Protopteris maletinensis GREGUŠ et J. KVAČEK

Greguš, Josef & Kvaček, Jiří, 2015, Revision Of Cenomanian Flora From The Maletín Sandstone, Acta Musei Nationalis Pragae Series B 71 (3 - 4), pp. 315-364 : 319

Protopteris maletinensis GREGUŠ et J. KVAČEK

Pl. 2, Fig. 3–6

H o l o t y p e: NHMW_1878B/0006/7141, Pl. 2, Fig.

3a–c; Greguš et al. 2013, p. 74, pl. 3, fig. 1–3.

Ty p e l o c a l i t y: Maletín.

S t r a t i g r a p h y: Peruc-Korycany Formation, Cenomanian, Upper Cretaceous.

M a t e r i a l s t u d i e d: GBA_2013/019/0001, 0002; UGV/S17_2.

O c c u r r e n c e: Vyšehořovice.

D i a g n o s i s. See Greguš et al. (2013).

D e s c r i p t i o n. The holotype ( NHMW/1878 B/0006 / 7141, Pl. 2, Fig. 3a–c) described by Greguš and J. Kvaček ( Greguš et al. 2013, p. 74, pl. 3, fig. 1–3) is an 80 mm wide and 180 mm long cast of a stem, with helically arranged large leaf saccate cushions, 18–27 mm wide and 32–43 mm high. Within each leaf cushion, an oval leaf scar is preserved, containing a horseshoe-shaped vascular bundle scar (Pl. 2, Fig. 3b, c). Leaf scars are generally 18–20 mm wide and 8–13 mm high. Small pits under the leaf scars are probably remnants of aerial roots. Grooves, which run longitudinally through the leaf cushion, may also be aerial root remains. The leaf scar ratio of height to width is 0.4–0.7, and on the stem it appears at an average density of 10/dm 2. Additional material from Maletín consists of poorly preserved specimens ( UGV / S17 _2, Pl. 2, Fig. 4; GBA _2013/019/0001, Pl. 2, Fig. 5; GBA _2013/019/0002, Pl. 2, Fig. 6), which show helically arranged leaf cushions with leaf scars similar to the holotype. Fragments of stem casts are usually 55–85 mm in diameter. Specimen UGV / S17 _2 has well-pronounced leaf cushions 14–26 mm wide and 23–45 mm high. Height to width leaf scar ratio is 0.4. On this specimen, small pits are apparent, which are probably the remnants of aerial roots .

D i s c u s s i o n. Protopteris maletinensis has “saccate” leaf cushions (Sternberg 1838, Corda 1845), in comparison with P. punctata (STERNBERG) C. PRESL in STERNBERG from the Cenomanian locality Kounice, and P. punctata (STERNBERG) C. PRESL in STERNBERG from the Polish locality Źeliszów (Turonian-Coniacian). P. maletinensis is very similar to P. laubei (ENGELHARDT) STENZEL from the Late Eocene of Staré Sedlo Formation ( Engelhardt 1881, Knobloch et al. 1996), which also has “saccate”, helically arranged leaf cushions on the stem. Leaf scar widths in both species are almost the same. They vary primarily in height, which is 8–13 mm for P. maletinensis and 14–19 mm for P. laubei . Average height-width ratios are 0.5 for P. maletinensis , and 0.8 for P. laubei . P. laubei has leaf cushions splitting away more from the stem, with wider gaps between cushions than in P. maletinensis . Another similar species is P. witteana SCHENK , from the Early Cretaceous of Germany ( Schenk 1871), which has smaller leaf cushions (12–15× 17–24 mm) than P. maletinensis . Between the cushions, there are 5–7 mm wide gaps. Leaf scars of P. witteana have a height-width ratio greater than one, as opposed to P. maletinensis , where it is less than one. Height to width leaf scar ratio for P. witteana averages 1.2; the same is true for P. punctata . Apical parts of leaf cushions of P. witteana are more pressed to the stem, and their density is two times higher than in P. maletinensis .