Biometrical investigations on Homalothecium aureum, H. pinnatifidum, and related taxa

Abstract

Eleven quantitative, morphological gametophyte characters, two ratios, and seven qualitative characters were investigated on five currently accepted species: Homalothecium aeneum (Mitt.) Lawt., H. arenarium (Lesq.) Lawt., H. aureum (Spruce) Robins., H. nevadense (Lesq.) Ren. & Card., and H. pinnatifidum (Sull. & Lesq.) Lawt. A total of 102 specimens was examined. Based on quantitative characters a statistical analysis was performed mainly using canonical discriminant analysis and multivariate analysis of variance. Qualitative gametophyte and sporophyte characters were used for an additional comparison of the taxa. In the statistical analysis the North American H. pinnatifidum could not be separated from the European H. aureum. As no qualitative characters could be found to distinguish these two taxa either, it is concluded that they should be synonymized. The name to be adopted is H. aureum. The gametophyte of H. aeneum is intermediate between H. aureum and H. nevadense. The sporophyte is close to that of H. aureum, but can also show characters of H. nevadense. The possibility of a hybrid origin is discussed. H. aeneum is not well separated from either of its potential parents. As the multivariate analysis of variance indicates that it is slightly closer to H. nevadense, it is suggested that it should be treated as subspecies of H. nevadense. All other taxa (H. aureum, H. nevadense, and H. arenarium) can be separated by statistical methods and by additional qualitative characters, and deserve the rank of species.