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

Studia bot. hung. 32, pp. 87-105, 2001 DITRICHUM CRISPATISSIMUM (MUELL. HAL.) PARIS, A NEW SPECIES OF THE HUNGARIAN BRYOFLORA, AND DITRICHUM FLEXICAULE (SCHLEICH. EX SCHWAEGR.) HAMPE IN HUNGARY P. ERZBERGER Beiziger Str. 37, D-10823 Berlin, Germany During the revision of 181 herbarium specimens of Ditrichum flexicaule s. 1. from BP a single tuft of Ditrichum crispatissimum was found in a specimen that had been collected in 1963 by L. Vajda at Koloska rocks, north of Lake Balaton. The features of these Hungarian plants and the character states separating D. crispatissimum from D. flexicaule s. str. are described in detail. Among the specimens of D. flexicaule s. str. some have character states approaching D. crispatissimum. Aspects of the taxonomy of the D. flexicaule complex are discussed. Key words: Ditrichum crispatissimum, Ditrichum flexicaule, distribution, Hungary, map, diagnostic characters INTRODUCTION In a taxonomic and nomenclatural study of the variable and heterogeneous Ditrichum flexicaule complex, FRISVOLL (1985) presented the concept of two distinct taxa treated by him as species, D. flexicaule s. str. and D. crispatissimum. (From this point onwards, D. flexicaule always means D. flexicaule s. str. unless stated otherwise.) His concept was obviously accepted by several authors who enumerated D. crispatissimum and D. flexicaule as separate species in checklists, e.g. CORLEY and CRUNDWELL (1991), CASAS (1991), SÉRGIO et al. (1994), LUDWIG et al. (1996), WERNER (1999), or studied the distribution of Frisvoll's taxa in certain regions of Europe, e.g. the Iberian peninsula (CASAS et al. 1990, 1992), the British Isles (SMITH 1993) and the Czech and Slovak Republics (NOVOTNY 1997). From these studies it appeared that the segregate D. crispatissimum is widespread and frequent in western Europe, but becomes rarer towards the east, while D. flexicaule is e.g. rare in Britain, but frequent in more continental parts of central Europe. In the Iberian peninsula, the two species occupy areas that overlap in the northeast, otherwise D. crispatissimum is nearly completely restricted to a zone along the south coast of the Bay of Biscay in northern Spain, whereas D. flexicaule extends far south along a zone parallel to the western coast of the Mediterranean. This distributional pattern is interpreted as reflecting different ecological needs of the two species: D. crispatissimum requires more and more constant humidity, D. flexiStudia Botanica Hungarica 32, 2001 Hungarian Natural History Museum, Budapest