Fascinating Lichens of Sri Lanka

5. Graphidaceae:
the most speciose lichen
family in Sri Lanka
Genera 103+
Ostropales Graphidaceae
c.2500
Graphidaceae is the largest family of tropical crustose lichens, with 103 genera
known to date comprising 2500 accepted species. Recent phylogenic and
statistical analysis showed that Sri Lanka and South India are the Graphidaceae
hotspots in the world with 499 species (Lücking et al. 2014).
Usneaceae
Fr R IC
Usnea subcornuta
Description Fruticose. The species is found on bark or rocks. The thallus is erectshrubby
to subpendent and small. The trunk is of the same colour as the tapering
branches. Lateral branches with annular cracks that are constricted at the point
of attachment. Bases are pale. Long and slender fibrils are present, and are scarce
to abundant. Soralia are usually large. The cortex is glossy and thin. The medulla is
loose, and contains an orange-reddish pigment sub-cortically (inside the cortex).
Medullary chemistry Stictic and norstictic acids as main substances (K+ yellow
to red, Pd+ orange).
Has been considered as identical to U. cornuta, however, it is indicated that this
is a distinct species characterized by the presence of orange-reddish pigment in
the cortical layers.
Status Rare species. ‘New record for the Indian subcontinent and Sri Lanka.
Habitat Restricted to humid high elevation forests above 1400 m. Found on the
exposed branches of young trees, on bark or wood in open places, forest relics,
evergreen lower montane forests, and secondary montane cloud forests.
Locations Kalupahana area- Knuckles mountain region.
This is the most speciose lichen family in Sri Lanka with c.400 species known
from over 40 genera. More than 175 species in this family are new records for the
country (Weerakoon et al. in preparation). Since 2012, over 42 new species have
been discovered in family Graphidaceae by local lichenologists from Sri Lanka
(Weerakoon et al. 2012 a & b; Weerakoon et al. 2014; Weerakoon et al. A in press,
Wijeyaratne et al. 2012). Out of the recently described species, 97% are endemic
to Sri Lanka, with majority retaining point endemics.
Hale’s (1981) extensive monograph of the species, which at the time included
Thelotremataceae, but now forms part of the Graphidaceae, no doubt represents
the turning point of monographic work on lichen fungi in Sri Lanka. Several
recent publications now in press (Weerakoon et al. 2014; Weerakoon et al. A, &
B, in preparation) continue the inventory of the Graphidaceae of the country,
confirming the extraordinary diversity in Sri Lanka.
As the family is extremely diverse and includes over 40 genera, trained
lichenologists should identify the species using advanced morphological and
chemical characters. Most of the species are inconspicuous crustose lichens
in Graphidaceae, therefore only a few conspicuous species that are within the
reach of the casual observer in natural habitat are included in this book. Except
for the genus Diploschistes (single most easily identified species known for Sri
Lanka), generic and species descriptions are not given. Readers who wish to
confidently identify the species of this family should use recent keys. However, I
hope the colourful photos included in the book will give you an idea about the
diversity of family Graphidaceae in Sri Lanka.
Graphidaceae
162 Fascinating Lichens of Sri Lanka
Fascinating Lichens of Sri Lanka 163