Predictive modelling of the distribution and evaluation of the conservation status with a taxonomic clarification of Macromitrium fortunatii Ther. (Orthotrichaceae, Bryophyta) in China and adjacent regions

摘要

Macromitrium fortunatii Then was included in the first Red List of Chinese endangered bryophytes, but later its inclusion was considered as uncertain because of taxonomic uncertainty and insufficient distribution data. Though the species was recently excluded from the latest threatened species list of China's higher plants, no detailed geographical records, voucher specimens or relevant references were included. From our morphological studies of type and other specimens, together with phylogenetic analyses based on ITS2, trnL and trnG sequences, we confirm its taxonomical identity and provide a detailed description and illustrations of the species. Macromitrium fortunatii var. nigrescens Tixier is reduced to synonymy with M. fortunatii. Since 2013 we have found 24 populations of M. fortunatii in Southwest and South China and North Vietnam. According to nine environmental variables and recent records of the species, we predict its potential distribution range with an aid of the maximum entropy algorithm modeling program (Maxent) and ArcGis 10.2. We find a high environmental suitability of the species in a wide region covering South and Southwest China, North Vietnam, North Myanmar, Nepal, and Northeast India. The predicted climate suitability for M. fortunatii is highest in areas where the annual precipitation is 1200 mm, the driest quarter receives 50 mm, and the wettest month 250 mm, the mean temperature of the coldest quarter is 10 degrees C, and the altitude is about 1200 m. The exclusion of M. fortunatii from the threatened species list of China's higher plants is supported.