Phaeographis delicatula
Phaeographis delicatula is a species of crustose lichen in the family Graphidaceae. It is known from subtropical Florida and Brazil, where it grows on the branches of hardwoods. It is characterized by delicate in dense clusters that often branch in a star-like pattern. Chemically, its main lichen substance is stictic acid.
Taxonomy
Phaeographis delicatula was described as a new species in 2011 by Ralph Common and Robert Lücking. The holotype was collected in April 1997 in Fakahatchee Strand Preserve State Park, along the K2 trail among royal palms in a second-growth area, and is kept in the herbarium of the Michigan State University Museum.The specific epithet delicatula refers to the species' delicate. The species is placed in the Phaeographis intricans aggregate, a group defined by a clear hymenium, clustered lirellae, and small ascospores. It differs from most close relatives in containing norstictic acid rather than stictic acid.
Description
The thallus is corticolous, forming a continuous crust across and about 50–100 micrometers thick.Its surface is uneven, with small wart-like bumps, and ranges from pale yellow-gray to olive-yellow. The is a Trentepohlia-type green alga.The lirellae are and form dense clusters, but these clusters but these clusters do not form a . The lirellae are often stellately branched and. Individual lirellae are typically 1–3 mm long, about 0.1 mm wide, and 0.12–0.15 mm high. The disk is chocolate-brown and may have a thin gray ; the are indistinct and dark brown, with a thin, yellow-white. The disk is exposed and chocolate-brown and may carry a thin gray pruina, while the labia are indistinct and dark brown, with a thin, yellow-white thalline margin.
Under the microscope, the excipulum is divergent and dark brown, and the hymenium is clear and about 50–60 μm high. The asci are fusiform to clavate and produce eight oblong ascospores with three septa measuring about 13–18 × 5–7 μm. The spores are I+. Chemically, the thallus contains stictic acid as its major secondary metabolite with a trace of constictic acid. In section, the K test is positive, producing a yellow efflux that is visible under the microscope.