Macromitrium maolanense Zeyou Zhang,D.D.Li,Jing Yu & S.L.Guo,a new species from China based on molecular and morphological evidence

Introduction. During a field excursion in Guizhou Province, China, we collected some interesting moss specimens with branch leaves subulate in the upper part, partially and variably bistratose laminae, and a Macromitrium-like epiphytic growth habit on tree trunks. We present morphological and phylogenetic arguments for recognising these plants as a new moss species in the genus Macromitrium Brid. (Orthotrichaceae).

Methods. We compared the morphology of the potential new species with closely related species of Macromitrium, and constructed a phylogenetic tree based on ITS2, trnL and trnG including sampling from 14 other morphologically similar species of Macromitrium.

Key results. The proposed new species belongs to the genus Macromitrium (Orthotrichaceae, Musci). It is closely related to M. gymnostomum Sull. & Lesq. in the phylogenetic tree and according to gametophytic morphological features, represents a hitherto undescribed species.

Conclusions. A new moss species, Macromitrium maolanense Zeyou Zhang, D.D.Li, Jing Yu & S.L.Guo, is described and illustrated. The new species can be distinguished from all congeners by the combination of the following features of the branch leaves: (1) oblong-lanceolate, lanceolate to linear-lanceolate, gradually narrowed to an easily broken subula; (2) rather obscure upper and medial cells, often with blackish stains among cells, densely pluripapillose; (3) variably and partially bistratose laminae in the upper 1/3 portion; (4) basal cells clear, hyaline and smooth, those near costae forming a ‘cancellina region’; and (5) with numerous brownish, clavate gemmae on upper portion. We also discuss the principal distinctive characters separating the new species from its nearest congeners.