Saxicolous and Terricolous Lichens from the Foothills of Northern Oman

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Saxicolous and terricolous lichens from the foothills of northern Oman

Article in Nova Hedwigia · August 2002 DOI: 10.1127/0029-5035/2002/0075-0177

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Saxicolous and terricolous lichens from the foothills of northern Oman

G. Brown* Universität Rostock, Institut f. Biodiversitätsforschung, Abtlg. Allg. & Spez. Botanik Wismarsche Str. 8, 18051 Rostock, Germany M. Schultz Universität Hamburg, Institut für Allgemeine Botanik und Botanischer Garten Ohnhornstr. 18, 22609 Hamburg, Germany and M.D. Robinson Sultan Qaboos University, Department of Biology P.O. Box 36, Al-Khod 123, Sultanate of Oman

With 4 plates

Brown, G., M. Schultz, & M.D. Robinson (2002): Saxicolous and terricolous lichens from the foothills of northern Oman. - Nova Hedwigia 75: 177-188. Abstract: To date, 36 species of lichens have been recorded from the Sultanate of Oman, a rather short list in view of the number of potential suitable habitats. During a field trip to the foothills of northern Oman, twenty-four morphologically distinct taxa were found, 20 of which have been positively determined to specific level. Seventeen of these species are new records for the country. The majority of species (13) are cyanobacterial lichens. Most species occurred on compacted soil, mainly in partially shaded habitats such as in crevices in rocks, but occasionally, some species were found in sun-exposed situations on open ground ( Heppia adglutinata ). A few species were found growing on limestone rock. All species recorded during this study have been found in various countries of the Arabian Peninsula, and a marked similarity is evident with the lichen flora of southern Yemen. Zusammenfassung: Bislang waren Vorkommen von lediglich 36 Flechtenarten aus dem Sultanat Oman bekannt. Die Zahl erscheint klein in Anbetracht der Vielfalt der potentiellen Lebensräume. Im Zuge von Feldarbeiten im Hügelland des nördlichen Omans konnten nun 24 Flechten nachgewiesen und 20 davon bis zur Art bestimmt werden. 17 Arten sind Neufunde für das Sultanat Oman. Es dominierten cyanobakterielle Flechten. Bevorzugte Habitate waren Bodenkrusten in zum Teil be- schatteten Felslücken. Gelegentlich wurden auch offene, sonnenexponierte Bodenkrusten besiedelt (Heppia adglutinata ). Einige wenige Arten kamen direkt auf Kalkstein vor. Alle Flechten, die im Rahmen der vorliegenden Studie gefunden wurden, waren bereits aus verschiedenen Teilen der Arabischen Halbinsel bekannt. Es bestehen v.a. aber markante Übereinstimmungen in der Arten- zusammensetzung mit der Flechtenflora des südlichen Jemen.

Information on the lichen flora of the Arabian Peninsula remains quite fragmentary, despite a number of studies that have been undertaken in recent years. Most species have been recorded from Saudi Arabia, although studies in this huge country have been restricted to rather a few localities (Bokhary et al. 1993). The lichen flora is probably best known from Kuwait, a small country in the north-east of the Arabian Peninsula. Thirty-eight lichens have been recorded from there by Brown (1998) and Schultz et al. (2000), and in the meantime, several more have been identified (Brown & Schultz, unpubl. results). Thirty-six species collected at a few localities in SE and SW Yemen were recently listed by Schultz (1998). In a recent study of the lichen flora of the Sultanate of Oman, Ghazanfar & Gallagher (1998) listed 36 species for the whole of the country. However, during a visit to the northern Oman by the first author in 2000, it soon became clear that this list in no way reflected the true wealth of lichens. In the present study, we report on the occurrence of lichens in the northern foothills of Oman in the general vicinity of Muscat, from where virtually no data are available, but where lichens are locally quite conspicuous.

Material and methods

During a two-week exploration of northern Oman in March 2000, the landscape was surveyed for the occurrence of lichens, and samples were collected by the first and third authors from various sites in distinct areas: 1. in the vicinity of Sultan-Qaboos University on limestone rock, on compacted soil in rock crevices or in the partial shade of rocks, and also on compacted soil fully exposed to the sun (60 - 80 m asl.), 2. on compacted, fully exposed soil of a natural drainage channel near Barka (50 m asl.), and 3. on limestone rocks and compacted soil in rock crevices near Falaj Bani Khazeer (High- way 13 between Nakhl and Rustaq, approx. 475 m asl.). Sections of most species were prepared with a freezing microtome and stained with lactophenol cotton blue. Identification of species is in accordance with Schultz et al. (2000), as well as the works mentioned in this publication.A digital-camera (Hitatchi HV-C20AMP) attached to a stereo microscope (Leica MZ 125) was used for photography. Most of the material is currently in the private herbarium of the first author, with additional specimens having been deposited with the herbarium at Sultan Qaboos University.

Results

Lichens appeared to be absent from much of the area surveyed, but a relatively rich lichen flora was found in the vicinity of Sultan Qaboos University and at Falaj Bani Khazeer. The collection probably contains 24 taxa, 20 of which were positively identified to specific level. These are listed together with brief details of their ecology and abundance. Apart from Buellia subalbula , Gloeoheppia turgida and Psora decipiens, all species are new records for Oman.

178 Buellia subalbula (Nyl.) Müll. Arg. Abundant and forming conspicuous crusts on calcareous rocks on hillsides in the immediate vicinity of Sultan Qaboos University, Al-Khod (Brown 50506, Plate 1a). Recorded by Ghazanfar & Gallagher (1998) from a variety of locations in Oman (but not in the current study area), and is thus probably widespread. Also known from Bahrain (Lamb 1936), Saudi Arabia (Abu-Zinada et al. 1985, Bokhary et al. 1993) and Yemen (Schultz 1998).

Catapyrenium contumescens (Nyl.) Breuss Common at Falaj Bani Khazeer on calcareous rock (Brown 50517, Plate 1d). Otherwise known from Saudi Arabia (Bokhary et al. 1993), and recently collected in Kuwait (Brown, unpubl results).

Catapyrenium squamulosum (Ach.) Breuss Not uncommon at Falaj Bani Khazeer on calcareous rock (Brown 50516). Otherwise known from Yemen (Schultz 1998).

Digitothyrea divergens (Henss.) Moreno & Egea Found at Al-Khod (Brown 50540) and at Falaj Bani Khazeer (Brown 50543) on compacted soil in rock crevices. An easily overlooked species that has also been recently recorded from Yemen (Schultz 1998) and Socotra (Mies 2000), and is probably quite widespread in rocky areas of Oman. Selected material studied: CAPE VERDE ISL.: Santiago, Mt. Craciosa, 140 m, basaltic rock, B. Mies, 12.11.1987 [Almborn, Lich. afric. no. 147; as Thyrea divergens Henss., det. A. Henssen] (ASU). YEMEN: SW, 4 km N of Schureida, road from Aden to Ta’izz, exposed balsaltic rock, seepage track, 13° 22.95’ N, 44° 24.65’ E, M. Schultz 14001, 10.03.1997; Socotra, E of Hadibu, Djebel Hawari, in limestone clefts, c. 25 m, 12° 40.1’ N, 54° 3.7’ E, M. Schultz 14023a, 14024, 15.03.1997.

Gloeoheppia erosa (J. Steiner) Marton

An inconspicuous species on compacted soil and calcareous rock, usually associated with other blue-green species. Widespread, but not abundant at Falaj Bani Khazeer (Brown 50513, 50514, 50544). Also recorded from Kuwait (Schultz et al. 2000) and Yemen (Schultz 1998). Selected material studied: YEMEN: Al-Mukallah region, road from Riyan into Wadi Hadramaut, escarpment of the Djol Mts., shady, vertical limestone face, 500 m, 14°50.9’ N, 49° 8.84’ E, M. Schultz 14010d, 13.03.1997; Aden region, Jahein, 80 km E of Aden, soil over limestone rock, 950 m, 13°34’ N, 45°49’ E, B. Mies 14753, 04.02.1998; Socotra, c. 20 km SE of Hadibu, trail to Nogeed, valley slope, in sand-filled limestone crevices, c. 200 m, 12°31.7’ N, 54°10.6’ E, M. Schultz 14029e, 16.03.1997. KUW AIT: Umm Al-Rimam, N of Kuwait Bay, soil crust over calcareous rock, M. Schultz [15012f] & G. Brown, May 1998.

179 Plate 1. – a. Buellia subalbula (Brown 50506a), thallus with numerous apothecia. b. Gloeoheppia turgida (Brown 50511), several inflated squamules. Note the finely cracked, slightly pruinose surface typical of older squamules. c. Psora spec. (Brown 50515), several squamules. d. Catapyrenium contumescens (Brown 50517), numerous squamules with several intact perithecia (above right). The remaining small, black holes are where perithecia have fallen out of the thallus. Scale-bar = 1 mm.

Gloeoheppia turgida (Ach.) Gyeln. A widespread and conspicuous species that can form large populations. Old thalli are often pruinose and develop minute cracks (see Plate 1b). Found abundantly at Al-Khod (Brown 50508, 50510, 50511, 50512) and Falaj Bani Khazeer (Brown 50522), often with apothecia. Listed in Oman only for Masirah Island (Ghazanfar & Gallagher 1998), but due its abundance at the above sites in northern Oman and its widespread occurrence throughout Arabia, is probably also common in suitable locations in other parts of Oman. Selected material studied: ERITREA: hill close to Mai Atar, coastal plain between Massaua and Ghinda, on granite, 150 m, 15°31’ N, 39°12’ E, B. Mies 13861, 14.03.1995. YEMEN: Al Mukalla region, road from Riyan into Wadi Hadramaut, escarpment of the Djol Mts., shady, vertical limestone face, 500 m, 14°50.9’ N, 49°8.84’ E, M. Schultz 14010f, 13.03.1997; Socotra, R’as Hebak, c. 5 km W of Hadibu, coastal rock, limestone, c. 25 m, 12°38.7’ N, 53°58.5’ E, M. Schultz 14036e, 14039b, 14040b, 18.03.1997. KUWAIT: Umm Al-Rimam, N of Kuwait Bay, soil crust on calcareous sandstone, M. Schultz [15009d, 15017g] & G. Brown, May 1998.

180 Plate 2. – a. Peccania coralloides (Brown 50524), thallus with flattened lobes and ascending margins, as well as numerous apothecia. b. Lichinella iodopulchra (Brown 50531), thallus with slightly inflated lobules, these with down-curved margins. c. Lichinella cribellifera (Brown 50527), detail of thallus lobes with flattened, partly ascending margins. d. Synalissa symphorea (Brown 50529), thallus forming small, dense cushion. Scale-bar = 1 mm.

Heppia adglutinata (Krempelh.) Massal. The only species found growing on compacted soil in fully exposed locations, often in dried out wadi beds and other small drainage channels. Found at various locations around Al-Khod (e.g. Brown 50502, 50503), sometimes fruiting (Brown 50501, Plate 4a), and in a small drainage channel in a desert gravel plain near Barka (Brown 50504). Juvenile samples, that form distinctive rosettes (Plate 4b), are often difficult to identify. This lichen is probably widespread throughout the area and collected by the second author on Socotra and in southern Yemen (unpubl. records). Selected material studied: YEMEN: Al-Mukallah region, W of the road from Riyan into Wadi Hadramaut, plateau of the Djol Mts., close to slope with uprising clouds, exposed, c. 2000 m, 14°49.43’ N, 48°48.57’ E, M. Schultz 14069e, 25.03.1997; Socotra, Hamaderoh Mts., c. 28 km E of Hadibu, ascent to plateau, in sand-filled limestone clefts, shady, c. 450 m, 12°36.0’ N, 54°16.9’ E, M. Schultz 14064b, 23.03.1997.

181 Plate 3. – a. Phloeopeccania pulvinulina (Brown 50507), thallus consisting of numerous minute and irregular cushions. b. Peccania tiruncula (Brown 50536), rather poorly developed thallus with short knot-like lobes and marginal apothecia. c. Lichinella nigritella (Brown 50537), thallus consisting of small, flattened lobes. d. Heppia solorinoides (Brown 50544), very distinctive, whitish cracked thallus. Scale-bar = 1 mm.

Plate 4. – a. Heppia adglutinata (Brown 50501), typical squamules, these somewhat funnel-like, and each with a central apothecium (and therefore appearing very dark). b. Heppia adglutinata (Brown 50505), juvenile sample forming a distinctive rosette on compacted soil. Scale-bar = 1 mm.

182 Heppia solorinoides (Nyl.) Nyl. Very little material of this distinctive species was found growing together with Gloeoheppia erosa at Falaj Bani Khazeer (Brown 50544, Plate 3d). Otherwise known only from southern Yemen on the Arabian Peninsula and Socotra (unpublished). Material studied: YEMEN: Al-Mukallah region, road from Riyan into Wadi Hadramaut, plateau of the Djol Mts., sand-filled limestone clefts, partly shaded, 1250 m, 14° 57.78’ N, 48° 58.83’ E, M. Schultz 14013l, 13.03.1997; Al-Mukallah region, W of the road from Riyan into Wadi Hadramaut, plateau of the Djol Mts., close to slope with uprising clouds, exposed, c. 2000 m, 14°49.43’ N, 48°48.57’ E, M. Schultz 14069a, 14070g, 25.03.1997; Socotra, E of Hadibu, Djebel Hawari, in partly shaded calcareous rock clefts, c. 25 m, 12°40.1’ N, 54°3.7’ E, M. Schultz 14020d, 15.03.1997; Socotra, c. 4 km S of Hadibu, ascent to Muqadrihon Pass, in sand-filled cleft of limestone boulder, c. 150 m, 12°37.0’ N, 54°0.9’ E, M. Schultz 14044d, 19.03.1997.

Lichinella cribellifera (Nyl.) Moreno & Egea Found growing in small amounts on calcareous rock at Falaj Bani Khazeer (Brown 50525a, 50527, Plate 2c). Otherwise recorded from Saudi Arabia (Bokhary et al. 1993) where it was listed under its synonym Gonohymenia mesopotamica J. Steiner. Selected material studied: ISRAEL: Hagalil, upper Jordan valley, Almagor near Korazim, basalt, 85 m, A. Henssen & J. Garty, 26.3.1971 [Henssen, Lich. cyan. fungi sax. exs. no. 36; as Gonohymenia c. (Nyl.) Henss.] (M).

Lichinella iodopulchra (Crozals) Moreno & Egea Found on calcareous rock at Falaj Bani Khazeer (Brown 50531, Plate 2b). Previously recorded on the Arabian Peninsula from Kuwait (Schultz et al. 2000) and Yemen (Schultz 1998). Selected material studied: KUWAIT: northern edge of Kuwait Bay, W of Sobiya, thin soil crust on calcareous sandstone, Brown & Schultz [15001c, 15003c, 15006d], V/98. YEMEN: South Yemen, south-eastern part, Djol Plateau, limestone, 2000 m, Schultz 14071d, III/97. SPAIN: Andalusia, Sierra de Cabo de Gata, Las Negras, on chalk, 20 m, G. Willems 10793/75, 10793/80, 1990 (hb. Büdel).

Lichinella nigritella (Lettau) Moreno & Egea On calcareous rock at Falaj Bani Khazeer (Brown 50537, Plate 3c). Recorded from neighbouring Saudi Arabia (Abu Zinada et al. 1986) and referred to as Thyrea nigritellla , where it was described as being very rare. Selected material studied: SPAIN: Andalusia, Granada region, Sierra de Huetor, Solana de Alfacar, rocky slope, steep boulder face, in sheltered clefts, 1450 m, 37°15’ 30"N, 03°33’ 07"W , M. Schultz 17036a, 01.09.2000; Canary Isl., Tenerife, between Santiago del Teide and Masca, 500-600 m, A. Henssen & M. Küthe, 02.04.1969 [Henssen, Lich. cyan. fungi sax. exs. no. 38; as Gonohymenia n. Lettau] (M).

Lichinella sinaica (Galun & Marton) Moreno & Egea On calcareous rock at Falaj Bani Khazeer (Brown 50525). In Arabia recorded from Kuwait (Schultz et al. 2000) and southern Yemen (Schultz 1998) where it occurs on similar substrates.

183 Selected material studied: YEMEN: Al-Mukallah region, W of the road from Riyan into W adi Hadramaut, plateau of the Djol mts., limestone clefts, c. 2000 m, 14° 49.43’ N, 48° 48.57’ E, M. Schultz 14071e, 25.03.1997. KUW AIT: northern edge of Kuwait Bay, W of Sobiya, calcareous sandstone, M. Schultz [15008, 15018d] & G. Brown, May 1998.

Lichinella stipatula Nyl. On calcareous rock at Falaj Bani Khazeer (Brown 50523). Otherwise, only recorded in Arabia from southern Yemen (Schultz 1998), but the species appears to be rather common in the Mediterranean region (Moreno & Egea 1992). Selected material studied: YEMEN: Al-Mukallah region, road from Riyan into Wadi Hadramaut, escarpment of the Djol Mts., shady vertical limestone face, 500 m, 14°50.9’ N, 49°8.84’ E, M. Schultz 14010c, 13.03.1997. SPAIN: Andalusia, Sierra de Cabo de Gata, Las Negras, 20 m, on chalk, G. Willems 10795/08, 10793/77, 10794/17 (hb. Büdel), 1990.

Peccania coralloides (Massal.) Massal. On calcareous rock at Falaj Bani Khazeer (Brown 50524). The large flattened lobes and terminal apothecia are quite distinctive (Plate 2a). In Arabia previously recorded from Kuwait (Schultz et al. 2000) and southern Yemen (Schultz 1998). Selected material studied: YEMEN: Al-Mukallah region, road from Riyan into Wadi Hadramaut, escarpment of the Djol Mts., shady vertical limestone face, 500 m, 14°50.9’ N, 49°8.84’ E, M. Schultz 14010a, 13.03.1997. KUW AIT: Umm Ghudi, northern edge of Kuwait Bay, W of Sobiya, G. Brown 50034, January 1996; Umm Al-Rimam, N of Kuwait Bay, soil crust on calcareous rock, M. Schultz [15017a] & G. Brown, May 1998. SPAIN: Andalucia, Sierra de Cabo de Gata, Las Negras, on chalk, 20 m, G. Willems 10795/05 (hb. Büdel), 1990. TURKEY: Prov. Ç orum, Central Anatolia, G. Ç obanoÈlu (hb. V. John), July 2000.

Peccania tiruncula (Nyl.) Henssen On calcareous rock at Falaj Bani Khazeer (Brown 50536, Plate 3b). Also known in Arabia from Saudi Arabia, where it occurs at higher altitudes on Jabal Tuwaiq, between Riyadh and Qaseem (Bokhary et al. 1993). Material studied: The sample listed (50536) above from Oman.

Peltula obscurans (Nyl.) Gyeln. Marton & Galun (1981) treated Heppia obscuratula Nyl. as a synonym of Peltula obscurans var. deserticola (Zahlbr.) Wetm. In contrast, Egea (1989) considered it as a distinct species, clearly delimited from Peltula obscurans . Peltula obscuratula (Nyl.) Poelt ex Egea was reported by Bokhary et al. (1993) from Saudi Arabia. Our samples from Oman agree with Peltula obscurans s.l., but actually may be identical to P. obscuratula . As the taxonomic situation of the latter species remains unresolved, and Peltula obscurans is quite variable, we decided to refer our samples to Peltula obscurans in a broad sense. The species was erroneously cited as “Peltula obscurans (Zahlbr.) Wetm.” by Schultz (1998). The citation actually referred to Peltula obscurans var. hassei (Zahlbr.) Wetm., a distinct variety of the

184 species with lobate thallus margins and with a large, sessile apothecium in the centre of the squamules (see Büdel 1987). The species was found at both Al-Khod (Brown 50509) and Falaj Bani Khazeer (Brown 50535), and was particularly widespread at the first site. The species has otherwise been recorded from various locations around the world (Büdel 1987). Selected material studied: (as P. obscurans s.l.) KUWAIT: N of Kuwait Bay, Umm Al-Rimam, thin soil crust on calcareous sandstone, G. Brown & M. Schultz [15016c], V/98; northern edge of Kuwait Bay, W of Sobiya, thin soil crust on calcareous sandstone, G. Brown & M. Schultz [15001d], V/98; south-eastern part, 2 rocky outcrops close to Khiran, thin soil crust on calcareous sandstone, G. Brown & M. Schultz 15020e, V/98. (as P. obscurans var. hassei) YEMEN: SW, S of Ta’izz, volcanic rock, 1350 m, M. Schultz 14005, III/97; similar locality, 1180 m, M. Schultz 14008, III/97.

Peltula radicata Nyl. On compacted soil at Falaj Bani Khazeer, where it was found in small amounts (Brown 50520). Otherwise recorded in Arabia from Kuwait (Schultz et al. 2000), Saudi Arabia (Abu-Zinada et al. 1985) and southern Yemen (Schultz 1998). Selected material studied: KUWAIT: N of Kuwait Bay, Umm Al-Rimam, thin soil crust on calcareous sandstone, G. Brown & M. Schultz [15012b], V/98; northern edge of Kuwait Bay, W of Sobiya, thin soil crust on calcareous sandstone, G. Brown & M. Schultz [15031c], V/98. YEMEN: South Yemen, south-eastern part, Djol Plateau, thin soil crust on limestone, 1250 m, M. Schultz [14013d], III/97.

Phloeopeccania pulvinulina J. Steiner Common on calcareous rock at both Al-Khod (Brown 50507, Plate 3a), where it often occurred with Buellia subalbula , and at Falaj Bani Khazeer (50528). Otherwise known in Arabia from southern Yemen and Socotra Island (Schultz, unpublished). Selected material studied: YEMEN: SW, vulcano “El Harida del Hamra”, December 1898, O. Simony (WU 193-holotype);Al Mukalla region, road from Riyan into Wadi Hadramaut, plateau of Djol Mts., limestone, 1250 m, 14°57.78’ N, 48°58.83’ E, M. Schultz 14014a, 13.03.1997; Socotra: 7 km E of Hadibu, valley S of Djebel Hawari, on base-rich siliceous boulders on the ground, c. 50 m, 12°39.1’ N, 54°5.8’ E, M. Schultz 14025b, 16.03.1997.

Psora decipiens (Hedw.) Hoffm. Very little material and often poorly developed (although one or two thalli were fruiting) at Falaj Bani Khazeer growing together with Catapyrenium sp. (Brown 50518). Probably widespread in suitable locations throughout the Arabian Peninsula, as implied by the records from various countries. Ghazanfar & Gallagher (1998) state that the species is common throughout the northern and southern mountains of Oman above 1500 m.

Synalissa symphorea (Ach.) Nyl. This widespread species (N. Africa, Europe) was previously unknown from the Arabian Peninsula, and was found in small amounts at Falaj Bani Khazeer (Brown 50529,

185 Plate 2d, 50545). In the meantime, further new localities (listed below) have been discovered in southern Yemen and the island of Socotra. Selected material studied: YEMEN: Al-Mukallah region, road from Riyan into Wadi Hadramaut, escarpment of the Djol Mts., shady vertical limestone face, 500 m, 14°50.9’ N, 49°8.84’ E, M. Schultz 14010i, 13.03.1997; Socotra: Wadi Ma’nifoh, c. 4 km S of Hadibu, foot of Hajhir Mts., limestone, c. 50 m, 12°37’ N, 54°1.1’ E, B. Mies 14041c, 18.03.1997. GERMANY: Baden-Württemberg, Schwä- bische Alb, Seeburg, limestone, c. 600 m, M. Schultz 03167, 03192, 03197c, 18.04.1998. GREECE: Northern Sporades, Skopelos, wayside boulders, coll. site. 12, pine forest, G. Willems 10740/2 (hb. Büdel), 24.06.1989. SPAIN: Andalucia, Sierra de Cabo de Gata, Las Negras, on chalk, G. Willems 10654/1 (hb. Büdel), 02.01.1989.

Unidentified species Several other species were collected, but a clear identification was not possible, mainly due to insufficient material. A species closely resembling Catapyrenium contumescens (50518, 50519) was found at Falaj Bani Khazeer. A species probably belonging to the genus Psora was also found in quite large amounts on compacted soil over rocks at Falaj Bani Khazeer, but so far remains undetermined (Plate 1c). A rather poor sample probably belonging to Heppia lutosa , a species known from Saudi Arabia (Abu-Zinada et al. 1986), was collected at Falaj Bani Khazeer. An endolithic species of Verrucaria is quite common at Al-Khod, often growing together with Buellia subalbula, Peltula obscurans s.l. and Phloeopeccania pulvinulina .

Discussion Ghazanfar & Gallagher (1998) suggest that lichens are restricted to the higher altitudes of northern Oman (i.e. above 400 m) where temperatures are cooler. This is clearly not the case, as a relatively rich lichen flora is reported here from rocky substrates in the immediate vicinity of Sultan Qaboos University (60-80 m asl.). However, it does appear that lichen occurrences are very localised in northern Oman at lower altitudes, and restricted to sites with suitable substrates and microclimatic conditions. It is likely that with increasing altitude, species richness of the lichen flora will increase. This trend is indicated by the greater diversity and density of lichens at Falaj Bani Khazeer (c. 475 m asl.). A number of species mentioned by Ghazanfar & Gallagher (1998) from the northern mountains of Oman were not found at the lower altitudes of this study. This could be due to the fact that either suitable sites were not discovered, or that the species are actually restricted to higher, cooler altitudes. The conspicuous Psora decipiens was rather uncommon at the lower altitudes where we collected, although according to Ghazanfar & Gallagher (1998), it was common at higher altitudes, suggesting that some species do increase considerably in frequency under more amenable climatic conditions. Similar observations were made by the second author when studying lichen habitats in southern Yemen (Schultz 1998). Here, species abundance and coverage were found to increase along a transect from the coastal plain in the Al-Mukallah region, along the escarpment of the Djol plateau, to the summit of the Djol plateau with its fog-influenced upper valleys slopes. The only species able to withstand the harsh, dry climate of the coastal plains of southern Yemen were the cyanolichens Phloeopeccania pulvinulina and Gloeoheppia turgida .

186 A few remarks on other cyanobacterial lichens from the Arabian Peninsula seem warranted, especially as these species may also occur in Oman. Anema decipiens (Massal.) Forss. has now been collected from basaltic rocks in SW Yemen, thus adding a further species to the lichen flora of the Arabian Peninsula (Schultz, unpubl. results). Pyrenopsis picina (Nyl.) Forss. and Heppia conchiloba Zahlbr. were erroneously reported from southern Yemen (Schultz 1998). The sample of the former species is in fact Pterygiopsis affinis (Massal.) Henss., and is the first record of the genus from the Arabian Peninsula. The latter belongs to the genus Heppia, but is not H. conchiloba . The thallus consists of small, heavily pruinose areolate squamules, but lacks the conspicuous large squamules, often with sorediate margins, displayed by typical thalli of Heppia conchiloba . Bokhary et al. (1993) reported Heppia turgida (Ach.) Nyl. as new for Saudi Arabia. However, this is a synonym of the valid name Gloeoheppia turgida (Ach.) Gyeln. that was also included in their list. The 17 new lichen records reported here from a relatively small geographical area suggests that the lichen flora of Oman must be considerably richer than that indicated by the 35 taxa listed by Ghazanfar & Gallagher (1998) for the whole country. 52 species are now known to occur in Oman, and future collecting efforts, especially in more favourable locations, should add substantially to Oman’s flora. Despite the limited scope of this study, our field observations suggest that the results give a good reflection of the typical lichen flora in this rather inhospitable part of the country for lichen growth, and possibly for much of northern Oman at lower altitudes (i.e. below 500 m), especially as lichens appear to be absent over large areas of the landscape.

Acknowledgements

We would like to thank Drs G. Matzke-Hajek and B.M. Möseler (University of Bonn, Abtlg. f. Landwirts. Botanik) for allowing us the use of photographic facilities in their department. We are also grateful to Dr Othmar Breuss (Vienna) for determination of Catapyrenium samples. G.B. would also like to thank Ms Amina Al-Farsi (Herbarium, Sultan Qaboos University) for providing useful information.

References

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187 LAMB, I.M. (1936): Lichens from Bahrein Island. - J. Botany 74: 346-351. MARTON, K. & M. GALUN (1981): The cyanophilous lichen population of the ‘Arava Valley and the Judean Desert (Israel). - Israel J. Botany 30: 125-155. MIES, B.A. (2000): Flora und Vegetationsökologie der Insel Soqotra. - Habilitation thesis, University of Essen. MORENO, P.P. & J.M. EGEA (1992): El género Lichenella Nyl. en el sureste de España y norte de África. - Cryptogamie, Bryol. Lichénol. 13: 237-259. SCHULTZ, M. (1998): Studies on lichens from southern Yemen (Arabian Peninsula). - Lichenologist 30: 293-297. SCHULTZ, M., G. BROWN & B. BÜDEL (2000): Cyanophilous lichens from Kuwait. - Nova Hedwigia 70: 193-216.

Received 10 June 2001, accepted in revised form 15 January 2002.

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