A New Rhaphidopteris from the Lower Liassic of Bavaria, Germany*
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Acta Palaeobot. 41(2): 107–113, 2001 A new Rhaphidopteris from the Lower Liassic of Bavaria, Germany* JOHANNA H.A. VAN KONIJNENBURG-VAN CITTERT1, STEFAN SCHMEIßNER2 and GÜNTHER DÜTSCH3 1 Laboratory of Palaeobotany and Palynology, Budapestlaan 4, NL-3584 CD Utrecht, The Netherlands, e-mail: [email protected] 2 Matthäus-Schneider-Straße 14, D-95326 Kulmbach, Germany, e-mail: [email protected] 3 Eichbergstraße 25a, D-95369 Untersteinach, Germany, e-mail: [email protected] Received 5 March 2001; accepted for publication 6 June 2001 ABSTRACT. A new species of the genus Rhaphidopteris Barale, Rhaphidopteris duetschii (created by the first author), is described from a clay lens in a sandpit (‘Grube Dietz’) near the village of Pechgraben, northern Ba- varia. As good cuticle preparations could be made, the specimen is described in detail and compared to other species of the genus Rhaphidopteris (including species that were formerly described under Stenopteris Saporta). It is for the first time that a species of Rhaphidopteris has been recorded from Germany. So far, well-known species have been recorded from Greenland, Yorkshire (UK), France and China and vary in age between Rhaetian (latest Triassic) and Kimmeridgian (late Jurassic). KEY WORDS: Rhaphidopteris, cuticle, Lower Liassic, Germany INTRODUCTION The Lower Liassic (Hettangian) sediments species of this relatively rare genus. It is de- in Bavaria (Germany) contain a diverse fossil scribed here in detail. flora, mainly preserved in clay lenses in sandy sediments. Many of the old localities are inac- MATERIAL AND METHODS cessible nowadays but new sandpits provide The holotype originates from the sand pit (‘Grube’) often important new localities. In the last de- Dietz, south of Pechgraben (district Kulmbach); cade, many specimens have been found in TK 1:25.000, Blatt 5935 Marktschorgast, R 4467250, various clay lenses in two sand pits near the H 5541250. In sand pit Dietz an up to 10 m thick village of Pechgraben (district Kulmbach) in- Lower Liassic (Hettangian) fluviatile deltaic succes- cluding some interesting material and some sion is exposed. Clay lenses in various sizes are pres- ent in the so-called ‘Pflanzensandstein’ (Weber 1968). new species. For an up to date review, see Van They represent among others deposits of old water- Konijnenburg-van Cittert et al. (1998) and Van courses. When the sand is dug from the pit, the clay Konijnenburg-van Cittert & Schmeißner (1999). lenses disappear as well, so often they are only ex- From one of these sand pits, a specimen re- posed for a short period. In the lowermost of the re- sembling the Mesozoic genus Rhaphidopteris cently exposed clay lenses in sand pit Dietz the Rha- phidopteris specimen was found by Mr. Dütsch. It has was collected. Cuticular analysis indicates been deposited at the Staatliches Museum für Natur- that the specimen indeed belongs to this kunde Stuttgart (SMNS no. P.1879). The later found genus, and comparison with other well-known similar, smaller specimen from the same sand pit is species learns that we are dealing with a new kept in his private collection. The morphology of the type specimen was studied under a dissecting microscope and its cuticle was pre- pared by macerating in Schulze’s reagent (a saturated * This publication is NSG (Netherland School of Sedimen- mixture of KClO3 and 33% HNO3), followed by neu- tary Geology) Paper No. 20010604. tralisation in 5% ammonia. After rinsing thoroughly in 108 water, the upper and lower cuticles were separated longing to the genus Dicroidium because of the with needles and transferred to slides for LM study basal forking of the rachis. (Leitz Ortholux). There was too little material to do a SEM study as well. Zhou and Zhang (2000) divided the genus Rhaphidopteris into five morphological groups, in the same time describing two new species SYSTEMATIC PART from the Jurassic of China: Group 1, the R. astartensis-group (with the type species R. astartensis, R. nitida, R. nana, Pteridospermae R. gracilis and R. shaohuae, the latter two from the Jurassic of China) is characterized by Rhaphidopteris Barale 1972a pinnate or dichotomous leaves with segments of the different orders with more or less the Material of this particular type of leaf is for same width, containing one vein dividing only the first time described from the Liassic of Ba- below the division of the lamina. Cuticle thin varia (Germany). The genus Rhaphidopteris is with sparse stomata. characterized by usually bi-tripinnate, coria- Group 2, the R. williamsonis-group (R. wil- ceous leaves with narrow segments (pinnules). liamsonis, R. fragilis and R. cornuta, the latter The ultimate segments possess only one vein from China) differs from group 1 in having extending (almost) to the rounded apex. The more slender ultimate segments than the leaves are usually amphistomatic (stomata on other segments, and in the fact that only the both the upper and lower cuticle), but some- ultimate segments have only one vein. times the number of stomata on the upper cu- Group 3, the R. rhipidoides-group (with R. ticle is considerably less than on the lower one. rhipidoides from China) with wide, lobate seg- The haplocheilic stomata are typically sparse- ments and a flabellate venation. Cuticle is ly scattered and longitudinally oriented. The again thin with sparse stomata. number of subsidiary cells is around 4–6 but Group 4, the R. praecursoria-group encom- they are often uneven in size and shape, and passes some Russian, Chinese and a Japanese usually carry papillae. The guard cells are species, and is characterized by pinnate leaves situated at the bottom of a small rectangular with wide segments, a pinnate venation and a pit, thinly cutinised. Trichomes are usually thick cuticle with numerous actinocytic stomata. present. Group 5, the R. dinosaurensis-group (R. di- Harris (1932, 1964) described similar seed nosaurensis and Stenopteris spectabilis from ferns from the Rhaeto-Liassic of Greenland the Liassic of China) has dorsiventral organs and the Middle Jurassic of Yorkshire in the with sessile, mostly bifurcating leaves. The cu- genus Stenopteris Saporta 1873. This genus, ticle is rather thick with usually numerous however, does not exist anymore as its type stomata. species, Stenopteris desmomera, was at- Zhou and Zhang (op. cit.) considered that tributed to the genus Pachypteris Brongniart. group 4 with its thick cuticle and numerous Therefore, Barale (1972a) created the new actinocytic stomata had little in common with genus Rhaphidopteris for the material of Ste- R. astartensis and might rather belong to the nopteris that was clearly different from Pa- genus Pachypteris. Group 5 is completely dif- chypteris. He choose Rhaphidopteris astarten- ferent in leaf organisation from the type sis (Harris)Barale from the Jurassic of species and was placed as the type species in Greenland as the type species for the new the genus Tharrisia Zhou, Wu & Zhang (Zhou genus, and made five new combinations in et al. 2001). Thus they restricted the genus Rhaphidopteris (two from the Rhaeto-Liassic Rhaphidopteris to the groups 1 to 3. of Greenland and three from the Middle Juras- As to the affinities of this genus, both Har- sic of Yorkshire). Harris (1981) agreed with ris (1932, 1964) and Barale (1972a, b) believed this. In the same year Barale (1972b) de- that it is related to the Mesozoic pterido- scribed a new species of Rhaphidopteris, R. sperms. Unfortunately, no fructification has fragilis, from the Kimmeridgian of France. He ever been found in connection with any of the also considered the three Southern Hemis- species. The only reason for this assumption is phere species of Stenopteris (see Jones & De the pinnate leaf morphology in combination Jersey 1947) as being different and rather be- with the presence of a resistant cuticle. How- 109 ever, Rhaphidopteris differs from e.g. the Co- from the lowermost part of the pinna rachis. rystospermales and Peltaspermales in cuticu- The following pinnules arise more or less al- lar structure and especially in the configura- ternating with a long (up to 3 mm) decurrent tion of the stomata. According to Harris (1932, base along the rachis and a lamina that then 1935, 1964) the cuticle even resembles that of curves outwards at 30–45°. The basal pinnules Czekanowskia and narrow leaves of Baiera. (ca. 5 mm long and 1–2 mm wide) are slightly So, the relationship of the form genus Rhaphi- lobed, the more apical ones (3 mm long, 1 mm dopteris remains unclear. wide) are entire. The apices are obtuse and there are no veins visible. Next to the here described leaf fragment, Rhaphidopteris duetschii van some apical parts of another fragment are Konijnenburg-van Cittert sp. nov. visible that might have belonged to the same Pl. 1 figs 1–8 leaf. If this was the case, then the leaf was tri- pinnate at least. H o l o t y p e. Pl. 1 figs 1, 2. The relatively thin cuticle is amphistomatic R e p o s i t o r y. Staatliches Museum für Natur- (ca. 2 μm thick) but the majority of stomata oc- kunde Stuttgart (SMNS no. P.1879). curs on the lower cuticle (compare Pl. 1 figs 5 Type locality. Sand pit Dietz, Pechgraben, and 8). The midrib is clearly indicated by lon- Bavaria, Germany. gitudinal epidermal cells on both cuticles, sec- Stratigraphy and age. Early Liassic, ondary veins are only vaguely indicated by Hettangian. a few rows of slightly elongated cells. All other E t y m o l o g y. After Mr. G. Dütsch who found epidermal cells are more or less isodiametric. the holotype. The stomata are simple, consisting of 2 unsun- ken guard cells surrounded by 5–6 subsidiary D i a g n o s i s.