Fascinating Lichens of Sri Lanka

Diploschistes
Crater lichens
Ostropales Graphidaceae
c.40
Diploschistesis a cosmopolitan genus that mainly occurs in xeric (very dry)
situations, usually in full sun. They are found on rocks, soil, and sometimes on
mosses or as parasitic on other lichens.
The species are crustose, with rather thick thalli and are creamy white to grey
or yellowish in colour. Some species are heavily pruinose, but none sorediate.
Only four species are known from this genus in Sri Lanka. However the three
species previously recorded in Sri Lanka are questionable. The species recently
collected in Nawalapitiya, Diploschistes muscorum is a new record for the genus
in Sri Lanka.
Apothecia with a well-developed brown to black exciple (tissue forming margin
or walls of an ascomata) surrounded by a thalline margin, apothecia open by a
deep, relatively wide cavity Asci: 1-4-8-spored; Spores: ellipsoid, brown to dark
brown or purple black, muriform.
Chemistry Sri Lankan species thallus C+ red, KC +red, K+ yellow turning to
purple, PD-.
Diploschistes muscorum Cowpie lichen
SL
R
Cr
Graphidaceae
Description The thallus is crustose, white to pale grey, and continuous with
an uneven surface and has a white prothallus. Apothecia 1-2mm in diameter,
disc black to dark brownish, crater-like, embedded in thallus, often with a double
margin, white pruinose, thalline margin slightly raised above the thallus. Asci
4-spored.
Status This rare species is a new record for Sri Lanka, and can become
established as a parasite on other lichens, especially Cladonia species. This
is usually an aggressive crust that can invade other lichens and compete for
resources or space.
Graphidaceae
Habitat Mostly found in disturbed conditions, in fully-exposed, sunny conditions.
The specimens examined were collected from soil banks above 900 m.
Locations Nawalapitiya.
72 Fascinating Lichens of Sri Lanka
Fascinating Lichens of Sri Lanka 73