Dicotylophyllum macrophyllum (HEER) GREGUŠ et J. KVAČEK 2015

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 : 333-334

Dicotylophyllum macrophyllum (HEER) GREGUŠ et J. KVAČEK comb. nov.

Pl. 18, Fig. 1–6; Pl. 19, Fig. 1–3

1869 Credneria macrophylla HEER , p. 16, pl. 4, fig. 1 (Basionym).

1999 Dicotylophyllum aff. nordenskioeldii (HEER) KNOBLOCH , p. 44, pl. 15, fig. 5.

1999 Dicotylophyllum sp. 7 ; Knobloch, p. 48, pl. 8, fig. 4.

H o l o t y p e: GPIT/PL_749, Pl. 18, Fig. 1 and GPIT/ PL_692, Pl. 18, Fig. 3 (part and counterpart); Heer 1869, p. 16, pl. 4, fig. 1.

T y 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: CGS/EK_254, 255; GBA_20,

40, 70, 98; GPIT/PL_667, 692.

E m e n d e d d i a g n o s i s: Leaves large entire-margined cordate. Apex acute to obtuse, base cordate. Primary venation pinnate, first three pairs of secondary veins decusate, dichotomously dividing at 2/3 of distance to leaf margin, ending before completely reaching margin. Suprabasal veins often run out towards the base. Other decusatelly arranged secondaries depart from midrib at wide angles. Finer and shorter intersecondary veins occur irregularly among secondaries.

D e s c r i p t i o n: The holotype (GPIT/PL_749, Pl. 18, Fig. 1) described by Heer (1869, p. 16, pl. 4, fig. 1) as Credneria macrophylla HEER is a 215 mm wide leaf impression of cordate shape, without preserved apical part. This leaf impression is entire-margined and petiolated. Primary venation is pinnate. The first observed pair of secondary veins is decusatelly arranged departing at almost right angle from midvein. Third order veins depart from second pair of secondaries at wide angles, and at approximately their midpoints, turn towards the apex. Leaf impression no. GPIT/PL_692 (Pl. 18, Fig. 3) without preserved basal and apical part is counterpart of specimen illustrated by Heer (1869). Specimen no. CGS/EK_254 (Pl. 18, Fig. 2) is an entire-margined cordate leaf impression, showing first three descusatelly arranged secondaries. This leaf impression is 155 mm long and 155 mm wide, and has clearly cordate base with rounded apical part, forming an obtuse apex. Entire-margined leaf impression no. GBA_20 (Pl. 18, Fig. 6) is 165 mm wide a 192 mm long, with cordate base and acute apex. First two pairs of secondaries are decustaelly arranged. Secondary veins do not reach leaf margin, and sometimes dichotomise at 2/3 of their length, forming poorly preserved third order reticulate venation in marginal part of leaf. Intersecondary veins present, irregularly distributed. Leaf impression no. GBA_40 (Pl. 18, Fig. 4) is morphologically similar to the previous specimen, but is 170 mm wide and 270 mm long. This leaf impression has long narrow grooves. Specimen no. GPIT/PL_667 (Pl. 18, Fig. 5) is preserved only as a fragment of leaf base. Its better preserved right part is 64 mm wide. Poorly preserved base suggests it was originally cordate. Typically, first three pairs of secondaries are almost opposite to each other, departing at obtuse angles. Other secondaries are arranged alternately on the midvein. The fragmentarily preserved leaf impression no. GBA_98 (Pl. 19, Fig. 2) is rhombical in shape, showing robust veins (midvein up to 4 mm). This impression is 145 mm wide, lacking its basal part. Secondaries alternate, at obtuse angle to the midvein. The specimen is covered by ridges caused probably by burrowing activities of worm-like organisms. Poorly preserved specimen no. CGS/EK_255 (Pl. 19, Fig. 1) is an impression of entire-margined leaf, with cordate shape and acute apex, approximately 130 mm wide and 130 mm long. An entire-margined leaf impression, no. GBA_70 (Pl. 19, Fig. 3) is widely elliptic in shape, and does not have preserved leaf base. Its secondaries are often dichotomously divided, especially in apical parts, forming poorly preserved reticulate venation. Its widely elliptic shape of lamina and absence of basal part makes its classification difficult, but its identical venation pattern allow us to identify it as D. macrophyllum .

D i s c u s s i o n. Knobloch (1999) identified leaf impressions of this type as Dictotylophyllum aff. nordenskioeldii (HEER) KNOBLOCH , based on their morphology. However, this species was described as Apeibopsis nordenskioldii HEER from the Late Cretaceous of Puilasok in Greenland ( Heer 1874, Seward 1927) having the same secondary venation and shape of lamina, but lacking acute apex. Apical part of A. nordenskioldii is likely emarginated ( Heer 1874, pl. 5, fig. 6). Leaf impressions of similar morphology and the same type of venation were described by Heer (1869) as Credneria macrophylla HEER. This name therefore has priority, and we suggest using it in new combination Dicotylophyllum macrophyllum GREGUŠ et J. KVAČEK comb. nov. It clearly differs from Credneria , which has typical percurrent third order venation. This type of venation was not observed on any specimen of the studied taxon. Seward (1927) and Knobloch (1995a) classified specimens of similar leaf morphology as the studied taxon to the genus Menispermites LESQUEREUX. However , this taxon differs from the studied material in having peltate base, palmate venation and lobate leaf lamina. Leaf impression (CGS/EK_255, Pl. 19, Fig. 1) from Maletín is briefly described as Dicotylophyllum sp. 7 by Knobloch (1999). This poorly preserved leaf impression has cordate base with acute apex. Midvein is relatively wide. First pairs of secondaries are decussate and depart from midvein at wide angles. D. macrophyllum differs from Dicotylophyllum sp. 1 , Dicotyllophyllum sp. 2, Dicotyllophyllum sp. 3 and Dicotyllophyllum sp. 4 described here in having cordate base and larger size of leaf lamina.