Parmotrema specimen 4

Specimen.

Geoscientific Collection of the University of Göttingen, Germany (GZG), GZG.BST.22085; syninclusion Frullania chiapasensis.

Age and stratigraphic level.

15‒23 Ma, Langhian – Aquitanian (early to middle Miocene), Simojovel, Chiapas, Mexico.

Description.

Lichen fragment approximately 2.3 × 4.5 mm in diameter. Thallus foliose, lobate. Lobes flat and linear, 0.5-1.0 mm wide, lobe apices truncate to slightly rounded (Fig. 8 D). Upper surface smooth, brown (Fig. 8 D). Marginal cilia dark, mainly simple, up to 0.5 mm long (Fig. 8 D). Medulla not visible. Lower cortex concolorous with the upper surface (Fig. 8 E). Rhizines dark, abundantly branched (Fig. 8 E). Apothecia, isidia, soredia, or pycnidia not present.

Discussion.

The general habit and long, tapering marginal cilia identify the specimen as Parmotrema. The branching rhizines and long, tapered marginal cilia resemble the Canomaculina group. However, unlike the Canomaculina group, the fossil inclusion seems to possess a smooth upper surface of the lobes that visibly lack maculae.