Fascinating Lichens of Sri Lanka

Usneaceae
Fr
VC
Misidentification Usnea barbata
Possible Species Ramalina thrausta OR Ramalina usnea
Description for Usnea barbata Fruticose. The thallus is pendulous and long,
and may partly be divided into irregular segments by annular cracks. The
branches are uneven in thickness, often with depressions and/or ridges. Fibrils
are short ranging from few to numerous. Isidia are few or absent. Papillae could
be abundant, sparse or absent. Soralia are punctiform (with small spots or pits)
irregular, few to abundant, develop on the top of eroded papillae, tubercles or
ridges. The cortex is thin. The medulla is thick and loose. Apothecia are not seen.
Most of the Usnea species collected from Sri Lanka are identified as Usnea
barbata by most of the collectors, but is not in actuality the aforementioned
species. The lichen Usnea barbata has been referred to as a common lichen in
Horton Plains in the historical records of hunters and explorers. However, this is
a misidentification.
Status Recorded as a very common species especially at Horton Plains as “old
man’s beard” lichen. Further studies using molecular, morphology and chemistry
is recommended for the correct identification of the Usnea and Ramalina species
in Horton Plains and similar habitats.
Usneaceae
This species is very polymorphic and may represent a collection of intergrading
taxa (species that pass into another form by a series of intervening forms). Several
characteristics (e.g. presence of fibrils, papillae, isidia, degree of depressions and
ridges) vary greatly. Careful observation under the microscope is required.
Medullary chemistry Two chemotypes have been recorded for Usnea barbata:
(1) with salazinic acid as a main substance (K+ yellow, orange or red, Pd+ yellow to
orange) and protocetraric acid as an accessory substance; (2) without medullary
substances (K–, Pd–).
Habitat Usnea barbata is mostly restricted to humid high elevation forests as
a corticolous species. Reported in Europe: Austria, Bulgaria, Czech Republic,
Denmark, Estonia, Finland, Germany, Italy, Latvia, Lithuania, Norway, Poland,
Romania, Russia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Ukraine and
Estonia. However, it is worth noting that this species has not been recorded in
India, Nepal or other South Asian regions.
Locations Historical identification of locations lists Horton Plains and the
Nuwara Eliya district.
158 Fascinating Lichens of Sri Lanka
Fascinating Lichens of Sri Lanka 159