Fossil leaves of Nelumbo changchangensis, collected from the Eocene of Hainan Island, China, were studied and compared with those of the extant species of Nelumbo, N. nucifera Gaertn. and N. lutea Willd. The fossil leaves have all the specialized features of extant Nelumbo in leaf architecture, except that the organization of the areolae looks much more irregular than that of extant Nelumbo. Comparisons of the cuticle and epicuticular ultrastructure indicate that: (1) N. changchangensis resembles N. nucifera in that anticlinal cell walls of the lower epidermis are straight along the major veins and near leaf bases and are shallowly undulate with U‐ to V‐shaped undulations inside the areolae; (2) N. changchangensis differs from N. lutea in that anticlinal cell walls of the lower epidermis of the latter are deeply undulate with U‐, V‐ to reversed Ω‐shaped undulations inside the areolae; and (3) epicuticular wax crystals are more densely distributed on the leaves of N. changchangensis and N. nucifera than they are in N. lutea. These findings shed significant light on the cuticle differentiation of fossil and extant Nelumbo species. The morphometric comparisons indicate that almost all the synapomorphies of extant Nelumbo were already present by the Eocene, © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2016, 180, 123–137.
Filmy ferns (Hymenophyllaceae) are the most diverse lineage of the early-diverging leptosporangiate ferns with ca. 430 species widely distributed around the world but with the highest diversity in the humid tropics. However, their fossil record is scarce because of the low preservation potential of the delicate, membranous laminae. So far, no Hymenophyllaceae fossils have been reported from tropical Asia. Here, we describe some fern remains and their syninclusions (spike-mosses) in four pieces of Kachin amber from the mid-Cretaceous of Hukawng Valley, Northern Myanmar, as Hymenophyllites angustus sp. nov., H. kachinensis sp. nov., H. setosus sp. nov. (Hymenophyllaceae) and Selaginella alata sp. nov. (Selaginellaceae), respectively. These fern remains are assigned to Hymenophyllaceae based on the filmy, one-cell thick, decompound pinnatifid laminae and dichotomous venation. They represent the first fossil record of Hymenophyllaceae in tropical Asia. The growth habits of these ferns and associated spike-mosses and their implication for paleoenvironment are discussed. Our study expands the diversity of the cryptogams in mid-Cretaceous Kachin amber. Together with other contemporaneous findings, the present fossils indicate that Hymenophyllaceae have already accumulated some notable diversity in the Cretaceous.
With over 300 extant species, the nearly worldwide-distributed genus Frullania is one of the most species-rich genera of leafy liverworts and the sole extant genus of Frullaniaceae. Amber fossil record of Frullania is also rather diverse, with inclusions known from several amber deposits. The earliest fossils are F. baerlocheri, F. cretacea, and F. partita from the mid-Cretaceous Kachin amber, Myanmar. Here, we describe a new fossil species of Frullania as F. kachinensis sp. nov., based on seven sterile gametophyte fragments from three pieces of Kachin amber. This new species is characterized by leaf dorsal lobes mostly with rounded apexes, leaf ventral lobules inserted in approximately 30-90 μm distance to stem, lanceolate styli, and deeply bilobed underleaves with entire-margined to toothed lobes and Vshaped sinuses. Morphological comparisons indicate that F. kachinensis shows mosaic character combinations of two coeval species F. cretacea and F. partita. The leaf lobes of F. kachinensis resemble those of F. cretacea, while the underleaves are more similar to those of F. partita. But in taphonomy, F. kachinensis is preserved together with Protofrullania cornigera or F. baerlocheri in the same amber, which could indicate that these three species might live in the same habitat and even on the same tree. The fossils presented in this study provide additional evidence for the presence of a diverse liverwort flora, mostly composed of Frullaniaceae lineages in the mid-Cretaceous Kachin amber forest.
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