| ABSTRACT |
Three species of Macrothamnium M. Fleisch., two species of Leptohymenium Schwaegr., two species of Leptocladiella M. Fleisch., and one species of Orontobryum M. Fleisch. were revised. Macrothamnium submacrocarpum Renauld & Cardot and M. longirostre Dix. were synonymized with M. macrocarpum (Reinw. & Hornsch.) M. Fleisch. Macrothamnium hylocomioides M. Fleisch. and Chaetomitriopsis diversifolia Zanten were considered identical to M. javense M. Fleisch. A new combination, Hypnum flagellaris (T. J. Kop. & D. H. Norris) T.Y. Chiang, was proposed and excluded from genus Leptocladiella. The phylogeny of Macrothamnium and the related genera was reconstructed based on ontogenetic transformations of paraphyllia, axillary hairs, central strand, and other morphological characters. Whole ontogenetic transformations, instead of instantaneous stages, were recognized as characters and polarized by outgroup comparison. To test the phylogenetic relationship (familial position), Hypnum lindbergii Mitt. and Gollania ruginosa (Mitt.) Broth. of the Hypnaceae and Hylocomium splendens (Hedw.) B.S.G. and Loeskeobryum cavifolium (Lac.) M. Fleisch. of Hylocomiaceae were chosen as outgroups. The monophyly of the clade of Macrothamnium, Leptohymenium, and Orontobryum was supported, with a bootstrapping value of 96%, and was characterized by sharing regularly pinnate branching pattern, amplified costa, and a lack of foliose pseudoparaphyllia, whereas Macrothamnium appeared to be a paraphyletic group, in which M. leptohymenioides Nog. is more related to Leptohymenium than it is to any other species of Macrothamnium. The three genera are more related to the Hypnaceae than to the Hylocomiaceae. In contrast, Leptocladiella appears to be a genus of Hylocomiaceae. Patterson's tests were applied to the homology of the horn-type paraphyllia of Hylocomium splendens and Loeskeobryum cavifolium, and the foliose-type paraphyllia of Orontobryum hookeri. They passed the similarity and conjunction tests, but failed the congruence test. This suggests that the two types of paraphyllia are homoplasticˇXthat is, they evolved independently rather than being derived from a most recent ancestor. |
