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Jan.  2020
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Ufadendron elongatum sp. nov., an Angaran Lycopsid from the Upper Permian of Inner Mongolia, China

  • A new species Ufadendron elongatum sp. nov.,attributed to the family Tomiodendraceae Naugolnykh,is represented by two well-preserved stems in the collection under study. This new species was recently discovered from the Upper Permian Linxi Formation in the Jalaid locality,the Inner Mongolia Autonomous region,China. The genus Ufadendron is characterized as having the long fusiform leaf cushions,with small and rounded leaf scar containing a central point-like scar which is situated at the upper part of leaf cushion; the infrafoliar bladder of fusiform shape positioned in the middle part of leaf cushion; the wings and heel well-developed in the lateral parts and the lower part of leaf cushion,respectively. The new species is different from the type species U. ufaense (Naugolnykh 2014) collected from the Lower Permian of the Cis-Urals,western limits of Angaraland,in the elongated leaf cushion and in the well-pronounced heel. It should be noted,that a vascular bundle (conductive strand) occupied the middle part of the central point-like scar. So far,only 5 genera of Angaran elements among lycopsids have been discovered in the region geographically belonging to Angaran Realm (Phytogeoprovince) in China. The new species U. elongatum not only enlarges our knowledge on the taxonomy of Tomiodendraceae lycopsids,and also provides an opportunity to understand the difference between Angaran and Cathaysian floras in paleoclimatic context.
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  • Archangelsky, S., Azcuy, C. L., Wagner, R. H., 1981. Three Dwarf Lycophytes from the Carboniferous of Argentina. Scripta Geology, 64: 1-35
    Baud, A., 2018. Final Results and Recommendations of the Last 10 Years IGCP 572 and 630 Field Workshops in South Turkey, Oman, India (Kashmir) and Armenia. Journal of Earth Science, 29(4): 733-744. https://doi.org/10.1007/s12583-018-0796-2
    Boucot, A. J, Chen, X., Scotese, C. R., et al., 2013. Phanerozoic Plaeoclimate: An Atlas of Lithologic Indicators of Climate. Society for Sedimentary Geology, Oklahoma. 478
    Chaloner, W. G., Leistikow, K. U., Hill, A., 1979. Brasilodendron gen. nov. and B. pedroanum (Carruthers) comb. nov., a Permian Lycopod from Brazil. Review of Palaeobotany and Palynology, 28(2): 117-136. https://doi.org/10.1016/0034-6667(79)90004-6
    Halle, T. G., 1937. The Relation between the Late Paleozoic Floras of Eastern and Northern Asia. C. R. Deuxième Congrès Pour L'Avancement des Etudes de Stratigraphie Du Carbonifère, 1: 237-245
    Huang, B. H., 1977. Permian Flora from the Southeastern Part of the Xiao Hinggan Ling (Lesser Khingan Mt.), NE China. Geological Publishing House, Bejing. 79 (in Chinese)
    Huang, B. H., 1993. Carboniferous and Permian Systems and Floras in the Da Hinggan Range. Geological Publishing House, Bejing. 141 (in Chinese)
    Khan, M. A., Bera, S., 2016. Occurrence of Persea Mill. from the Siwalik Forest of Darjeeling, Eastern Himalaya: Paleoclimatic and Paleogeographic Implications. Journal of Earth Science, 27(5): 883-890. https://doi.org/10.1007/s12583-016-0902-2
    Leven, E. J., Naugolnykh, S. V., Gorgij, M. N., 2011. New Findings of Permian Marine and Terrestrial Fossils in Central Iran (the Kalmard Block) and Their Significance for Correlation of the Tethyan, Uralian and West European Scales. RivistaItaliana di Paleontologia e Stratigrafia, 117(3): 355-374. https://doi.org/10.13130/2039-4942/5981
    Li, X. X., Shen, G. L., Tian, B. L., et al., 1995. Some Notes on Carboniferous and Permian Floras in China. In: Li, X. X., ed. Fossil Floras of China through the Geological Ages. Guangdong Science and Technology Press, Guangzhou. 244-302
    Meyen, S. V., 1972. Are There Ligula and Parichnos in Angara Carboniferous Lepidophytes?. Review of Palaeobotany and Palynology, 14(1/2): 149-157. https://doi.org/10.1016/0034-6667(72)90016-4
    Meyen, S. V., 1976. Carboniferous and Permian Lepidophytes of Angaraland. Palaeontographica Abt. B., 157: 112-157
    Naugolnykh, S. V., 2014. Fossil Flora from the Aleksandrovskoe Locality (Lower Permian, Kungurian; Krasnoufimsk District of the Sverdlovsk Region): Taxonomical Composition, Taphonomy, and a New Lycopsid Representative. Paleontological Journal, 48(2): 209-217. https://doi.org/10.1134/s0031030114020105
    Naugolnykh, S. V., 2016. Flora Permica. Plant World of Permian Period. Geos Press, Moscow. 336 (in Russian)
    Naugolnykh, S. V., Uranbileg, L., 2018. A New Discovery of Glossopteris in Southeastern Mongolia as an Argument for Distant Migration of Gondwanan Plants. Journal of Asian Earth Sciences, 154: 142-148. https://doi.org/10.1016/j.jseaes.2017.11.039
    Radczenko, G. P., 1955. Index-Fossils of the Upper Palaeozoic Flora of the Sayan-Altai Region. Atlas Rukovod. Form Iskop. Fauny i Flory Zap. Sibiri, 2: 42-153
    Sun, K. Q., Cui, J. Z., Wang, S. J., 2010. Fossil flora of China, Volume 2: Fossil Pteridophytes in China. Higher Education Press, Bejing. 438 (in Chinese)
    Sun, Y. W., Ding, H. S., Liu, H., et al., 2016. Fossil Plants from the Guadalupian Yujiabeigou Formation in the North Margin of North China Plate and Their Tectonic Implications. Journal of Jilin University (Earth Science Edition), 46(5): 1268-1283 (in Chinese with English Abstract)
    Taylor, T. N., Taylor, E. L., Krings, M., 2009. Paleobotany-The Biology and Evolution of Fossil Plants. Academic Press (Elsevier), Boston. 1230
    Thomas, B. A., Meyen, S. V., 1984. A System of Form-Genera for the Upper Palaeozoic Lepidophyte Stems Represented by Compression-Impression Material. Review of Palaeobotany and Palynology, 41(3/4): 273-281. https://doi.org/10.1016/0034-6667(84)90049-6
    Wang, X. F., Chen, X. H., 2015. Stratigraphic Division and Correlation of Each Geological Period in China. Geological Publishing House, Beijing. 596 (in Chinese)
    Zalessky, M. D., 1918. Flore Paléozoique de la Série d'Angara. Atlas. Mémoires du Comité Géologique: Nouvelle Série, 147: 5-76
    Zalessky, M. D., 1936. Sur Quelques Plantes Nouvelles du Système Anthracolitique du Bassin de Kousnetzk. Problems of Paleontology, Moscow University, 1: 223-236
    Zhang, Y. S., Niu, S. W., Tian, S. G., et al., 2012. The Discovery of Conchostracan Fossils in the Upper Permian Linxi Formation of Linxi Area, Inner Mongolia, and Its Geological Significance. Geological Bulletin of China, 31(9): 1394-1403 (in Chinese with English Abstract)
    Zhang, Y., Wang, J., Wu, X. Y., 2006. Cathaysiodendron Yangshanense sp. nov. from the Early Carboniferous Yangshan Formation of Gushi, Henan. Acta Palaeontology Sinica, 45(2): 265-267 (in Chinese with English Abstract)
    Zhang, Y., Zheng, S. L., Naugolnykh, S. V., 2012. A New Species of Lepidopteris Discovered from the Upper Permian of China with Its Stratigraphic and Biologic Implications. Chinese Science Bulletin, 57(27): 3603-3609. https://doi.org/10.1007/s11434-012-5282-0
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Ufadendron elongatum sp. nov., an Angaran Lycopsid from the Upper Permian of Inner Mongolia, China

    Corresponding author: Yi Zhang, zhangyihzlmh@synu.edu.cn
  • 1. College of Earth Sciences, Jilin University, Changchun 130061, China
  • 2. Shenyang Center of Geological Survey, China Geological Survey, Shenyang 110034, China
  • 3. College of Paleontology, Shenyang Normal University, Shenyang 110034, China
  • 4. Key Laboratory for Evolution of Past Life in Northeast Asia, Ministry of Natural Resources, Shenyang 110034, China
  • 5. Geological Institute, Russian Academy of Sciences, Moscow 119017, Russia
  • 6. Kazan Federal University, Kazan 420000, Russia

Abstract: A new species Ufadendron elongatum sp. nov.,attributed to the family Tomiodendraceae Naugolnykh,is represented by two well-preserved stems in the collection under study. This new species was recently discovered from the Upper Permian Linxi Formation in the Jalaid locality,the Inner Mongolia Autonomous region,China. The genus Ufadendron is characterized as having the long fusiform leaf cushions,with small and rounded leaf scar containing a central point-like scar which is situated at the upper part of leaf cushion; the infrafoliar bladder of fusiform shape positioned in the middle part of leaf cushion; the wings and heel well-developed in the lateral parts and the lower part of leaf cushion,respectively. The new species is different from the type species U. ufaense (Naugolnykh 2014) collected from the Lower Permian of the Cis-Urals,western limits of Angaraland,in the elongated leaf cushion and in the well-pronounced heel. It should be noted,that a vascular bundle (conductive strand) occupied the middle part of the central point-like scar. So far,only 5 genera of Angaran elements among lycopsids have been discovered in the region geographically belonging to Angaran Realm (Phytogeoprovince) in China. The new species U. elongatum not only enlarges our knowledge on the taxonomy of Tomiodendraceae lycopsids,and also provides an opportunity to understand the difference between Angaran and Cathaysian floras in paleoclimatic context.

0.   INTRODUCTION
  • The genus Ufadendron (Naugolnykh 2014), as a typical element of the Paleozoic lycopsids found in the Lower Permian of the Cis-Urals, western limits of Angaraland, is characterized as having the long fusiform leaf cushions, with small and rounded leaf scar containing a central point-like scar, situated at the upper part of leaf cushion; the infrafoliar bladder of fusiform shape positioned in the middle part of leaf cushion; the wings and heel well developed in the lateral parts and the lower part of the leaf cushion, respectively; ligula absent (Fig. 1). The genus is attributed to the family Tomiodendraceae (Naugolnykh, 2016), characterized by the presence of leaf cushions forming clear parastichies, and each leaf cushion developing central infrafoliar bladder. The family includes the following genera: Tomiodendron (Radczenko 1955) Meyen 1976, Angarodendron (Zalessky 1918) Meyen 1976, Lophiodendron (Zalessky 1936) Meyen 1976, Angarophloios Meyen 1972, and Ufadendron (Naugolnykh 2014). Most of them are representing endemic elements of the Division Lycophyta from the Upper Paleozoic Angaran flora (Naugolnykh, 2016; Meyen, 1976).

    Figure 1.  Ufadendron ufaense (Naugolnykh 2014), Zhang et Naugolnykh emend. nov. ① Showing a leaf cushion with clear structures, including LS, CS, KL and IB; ② showing a leaf cushion with a suggested heel because the lower part of the leaf cushion enters the matrix, indicating the presence of a heel (Meyen, 1976); ③ showing a leaf cushion with two suggested wings because the lateral corners of the leaf cushion enters the matrix, indicating the presence of wings (Meyen, 1976); ④ showing a leaf cushion with a keel. LC. Leaf cushion; LS. leaf scar; CS. central point-like scar; KL. Keel; IB. infrafoliar bladder; WG. wing; HL. heel.

    The genus Ufadendron is very similar to Angarophloios in presence of the infrafoliar bladder, but the former genus develops a marked leaf scar (Naugolnykh, 2014), while the latter shows only a leaf basis, which is buried in the matrix (Meyen, 1976, 1972). Although no clear evidence demonstrates that the wings and heel are developed in the U. ufaense specimens as those in A. leclercqianus, Meyen has given us an useful approach to analyze if wings and heel are present or not, i.e., the lateral corners and the lower part of leaf cushion entering the matrix infer that wings and heel are present, respectively (Meyen, 1976). According to the Meyen's terminology, the genus Ufadendron also develops the wings and heel (Fig. 1, WG, HL). This suggestion has been demonstrated by our finding of a new representative of Ufadendron, i.e., U. elongatum sp. nov., represented by two stems collected from the Upper Permian Linxi Formation at the Jalaid locality of Inner Mongolia, China (Figs. 2a, 2b). Based on presence of the wings and heel characteristic in the leaf cushions of both these two species, the emended generic diagnosis of Ufadendron is given.

    Figure 2.  The location of the study area where Ufadendron elongatum sp. nov. was found. (a) The geographic map of Northeast China. XMR. Xar Moron River (Silas Mulun River), LR. Liaohe River; (b) the geologic map of the Jalaid locality in Inner Mongolia, China, enlargement of the frame in (a); (c) the stratigraphic column of the Linxi Formation in the Nanmalatu Village of Jalaid and the bed yielding U. elongatum sp. nov; (d) the locality where the specimens of U. elongatum sp. nov. were collected. Fm. Formation.

1.   MATERIAL AND METHODS
  • The Linxi Formation consists of two members (Wang and Chen, 2015). The lower member predominately is composed of a set of dark-gray silty slates and fine-grained, tuffaceous clastic rocks intercalated with intermediate to acidic volcanic rocks, yielding fossil plants and bivalves; while the upper member is mainly constituted by yellow-green clastic rocks with mud pebbles, bearing fossil plants. The Linxi Formation is mainly distributed in the area of Inner Mongolia, i.e., the Great Khingan Range (Da Hinggan Mountain Range), northwards of the Silas Mulun River (Fig. 2a) (Zhang et al., 2012). The Silas Mulun River is the plate boundary between Inner Mongolia and North China (Sun et al., 2016).

    The thickness of the Linxi Formation markedly changes in different areas of the region studied. In the area studied, where we found Ufadendron, only a part of the lower member of the Linxi Formation is outcropped, exposing about 90 m of thickness. The Linxi Formation here overlies conformably the Middle Permian Zhesi Formation, and unconformably underlies the Upper Jurassic Manitu Formation (Figs. 2b, 2c).

    Two fossil specimens representing the outer surface of the Ufadendron stems, preserved as impressions (Figs. 3a, 3b), were collected from the dark-gray argillaceous slates, about 300 m northwest of the Nanmalatu village in Jalaid, Inner Mongolia, China (121°58′40.22″E, 46°57′4.27″N) (Figs. 2b, 2d). The Jalaid locality geographically belongs to the area of Great Khingan Range. The associated fossil plants are Paracalamites frigidus, Noeggerathiopsis sp. and Psygmophyllum sp., representing the typical elements of the Angaran flora. The associated lacustrine bivalves, Paleomutela khinganensis were collected in this locality also. The genus Paleomutela is one of the most typical elements of the Paleonodonta-Paleomutela assemblage in the Upper Permian Linxi Formation. The Paleonodonta-Paleomutela assemblage is widely distributed in the Upper Permian of Inner Mongolia-the Great Khingan Range, Middle Jilin, Heilongjiang as well as Siberia and the Russian Far East (Zhang et al., 2012).

    Figure 3.  Specimens of Ufadendron elongatum Zhang, Naugolnykh, et Tang sp. nov. (a) Specimen No. TF009HS2, showing the stem with leaf cushions preserved; (b-d) specimen No. TF009HS3. (b) the stem with leaf cushions preserved; (c) enlargement of the frame in Fig. 3b, showing the length and width of leaf cushions (LC) and lycopsid phyllotaxy with well expressed even parastichies (dotted lines), but orthostichies absent; (d) enlargement of the frame in Fig. 3c, showing the structure of leaf cushions, including leaf scars (LS), infrafoliar bladders (IB), and a heel (HL).

    Morphology of the leaf cushion with wings and heel was studied by means of the VEX-600E microscope and digital camera Canon A700 made in Japan. Leaf scars, infrafoliar bladders and heels preserved in the specimen No. TF009HS3 are able to be observed on the horizontal plane (Fig. 3d); while wings and heels are able to be confirmed when the specimen No. TF009HS2 was observed from a slightly inclined plane (Fig. 4b). Pictures of the stems were taken by Canon A700, while those of leaf cushions were taken by VEX-600E.

    Figure 4.  Specimens of Ufadendron elongatum Zhang, Naugolnykh, et Tang sp. nov., No. TF009HS2. (a) Enlargement of Fig. 3a, showing the structure of the leaf cushions ①-⑤, and infrafoliar bladders (IB) and heels (HL); (b) enlargement of the frame ① in Fig. 4a, showing a leaf cushion with distinct infrafoliar bladder (IB), wings (WG) and a heel (HL) imbedded in the matrix; (c) enlargement of the frame ② in Fig. 4a, showing a leaf cushion with a leaf scar (LS), a central point-like scar (CS) and a keel (KL).

    Based on leaf cushions shown in two known species of Ufadendron, which develop wings and heels, the genus diagnosis of Ufadendron is emended. Specimens of the new species are housed at Shenyang Center of Geological Survey, China Geological Survey.

2.   RESULTS
  • Division: Lycophyta (Lycopodiophyta)

    Family: Tomiodendraceae (Naugolnykh 2016)

    Genus: Ufadendron (Naugolnykh 2014), Zhang et >Naugolnykh emend. nov.

    Type species: Ufadendron ufaense (Naugolnykh 2014), Zhang et Naugolnykh emend. nov.

    Emended diagnosis: Lycopsids with long fusiform leaf cushions, arranged in even well-defined parastichies. Leaf scar small and rounded, point-like, central or positioned at upper part of leaf cushions. Longitudinal keel developed in different extent, located just below the leaf scar. Infrafoliar bladder of fusiform shape, situated at the middle axial part of the leaf cushion. Wings and heel developed at the both sides and the lower part of leaf cushion, respectively. Ligule absent.

    Ufadendron ufaense (Naugolnykh 2014), Zhang et Naugolnykh emend. nov.

    2014 Ufadendron ufaensis, Naugolnykh, pp. 213; Pl. 17, Figs. 2, 3.

    Diagnosis and detailed description: in the protologue.

    Etymology: The specific epithet is after the Ufa River.

    Holotype: GDM, no. OF 15450, imprint of bark.

    Occurrence: Krasnoufimsk District, Sverdlovsk Region,

    Aleksandrovskoe locality; Koshelevsk Formation, Irenian Horizon, Upper Kungurian, Lower Permian.

    Ufadendron elongatumZhang, Naugolnykh et Tang sp. nov.

    Diagnosis: Lycopsids with long fusiform leaf cushions arranged in even parastichies. Leaf scar small and rounded with a central point-like scar, positioned at the upper part of leaf cushion. The middle area of the central point-like scar occupied by a vascular bundle. Longitudinal keel very short, located just below leaf scar. Infrafoliar bladder of fusiform shape, situated at the middle part of leaf cushion. Wings developed at the both sides of leaf cushion, while heel well developed, situated at the lower part of leaf cushion. Ligule absent.

    Etymology: The specific epithet is based on the morphology characteristic of leaf cushions.

    Holotype: The specimens Nos. TF009HS2 and TF009HS3.

    Occurrence: Nanmalatu of Jalaid, Inner Mongolia, China; the Linxi Formation (Upper Permian).

    Description: The collection studied includes two specimens of the lycopsid stems assigned to this new species. Both stems are eligulate with long fusiform leaf cushions, arranged in regular helical order. Even parastichies are well expressed in the stems.

    The smaller specimen (No. TF009HS2), showing a stem about 3 cm in length and 6 cm in width (Fig. 3a), preserves clear structures including leaf cushions (Fig. 4a, ①-⑤), infrafoliar bladders (Fig. 4a, IB), wings (Fig. 4b, WG), heels (Fig. 4b, HL), leaf scars (Figs. 4c, 5b, LS), a central point-like scar disposed at the middle of the leaf scar (Figs. 4c, 5b, 5c, CS) and keels (Figs. 4c, 5b, KL). Leaf cushions are relatively large, attaining 20 mm in length and 5 mm in width. The leaf scar is small, rounded, attaining a diameter of 2.5 mm (Fig. 5b, LS), positioned at the upper part of the leaf cushion (Fig. 5a). A central point-like scar is situated at the middle of the leaf scars, attaining a diameter of 0.8 mm (Fig. 5b, CS), with a vascular bundle enclosed by a sheath (Fig. 5c, BS), attaining a diameter of 260 μm. The thickness of the vascular bundle sheath is up to 20 μm. Individual tracheids are not clearly visible. Longitudinal keel is very short, less than 1 mm in length, located just below the leaf scar (Figs. 4c, 5b, KL). The infrafoliar bladder of fusiform shape, is located at the middle part of the leaf cushion, attaining 4 mm in length and 1.5 mm in width. Wings are developed at the both sides of the leaf cushion, while the heel is marked at the lower part of the leaf cushion. Ligule is absent.

    Figure 5.  Specimens of Ufadendron elongatum Zhang, Naugolnykh, et Tang sp. nov., No. TF009HS2. (a) Enlargement of the frame ③ in Fig. 4a, showing a leaf cushion; (b) enlargement of the frame in Fig. 5a, showing a leaf scar with a central point-like scar, and a keel; (c) enlargement of the frame in Fig. 5b, showing a vascular bundle enclosed by a sheath, occupied in the middle of the central point-like scar. LS. Leaf scar, CS. central point-like scar, KL. keel, BS. vascular bundle sheath.

    The larger specimen (No. TF009HS3), showing a stem about 7 cm long and 6 cm wide, also demonstrates some important structures of the species, especially its infrafoliar bladders and the leaf scars. The leaf cushions are somewhat smaller in relation to the specimen described above, attaining 15 mm in length and 3.5 mm in width (Fig. 3c, LC), with the infrafoliar bladders attaining 3 mm in length and 1.2 mm in width (Fig. 3d, IB).

3.   DISCUSSIONS
  • The genus Ufadendron is very similar to the closely related genus Angarophloios in presence of the infrafoliar bladder as well as the wings and heel, but the former genus develops the leaf scar with a central point-like scar containing conductive tissues, disposed at the upper part of leaf cushion (Naugolnykh, 2014), while the latter genus shows only the leaf base buried in the matrix. The new species is different from the type species U. ufaense (Naugolnykh 2014) collected in the Lower Permian of the Cis-Urals, western limits of Angaraland, in its elongated leaf cushions, well developed heel and shorter keel.

    The wings and heel are special morphological structures of Angaran lycopsids, which are defined as lateral extensions present in the leaf cushion and/or along the lower limits (margin) of the leaf cushion, which are more distinct than the upper limits, respectively. Occasionally, they can be observed in transverse section and/or in longitudinal section, respectively, such as it was recorded for the species Angarophloios leclercqianus (Meyen, 1972, pp. 155); sometimes the wings and heel could be inferred by the lateral corners and the lower part of the leaf cushion entering the matrix (Meyen, 1976, pp. 133). In our study, the new species clearly shows the wings when the specimen No. TF009HS2 is observed from a slightly inclined plane (Fig. 4b, WG), and the heel can be easily found on the trunk (Figs. 4a, 4b, HL).

    Before Ufadendron elongatum is discovered in China, four genera of Angaran elements of lycopsids have been discovsered in the region geographically belonging to Angaran Phytogeoprovince in China (Sun et al., 2010; Huang, 1993, 1977). Angaran elements of lycopsids recorded in China are shown in Table 1, while their localities in Fig. 6.

    Genera Species Ages Occurrences References
    Caenodendron C. primaevum Mississippian Xinjiang Sun et al. (2010)
    C. karagandense Mississippian Xinjiang Sun et al. (2010)
    "Angarodendron?" "A.?" baoligeense Pennsylvanian Da Hinggan Range of Northeast China Huang (1993)
    Eichwaldia E. biarmica Lopingian Da Hinggan Range of Northeast China Huang (1993)
    E. ulanzhaoensis Lopingian Da Hinggan Range of Northeast China Huang (1993)
    Viatscheslavia V. sp. Lopingian Xiao Hinggan Range of Northeast China Huang (1977)
    Ufadendron U. elongatum sp. nov. Lopingian Da Hinggan Range of Northeast China

    Table 1.  Angaran elements of lycopsids recorded in China

    Figure 6.  The localities of Angaran lycopsids in China. ① Caenodendron primaevum; ② C. karagandense; ③ "Angarodendron?" baoligeense; ④ Eichwaldia biarmica; ⑤ E. ulanzhaoensis; ⑥ Viatscheslavia sp.; ⑦ Ufadendron elongatum sp. nov. GP. Gondwanan phytogeoprovince, AP. Angaran phytogeoprovince, EP. Euramerican phytogeoprovince, CP. Cathaysian phytogeoprovince. Black and white circles representing Carboniferous and Permian taxa, respectively. The background figure is referenced to Halle, 1937.

    Four phytogeoprovinces (paleofloristic realms), i.e., Euramerian, Cathaysian, Angaran, and Gondwanan phytogeoprovinces, were differentiated in the world during the Carboniferous and Permian time (Fig. 6). Taxonomical composition of lycopsids in these realm is different, as it is very well-known and broadly discussed in paleobotanical literature. Compared with the lycopsids from Euramerian Phytogeoprovince, the Cathaysian lycopsids generally have larger leaf scars, most commonly rhomboid-quadrate in shape, and characterized by absence of the lower parichnos. This morphological pattern forms the characteristic morphology of such oriental lycopsids as Cathaysiodendron (Zhang et al., 2006; Li et al., 1995), for instance.

    Some Angaran and Gondwanan lycopsids are generally lack of ligule, for example, the genera Angarophloios (Thomas and Meyen, 1984) and Ufadendron. Same or similar morphology is characteristic for some Gondwanan lycopsids, such Bumbudendron, Malanzania (Archangelsky et al., 1981) and Brasilodendron (Chaloner et al., 1979). Nonetheless, there are some cosmopolitan taxa, such as Lepidodendron and Sigillaria, which are widely distributed in Upper Paleozoic (mostly, Carboniferous) floras of the northern hemisphere.

    Lycopsids were widely distributed in the Late Paleozoic world. The difference of the leaf cushions and leaf scars among the lycopsids from the four phytogeoprovinces indicates that the paleoclimates were different during the Late Paleozoic. Lycopsids from the Euramerican phytogeoprovince with the most complicated leaf cushions and leaf scars, grew in tropical climatic conditions existed in the Euramerican phytogeoprovince (Boucot et al., 2013; see this paper for further references), and this region was the most comfortable and suitable area for the arborescent lycopsids.

    Lycopsids from the Angaran and Gondwanan phytogeoprovinces represent plants well-adapted for existing in the temperate climate, which took place in high latitude regions of both the northern and southern hemispheres, respectively. Some of these lycopsids are similar in absence of ligule, implying in a sort of way that those plants did not develop very well in temperate continent regions because the leaf cushions of lycopsids from the tropical regions, i.e., the Euramerican and Cathaysian phytogeoprovinces, are more complicated and more well-adapted for humid low-latitude tropical climate.

    Although both the Euramerian and the Cathaysian phytogeoprovinces were located in the tropical region, the former was actually controlled by tropical continent climate without good air circulation, while the latter was characterized by tropical island climate with good air circulation with possible monsoon effects. The difference of the leaf cushions of the lycopsids, which grew in these two phytogeoprovinces, was probably caused by the different climate conditions. Lycopsids with the lower positioned parichnos in leaf cushion were probably better adapted for highly effective exchange of O2 and CO2, as well as for effective regulation of the content of water in the plant, which was more convenient than for lycopsids without lower positioned parichnos.

    The difference between the Euramerian and Cathaysian phytogeoprovinces were reflected not only in lycopsid morphology and anatomy, but also in morphology of ferns and pteridosperms ("seed ferns"), such as uppermost Permian and Triassic Lepidopteris and Permian gigantopterids. For example, the leaves of Lepidopteris with special subepidermal swellings were widely distributed in the Late Permian of Europe, has not been discovered in the Late Permian of China until recently (Zhang et al., 2012). In China, there are abundant taxa of gigantopterids, but in the Euramerian Phytogeoprovince, only several genera of possible gogantopterid affinity were found in the United States (Taylor et al., 2009).

    Permian is the last period of the Paleozoic. What happened in the Permian of Gondwanan and Angaran lands, as well as localities surrounding the Tethys Ocean (Baud, 2018) are always a research hotspot in the geology and paleontology. Now it can be regarded as quite possible tendency that at least some of the higher plant taxa were able to migrate along the Tethys coasts both southwards and northwards (Naugolnykh and Uranbileg, 2018; Leven et al., 2011). Most probably such distant migrations were more or less common in Central and East Asia as well, especially if we take climatic reasons in account, which could provoke the considerable changes in the initial areal of formerly endemic taxa. In the case of the lycopsids of the family Tomiodendraceae we can suppose that this group initially were endemic for central Angaraland in Early Carboniferous, then migrated outwards after considerable cooling of the climate in boreal regions in the middle of Carboniferous. The presence of the species Ufadendron elongatum in the Permian deposits of Inner Mongolia is a good illustration of this process resulted from migration of tomiodendroid lycopsids far away from their initial area in Central Angaraland. The plant migrations triggered by climate change also is found in angiosperms. For example, Persea probably migrated from East Himalaya to Southeast Asia in the condition of the uplift of Himalaya through Miocene to Early Pleistocene resulting considerable changes in climate (Khan and Bera, 2016).

4.   CONCLUSIONS
  • In this article, the present specimens collected at the Jalaid of Inner Mongolia, China, from the Upper Permian Linxi Formation, are ascribed to Lycophyta due to their leaf cushions representing typical lycopsid morphology. Well-developed infrafoliar bladder, which is characteristic of these plants, presence of the wings and heel, as well as a leaf scar positioned at the upper part of leaf cushions, small and rounded with a central point-like scar containing conductive tissues, demonstrate that they should be assigned to the genus Ufadendron. The elongated leaf cushion of the specimens studied, the well-developed heel, and the short keel, show different characteristics from the typical species of the genus Ufadendron, i.e., U. ufaense (Naugolnykh 2014), giving evidences to establish a new species Ufadendron elongatum sp. nov. The diagnosis of the genus Ufadendron is emended on the basis of study of the additional specimens from China, which are described in the present paper.

    Although the diversity of lycopsids in Angaran Phytogeoprovince is higher than in Cathaysia, including the genus Ufadendron under the family of Tomiodendraceae, only five Angaran elements of lycopsids are recorded from the Upper Paleozoic Angaran Phytogeoprovinces in China. The new species U. elongatum enlarges our knowledge on taxonomy of Tomiodendraceae lycopsids, and also provides an opportunity to understand the morphological and functional differences between the lycopsids from Angaran Phytogeoprovince controlled by temperate continent climate, and lycopsids from Cathaysian Phytogeoprovince controlled by tropical island climate with monsoon influence.

ACKNOWLEDGMENTS
  • This work was financially supported by the Geological Survey of China (No. DD20160048-02) and the National Natural Science Foundation of China (No. 31470324), the Project 111 of China (No. B06008), and the Doctoral Fund of Shenyang Normal University (No. 054/55440109030). We are very grateful to Prof. Ge Sun, Dean of College of Paleontology, Shenyang Normal University; Qun Zhu, General Engineer, and Lidong Zhang, Director of the Department of Fundamental Research of Shenyang Center of Geological Survey, China Geological Survey for their supports to the work. Thanks also to two anonymous reviewers for their useful comments. Research of Serge V. Naugolnykh is supported by the State Program (Geological Institute, Russian Acad. Sci.) (No. 0135-2019-0044) and the Russian Government to support the Program of Competitive Growth of Kazan Federal University among World's Leading Academic Centers. The final publication is available at Springer via https://doi.org/10.1007/s12583-019-1230-0.

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