Friday, December 15

An Overview of Lichens of Mainland Yemen

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An Overview of Lichens of Mainland Yemen

Mainland Yemen is home to some of the most varied and lush vegetation although until recently, it has not had much attention from lichenologists. However, this is slowly changing. In recent years, lichenologists have identified 18 new lichens from mainland Yemen.

Teloschistes austroarabicus:

Thallus fruticose, this lichen has only been found in southern Arabia and adjacent Africa. With densely branched, forming rounded, pale brownish-grey cushions, it grows “on twigs of scattered trees in xerophytic vegetation on mountains with frequent fog, perhaps always in remnants of primary savannah forest.” The Ascomata and conidangia are not known.

This new species of lichen is very similar to Teloschistes californicus and is a relative of T. villosus. The way to tell them apart is the region origin. “The lobes of T. californicus are thinner, become more rapidly attenuate with narrower tips, 0.2 mm wide or less, and are wider near the base, to over 10 mm, with many perforations; the veins on the lower side are sharper and more numerous; the thalli are more frequently hairy, usually over much of their surface and not as pronounced at the lobe tips as in T. austroarabicus”.

Teloschistes stenophyllus:

Teloschistes austroarabicus is well recognised by the rather relentless hairs on the higher side, the strap-shaped lobe and swollen marginal rims.

New lichens are constantly being found as well as new information concerning already identified lichens. Some of these include:

Acarospora lavicola (from Harida el Hamra)

Arthonia cinnabarina (which prefers tropical and humid-temperate regions)

Arthonia elegans (also found in Europe and Siberia)

Arthothelium ruanum (found in Western Europe and North America)

Aspicilia circummunita

Buellia subalbula

Caloplaca (Amphiloma) lobulascens

Caloplaca ochraceofulva

Catapyrenium semaforonense

Catapyrenium squamulosum

Collema coccophorum

Cresponea chloroconia (“this species is restricted to cool areas of Europe and North America, and is not reported from Yemen in the recent revision”)

Dictyographa Arabica

Dictyographa varians (previously only known from Socotra)

Digitothyrea divergens

Diploicia canescens (a species found widely in areas with a Mediterranean climate and in the coastal regions of Yemen)

Diploicia subcanescens (previously identified in the west-ern part of the Mediterranean basin and Macaronesia)

Diploschistes ocellatus

Diploschistes gypsaceus

Physcia nubila (one of the most common lichens found in mainland Yemen. It is generally thinner than is Australian cousin).

Ramalina celastri (Not found in Yemen before, scholars believe that the original material may have been sold on a market).

These are just a few of the lichens found in the mainland of Yemen, but they show that not only is this region rich and diverse, but that our knowledge on them is constantly improving.

Bibliography:

Sipman, Harrie J. (2002) Lichens of Mainland Yemen, Willdenowia, Botanischer Garten und Botanisches Museum, Berlin-Dahlem.

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