A new species of Liquidambar (Altingiaceae) from the late Eocene of South China

Structurally Preserved Liquidambar Infructescences, Associated Pollen, and Leaves from the Late Oligocene of the Nanning Basin, South China

Liquidambar L. is a significant constituent of the Cenozoic flora in the Northern Hemisphere. Currently, this genus exhibits a discontinuous distribution across Asia and North America, with the center of diversity being in southeastern Asia. This study presents the first occurrence of Liquidambar in the Oligocene of South China. Fossil sweetgum infructescences, associated pollen, and leaves have been found in the Nanning Basin, Guangxi. A new species, Liquidambar nanningensis sp. nov., is described based on the morphological and anatomical characteristics of three-dimensionally preserved infructescences. The Liquidambar fossils from the Nanning Basin show a combination of features indicative of the former genera of Altingiaceae, Altingia, Liquidambar s. str., and Semiliquidambar. The new occurrence expands the taxonomic and morphological diversity of the Paleogene Liquidambar species in South China.

Variations in morphological and epidermal features of shade and sun leaves of two species: Quercus bambusifolia and Q. myrsinifolia

PREMISE

Microclimatic differences between the periphery and the interior of tree crowns result in a variety of adaptive leaf macromorphological and anatomical features. Our research was designed to reveal criteria for sun/shade leaf identification in two species of evergreen oaks, applicable to both modern and fossil leaves. We compared our results with those in other species similarly studied.

METHODS

For both Quercus bambusifolia and Q. myrsinifolia (section Cyclobalanopsis), leaves from single mature trees with well-developed crowns were collected in the South China Botanical Garden, Guangzhou, China. We focus on leaf characters often preserved in fossil material. SVGm software was used for macromorphological measurement. Quantitative analyses were performed and box plots generated using R software with IDE Rstudio. Leaf cuticles were prepared using traditional botanical techniques.

RESULTS

Principal characters for distinguishing shade and sun leaves in the studied oaks were identified as leaf lamina length to width ratio (L/W), and the degree of development of venation networks. For Q. myrsinifolia, shade and sun leaves differ in tooth morphology and the ratio of toothed lamina length to overall lamina length. The main epidermal characters are ordinary cell size and anticlinal wall outlines. For both species, plasticity within shade leaves exceeds that of sun leaves.

CONCLUSIONS

Morphological responses to sun and shade in the examined oaks are similar to those in other plant genera, pointing to useful generalizations for recognizing common foliar polymorphisms that must be taken into account when determining the taxonomic position of both modern and fossil plants.

Paleoaltingia gen. nov., a new genus of Altingiaceae from the Late Cretaceous of New Jersey

PREMISE

Altingiaceae is a small family with a bimodal Northern Hemisphere distribution in eastern North America and eastern Asia, and a rich Cenozoic fossil record. The charcoalified fossil infructescence Paleoaltingia gen. nov. from Turonian (Late Cretaceous) deposits of New Jersey, provides new evidence of early Altingiaceae reproductive structures and has biogeographical implications in understanding modern distribution.

METHODS

Fossils were prepared using standard methods for obtaining and processing mesofossils. The fossils were examined with light microscopy, and scanning electron microscopy for observing structural and anatomical details. Phylogenetic analyses were performed using a combined matrix of molecular and morphological data.

RESULTS

Based on morphological features of the fossil and the phylogenetic analyses, the new genus, Paleoaltingia, with two species (Paleoaltingia ovum-dinosauri and P. polyodonta) is erected. The phylogenetic position of Paleoaltingia confirms affinities with living Altingiaceae.

CONCLUSIONS

The combination of characters-simple capitate infructescence, syncarpous bicarpellate, and bilocular ovary, unique sterile phyllome structures-indicates that the fossil taxa have close affinities to modern Altingiaceae. The unique characters of the phyllomes provide new information on the floral diversity of Altingiaceae. The emergence of Paleoaltingia in Late Cretaceous sediments of Northeastern North America represents the earliest fossil record of Altingiaceae and provides new insights into its biogeography.