Based on a worldwide dataset of molecular sequence data from three plastid DNA markers (rbcL, rbcL-accD-accD, rps4-trnS) obtained from 109 species of Hymenophyllum (Hymenophyllaceae), we investigated ...the systematics and biogeographic origins of the New Caledonian (NC) members of this fern genus, which were thought to include 16 species with 10 endemics. Located in the southwest Pacific, NC is a continental Gondwanan island that was long supposed to harbour phylogenetic relicts. However, molecular and geological data suggest that the current flora and fauna are the result of recent colonizations that occurred after total submersion (during the Eocene) and subsequent re-emersion of NC ca. 37 Ma. Our molecular phylogenetic results, complemented by morphological observations of herbarium specimens, show the existence of a new species that was as yet undescribed, and suggest that a previously recognized variety should be elevated to the rank of species to avoid species polyphyly. These two species, which are recognizable based on several morphological features, are endemic to NC: (i) Hymenophyllum soriemersum sp. nov. is sister to the other NC endemic H. dimidiatum; and (ii) H. neocaledonicum comb. & stat. nov, previously described as a variety within H. lyallii, was retrieved as a distinct lineage. We also confirmed the synonymy of H. streptophyllum and H. subdimidiatum (both previously considered as endemic to NC) with the more widely distributed H. javanicum and H. holochilum, respectively. These synonymies were previously hypothesised based on morphology alone. New Caledonia thus has as total of 17 Hymenophyllum species, 12 (71%) of which are endemics. Biogeographic inferences based on the results of our phylogenetic analyses suggest that Hymenophyllum originated in New Zealand ca. 49.8 Ma (95% HPD: 40.7–59.5 Ma). Its spatio-temporal history may in part have been influenced by vicariance (with potential exchange via the Antarctica land bridge that persisted between Australia and South America until 34 Ma), but long-distance dispersal (LDD) appears as the predominant process leading to the present-day distribution of species. At least eight LDD events are needed to explain the presence of the 10 NC endemics analysed here (H. francii and H. humboldtianum were not included), each of which occurred < 22.1 Ma and originated from a surrounding territory: Southeast Asia was probably the dispersal source for the NC endemic clade comprising H. soriemersum , H. dimidiatum, and H. rolandi-principis while the ancestors of the other NC endemics most likely dispersed from New Zealand, Australia or other Pacific Islands. Such a regional pattern is congruent with the distribution of non-endemic species, which are mostly shared among neighbouring territories. Lastly, we found evidence for only two cases of diversification within NC, yielding two and three species each (H. soriemersum, H. dimidiatum and H. rolandi-principis; and H. lyallii and the ancestor of H. braithwaitei and H. tomaniiviense). Such a low level of in situ diversification may be explained by the high dispersal abilities of ferns in general (via dust-like spores), which slow down the differentiation process among populations and make a newly available niche likely to be filled by an immigrant before a new species might evolve locally.
Rapid cooling during the Eocene-Oligocene transition resulted in a vegetation shift in southern France, from warm, humid vegetation to open savannah-like vegetation; however, the precise nature of ...this shift is uncertain. In this paper, we study the latest Eocene flora from the Saint-Chaptes and Alès basins (southern France) and compare it with other well-known southern European localities to evaluate vegetation changes near the Eocene-Oligocene boundary. Five plant communities are recognised: 1) hydrophytic vegetation dominated by water lilies and a Limnobiophyllum-like plant; 2) reeds that formed a palustrine belt around the lake; 3) ferns with Osmunda aff. parschlugiana and Pronephrium stiriacum, conifers with Doliostrobus taxiformis, a Sequoia-like plant, angiosperms with Daphnogene sp., Byttneriopsis sp., Myrica sp., Comptonia difformis and palms, which inhabited the lake shores and constituted the riparian vegetation; 4) Tetraclinis, which grew just behind the riparian vegetation but not far from watercourses, forming open landscapes and 5) Zizyphus ziziphoides, Fabaceae, and probably Ailanthus sp. and Tetraclinis forming an open woodland distal to the lake. The flora of the Saint-Chaptes and Alès basins resembles coeval floras from Sarral (Catalonia, Spain) that are characteristic of Southern Europe, although riparian vegetation is more diverse in the Saint-Chaptes and Alès basins, and Fabaceae diversity is higher at Sarral. We hypothesise that vegetation composition was mainly controlled by (1) basin architecture, allowing for a variety of wetland habitats and (2) climate. The coexistence of genera that are restricted to Central Europe (e.g., Byttneriopsis or Doliostrobus), together with genera more typical of Southern Europe (e.g., diversity of Fabaceae, C. difformis and Z. ziziphoides) suggests that the Saint-Chaptes and Alès basins contain latest Priabonian floras that are transitional between these two regions.
•Plant paleoecology at the EOT is studied in the Alès and Saint-Chaptes basins (France).•Plant communities range from lacustrine, wetlands to savannah-like woodlands.•The riparian vegetation is more diverse than in other coeval South European plant sites.•Alès and Saint-Chaptes flora shows taxa characteristic either South or Central Europe.•These plants represent a transitional flora between the two main European vegetations.
Premise of research. Koelreuteria encompasses three extant species that are discontinuously distributed in East Asia and the Fiji Islands. Koelreuteria had a wide distribution in the Northern ...Hemisphere during the Paleogene, with the first known fossil record being from the early Eocene of western North America. This study reports early fossil occurrences of Koelreuteria in Asia with a detailed morphological investigation and considers the history of its biogeographical dispersal in light of these finds.
Methodology. Four capsular valve fossil species of Koelreuteria are recognized from the early middle Eocene of the Niubao Formation at the Jianglang site (present altitude 4850 m), Bangor County, central Tibetan Plateau, China. They are compared with previous fossil occurrences using existing literature and herbarium records of extant material.
Pivotal results. We describe a new species, Koelreuteria kvacekii P.-R. Chen, C. Del Rio & T. Su sp. nov., characterized by its oblate capsular valve, lobed apex, and cordate base of the valve, as well as one or two suborbicular seeds per locule. Other material is assigned to species previously described from other locations, extending the geographic and stratigraphic ranges for K. miointegrifoliola, K. allenii, and K. lunpolaensis.
Conclusions. Fossil records of Koelreuteria and other co-occurring plants evidence a subtropical climate in central Tibet during the middle Eocene, contrasting with the present cold and dry climate in this region. These are the earliest fossil records of Koelreuteria from what is now the Tibetan Plateau. It seems that the Tibetan region served as an early diversification center for Koelreuteria during the Paleogene in Asia. All species of this flora disappeared locally because of the formation of the Tibetan Plateau by the Neogene.
Premise of research. The fossil record of Rhamnaceae is geographically widespread and ranges from the Cretaceous to the Pleistocene, but only a few fossil fruits, namely, Ventilago engoto from the ...Oligocene of Mexico and V. lincangensis from the late Miocene of southwestern China, have been attributed to the tribe Ventilagineae based on the recognition of their typical fruits with an apical wing. Here we document new fossils from the middle Eocene of Jianglang, central Tibetan Plateau. We discuss their systematic affinity, the biogeographic history of the tribe, and the paleoenvironment in central Tibet on the basis of this discovery.
Methodology. Fossil fruits were studied using a smart digital microscope and were extensively compared with the relevant literature as well as with specimens of extant species from herbaria.
Pivotal results. These fossil fruits conform to the typical fruit type of Ventilago in having a prominent apically extended elongate-elliptical wing appendage and a hypanthium enclosing two-thirds of a seed chamber. We describe a new species, V. tibetensis sp. nov., based on the conical shape of the hypanthium, the pointed apex of the seed chamber, and the ratio of the length of the fruit and the seed chamber, which differ from other fossil records of Ventilago.
Conclusions. Ventilago tibetensis is the earliest fossil record of Ventilagineae, and the age of the diversification of Ventilago should be reevaluated. The Indo-Tibetan area may represent the region of origin of this genus. It is difficult to directly assess the paleoenvironment of Jianglang solely on the basis of the occurrence of V. tibetensis, even if the group mainly lived in a subtropical to tropical area in Asia, but together with previous paleobotanic studies, the floristic assemblage indicates a subtropical flora in central Tibet during the middle Eocene.
The Ranunculales are a hyperdiverse lineage in many aspects of their phenotype, including growth habit, floral and leaf morphology, reproductive mode, and specialized metabolism. Many Ranunculales ...species, such as opium poppy and goldenseal, have a high medicinal value. In addition, the order includes a large number of commercially important ornamental plants, such as columbines and larkspurs. The phylogenetic position of the order with respect to monocots and core eudicots and the diversity within this lineage make the Ranunculales an excellent group for studying evolutionary processes by comparative studies. Lately, the phylogeny of Ranunculales was revised, and genetic and genomic resources were developed for many species, allowing comparative analyses at the molecular scale. Here, we review the literature on the resources for genetic manipulation and genome sequencing, the recent phylogeny reconstruction of this order, and its fossil record. Further, we explain their habitat range and delve into the diversity in their floral morphology, focusing on perianth organ identity, floral symmetry, occurrences of spurs and nectaries, sexual and pollination systems, and fruit and dehiscence types. The Ranunculales order offers a wealth of opportunities for scientific exploration across various disciplines and scales, to gain novel insights into plant biology for researchers and plant enthusiasts alike.
The floristic diversity of the Le Quesnoy amber locality (Ypresian, Oise France) remains understudied. Icacinaceae Miers, particularly, require careful study, as they are the most abundant family in ...the site, with 185 nearly complete lignitic endocarps specimens and numerous fragments. In this paper, we recognise three species of Icacinaceae, two of which are new, that belong to the genus Iodes. Indeed, all Iodes species from this site have the following diagnostic characters: a vascular bundle inside the endocarp wall, a reticulum of external ridges, and papillae on the surface of the locule. Iodes rigida sp. nov differs from the others in having a hole at the apex, a pattern of reticulation that delimits some areoles, an “I-Beam” ridge structure, and punctuated and heterogeneous sessile, rounded papillae. Iodes acuta sp. nov. is distinct from the others due to its unique apical outgrowth (composed of the main ridge that runs from the base up to the apex and a protuberance from the keel merged), a very thin wall, and sharp ridges. Therefore, these new species have a combination of new morpho-anatomical characters never observed before and not found in extant Iodes species. Despite some scarce differences, some specimens from Le Quesnoy are attributed to I. parva. Finally, several seeds are recognised as Icacinaceae without particular affinity. These seeds are elliptical in shape, lenticular in transverse section, and slightly asymmetrical to completely asymmetrical at the apex. A review of the Iodes fossil record is provided. The significance of endocarp ridge morphology is discussed in light of new fossils and extant data. These fossils show affinities with representatives from other Eocene sites of Europe and with the Thanetian Rivecourt site (Oise, France) and appear to have mixed affinities with the modern floras of Asia and Africa. Other studies on this remarkable site, focusing on additional taxonomic groups, are necessary to elucidate the relationship between Le Quesnoy and other floras from the past and the present.
•Iodes ridiga and I. acuta are two new species from Early Eocene of the Paris Basin.•Iodes parva is present during Palaeocene and Eocene of the Paris Basin.•Mineralised seeds could be related to the Icacinaceae family.•The fossils show affinities with African and Asian extant floras.
Icacinaceae are well represented in the modern tropical flora of East Asia, but this family has no confirmed macrofossils from this region. Most of the unambiguous fossils (e.g., endocarps) are from ...the Paleogene of North America and Europe, where the family is no longer present. Here we report a fossil endocarp of the liana genus Iodes from the Oligocene Wenshan flora, southwestern China. The fossil is relatively large (ca. 20 mm length, 11 mm width) and documents a vascular bundle inside the endocarp wall, a pattern of ridges enclosing few areoles, and an asymmetrical apex and rounded base. On the basis of these characteristics, we described a new species, Iodes elliptica, which represents the first Icacinaceae fruit fossil record from Asia. This fossil, consistent with recent reports of Iodes pollen from the Eocene of Hainan, indicates a long‐standing presence of the genus in SE Asia, dating back to the Paleogene. Based on the climatic data of modern Iodes, and other fossil occurrences from Wenshan, we hypothesize that the climate in the region was subtropical during the Oligocene, supporting a rainforest, with an overall mixed regional flora of subtropical and tropical elements.
Iodes elliptica sp. nov. represents the first unambiguous macrofossil record of Icacinaceae in Asia. This fossil attests to a subtropical area in East Asia during the Oligocene. The Oligocene environment of Wenshan, Yunnan, supported a rainforest with an overall mixed regional flora of subtropical and tropical elements.
Menispermaceae are a pantropical and temperate family with an extensive fossil record during the Paleogene period, especially in North America and Europe, but with much less evidence from Asia. The ...latest fossil evidence indicates a succession of tropical to subtropical flora on the central Tibetan Plateau during the Paleogene. However, the biogeographic histories of these floras are still unresolved. Here, we report on endocarps and leaves of Menispermaceae from the Middle Eocene of Jianglang village, Bangor County, central Tibetan Plateau. The endocarps belong to two genera: Stephania, which is characterized by a horseshoe‐shaped endocarp and with one lateral crest ornamented by spiny to rectangular ribs, and a condyle area; and Cissampelos (s.l.), which has two characteristic lateral ridges and a conspicuous external condyle. Associated leaves belong to the genus Menispermites, and are characterized by actinodromous primary venation, brochidodromous secondary veins, entire margins, and the presence of marginal secondary veins. The biogeographic history of Menispermaceae is complex, but evidence from these new fossils indicates an early diversification of the group in Asia, probably in response to the warming climate during the Eocene. The Jianglang flora appears to be part of a boreotropical flora, connecting Asia with North American and European floras during the Middle Eocene. The modern distribution of menispermaceous taxa found in Jianglang, as well as other families represented in the Jianglang flora, show that a tropical to subtropical climate occurred during the Eocene in central Tibet.
Trapa (water chestnut or water caltrop) is a genus of annual free-floating plants mostly native to Africa and Eurasia and included in the family Lythraceae. The genus only contains 10 species today ...but has a large number of species in the Neogene record, mainly based on fruits but also on the occurrence of pollen grains. In China, several species have previously been recorded from the Neogene, but few have a detailed description. Here we describe a new species of fruit from the Pliocene of the Sanying Formation, Yangjie coalmine, western Yunnan, namely Trapa sanyingensis sp. nov., based on the following characters: the size of the fruit, the relatively long upper horns, the well-developed and triangular lower horns, the well-developed tubercles between the lower and upper horns, and a long and wide neck bearing hairs without a corona. In addition, pollen grains belonging to Sporotrapoidites cf. weiheensis were uncovered from the same sediment and have the following characters: tricolpate, obtuse triangular shape in polar view, and three meridional crests covering the apertures. T. sanyingensis sp. nov. shows a close morphological similarity to the Miocene species Trapa chengsenii from the Yunnan and to the modern species Trapa natans. The pollen grains also closely resemble those of Trapa natans. The occurrence of T. sanyingensis sp. nov. suggests that the sedimentary site corresponds to open and shallow water with a water temperature above 20 °C during the growing season.
•Trapa sanyingensis sp. nov. is described from the Pliocene of western Yunnan.•Pollen grains of Sporotrapoidites cf. weiheensis were uncovered from the same sediment.•Both pollen grains and fruits share close morphological similarity with Trapa natans.•The sedimentary site corresponds to open, warm and shallow water.
Illigera (Hernandiaceae) is a liana genus distributed mainly in the tropical Asia and Africa. Previous fossil records suggested that Illigera was restricted in western North America during the ...Eocene. Recent paleobotanical investigation has unveiled a Paleogene flora that is totally different from today's vegetation in central Tibet. This provides novel insights into the paleoenvironmental change during the evolution of the Tibetan Plateau (TP). Here, we investigated 10 fruit impressions of Illigera from the early middle Eocene Niubao Formation in the Bangor Basin, central TP. The fossil winged fruits are characterized by their eroded fruit wings, well preserved fusiform locular areas with a median ridge bisecting the fruit, and short veins fanning radially outward. These features allow us to assign these fossils to Illigera eocenica, a species originally discovered in the Eocene of western North America. This is the second fossil occurrence of Illigera worldwide, and the first in Asia. Our finding suggests a warm and humid climate in the central TP during the early middle Eocene, and a close floristic link between Asia and North America during the Paleogene. We also propose a Northern Hemisphere origin and a Paleogene dispersal event from Northern Hemisphere to Africa for Illigera.
New Illigera fossil fruits from the Eocene Tibetan Plateau reveal floristic links between Asia and other parts of world.
PDF
