei (0.2722). The Maxent model also indicates that predicted suitabilityof Macromitrium increases with the increasing of the annual precipitation, theprecipitation of wettest month, the precipitation of coldest quarter, and the precipitationof wettest quart The habitat suitability of Orthotrichum firstly increases rapidly with theincrease of the annual precipitation under200mm, and then decreases after the factorexceeds200mmï¼›the effect of the precipitation of driest month on the distribution of Orthotrichum is similar to that of the annual precipitation. The distribution probability ofOrthotrichum is highest when the mean temperature of warmest quarter is at15-20℃;with the increasing of the temperature seasonality (bio-4), the distribution probability ofOrthotrichum increases. The mathematical models of the relationships between thespecies numbers of Macromitrium and Orthotrichum in a given area with the annualrainfall and temperature were established. The species number of Macromitrium in agiven area (Y) with the annual rainfall (X1) follows Y=-0.03685+0.00028*X1(r=0.5347, P<0.001, n=131), and with the annual temperature (X2) follows Y=0.0831*e0.001*X2(r=0.5525, P<0.001, n=131); that of Orthotrichum (Y) with the annualrainfall follows Y=1.0008279-0.118429*lnX1(r=0.4199, P<0.001, n=66), with annualtemperature (X2) follows Y=1/(0.1309*X2+3.4581),(r=0.2524, P<0.01, n=66).Thepotential species number of Macromitrium and Orthotrichum in relation to annualtemperature and rain in China were showed by using the geographic information system(ArcGIS9.3).The results show that the areas in the southeast, south China and centralChina, as well as southeast of Yunnan and Xizang provinces potentially have morespecies of Macromitrium, and the climatic conditions in the areas such as Qinghai-TibetPlateau, Xinjiang, inner Mongolia, Heilongjiang, Jilin, Gansu, and Ningxia are notsuitable for Macromitrium. In term of Orthotrichum, it has more species in northwest,Qinghai-Tibet Plateau, Inner Mongolia, and Heilongjiang, less in southeast, southwestand south China.