B. Papp szerk.: Studia Botanica Hungarica 32. 2001 (Budapest, 2001)

Erzberger, Peter: Ditrichum crispatissimum (Muell. Hal.) Paris, a new species of the Hungarian bryoflora, and Ditrichum flexicaule (Schleich. ex Schwaegr.) Hampe in Hungary

Of the seven characters used by Novotny four are more or less evident (nrs 3, 5, 6 and 7), three are rather obscure (nrs 1, 2 and 4), but the meaning of one can be guessed (nr 4). In spite of these obvious shortcomings, the application of multivariate methods leads to some interesting results. According to Novotny'

s principle component analysis leaf length (3) and shape (4) discriminate strongest between D. crispatissimum and D. flexicaule. Of slightly less importance seem characters related to the hyaline border (1), to cell structure in the sheathing leaf base (2) and to the relation of costa to lamina cells (5). Characters related to subula apex appear to be least significant in separating taxa: only a fraction of the D. crispatissimum specimens show the typical denticulation, and only part of the D. flexicaule specimens have a broader subula apex. Perhaps the most interesting result of Novotny'

s work is his claim of intermediates. Due to the fact, however, that it is not clear in which way he applied some crucial differentiating characters like porosity of basal juxtacostal cells, it remains open to question whether his so-called "transitive forms" could not in fact be referred to one of Frisvoll's taxa by the consequent application of all features stressed by Frisvoll as important. As an explanation for the existence of intermediates Novotny suggests that D. crispatissimum is a relatively young taxon which is separated from D. flexicaule by a barrier of different intensity in different parts of its range, without giving further evidence for this. According to the revision of the Hungarian material presented here, the situation may be similar to the findings of NOVOTNY ( 1997) for the Czech and Slovak Republics: some specimens could be named only with difficulty, due to the fact that they showed a combination of features of both species, or the character states were intermediate or variable. Perhaps the revision of D. flexicaule s. 1. from a wider geographical range could elucidate some of these still controversial questions. Outside of Europe, D. flexicaule s. 1. occurs in the High Arctic, Subarctic America, North America, Guatemala and Colombia, western South America, Madeira, N Africa, Middle, northern and eastern Asia, Himalayas, Malesia, New Zealand and New Guinea (PORLEY 1992, SEPPELT 1982, B

ARTRAM 1949, ALLEN et al. 1994). MATSUI and IWATSUKI (1990) report D. crispatissimum from Japan and Taiwan. In central America, according to ALLEN et al. (1994), there are three intergrading expressions in the D. flexicaule complex, associated with the names of D. gracile (Mitt.) O. Kuntze, D. crispatissimum, and D. longicaule Bartr., and related to taxa occurring outside central America like D. punctulatum Mitt, and D. flexicaule s. str. These authors consider the possibility that this complex represents