Fissurina pseudostromatica
Fissurina pseudostromatica is a lichen that forms a thin, crust-like growth on bark and belongs to the family Graphidaceae. It was first described from subtropical Florida. It forms pale clusters of very small, immersed that look like tiny stromata, and standard chemical screening did not detect any lichen substances. It has since been reported from Brazil and from Yunnan in southern China.
Taxonomy
Fissurina pseudostromatica was described as a new species in 2011 by Robert Lücking and Eimy Rivas Plata, based on a collection made in Fakahatchee Strand Preserve State Park. The holotype was collected in March 2009 along Janes Scenic Drive in a Taxodium–''Sabal hardwood hammock. It is deposited in the Field Museum herbarium. The epithet pseudostromatica refers to the conspicuous, -like clusters formed by the aggregated lirellae. The material was initially identified as Fissurina mexicana, but it was separated because F. mexicana has ascospores and a less strongly contrasting thallus pattern.A later study using morphology and anatomy, chemical tests, and DNA data from three gene regions reported the species as new for China based on collections from Yunnan. In that analysis, not all specimens identified as Fissurina pseudostromatica'' grouped together, suggesting that the species may be defined too broadly and may need re-evaluation.
Description
The thallus grows on bark and is typically 1–3 cm across and about 40–60 μm thick. It forms a continuous crust with a smooth to slightly uneven, olive-green surface, and contains a photobiont. In cross-section, the upper is, with an irregular and scattered clusters of crystals.The are densely aggregated into small, white clusters that give a pseudostromatic appearance. Individual lirellae are straight to curved, unbranched, and immersed, with a thin. Individual lirellae are about 0.1–0.3 mm long and about 0.1 mm wide and high. The is concealed to slightly gaping, while the labia are inconspicuous and white. Microscopically, the asci are fusiform and contain eight ellipsoid ascospores. The spores are 3-septate, about 15–20 × 5–7 μm, and non-amyloid. No lichen substances were detected by thin-layer chromatography. Material reported from China was described as matching the type material in overall morphology and chemistry, but with broader ascospores. A K+ thallus reaction was also reported, despite no secondary metabolites being detected by thin-layer chromatography.