Crustose Research Articles

DIVERSITY AND ADAPTIVE FEATURES OF CORTICOLOUS LICHENS IN THE HUNDRED ISLANDS, PHILIPPINES

This study is a survey of corticolous lichens in the Hundred Islands, Philippines noting their diversity and morpho-anatomical adaptive features. There were only six islands visited due to accessibility and safety reasons. There are at least thirty-two identified species of lichens; majority is crustose dominated by Graphidaceae lichens followed by pyrenolichens in terms of diversity. Morpho-anatomical features considered to be adaptive include crustose and narrow-lobed foliose growth forms, homiomerous thallus organization, thick upper cortex, and presence of pruina in the cortical or medullary layers. KEYWORDS : Hundred islands; epiphytic lichens; adaptive features

TWENTY-THREE YEARS OF GROWTH MEASUREMENTS ON THE CRUSTOSE LICHEN CALOPLACA AURANTIA IN THE CENTRAL NEGEV DESERT

ABSTRACT Over a period of 23 years, growth rates of primarily circular thalli of the crustose epilithic lichen Caloplaca aurantia (Pers.) Hellb. var. aurantia Poelt were measured in the highlands of the Negev Desert near Avdat. Thalli with an area greater than 3 to 4 cm2have reached the “linear phase” of growth, i.e., they show an almost constant annual increment in their radius. In an average of 11 samples, this growth amounted to 0.371 mm yr−1. In order to determine the width of the marginal annulus which contributes to the extension growth of the lichen, different portions of the center of some of the thalli were removed. A remaining annulus with a width of 12 mm provides sufficient assimilates for unimpaired centrifugal growth, which was not the case with an annulus 6 mm in width. Thalli of Diploschistes calcareus (Mull. Arg.) Stein., another crustose lichen species, showed an annual radial growth increment of 0.17 mm yr−1; however, data from only two samples could be collected. From diameter and grow...

A New Crustose Stereocaulon From the Mountains of Scotland and Wales

A New Crustose Stereocaulon From the Mountains of Scotland and Wales

Sessile invertebrate coelobite communities from reefs of Bermuda: Species composition and distribution

Sessile invertebrate coelobite communities attached to the walls and roof of cavities in coralgal reefs on the annular rim of the Bermuda platform near North Rock (4 sites) and in the algal cup reef tract on the south shore (3 sites) have been studied by belt photo-transects and direct sampling. Irradiance measurements reveal a light gradient which appears to exert a strong influence on the composition, relative coverage and zonation of the attached biotic communities. Two main communities are recognised from cluster analysis and relative areal coverage data. Near the cavity entrances is a community dominated by crustose coralline algae, with subsidiary ascidians, demosponges, bryozoans and Foraminifera. Species richness is high and there is total biotic coverage of walls and roof. This community grades laterally into an exclusively animal community characterised by encrusting sponges and Foraminifera, with subsidiary bryozoans and unidentified branching organisms. Coverage varies from 100% to 30%, the substrate often exhibiting high micro-relief from the branching growth forms of the Foraminifera. Species richness is high at North Rock sites, less so on the south shore. The distribution of coelobite species is compared with that described from previous studies in Bermuda, Grand Cayman and Madagascar.