Fissurina varieseptata is a species of crustose lichen in the family Graphidaceae. It is known from Florida. It has small, fissure-like (slit-like fruiting structures) and ascospores that usually have 5âÂÂ7 transverse septa (internal walls), rather than the more typical three in closely similar species.
Fissurina varieseptata was described as a new species in 2011 by Ralph Common and Robert Lücking. The holotype (the single specimen designated as the name-bearing type; Common 7413A) was collected in April 1997 in Fakahatchee Strand Preserve State Park (Collier County, Florida), at Big Cypress Bend in an old-growth cypress swamp. It is deposited in the herbarium of the Michigan State University Museum (MSC).
The specific epithet refers to the variable number of transverse septa in the ascospores. The species is superficially similar to Fissurina illiterata and may be closely related, but it can be separated by its much more strongly septate spores, a feature unusual in the genus.
The thallus forms a continuous crust on bark, 1âÂÂ5 cm across and about 40âÂÂ70 üm (micrometres) thick. The surface is smooth to uneven and typically yellowish white. The (the photosynthetic partner) is a alga (Trentepohlia-type). In cross-section, the upper is irregular and loosely developed, with an irregular and clusters of crystals.
Individual lirellae are about 0.5âÂÂ1 mm long and about 0.1 mm wide and high, with a complete . The is mostly concealed, and the are inconspicuous; the thalline margin is yellowish white but becomes yellow-brown along the slit. Microscopically, the asci are and produce eight ellipsoid ascospores. The spores are usually (3âÂÂ)5âÂÂ7-septate (divided by internal walls), 12âÂÂ18 à4âÂÂ5 üm, and non-amyloid (IâÂÂ). No lichen substances were detected by thin-layer chromatography.
The species was originally known only from the type collection from Fakahatchee Strand Preserve State Park in southwestern Florida, where it was recorded growing on hardwood in an old-growth cypress swamp at Big Cypress Bend. It was later documented on arborescent runner oak (Quercus pumila) in Miami-Dade County.