Crossidium laxefilamentosum Frey & Kürschner (Bryopsida: Pottiaceae), new to Europe and to North Africa

Journal of Bryology (2004) 26: 113–124

Crossidium laxefilamentosum Frey & Kürschner (Bryopsida: Pottiaceae), new to Europe and to North Africa* TAMÁS PÓCS1, MARKO SABOVLJEVICb 2, FELISA PUCHE3, JOSÉ GABRIEL SEGARRA MORAGUES4, CRISTINA GIMENO5 and HARALD KÜRSCHNER6 1

Eszterházy College, Eger, Hungary, 2University of Belgrade, Serbia, 3Universidad de Valencia, Universidad de Zaragoza, 5Fundación CEAM, Valencia, Spain and 6Freie Universität Berlin, Germany

4

SUMMARY Crossidium laxefilamentosum Frey & Kürschner is shown to be a distinct taxon that is easily distinguished from the related C. crassinerve. Discovery of two plants of C. laxefilamentosum with sporophytes has permitted the description of the capsule and spore characters for the first time. This species is recorded as new to Europe and to North Africa. The known range of this desert species is now expanded from South-West Asia to North Africa, to the steep loess cliffs along the River Danube, and to the dry S.E. coast of the Iberian Peninsula. Among these regions five localities are reported from northern Serbia, three from central Hungary, S. of the 47° line of latitude, one from Romania, 20 from Spain and six localities have been found in Tunisia. The distribution of C. laxefilamentosum suggests that it had a circum-Tethyan origin. KEYWORDS: Crossidium, Danube, deserts, Europe, Hungary, loess, North Africa, Pottiaceae, Romania, Serbia, Spain, Tunisia.

INTRODUCTION In a taxonomic revision of the genera Aloina, Aloinella and Crossidium, Delgadillo (1975) recognized and treated six species and two additional varieties of Crossidium. Field research since then in the Near and Middle East, North and South Africa, the Americas and Australia has raised this number to 11, of which Crossidium apiculatum Magill was transferred to the new genus Microcrossidium (Cano, Guerra & Ros, 1993), while Pseudaloina woodii Delgad. from Yemen has been moved to Crossidium woodii (Delgad.) R.H.Zander (Zander, 1993). Even in Europe new taxa have been recognized, and in a recent account by Privitera & Puglisi (2000) six Crossidium species and an additional variety are given. Outside continental Europe, in the Canary Islands, Dirkse & Bouman (1995) recognized five species, among them Crossidium davidai Catches., hitherto known only from Australia and from Saudi Arabia under the name of C. asirense (Frey & Kürschner, 1984; Cano et al., 1993). Among the new taxa from the Near East, Crossidium laxefilamentosum was described by Frey & Kürschner (1987) *Studies on the cryptogamic vegetation on loess cliffs, VII © British Bryological Society 2004 DOI: 10.1179/037366804225021074

from the central part of Saudi Arabia, where the type material was collected in 1985, in a Tortula atrovirens–Crossidium squamiferum community on desert soil between sandstone pebbles. The holotype of the species is kept in Berlin (B!: Frey 85-247a). Further specimens were collected in other parts of Saudi Arabia and later in Oman (Frey & Kürschner, 1991) and Yemen (Kürschner, 2000, Map 89). The species was first considered to be an endemic of the Arabian Peninsula (Frey & Kürschner, 1988, 1991; Kürschner, 2000). However, it has recently been collected in the northern Serbian province of Vojvodina, from central Hungary just S. of the 47th parallel, and in Romania, along the Danube River. It has also now been discovered at many localities in four provinces of the arid region of S.E. Spain, as well as in the Saharan Atlas and Matmata Hills of Tunisia, North Africa. The species is thus new to both Europe and North Africa. The S.E. European bryological group of Pócs & Sabovljevi, and the Spanish group of Puche, Segarra and Gimeno, in collaboration with Kürschner, found this species almost simultaneously in their respective countries, and later in Tunisia, and so decided to combine results. Including C. laxefilamentosum the number of Crossidium species known from Europe and North Africa is raised to eight. Received 23 January 2004. Revision accepted 27 February 2004

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The aims of this paper are to provide a fuller understanding of its distinctions from other similar species, to describe its distribution and to clarify the habitat requirements of C. laxefilamentosum, based on extensive field observations. A revised key to European and African Crossidium species is provided.

MATERIALS AND METHODS Field surveys The loess cliffs of S.E. Europe have desert characteristics owing to their orographic features including microclimates. Their near-vertical surfaces receive only very limited direct precipitation and they enjoy intense irradiation and special soil conditions (Pócs, 1999). It was expected that xerophytic and Mediterranean bryophyte species would be found, within the southern continental regions of Europe, where the abundant loess depositions form high natural and semi-natural cliffs, especially by large rivers like the Danube and Tisza (Tisa). T. Pócs conducted systematic field research from 1996, together with B.O. van Zanten (University of Gròningen) to explore the distinctive cryptogamic flora and vegetation of the loess cliffs in the Danube Basin and later (2002–2003), together with his wife, Sarolta Pócs, in Tunisia. More than 300 loess cliffs were examined in the Danube basin, resulting in many records of taxa new to the whole or parts of this region. For example, new localities of Ceratodon conicus (Hampe ex Müll. Hal.) Lindb. Leptophascum leptophyllum (Müll. Hal.) J.Guerra & Cano, Crossidium crassinerve (De Not.) Jur., Hilpertia velenovskyi (Schiffn.) R.H.Zander, Pterygoneurum compactum Cano, J.Guerra & Ros and P. squamosum Segarra & Kürschner in Hungary, Yugoslavia and in Romania (Pócs, 1999; Pócs et al., 2002; van Zanten,1999a, b, 2000). Both Kürschner (2002) and Orbán (2002) in the Pannonian Basin studied life strategies within the loess cliff habitat. M. Sabovljevi investigated the cliffs habitat along the Danube in Serbia. F. Puche conducted systematic field research, from 1998, with C. Gimeno and J. G. Segarra on the bryophyte flora of Valencia (Spain) and Iberia.

Microscopy and herbarium studies SEM micrographs were produced by J. G. Segarra at Valencia University and others, at the Institute of Botany, Systematics and Plant Geography, Freie Universität, Berlin, by T. Pócs on a LEO 430 computerized scanning electron microscope. T. Pócs later revised and identified many specimens, mainly from the University of Murcia Herbarium (MUB), Spain and from collections made in Hungary and in Tunisia, deposited in Eger College Herbarium (EGR), which revealed the occurrence of this species at many more localities. He also conducted statistical analysis on the morphological characters of the two related species, C. crassinerve and C. laxefilamentosum to clarify their distinction, analysing 76 populations.

RESULTS AND DISCUSSION Morphology and taxonomy We repeat here the description of the gametophyte of Crossidium laxefilamentosum, as it is given by Cano et al. (1993), with some additions and critical comments, because it is likely to be found elsewhere in Europe and in Africa, where appropriate habitats occur: “Stems up to 3 mm high. Leaves ovate 0.4–0.8 mm long, 0.3–0.5 mm wide; apex rounded; margin revolute to recurved. Costa 50–64 µm wide in middle of leaf, excurrent in a hyaline hair-point 0.2–0.4 mm long; cross section showing 2–3 stereid layers; filaments 4–8 cells high, the terminal cells cylindrical or conical, usually smooth, sometimes with 1–2 papillae. Upper and median cells of leaf quadrate to rectangular, sometimes hexagonal, 10–18 µm long, smooth, more rarely with 1 simple papilla; basal cells generally rectangular, sometimes quadrate, 15–30 µm long.” During our analysis the shape of the leaf apex proved to be almost useless as a distinguishing feature, as 14 out of 35 populations of Crossidium laxefilamentosum had rounded or at least blunt leaf apices (with 65° or more apex margin inclination), ten had an acute apex (inclination 30–60°) and 11 had mixed characters within one population. In 35 populations of C. crassinerve these figures were nine, 26 and ten, respectively. The most remarkable and usable feature is the smooth, elongate-ovate, thin-walled, blunt terminal cell in the majority of the filaments of C. laxefilamentosum (Figs 1B, 2), which distinguishes it well from the related and more widespread C. crassinerve (De Not.) Jur. (Fig. 1A), where the majority of filaments have (1–)2–4(–6) papillae. The laxity of the filaments mentioned by Frey & Kürschner in the protologue of C. laxefilamentosum in contrast to the more densely arranged filaments of C. crassinerve, could not be confirmed as a distinguishing character, as Dirkse & Bouman (1995) have also stated. According to our investigations the density of filaments in a 0.1 mm leaf length of C. laxefilamentosum can vary between 10 and 104, and in C. crassinerve between 17 and 92, showing a very high variability and overlapping ranges. It is noteworthy that C. laxefilamentosum is a perennial, caespitose plant usually embedded in the soil (cf. Frey & Kürschner, 1984), so that only the uppermost leaf rosettes can be seen. The stem and at least some leaves remain alive even underground (also observed on C. crassinerve by Stark & Delgadillo, 2003) on which one can observe segments according to the rainy periods. Leaves developed in years with differing amounts of rain show great morphological variety concerning their shape. But the fluctuation of rainfall amount does not influence the papillosity versus smoothness of the assimilating filaments. Dirkse & Bouman (1995) in their detailed revision of the Crossidium species of the Canary Islands do not accept C. laxefilamentosum, as a separate species, claiming that in C. crassinerve the filaments near the leaf base are always

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Figure 1. Scanning electron micrographs of adaxial surfaces of leaves with assimilatory filaments of Hungarian Crossidium specimens: (A) C. crassinerve (De Not.) Jur.; (B) C. laxefilamentosum Frey & Kürschner. Scale bar, 20 µm. (SEM micrographs made by T. Pócs, from 99231/S and 9814/ P, EGR).

leaf apex. We have examined this potential distinguishing character in detail, analysing 76 populations from the species complex. Figure 2 shows what we consider to be smooth (A) and papillose (B) filaments. Although it is true that in C. crassinerve a few filaments near the leaf base are smooth, the ratio of smooth to papillose filaments proved to be crucial (Fig. 3). Almost all populations show either a definite majority of smooth or papillose leaf filaments, and the number of other types of filaments, occurring at the tip or at the base of leaf, very seldom exceeds 20% and is usually below 14%. Thus there is a wide gap between the two types without continuous transition. Four populations were

Figure 2. Examples of smooth (A) and of papillose (B) assimilatory filaments, as interpreted by the authors. (Drawn by T. Pócs).

smooth and these smooth filaments may extend more or less high up the leaf. Frey & Kürschner (1987) mention that a few papillose filaments can also occur in C. laxefilamentosum alongside the smooth filaments. These papillose filaments, according to our investigations, occur mainly near the

Figure 3. Numbers of smooth and papillose assimilatory filaments in Crossidium laxefilamentosum (diamonds), in C. crassinerve (squares) and hybrid (open circles) populations. Each datum point represents the average of one population.

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intermediate between the two types and are most probably of hybrid origin, as their heterogeneity is much higher than that of the other populations. While within all other populations the individuals show the same trend; concerning the majority of smooth or papillose filaments, in these four populations, in all cases, there are different trends, even on the same plant some leaves have a majority of papillose, others of smooth filaments. Based on the above statistical analysis of the ratio of smooth and papillose supracostal filament cells, and on the characters represented by the sporophyte, we consider Crossidium laxefilamentosum to be a distinct species. The fertility rate in the European populations of Crossidium laxefilamentosum is only 12.3%. We were lucky enough to find mature sporophytes in two specimens (Fig. 4), enabling us to give a description of the sporophyte: seta reddish, 8.5–9 mm long; capsule cylindrical, slightly inclined, 1.5 mm long. Operculum conic-rostrate, with spirally arranged cells; 0.5 mm long. Peristome 350 µm long (Fig. 5), consisting of 32 filiform, articulate, papillose teeth which arise from a basal membrane (a typical character of the genus Crossidium; Cano et al., 1993). They are without appendages 5–7 (–10) µm wide, 6.2 µm on average. The spores were 6–10 µm in diameter, mean 8.33 µm (Fig. 5A, B). Although it is difficult to generalize from the observations made on only two specimens, the above data differ quite significantly from most C. crassinerve specimens, where the fertility rate is higher (51.4%) and we were able to examine many sporophytes. Its peristome teeth are larger, 400–800 µm long and 8–12 (–15) µm wide, with a mean width of 9.9 µm. Mature spores are 10–16 µm in diameter, mean diameter 13.3 µm (Fig. 5C, D). The sizes of the upper capsule mouth and annulus cells (which are very variable even within one specimen and one population) give a less usable distinction. In C. laxefilamentosum the widths of the capsule cells and those of the base of the annulus are 5–10 µm (mean 7.4 µm), with 12–14 cells per 0.1 mm length (Fig. 6A, B). In C. crassinerve the basal width of the annulus cells varies between 9 and 15 µm (mean 10.7 µm) with 8–11 cells per 0.1 mm length (Fig. 6C, D). Based on the above characters we could easily distinguish the two species and consider them to be independent. Below we provide a new identification key for the eight species of Crossidium known from Europe and from North Africa: 1 All leaves without hyaline hair-point 2 At least some leaves with hyaline hair-point 3 2 Leaves cucullate, with rounded apex, lamina cells smooth. End cell of each supracostal filament with 2–6 papillae C. laevipilum Leaves subacute or acute, ending in a few-celled mucro. Lamina cells multipapillose, supracostal filaments ending in multipapillose cells (up to 20 papillae) C. davidai 3 Upper lamina cells conspiciously papillose, with 1–8 simple or bifurcate papillae 4

4

5

6

7

8

9

Upper lamina cells smooth or with 1–2 inconspicious papillae 5 Upper lamina cells with 4–6 (–8) papillae; supracostal filaments consisting of only 1–2 (–3) cells, usually ending in a subspherical cell C. seriatum Upper lamina cells with 1–2 (–3) papillae; supracostal filaments of different height 5 Supracostal filaments only 1–2 (–3) cells high, terminal cells of variable shape C. aberrans Supracostal filaments 3–12 cells high 6 Supracostal filaments 3–6 cells high, forming a dense pad on the upper half of the costa, terminal cells subglobose, with 4–8 papillae C. geheebii Supracostal filaments up to 12 cells high, not forming a dense pad, terminal cells always more or less conical, with 1–5 (–6) papillae, or smooth 7 Upper and median cells of lamina thick-walled, submarginal cells with almost no lumen. Terminal cells of filaments very elongated, with 1–5 high papillae C. squamiferum Upper and median cells of lamina not thick-walled, all cells with similar lumen 8 End cells of supracostal filaments (except the uppermost ones) almost all smooth. Uppermost capsule cells and annulus cells at their bases 5–10 µm wide. Peristome teeth 350 µm long and 5–7 (–10) µm wide, spores 6–10 µm in diameter C. laxefilamentosum End cells of supracostal filaments mostly with (1–) 2–4 (–6) papillae 9 Leaf apex usually strongly cucullate with a short mucro. Peristome teeth straight, 200–300 µm long C. laevipilum Leaf apex acute or subacute, with a long hair-point. Uppermost capsule cells and annulus cells 9–15 µm wide at their bases. Peristome teeth twisted, 400–800 µm long and 8–12 µm wide, spores 10–16 µm in diameter. (In rare cases the peristome teeth can be very reduced, almost rudimentary in their length but their width remains as described) C. crassinerve

Distribution and ecology Crossidium laxefilamentosum is new to Europe and to Africa (cf. Corley et al., 1981; Ros, Cano & Guerra, 1999). The European and North African records are enumerated by country in the Appendix and summarized in the distribution maps (Figs 7, 8). In S.E. Europe Crossidium laxefilamentosum was found on near vertical loess cliffs at five localities in northern Serbia (Vojvodina), at three localities in central Hungary and at one in western Romania along the Danube River (Fig. 9). The habitat on the near vertical loess cliffs is occupied in all cases by an open cryptogamic community, forming a typical cryptobiotic soil crust. It is composed by xerophytic or xerotolerant mosses (mostly members of the family Pottiaceae), crustaceous lichens and some algae. Table 1 shows the bryophyte component of the community (at the different loess localities

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Figure 4. Crossidium laxefilamentosum Frey & Kürschner. (A) Habit; scale bar = 1 mm. (B) Leaf; scale bar = 500 µm. (C) Upper ventral part of leaf with filaments; scale bar = 100 µm. (D, E) Cross-sections from leaf; scale bar = 100 µm. (F) Peristome, scale bar = 100 µm. (Drawn by F. Puche from the specimen of Puche & Segarra,VAL-Bryoph. 5273).

in S.E. Europe: Hilpertio velenovskyi–Preygoneuretum compacti ass.; Kürschner & Pócs, 2002). The lichen component of this community was described first by Gallé (1964) under

the name of Endocarpetum pusilli, from Nagykopasz Hill in Tokaj, N.E. Hungary. He also found a very similar community in the loess gorges of Titel Plateau (Gallé, 1974)

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Figure 5. The spores of Crossidium laxefilamentosum (A, B) and of C. crassinerve (C, D). Median parts of the peristome teeth in C. laxefilamentosum (E) and C. crassinerve (F, G) are shown at the same magnification, from Spanish specimens. (A) Ros, MUB 3128; (B) Garcia-Zamora, MUB 6947; (C) Martínez-Sánchez, MUB 6096; (D) Ros & Moya, MUB 4433; (E) Puche & Segarra, VAL Bryoph 5273; (F) Ros, MUB 3128 (this sample contains specimens of both species); (G) Garcia-Zamora et al. MUB 7340. (Drawn by T. Pócs).

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Figure 6. The upper margin of the capsule mouth with the annulus cells in Crossidium laxefilamentosum (A, B) and in C. crassinerve (C, D).

Figure 8.

in N. Serbia, distinguishing it as the Endocarpetum pusilli titelicum association, which here consists of Endocarpon pusillum Hedw. and E. pallidum Ach. (dominants), Caloplaca citrina (Hoffm.) Th.Fr., C. pyracea (Ach.) Th.Fr., Candellariella vitellina (Hoffm.) Müll. Arg., Collema undulatum Flot., Catapyrenium cinereum (Pers.) Körb., Caloplaca decipiens (Arnold) Blomb. & Forssell, Lecanora dispersa (Pers.) Sommerf., L. umbrina (Ach.) A.Massal., L. crenulata Hook., L. albescens (Hoffm.) Branth & Rostr., Physcia tenella (Scop.) DC. and Xanthoria parietina (L.) Th.Fr., and is very similar in composition at the other localities too. For Hungary, L. Lòkös identified all the 520 lichen specimens collected by T. Pócs and his collaborators. He enumerated from these, and from earlier Hungarian

collections made on loess cliffs, 65 lichen species altogether. The most frequent from the 520 samples were Endocarpon pusillum Hedw.(22%), Caloplaca citrina (Hoffm.) Th.Fr. (10%), Candelariella aurea (Hoffm.) Zahlbr. (8%), Phaeophyscia orbicularis (Neck.) Moberg (7%), Caloplaca decipiens (Arnold) Blomb. & Forssell, (6%), Lecanora crenulata Hook. (6%), Caloplaca crenulatella (Nyl.) H. Olivier (5%), Lecanora dispersa (Pers.) Sommerf. (5%), Phaeophyscia nigricans (Flörke) Moberg (5%) and Verrucaria muralis Ach. (5%) (Lòkös, 2003). Specimens from S.E. Spain (Valencia, localities 10 and 11, see Appendix) were collected in dry marl-gypsiferous soil, with sparse shrubby vegetation of Lygeum spartum L., Rosmarinus officinalis L. and Pinus halepensis Mill. The average annual precipitation in these territories ranges

Figure 7.

The total distribution of Crossidium laxefilamentosum.

The distribution of Crossidium laxefilamentosum in Spain.

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Figure 9. The habitats of Crossidium laxefilamentosum in Yugoslavia and in Hungary. (A, B) Yugoslavia, Srem, Surduk (photographed by M. Sabovljevi). (C, D) Hungary, Mezòföld near Dunaföldvár. (E, F) Hungary, Mezòföld, near Kisapostag. (D) and (F) show a cryptobiotic crust formed by mosses and lichens on the near-vertical loess cliff surface (photographed by T. Pócs).

from 406 mm to 664 mm and the average temperature varies between 13ºC and 17.3ºC. Crossidium laxefilamentosum also grows here associated with xerophytic or xerotolerant mosses (often Pottiaceae). The authors have not seen all the other 18 Spanish localities, but from the herbarium labels

one can deduce that these were also mostly on open, exposed, dry, more or less horizontal gypsum soil, sometimes on marl, schist, clay or on salty sand, at an altitude from sea level to 700 m. The annual precipitation in the area concerned varies from about 100 mm (Almeria) to 500 mm

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Table 1. Associates of Crossidium laxefilamentosum at localities in Serbia (1–4), Hungary (6–8) and Romania (9–11). The presence and covering of species at each locality is expressed in the scale of Frey (1933, in Klement 1955). Species marked by * are new to Serbia while the one marked by ** is new to all countries and to Europe. Localities are listed in the Appendix. Locality Species

1

3

4

6

7

8

9

10

11

Acaulon triquetrum (Spruce) C.Müll. Aloina aloides (Schultz) Kindb. Aloina ambigua (Bruch & Schimp.) Limpr. Aloina rigida (Hedw.) Limpr. Barbula unguiculata Hedw. Bryum argenteum Hedw. Bryum bicolor Dicks. Bryum capillare Hedw. Bryum radiculosum Brid. Crossidium aberrans Holz. & Bartr. Crossidium crassinerve (De Not.) Jur.* Crossidium laxefilamentosum Frey & Kürschner** Crossidium squamiferum (Viv.) Jur. Didymodon cordatus Jur. Didymodon rigidulus Hedw. Didymodon vinealis (Brid.) R.H.Zander Grimmia pulvinata (Hedw.) Sm. Hilpertia velenovskyi (Schiffn.) R.H.Zander Phascum cuspidatum Hedw. Pseudocrossidium hornschuchianum (Schultz) R.H.Zander Pterygoneurum compactum Cano, J.Guerra & Ros* Pterygoneurum ovatum (Hedw.) Dicks. Pterygoneurum squamosum Segarra & Kürschner Pterygoneurum subsessile (Brid.) Jur.* Syntrichia ruralis (Hedw.) Web.& Mohr. Tortula brevissima Schiffn. Tortula atrovirens var. gasilenii (Venturi) Limpr. Tortula muralis Hedw. Weissia longifolia Mitt. Weissia triumphans (De Not.) M.O.Hill.

· 1 · 2 · + · · · · 1 1 · 1–2 · + · 2 · · 1 1 · + · · + 1 · ·

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· · · · · 1 · · · · · 1 · + · 1 · 2 · · · · · · + · · 1 · ·

· 1 · 1 · · · · · · · 1 · 2 · · 1 1 · · 2 1 · · · · · 2 · ·

+ 1 · 3 · + · · · · 1 + · 2 · · · 1 · · 2 + · 1 · 1 + 1–2 · ·

· 1 · 2 1 · · · · · + + · 2 · · · + · + 2 · + · · · + + · ·

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+ 1 · · 1 + + · · + 2 + 1 · + · · · + · · · · · · · · · + +

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year−1. Ros & Guerra (1987) described these terricolous bryophyte communities which included C. crassinerve but as C. laxefilamentosum was hardly known at this time, it is difficult to establish precisely in which communities it is found. In northern Africa (Tunisia) C. laxefilamentosum lives among climatic desert and semi-desert conditions (Fig. 10), with an average precipitation of 60–250 mm year−1. Similarly in the Arabian Peninsula, where Frey & Kürschner (1987) identified it in a Tortula atrovirens – Crossidium squamiferum synusium. Among real desert conditions (e.g. in the Jebel Tebaga mountain range, in the Jerid, Tunisia) this community occurs only under the protection of N.-facing limestone cliffs, in shade at midday and supported by some dripping water during the scarce rains and dew formation (Fig. 10A, B). In the semi-desert belt it is much more widespread. Crossidium laxefilamentosum usually occurs on stony, gypsum or loess soil, on bare earth surfaces, or among scattered semi-desert scrub or amongst grass (mostly Stipa tenacissima) tussocks (Fig. 10C, D). The cryptogamic community consists of small, densely crowded, semi-subterranean Pottiaceae, Ricciaceae and lichens forming a cryptobiotic crust, often mixed with cyanobacteria. The most common accompanying bryophyte species were:

1 · 1 · · + + · · 1 · · · · · · · · · · 1 · · · · · · ·

Aloina bifrons (De Not.) Delgad., Bryum funckii Schwägr, Crossidium laevipilum Thér. & Trab., C. squamiferum (Viv.) Jur., Didymodon aaronis (Lor.) J.Guerra, D. luridus Hornsch. & Spreng., Funaria pulchella H.Philib., Grimmia capillata De Not., G. crinita Brid., Gymnostomum viridulum Brid., Tortula atrovirens (Sm.) Lindb. and Tortula revolvens (Schimp.) G.Roth var. obtusata Reimers. Crossidium laxefilamentosum was hitherto reported only from the Arabian Peninsula (Oman, Saudi Arabia, Yemen; Frey & Kürschner, 1987; Al-Gifri & Kürschner, 1996). The new records in S.E. Europe, Spain and N. Africa indicate that it should probably be considered as a circum-Tethyan element [in the sense of Frey & Kürschner (1988) and Frey (1990)] like its cogeners, C. squamiferum and C. crassinerve.

ACKNOWLEDGEMENTS The senior author is indebted to the Hungarian Research Fund (OTKA, project No. T 022575) for its financial support to the fieldwork, and also to the exchange programme of the Deutscher Akademischer Austauschdienst (DAAD) and the Hungarian Grant Committee (MÖB, Project

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Figure 10. Habitats of Crossidium laxefilamentosum in the Saharan Atlas, Tunisia, North Africa. (A) Jebel Tebaga, at the northern edge of Chott el Jerid, annual precipitation 60 mm. (B) Bryophytes among these stony desert conditions occur only in the shade of the N.-facing summit cliff, at 90–100 m a.s.l. (C) N. slopes of Jebel Bou Dinar, 20 km E.S.E. of Sidi Bouzid, with semi-desert type vegetation of scattered tussocks of halfa grass on and among the 10–30 m high, N.-facing loess cliffs in a qued at 380 m a.s.l. (D) Cryptogamic community dominated by Crossidium laxefilamentosum on the steep loess surfaces.

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No. 31) for making possible the SEM investigations. He is very grateful to Dr Rosa Maria Ros Espin for providing the rich Crossidium material of the University Herbarium of Murcia Prov. (MUB) for investigation, and finally to Mrs Christine Grüber, Mrs Sarolta Pócs and Dr Sándor Dulai for their logistic help. The Spanish authors acknowledge financial support from Conselleria de Medi Ambient de la Generalitat Valenciana, and DGICYT (Project No. PB-96-1111-C02-02). TAXONOMIC ADDITIONS AND CHANGES: Nil.

REFERENCES Al-Gifri AN, Kürschner H. 1996. First records of bryophytes from the Hadramout and Abyan Governorate, Southern Yemen. Studies in Arabian bryophytes 20. Nova Hedwigia 62: 137–146. Cano MJ, Guerra J, Ros RM. 1993. A revision of the moss genus Crossidium (Pottiaceae) with the description of the new genus Microcrossidium. Plant Systematics and Evolution 188: 213–235. Corley MFV, Crundwell AC, Düll R, Hill MO, Smith AJE. 1981. Mosses of Europe and the Azores; an annotated list of species, with synonyms from the recent literature. Journal of Bryology 16: 337–356. Delgadillo C. 1975. Taxonomic revision of Aloina, Aloinella and Crossidium (Musci). Bryologist 78: 245–303. Dirkse GM, Bouman AC. 1995. Crossidium (Musci) in the Canary Islands (Spain). Lindbergia 20: 12–25. Frey W. 1990. Genoelemente prä–angiospermen Ursprungs bei Bryophyten. Botanische Jahrbücher für Systematik, Pflanzengeschichte und Pflanzengeographie 111: 433–456. Frey W, Kürschner H. 1984. Studies in Arabian bryophytes. 3. Crossidium asirense (Pottiaceae), a new species from Asir Mountains (Saudi Arabia). Journal of Bryology 13: 25–31. Frey W, Kürschner H. 1987. A desert bryophyte synusia from the Jabal Tuwayq mountain systems (Central Saudi Arabia) with the description of two new Crossidium species (Pottiaceae). Studies in Arabian bryophytes 8. Nova Hedwigia 45: 119–136. Frey W, Kürschner H. 1988. Bryophytes of the Arabian Peninsula and Socotra. Floristics, phytogeography and definition of the Xerothermic Pangean element. Studies in Arabian bryophytes 12. Nova Hedwigia 46: 37–120. Frey W, Kürschner H. 1991. Conspectus Bryophytorum Orientalum et Arabicorum. An annotated catalogue of the bryophytes of Southwest Asia. Bryophytorum Bibliotheca 39. Berlin: J. Cramer in Gebrüder Borntraeger. Gallé L. 1964. Új löszlakó zuzmótársulás a tokaji Kopaszhegyen: Endocarpetum pusilli [A new loess inhabiting lichen association on the Tokaj Kopasz Hill: Endocarpetum pusilli]. Gallé L. 1974. Lichenológiai adatok a jugoszláviai Vajdaság területéròl. Lichenološki nalazi sa teritorije Vojvodine

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(Jugoslavija). Lichenologische Angaben vom Gebiet der Woiwodina (Jugoslawien). Botanikai Közlemények 61: 37–41. Klement O. 1955. Prodromus der mitteleuropäischer Flechtengesellschaften. Feddes Repertorium Specierum Novarum, Beih. 135: 5–194. Kürschner H. 2000. Bryophyte flora of the Arabian Peninsula and Socotra. Bryophytorum Bibliotheca 55. Berlin: J. Cramer in Gebrüder Borntraeger. Kürschner H. 2002. Life strategies of Pannonian loess cliff bryophyte communities. Studies on the cryptogamic vegetation of loess cliffs, VIII. Nova Hedwigia 75: 307–318. Kürschner H, Pócs T. 2002. Bryophyte communities of the loess cliffs of the Pannonian basin and adjacent areas, with the description of Hilpertio velenovskyi–Preygoneuretum compacti ass. nov. Studies on the cryptogamic vegetation of loess cliffs, VI. Nova Hedwigia 75: 101–119. Lòkös L. 2003. Löszlakó zuzmók Magyarországon [Loess coloniser lichens in Hungary]. Acta Academiae Paedagogicae Agriensis, Sectio Biologiae, new series 24: 159–188. Orbán S. 2002. A löszfalak moháinak életstratégiái [Life strategies of loess cliff bryophytes]. In: Salamon-Albert É, ed. Magyar botanikai kutatások az ezredfordulón. Tanulmányok Borhidi Attila 70. születésnapja alkalmából. Pécs: Botany Department, Pécs University, 581–588. Pócs T. 1999. A löszfalak virágtalan növényzete. I. Orografikus sivatag a Kárpátmedencében. Studies on the cryptogamic vegetation of loess cliffs. I. Orographic desert in the Carpathian Basin. Kitaibelia 4: 143–156. Pócs T, Goia I, Kis G, Orbán S, Sass-Gyarmati A, van Zanten BO. 2002. Hilpertia velenovskyi (Schiffn.) Zander and other pottioid mosses Bryophyta) new to Romania. Studies on the cryptogamic vegetation onloess cliffs, IX. Contribut,ii Botanice 37: 13–24. Privitera M, Puglisi M. 2000. Crossidium geheebii (Broth.) Broth. (Musci, Pottiaceae), a new record from Europe. Cryptogamie, Bryologie 21: 171–177. Ros RM, Cano MJ, Guerra J. 1999. Bryophyte checklist of Northern Africa. Journal of Bryology 21: 207–244. Ros RM, Guerra J. 1987. Vegetación briofítica terrícola de la región de Murcia (sureste de España) Phytocoenologia 15: 505–567. Stark LR, Delgadillo CM. 2003. Is Crossidium crassinerve (Pottiaceae) an annual moss? Observations on vegetative allocation and viability from Mojave Desert populations. Lindbergia 28: 3–13. van Zanten BO. 1999a. Studies on the cryptogamic vegetation of loess cliffs. II. The genus Bryum Hedw. on loess cliffs in the Pannonian Basin, including Bryum gemmiferum Wilcz. & Demar. and Bryum violaceum Crundw. & Nyholm, new to Hungary. Kitaibelia 4: 157–162. van Zanten BO. 1999b. Studies on the cryptogamic vegetation of loess cliffs. III. Ceratodon conicus (Hampe) Lindb., new to Hungary. Kitaibelia 4: 163–164. van Zanten BO. 2000. Studies on the cryptogamic vegetation of loess cliffs. IV. Chenia leptophylla (C.Müll.) Zander, new to Hungary. Kitaibelia 5: 271–274. Zander RH. 1993. Genera of the Pottiaceae: mosses of harsh environments. Bulletin of the Buffalo Society of Natural Sciences 32. New York: Buffalo Society of Natural Sciences.

TAMÁS PÓCS, Research Group for Bryophytes of the Hungarian Academy of Sciences, Department of Botany, Esterházy Károly College, PO Box 222, Eger, H-3301, Hungary. Address for correspondence: Felsòtárkány, Ady E. u. 67, H-3324, Hungary. E-mail: [email protected] MARKO SABOVLJEVI, Department of Plant Ecology and Phytogeography, Institute of Botany and Botanical Garden, Faculty of Biology, University of Belgrade, Takovska 43, YU-11000, Belgrade, Serbia, and Department of Biology, Petnica Science Centre, PO Box 118, YU-14000, Valjevo, Serbia. E-mail: [email protected] FELISA PUCHE, Departamento de Biología Vegetal (Botánica), Universitat de Valencia, Facultad de Ciencias Biológicas, C/Dr Moliner 50, 46100- Burjassot, Valencia, Spain. E-mail: [email protected]

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JOSÉ GABRIEL SEGARRA MORAGUES, Departamento de Agricultura y Economía Agraria, Universidad de Zaragoza, C/Miguel Servet 177, E-50013 Zaragoza, Spain. E-mail: [email protected] CRISTINA GIMENO, Fundación Centro de Estudios Ambientales del Mediterráneo, C/Charles R. Darwin 14, Parque Tecnológico, 46980 Paterna, Valencia, Spain. E-mail: [email protected] HARALD KÜRSCHNER, Institut für Biologie, Systematische Botanik und Pflanzengeographie, Freie Universität Berlin, Altensteinstr. 6, D-14195 Berlin, Germany. E-mail: [email protected]

APPENDIX Summary of records of Crossidium laxefilamentosum and its hybrids with C. crassinerve in Europe and North Africa SERBIA, VOJVODINA Bach ka. 1. Just S. of the market place of Mosh orin village, in the western loess gorge of northern edge of Titel plateau on 40 m high, natural, S.W.-facing cliffs, rich in cryptogamic vegetation, at 80–120 m a.s.l. (45º17.7⬘N; 20º12⬘E). 18 June 1998, S. & T. Pócs, B. O. van Zanten, G. Kis, G. Jakab, B. Papp; guided by M. Sabovljevi. Pócs No. 9814/P (EGR). 2.Titel Plateaeu, E. of Moshorin village. On vertical loess cliffs exposed to Tisa (Tisza) River, 100 m, (45º17⬘N; 20º19⬘E). Among Aloina aloides and Didymodon cordatus. May 2001. M. Sabovljevi No. 2108a (Herb. M. Sabovljevi), 3. On the E. escarpment of Titel Plateau, N. of Titel town, on the W. bank of Tisa (Tisza) River. 40–50 m high S.E. facing loess cliffs in the side valleys, at 75–125 m a.s.l. (45º12.9⬘N; 20º19.5⬘E). 19 June 1998, S. & T. Pócs, B. O. van Zanten, G. Kis, G. Jakab, B. Papp; guided by M. Sabovljevi. Pócs No. 9819/K (EGR). Srem. 4. Stari Slankamen. Loess gorge in the Nature Reserve, cutting through the N.E.-facing Danube bank, opposite the Tisa (Tisza) river junction. On S.W.- and E.-facing, near-vertical, loess cliffs, at 150 m a.s.l. (45°8.2⬘N, 20°16.5⬘E). 19 June 1998, T. Pócs No. 9820/B (EGR), M. Sabovljevi No.1686 (Herb. M. Sabovljevi). 5. Surduk, On N.-exposed, near-vertical loess cliffs along the River Danube at 100–150 m a.s.l. (UTM: 34TDQ47). 18 March 2001, M. Sabovljevi 1829a (Herb. M. Sabovljevi). HUNGARY Mezòföld. Tolna County, 6. N. side of Dunaföldvár town, Alsó-Öreg h. E.-facing, vertical cliff along the right bank of River Danube, just above the water-sports compound, 100–120 m a.s.l. (46°49⬘N, 18°54.7⬘E). 28 August 2001, T. Pócs 011148/A (EGR). 7. Fejér County, NNE side of Kisapostag village, 4 km S. of Dunaujváros town. Stairlike, E.-facing, vertical cliffs not far from the River Danube, at 120–140 m a.s.l. (46°54⬘N, 18°57⬘E). 28 August 2001, T. Pócs No.01146/F (EGR). Déli Alföld. 8. Baranya County, Dunaszekcsò, Vár-hegy (Fort Hill), steep natural loess cliff facing E., to the Danube, at 150 m a.s.l. (46°05⬘N, 18°50⬘E). 29 August 2001, T. Pócs 01151/C (EGR). ROMANIA Oltenia. 9. Mehedint,i District, large loess cliffs facing N., near the Danube River below Cetatea village 55 km S.S.E. of Turnu Severin, at 50–80 m a.s.l. (44°00⬘N, 22°49⬘E). 17 October 2000 S. & T. Pócs, G. Kis, A. Gyarmati and B. O. van Zanten, 00210/J (EGR; see Pócs et al., 2002). SPAIN Albacete Prov. 10. National road, Madrid–Cartagena, cerca a Agramón (Hellín), 500 m, gypsum soils, UTM 30SXH 2060. 19 April 1991, Martínez, Sánchez, Ros & Guerra (MUB 4501, 4524). 11. Fuente Albilla, 700 m, gypsum soils, UTM 30SXJ 2646, Martínez, Sánchez, Ros & Guerra (MUB 4516). Alicante Prov. 12. Road Agost–Castalla, 17 km, 540 m, slope with gypsum, together with Crossidium crassinerve, UTM 30SYH 061617. 24 April 1989, Ros & Moya (MUB 4429). 27 April 1989, Ros & Moya (MUB 4434). Almeria Prov. 13. El Cerrón (Sorbes), 450 m, soil on gypsum, UTM 30SWG 8409. 18 March 1988, Martínez, Sánchez, Ros & Guerra (MUB 4147). 14. Llano del Duque (Tabernas), 250 m, gypsum soils and N. slopes, UTM 30SWF 4998. 19 February 1988, Martínez, Sánchez, Ros & Guerra (MUB 4026, 4027, 4147). 15. Near Narchalico Viñicas, 800 m, soil on gypsum, together with Crossidium crassinerve, UTM 30SW6 8508, Martínez, Sánchez, Ros & Guerra (MUB 4124). 16. Sierra Alhamilla, National road-340,

157 km (Tabernas), 600 m. exposed gypsum and clayey soil, UTM 30SWG 6602. 17 March 1990, Garcia-Zamora & Ros (MUB 7574). 17. Sierra Alhamilla, road from Níjar to L. de las Torres. 6 km near S. Ignacio, slopes, 410 m, UTM 30SWG7393. 25 March 1989, GarciaZamora 2513/1989 (MUB 6947). 18. Sierra de los Filabres. road from Senés to Tabernas, 10 km (Benizalón), 600 m, exposed slopes, UTM 30SWG 5810, Martínez, Sánchez, Ros & Guerra (MUB 6949). 19. Venta de los Yesos (Tabernas), soil on exposed slope, UTM 30SWG 60. 20 February 1988, Martínez, Sánchez, Ros & Guerra (MUB 4091). Murcia Prov. 20. Barrio el Ranero, exposed and dry soils. April 1997, Ramos & Ros (MUB 10430). 21. Cala Reona (Aguilas), 0 m, saltpan with Salsola, UTM 30SXG 2339, 1984, Ros (MUB 3128 p.p.). 19 February 1988. 22. Puerto de la Cadena, 200 m, on humid exposed soil, UTM 30SXG 6197 (MUB-3749). Valencia Prov. 23. Calles, near village, 400 m, UTM 30SXK7600. 23 February 2001, Puche (VAL Bryoph. 5410). 24. Calles, near village, 400 m, UTM 30SXK7600. 23 February 2001, Puche (VAL Bryoph. 5410). 25. Road from Quesa to Bicorp 280 m, UTM 30SXJ9333. 3 February 2000, Puche & Segarra (VAL Bryoph. 5273). Canary Islands. 26. From the descriptions and drawings of Dirkse & Bouman (1995) it is obvious that some of their records of Crossidium crassinerve from the islands refer to the occurrence of Crossidium laxefilamentosum. HYBRID POPULATIONS IN SPAIN (C. crassinerve × C. laxefilamentosum, in the presence of both parents) Almeria Prov. Tabernas, Llano del Duque, 250 m, exposed gypsum and clayey soil, UTM 30SWF4998, 19 February 1988, Martínez-Sánchez, Ros & Guerra (MUB 4027). Alicante Prov. 27. la Mata lagoon, near Maravillas (Guardamar del Segura), sandy soil, UTM 30SYH0410, Ros & Guerra (MUB 3025). 28. Laguna de la Mata, near to Villa Molino (Guardamar del Segura), in a bush opening, UTM 30SYH0211, Guerra & Ros (MUB 3026). 29. Guardamar, coastal dunes, UTM 30SYH0620, R. M. Ros (MUB 2868). TUNISIA The Jerid (on parallel mountain ranges of the Saharan Atlas, transition between desert and semi-desert belts with 60–120 mm annual precipitation). 30. Jebel Bou Hedma, near El Mech, 10 km S.W. of El Maknassy. Semi-desert with open dwarf bush on a rocky limestone ridge at 350–400 m a.s.l. (34°31⬘N, 09°32⬘E). On thin loess layer accumulated in rock crevices. 10 November 2002, S. & T. Pócs 02163/H, (EGR). 31. Jebel Bou Dinar, 13 km N.W. of Regueb. Scattered, dwarf semi-desert bush. Under N. facing, calcareous conglomerate cliff at 425 m a.s.l. (34°56⬘N, 9°42⬘E). Rock shelf covered by a thin loess layer. 17 November 2002. S. & T. Pócs 02183/N (EGR). 32. N. slopes of Jebel Bou Dinar, 20 km E.S.E. of Sidi Bouzid. Scattered tussocks of halfa grass (Stipa tenacissima) on 10–30 m high, N.-facing loess cliffs in a qued (wadi) at 380 m a.s.l. (34°58⬘N, 9°43⬘E). On steep loess surface (see Fig. 10C, D). 17 November 2002. S. & T. Pócs 02184/O (EGR). 33. Jebel Tebaga (the southernmost range of Sahara Atlas just bordering Chott el Jerid from the north; see Fig. 10A), 3 km N.N.E. of Kebili. Just below the N. cliff of summit ridge, at 90–100 m a.s.l. (33°43⬘N, 8°58⬘E). In the shade of the cliff, on stony soil with a thin cover of fine sand (see Fig. 10B). 1 April 2003, T. Pócs 03033/K (EGR). 34. Jebel Hachichina, 0.5 km N. of the ruins of Bordj Khanguet Oum Ali fortress, in a W. side valley at 225 m a.s.l. (34°8⬘N, 9°10⬘E). Rocky desert and semi-desert transition. On earth-covered rocks among boulders, partially shaded. 1 April 2003, S. & T. Pócs, 03036/S (EGR). Matmata Hills between the Chott el Jerid and the Gabes Bay, with 120–240 mm annual rainfall, transition between the semi-desert and evergreen Mediterranean belts. 35. N. plateau edge E. of Matmata near Toujane, at 480 m a.s.l. (33°29⬘N, 10°06⬘E). Stony tussock grassland with Stipa tenacissima. On bare earth surface between tussocks. 7 April 2003. S. & T. Pócs (EGR).