B. Papp szerk.: Studia Botanica Hungarica 39. 2008 (Budapest, 2008)

Erzberger, P.; Schröder, W.: The genus Schistidium (Grimmiaceae, Musci) in Hungary

Scbistidium elegantulum H. H. Blom (Figs 17, 18) Plants medium-sized to large, forming mats or decumbent tufts. Central strand absent. Hair-point 0.3-1.0 mm, erect, ± pellucid, hyaline but often brownish at insertion (Fig. 17A, C), straight and stiff, terete, narrow throughout, not decurrent (the transition between the hyaline and the chlorophyllose part of the apex smooth), distantly spinulose-denticulate throughout. Costa and leaf margins smooth. Lamina smooth, unistratose with bistratose patches in upper part. Lamina cells not or slightly sinuose, predominantly isodiametric, in upper part 8-10 urn wide, in lower wider. K+ red. Sporophytes common, immersed, but partly visible among the perichaetial leaves. Urn straw-yellow to orange, becoming finely striolated when old, oval, widest at middle (narrowed towards mouth), length/width ratio 1.6-2.0-2.4 (BLOM 1996), in Hungarian material (1.4-) 1.87 ±0.12(-2.5), n = 25. Exothecial cells predominantly elongate, 50-70 urn long. Stomata 6-8 per urn (8-16 in subsp. wilsonii). Peristome teeth 350-430 urn long, orange to red, entire or with narrow submarginal slits in central part, densely and coarsely papillose, in lower part smooth or with papillae more distantly arranged. S. elegantulum subsp. wilsonii (which has not yet been found in Hungary) differs from the typical subspecies in a broader and coarser hair-point that appears rather whitish (pellucid in subsp. elegantulum) and smooth (i.e. the spinulae are denser and smaller than in subsp. elegantulum and not visible with a hand lens). Other differences include growth form (dense tufts versus mats or decumbent tufts in subsp. elegantulum), hair-point length in perichaetial leaves (up to 1.0-1.5 mm versus up to 0.7-0.9 mm), costa width at leaf base (75-88 urn versus 53-78 urn), costa stratosity at leaf base (5-7 vs 4-5) and number of stomata (8-16 vs 6-8). In Hungarian plants of S. elegantulum, the hair-point appears smooth when viewed in low magnification (as in subsp. wilsonii), due to few / short spinulae as seen in the compound microscope. Otherwise, they possess the characteristics of subsp. elegantulum. The differentiation between S. elegantulum and S. crassipilum can be very difficult in Hungarian plants, although in other geographical regions (e.g. in Germany), S. elegantulum poses no problems. Some plants could be considered transitional between the two species, e.g. displaying sporophytes typical of S. elegantulum (oval urns with many stomata); but leaves characteristic of 5. crassipilum. The converse situation is observed as well. Such plants have been placed in the latter, variable species during the present revision. Habitat: S. elegantulum typically grows on ± shaded limestone or dolomite boulders and rocks, sometimes on concrete; in Hungary it has rarely also been found on base-rich siliceous rock (basalt, andésite). In Scandinavia, S. elegantulum subsp. wilsonii is reported to grow on exposed to semi-shaded calcareous rocks, often on wall-tops.