Marattiopsis vodrazkae J. Kvaček, 2014

Kvaček, Jiří, 2014, Marattiopsis Vodrazkae Sp. Nov. (Marattiaceae) From The Campanian Of The Hidden Lake Formation, James Ross Island, Antarctica., Acta Musei Nationalis Pragae Series B 70 (3 - 4), pp. 211-218 : 212-214

Marattiopsis vodrazkae J. Kvaček , sp. nov.

Pl. 1, figs 1–10, Pl. 2, figs 1, 2

H o l o t y p e: CGS No. AN 491 (pl. 1, figs 1–3) designated here.

P a r a t y p e: CGS No. AN 493 (pl. 1, fig. 7) designated here.

T y p e l o c a l i t y: A32-2; James Ross Island,

Antarctica.

T y p e h o r i z o n: Coniacian, Late Cretaceous, Hidden

Lake Formation.

E t y m o l o g y: After my colleague Radek Vodrážka who intensively collected fossils on James Ross Island in the period 2009-2011.

O t h e r m a t e r i a l: James Ross Island, Antarctica locality A32-2: AN 492, AN 495, AN 506ab (CGS); IAA 005-008, IAA 022; locality A32-1: IAA 083; locality A32-3: IAA 043.

D i a g n o s i s. Isolated pinnules oblong to oblong-lanceolate, tapering gradually towards the apex; base with basiscopic auricle and short petiolule; apex acute, pinnule margins varying from undulate, denticulate to dentate, venation simply pinnate, eucamptodromous consisting of one vein order. Lateral veins commonly forking immediately at, or near, the midrib, leaving the midrib at an acute angle. Synangia shortly stalked consisting of two deeply divided valves. Each valve consisting of 5–6 sporangia. Spores in situ monolete, granular to delicately rugate.

D e s c r i p t i o n. The holotype (Pl. 1, fig. 1) is an exceptionally well preserved specimen showing two synangia born on a pinnule fragment (40 x 50 mm). One synangium is broken longitudinally, another one perpendicularly (Pl.1, fig. 1). The synangia are arranged in the central part of the pinnule lamina (Pl. 1, fig. 2). The longitudinally broken synangium (Pl. 1, fig. 3) shows an elliptic valve with six sporangia. The valve is 1.6 mm long and 1 mm high. Each sporangium is elongate ovoid, 1 mm long and 0.2–0.5 mm in diameter. The synangium length occupies about 20–35% of the pinnule width (Pl.1, fig. 1). In the transversal section the synangium is deeply divided into two valves, bilaterally symmetrical and spindle-shaped. The valves are erect, ovate, pointed in apical parts. Both valves are born on a short common stalk 0.2 mm in length (Pl. 1, fig. 1). The sporangium walls consist of elongate cells (Pl. 2, fig. 1). Spores in situ 25–32 Μm in diameter are probably not mature. They are tightly pressed together and arranged in diades (Pl. 2, fig. 2). They are monolete, ellipsoid in equatorial outline showing a granular, rugate exospore (Pl. 2, fig. 2).

The lamina fragment of the holotype shows the same venation pattern and dentate margin as other isolated pinnules. Sterile material is typified by the paratype (Pl. 1, fig. 7) showing an oblong-lanceolate sterile pinnule nearly 20 mm in length with a vein density of 14 veins per cm. Its base is asymmetrical with a relatively well pronounced basiscopic auricle. Venation of each pinnule is pinnate, the robust main midrib reaching the pinnule apex. Robust lateral veins in basal and medial parts of the pinnule fork immediately at, or near, the midrib. Each lateral vein terminates in a tooth. Paired veins unite two adjacent teeth into pairs which form a characteristic double dentate pattern (see Pl. 1, fig. 7).

Other material comprises a number of isolated pinnules. The fertile pinnules (IAA 006, 007) usually do not have preserved synangia (Pl. 1, fig. 10). However, their scars or impressions show an arrangement of six to ten synangia in three to five pairs per pinnule. They were born on lateral veins nearby the midrib (Pl. 1, fig. 10). With respect to the sterile pinnules, a completely preserved pinnule is invaluable, with a low vein density (10 veins per cm), a denticulate - undulate margin, asymmetrical auriculate base and acute apex (Pl. 1, fig. 8). Further material (Pl. 1, fig. 4) displays pinnule fragments (18 x 8 mm) showing a nearly symmetrical, slightly cordate base with a delicate fragment of petiolule and fragmentarily preserved apex. Marginal teeth are blunt, inconspicuous forming an undulate margin. The specimen AN 506a (Pl. 1, fig. 5) shows an undulatedenticulate margin and asymmetrically auriculate base with a well pronounced short petiolule. The specimen AN 495 shows an apical fragment of a pinnule with bifurcating terminal part of the midrib (Pl. 1, fig. 6). The specimen IAA 008 shows a well preserved asymmetrical auricule with a suprabasal vein bent backwards (Pl. 1, fig. 9).

D i s c u s s i o n. Marattiopsis vodrazkae is known only from the Hidden Lake Formation on James Ross Island. It is unusual within the genus in having remarkably smaller pinnules than the rest of the Marattiopsis species. However, its typical type of sporangia forming synangia and the characteristic occurrence of only isolated pinnules with basiscopic auricles argue for inclusion of this material into the genus Marattiopsis .

The type species Marattiopsis crenulata LUNDBLAD from the Triassic of Sweden ( Lundblad 1950) proposed by Bomfleur et al (2013) differs from the present material in having marginally arranged synangia and remarkably larger sized pinnules. It also differs in lacking short stalked synangia.

Yang (et al 2008) and Esacpa (et al 2014) suggested a list of diagnostic characters which can help us compare M.

vodrazkae sp. nov. with the other species of the genus. The characters are in particular the type of pinnule margin, vein density, presence or absence of venuli recurrentes, number of septa per sporangium and ratio of synagium length to pinnule width ( Tab. 1). M. vodrazkae differs from all of the listed species in several important characters. It has short stalked synangia, 5–6 septa pairs per synangium and remarkably small pinnules. As it is clear from Table 1 M . vodrazkae differs from Marattiopsis aganzhenensis (YANG, WANG, PFEFFERKORN) ESCAPA, BOMFLEUR, CUNEO, SCASSO. from the Early Jurassic of China ( Yang et al. 2008) and M. anglica THOMAS from the Jurassic of Great Britain (van Konijnenburg van Cittert 1975) in absence of entire margined pinnules, round, symmetrical base and lower number of sporangia per valve. M. vodrazkae differs from M. angustifolia PRYNADA from the Jurassic of Russia ( Prynada 1938) and M. asiatica KAWASAKI from the Triassic of Korea, Japan, Vietnam and China ( Kawasaki 1939, Wang 1999), from M. curvinervis (LORCH) ESCAPA, BOMFLEUR, CUNEO, SCASSO from the Jurassic of Israel ( Lorch 1967), from M. hoerensis (SCHIMPER) SCHIMPER from the Triassic of Sweden ( Schimper 1869), from M. muensteri (GÖPPERT) SCHIMPER from the Rhaeto-Liassic of Germany, from M. intermedia (MÜNSTER) WEBER from the Rhaeto-Liassic of Bayreuth ( Weber 1968) and from M. patagonica ESCAPA, BOMFLEUR, CUNEO, SCASSO from the Early Jurassic of Argentina ( Escapa et al. 2014) in the absence of venuli recurrentes and lower number of sporangia per valve. M. vodrazkae differs from M. barnardii (SCHWEITZER, VAN KONIJNENBURG – VAN CITTERT, VAN DER BURGH) ESCAPA, BOMFLEUR, CUNEO, SCASSO from the Rhaeto-Liassic of Iran ( Schweitzer et al. 1997) in having a lower number of sporangia per valve, more asymmetrical bases and smaller size of pinnules. Those species of

Marattiopsis based on sterile foliage only are not compared with M. vodrazkae due to lack of the important synangia characters.