Frenelopsis

Mendes, Mário Miguel, Dinis, Pedro & Kvaček, Jiří, 2018, Some Conifers From The Early Cretaceous (Late Aptian - Early Albian) Of Catefica, Lusitanian Basin, Western Portugal, Fossil Imprint 74 (3 - 4), pp. 317-326 : 319

Frenelopsis cf. turolenis B.GOMEZ in Gomez et al., 2002

Text-fig. 3 a–c

D e s c r i p t i o n. Shoot fragments from bulk macerated material consist of one or two internodes – whorls of three

fused leaves each. Whorls alternate at 60º. Leaves are fused

along almost their entire lengths, forming an internode

(sheath) with no suture in between. The internodes show

terminally short triangular free tips with scarious margins

( Text-fig. 3a ) being up to 13 mm long, and 4 mm wide (the latter corresponding to half a perimeter). The three leaf

tips are usually less than 0.5 mm, but they are 2.1 mm in

one specimen ( Text-fig. 3a ). Cuticle surface is papillate to

generally smooth. Stomata are arranged in parallel but rather

ill-defined longitudinal rows running along to the internode

axis. They have typically 4, but sometimes 5 subsidiary

cells, each bearing outer papillae ( Text-fig. 3c , arrowed). The compound structure of the stomatal chamber shows

inner and outer papillae ( Text-fig. 3c , arrowed).

D i s c u s s i o n. Through the present, based on the study of their cuticles, up to 20 species of Frenelopsis have been described from the Valanginian – Maastrichtian of Belgium, China, the Czech Republic, France, Germany, Goban Spur, Greenland, Italy, Japan, Poland, Portugal, Spain, Sudan, Tajikistan, Ukraine and USA (e.g. Watson 1988, Kvaček 2000, Gomez et al. 2002, 2008, Mendes et al. 2010, Bartiromo et al. 2012, Batten et al. 2014, Barral et al. 2016).

The studied material most closely matches Frenelopsis turolenis from the Albian of Spain, but has some characters in common with F. ugnaensis B.GOMEZ from the Barremian of Spain ( Gomez et al. 2002). Our material shares the characters of a small inner papillae and a cuticle that is rather papillate, but not hairy, with F. ugnaensis. Therefore, we leave it for further study to determine whether the material definitively belongs to F. turolensis. Both species show cuticles with stomata arranged in rows. Their stomata are surrounded by typically four subsidiary cells. Typical number of subsidiary cells is a character in which our material differs from other three-leaved Frenelopsis species with approximately smooth cuticle: F. rubiescensis BARALE from the Berriasian – Barremian of Spain ( Gomez et al. 2002), F. occidentalis HEER from the Early Cretaceous of Portugal and Germany ( Alvin 1977), F. oligostomata ROMARIZ from the Late Cretaceous of Portugal and Spain, F. kanevensis BARALE et DOLUDENKO from the Albian of Ukraine ( Barale and Doludenko 1985). F. ramosissima FONTAINE from Barremian – Albian of the USA ( Berry 1910, Watson 1977) differs from our material in having stomata surrounded typically by five subsidiary cells and round rim of stomatal pit.

Figures

Text-fig. 3. SEM micrographs of two types of conifers from the Early Cretaceous mesofossil flora of Catefica, Portugal. (a) Shoot fragment of Frenelopsis turolensis with terminally short triangular free tips (P0357, sample Catefica 310). (b) Outer surface with papillae and stomata arranged in longitudinal rows (P0357, sample Catefica 310). (c) Stomatal chamber with outer and inner papillae (arrows) (P0357, sample Catefica 310). (d) Flat internode of Pseudofrenelopsis cf. parceramosa (P0132, sample Catefica 315). (e) Outer view of the abaxial surface showing stomatal rows (P0132, sample Catefica 315). (f) Detail of stomatal rows showing massive rings around the stomatal pits (arrows) (P0132, sample Catefica 315). Scale bars = 1 mm (a, d, e); 100 μm (b); 50 μm (f); 5 μm (c).