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

mens of D. flexicaule s. 1. could be allocated to one or other of the species with the naked eye or a x 10 lens", the question arises, whether Smith's results are in fact reliable. It seems possible that other discrepancies between Smith's and Frisvoll's accounts originate in this misconception. Misidentification of specimens of two closely related taxa could indeed result in what appears to blur boundaries that are in fact more clear-cut, as has happened, e.g. with Hedwigia stellata and H. ciliata: FRAHM (1995) stated the existence of intermediates between these taxa. His conclusions were, however, based on several misidentified specimens (ERZBERGER 1996«, b). Smith's comments on the 16 differences listed by Frisvoll, saying that "some are somewhat intangible or ambiguous". Among the characters Smith could not confirm is the structure of cells near the costa at the leaf base. This character, on the other hand, is considered by Frisvoll so important that he includes it in the abstract of his paper as the first of three features differentiating D. flexicaule and D. crispatissimum, and he comments on it (Table 2 in FRISVOLL 1985): "When naming plants in D. flexicaule s. 1. more importance should be put on the structure of cells than on cell measurements". This clearly is in contrast with Smith who states that in critical cases naming is possibly only "with difficulty on the basis of summation of characters". The possibility cannot be ruled out that a repeated revision of the material seen by Smith could lead to a different opinion on this and other character states of Frisvoll's taxa in the British Isles. At present, Smith's report cannot be taken as evidence for geographical variation of D. crispatissimum. in this important feature. Another point of disagreement between Smith and Frisvoll concerns the relation of length of dorsal cells on the costa and in the adjacent lamina. Smith states that the claimed difference (costa cells longer than lamina cells in D. flexicaule and shorter in D. crispatissimum) is variable and only sometimes applies in D. crispatissimum. Frisvoll himself concedes that in D. crispatissimum from northern areas costa cells are "sometimes more elongate". It is interesting to compare his illustrations of this feature (Figs 1,15 in FRISVOLL 1985) with those (Figs IF, 2F) of CASAS et al. (1990): the difference appears far more pronounced in the Spanish material. In the Hungarian specimen of D. crispatissimum, this character varies among individual leaves of a single plant. NOVOTNY (1997) reports results of a morphometrical analysis of D. flexicaule s. 1. evaluated by multivariate methods. From his principal component analysis the discriminating power of the characters used by him can be evaluated. How-