Pseudoctenis SEWARD , 1911

Kvaček, Jiří, 2008, New Cycad Foliage Of Pseudoctenis Babinensis From The Bohemian Cenomanian, Acta Musei Nationalis Pragae Series B 64 (2 - 4), pp. 125-131 : 126-127

Genus: Pseudoctenis SEWARD, 1911

T y p e: Pseudoctenis eathiensis (RICHARDS) SEWARD 1911: 692 , (= Zamites eathensis RICHARDS, 1834: 117 , H. Miller collection).

The genus Pseudoctenis was emended by Harris (1964) without knowledge of the cuticle of the type. Epidermal characters of the type material (specimen V. 12202) P. eathiensis were published later by Van Konijnenburg- van Cittert & Van der Burg (1989: 23, pl. 7, fig. 1) who reemended the diagnosis of the genus.

Pseudoctenis babinensis sp. nov.

Pl. 1, figs 1-7, Pl. 2, figs 1-6

E t y m o l o g y: The name of the species is derived from the name of the part of the Pecínov Quarry – the pit Babín.

H o l o t y p e: F 2448, designated here, housed in the

National Museum, Praha.

P a r a t y p e: F 2318, designated here, housed in the

National Museum, Praha.

T y p e l o c a l i t y: Babín north open pit, Pecínov quarry.

T y p e h o r i z o n: Cretaceous, Cenomanian, Peruc-Korycany Formation, unit 2 (according to Uličný and Špičáková 1996).

D i a g n o s i s: Bipinnate fronds; rachis robust with numerous longitudinal ridges. Pinnae linear – lanceolate, entire-margined; apex attenuate, apex rather blunt; margins in the base running straight. Veins parallel-sided simple or forking once in the basal region; many veins ending in margins. Pinnae arising at a sharp angle of about 50– 60˚. Leaves hypostomatic; adaxial cuticle showing quadrangular, isodiametric cells forming short rows, some cells slightly more cutinized. Abaxial cuticle bearing nearly isodiametric cells forming rows in costal areas and numerous trichome bases. Haplocheilic stomata sunken in pits surround- ed by 8 subsidiary cells forming a rounded or elliptical rim. Stomata irregularly orientated, scattered with tendency to avoid costal areas.

S p e c i m e n s s t u d i e d: F 2318, F 2448 – F 2450,

F 2790.

O c c u r r e n c e: Pecínov Quarry, Babín Pit, unit 2.

D e s c r i p t i o n: The holotype (Pl. 1, fig. 1) represents a part of the bipinnate leaf. Basal parts of 14 pinnae arising at angles of 50- 60˚. Although the frond displays only basal and medial parts of the pinnae it has been selected as the holotype as it also shows the ribbed rachis. The paratype F 2318 (Pl. 1, fig. 3) shows well preserved entire pinna bearing 15 veins running parallel with the leaf margins. The veins frequently end in the margin. The best preserved cuticle has been obtained from the specimens F 2449 (Pl. 1, fig. 6) and F 2450 – fragments of pinnae .

Adaxial cuticle is considerably thick without stomata (Pl. 1, fig. 4) showing ordinary cells (10-30 x 25-50 µm) and trichome bases (25–30 µm in diameter, Pl. 2, figs 1, 3). Anticlinal walls of the cells are straight or bent, 4–5 µm thick. Cells form short rows running parallel to the venation. The periclinal wall of some cells is more cutinized. The slightly thinner abaxial cuticle shows cells slightly divided into costal and intercostal files (Pl. 1, fig. 7). The epidermal surface is more cutinized and probably it also has different physical features than anticlinal walls. Due to this fact anticlinal walls are split from the periclinal walls (Pl. 2, fig. 2) and caused difficulties in SEM observation (Pl. 2, fig. 5). Ordinary abaxial cells (15–50 x 40–60 µm) are isodiametric, quadrangular, in costal areas slightly elongate where they form 2–5 rows. Stomata (Pl. 1, fig. 2) are surrounded by 6–10, typically 8, slightly more strongly cutinized subsidiary cells (10–35 x 40–70 µm) forming a shallow oval or elliptical stomatal pit (Pl. 2, fig. 6, Pl. 1, fig.5). SEM observation of the inner part of the abaxial cuticle was complicated because the cuticle did not have entirely preserved anticlinal walls (Pl. 2, fig. 5). Stomata are irregularly orientated and scattered over the leaf lamina with a slight tendency to avoid costal areas (Pl. 1, fig. 7).

D i s c u s s i o n: Pseudoctenis babinensis sp. nov. differs from Jirusia jirusii (BAYER) DOMIN ( Kvaček 1995), a most similar cycad foliage morpho-species from the Bohemian Cenomanian, in the lack of teeth, in having stomata irregularly oriented and having a higher number of subsidiary cells.

Species described by Watson and Cusack (2005) from the Lower Cretaceous English Wealden are rather weakly defined. Three species are based on three single specimens, one even without cuticle ( P. risehomaridae WATSON et CUSACK ). Pseudoctenis babinensis differs from P. foljambeae WATSON et CUSACK, 2005 in absence of strongly decurrent pinnae and having them arranged at a wider angle to the rachis. P. babinensis differs from P. divana WATSON et CUSACK, 2005 in having pinnae shortly decurrent and having a lower number of subsidiary cells per stoma. P. risehomaridae WATSON et CUSACK, 2005 is represented by a single pinna impression ( Watson and Cusack 2005, text-fig. 49D) without any cuticular details described, so it is considered here as doubtful, lacking clear diagnostic characters of Cycadales .

P. crassa S. ARCHANGELSKY et BALDONI, 1972 and P. ornata S. ARCHANGELSKY et al., 1995 from the Lower Cretaceous of Patagonia differs from P. babinensis in having smaller ordinary cells and large papillae on both subsidiary and ordinary cells. P. dentata S. ARCHANGELSKY et BALDONI, 1972 from the Lower Cretaceous of Patagonia differs from P. babinensis in having toothed pinnae and amphistomatic leaves.

P. pecinovensis differs from the type of the genus Pseudoctenis eathiensis (RICHARDS) SEWARD, 1911 from Culgower (Jurassic of Scotland) in having stomata surrounded by a higher number of subsidiary cells, in lacking cuticle striation and poorly differentiated costal and intercostal zones (Van Konijnenburg-van Cittert & Van der Burgh 1989). Both species P. spectabilis HARRIS, 1932 and P. depressa HARRIS, 1932 , described from the Rhaeto-Liassic of Greenland, differ in appearance of the frond which consists of broad segments. P. spectabilis is very similar in cuticle anatomy to P. babinensis , from which it differs in fewer (typically 6) subsidiary cells, presence of trichome bases and absence of a stomatal rim. P. depressa differs from P. babinensis in the presence of striation on the abaxial cuticle and well-exposed guard-cells. P. herriesii HARRIS, 1964 from the Jurassic of Yorkshire differs from P. babinensis in the expanded pinna base and slightly sunken stomata lacking the stomatal rim. P. locusta HARRIS, 1949 from the Jurassic of Yorkshire differs from P. babinensis in having short elliptical pinnae showing thick forked veins, in the presence of trichomes and in having stomata orientated mostly parallel to the veins. P. oleosa HARRIS from the same locality ( Harris 1964) differs from P. babinensis in the adaxial cuticle possessing striation and in having stomata longitudinally orientated to the veins. P. lanei THOMAS , another species from the same locality, differs from P. babinensis in uniformity of costal and intercostal areas of the abaxial cuticle, in having stomata orientated parallel to the veins and numerous papillae. P. latus DOLUDENKO et SVANIDZE from the Upper Jurassic of Georgia ( Doludenko and Svanidze 1969, pl. 29, figs 1-4, pl. 30, figs 1-5) differs from P. babinensis in the contracted bases of pinnae and in having stomata longitudinally orientated to the veins. P. barulensis DOLUDENKO et SVANIDZE from the Upper Jurassic of Georgia ( Doludenko & Svanidze 1969, pl. 26, figs 1-6, pl. 27, figs 1-6) differs from P. babinensis in the presence of papillae that are scattered on the abaxial cuticle and surround stomatal pits, and in slightly sunken guard cells. P. creysensis BARALE, 1981 from the Jurassic of Creys, France differs from P. babinensis in a smaller number of subsidiary cells and in stomata longitudinally orientated to the veins. Pseudoctenis sp. described by Carpentier (1939, pl. 8, figs 1-10, pl. 9, figs 1-9) shows differences in having stomata confined to well-defined costal zones and in extremely thickly cutinized subsidiary cells. P. cteniformis (NATHORST) HARRIS from the Rhaetic of Bjuf in Sweden ( Harris 1950) differs from P. babinensis in having numerous papillae on the adaxial cuticle and a lower number (4- 6) of subsidiary cells (compare Florin 1933, pl. 9, figs 1-7, text-figs 28, 29). Pseudoctenis florinii LUNDBLAD, 1950 differs from P. babinensis in having decurrent pinnae and stomata scattered on the complete abaxial surface of the pinnae (not avoiding veins). P. ensiformis HALLE (1913) lacks cuticles and therefore it is difficult to compare, it differs from P. babinensis in macromorphology of its pinnae which always show expanded bases ( Gee 1989). P. cornelii POTT recently described from the Triassic of Lunz ( Pott et al. 2007, pl. 1-3) differs from P. babinensis in having decurrent pinnae and well developed papillae on subsidiary and some ordinary cells.