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

Due to the fact that dorsal costa cells are not uniform in length even at a given point of the cell length gradient, several cells must be considered in an effort to obtain a representative average value. It is not correct to compare the longest costa cells to the shortest lamina cells, because that would result in costa cells appearing longer than lamina cells even in D. crispatissimum, as can be seen also on Figure 15 in FRISVOLL (1985); the converse procedure - comparing the shortest costa cells with the longest lamina cells - must also be rejected, since it might in some cases attribute the character state of D. crispatissimum to D. flexicaule. Comparing the shortest cells of costa and lamina respectively with each other, however, appears to give correct results in the majority of cases, as well as comparing the longest cells. The difficulties encountered in this feature are further aggravated by the variability due to growth conditions and geographical region, as FRISVOLL (1985) points out. SMITH (1993) rejects this character as too variable to be of use. In D. crispatissimum, auricles are absent, whereas in D. flexicaule they are frequently present, although this may vary within leaves of the same stem. Perichaetial leaves encircling a fully grown seta must be studied. It is essential to examine the innermost 1-2 leaves, because in D. flexicaule some outer leaves can have a sheathing leaf base that is rather abruptly narrowed into the subula. Therefore it is better not to dissect the perichaetium but to observe the leaves in situ. In fertile specimens this appears to be a very valuable character. RESULTS Among the 181 specimens from BP examined, one was found to contain typical D. crispatissimum, 178 specimens were referred to D. flexicaule s. str., and two belonged to genera other than Ditrichum (Dicranum, Dicranella). A few specimens of D. flexicaule showed to a various degree certain of the features ascribed to D. crispatissimum by FRISVOLL (1985). These might thus be interpreted as intermediates. Ditrichum crispatissimum and D. flexicaule at Koloska rocks in Hungary A single tuft of D. crispatissimum was found together with several tufts of D. flexicaule s. str. in a specimen collected by L. Vajda in 1963 in the hills north of Lake Balaton (Fig. 1): BP 68224, Herbarium Musei Hist. Nat. Hung., Budapest, Flora Hungarica, Ditrichum flexicaule (Schleich.) Hampe cum Scapania calcicola. Comit. Veszprém. In rupibus dolomiticis Koloska sziklák supra vail. Koloska-