| Description: |
Frullania chiapasensis Mamontov, K. Feldberg, Schäf.-Verw., Gradst. sp. nov. Holotype. Geoscientific Collection of the University of Göttingen, Germany (GZG), GZG.BST.22085; syninclusion Parmotrema specimen 4. Etymology. The species is named after the location of the amber deposit in Chiapas, Mexico. Age and stratigraphic level. 15‒23 Ma, Langhian – Aquitanian (early to middle Miocene), Simojovel, Chiapas, Mexico. Diagnosis. Incubously foliated liverwort with conduplicate-trilobed, entire-margined leaves; dorsal lobe obliquely ovate to elliptical, apex rounded to obtuse, lacking ocelli; ventral lobule Frullania - type, saccate, adnate to lobe at a distance of ca. 0.8 of the stem width, parallel or somewhat converging to stem and at places leaning against it, clavate to obovate, not constricted above the postical opening, surface smooth, opening extending along the abaxial side of the lobe for ca. 0.32–0.50 of the lobule length, sickle-shaped; underleaves triangular to obovate, longer than wide, widest in the upper half, bilobed 0.2–0.3 × their length, upper half of underleaves armed with 2 short teeth on both sides. Description. Two gametophyte fragments. Intact shoot ca. 2.64 mm long, 0.33–0.35 mm wide with leaves, dark reddish brown (Figs 1 A, B, 2); with three broken, lateral branches [not clearly visible]. Stem only slightly darker in color than leaves, 35–45 µm in diameter, surface cells not visible. Lateral leaves incubous, alternate, contiguous to imbricate near apex, widely spreading, conduplicate-trilobed (Figs 1 A – C, 2 A). Dorsal lobe in dorsal aspect convex to nearly flat, partially with reflexed margin, obliquely ovate to elliptical (Figs 1 A – D, 2 A), 150–200 µm long × 120–150 µm wide, slightly longer than wide, length: width ratio ca. 1.2–1.3: 1; margin entire, apex rounded to obtuse, inner margin barely extending beyond the farther edge of the stem; lobe base not clearly visible. Lobe cells almost isodiametric or rectangular to 5–6 - angled (Fig. 1 D, F), 15–20 × 10–20 µm in the middle of the ... |