Fossil Leaves of Meliosma (Sabiaceae) With Associated Pollen and a Eupodid Mite From the Eocene of Maoming Basin, South China

Maria G Moiseeva,Tatiana M Kodrul,Xinkai Wu,Maria V Tekleva,Natalia P Maslova,Jianhua Jin

doi:10.3389/fevo.2021.770687

Abstract

A first occurrence of the genusMeliosma(Sabiaceae) is reported from the upper Eocene of the Maoming Basin of South China. This fossil is one of the oldest reliable records of the genus within its modern center of diversity. Fossil leaves are assigned to a new species,Meliosma eosinicasp. nov. based on leaf morphology and epidermal characters. The leaf epidermal anatomy of fossilMeliosmais illustrated for the first time. We also provide the first SEM observation of pollen grains associated withMeliosma. This study also documents an occurrence of mites within the leaf domatia previously unknown from the fossil record. We presume that the studied mite belongs to the superfamily Eupodoidea (Arthropoda), and probably the family Eupodidae, which comprises very small soft-bodied cosmopolitan mites occupying a wide range of terrestrial habitats. Additionally, we analyze the damage types on the fossil leaves ofMeliosma. They exhibit exclusively external foliage feeding damage caused by arthropods and traces of probable fungal infection. A review of currently known fossil occurrences of leaves, fruits, and wood ofMeliosmaprovides evidence for the geological and geographical distribution of the genus.

Highlights

Sabiaceae are a small family of trees, shrubs, and lianas comprising four genera: Meliosma Blume, Kingsboroughia Liebm., Sabia Colebr., and Ophiocaryon Endl. (Yang et al, 2018)
We examined the leaves and pollen of the extant species of Meliosma using specimens available in the Herbarium of Sun Yatsen University (SYS), Guangzhou, China, as well as specimens collected by S.R
The new species of M. eosinica from the Eocene of the Maoming Basin adds to the diversity of the genus in the Paleogene and extends its paleogeographical range to South China

Summary

Introduction

Sabiaceae are a small family of trees, shrubs, and lianas comprising four genera: Meliosma Blume, Kingsboroughia Liebm., Sabia Colebr., and Ophiocaryon Endl. (Yang et al, 2018). Sabiaceae are a small family of trees, shrubs, and lianas comprising four genera: Meliosma Blume, Kingsboroughia Liebm., Sabia Colebr., and Ophiocaryon Endl. The family is distributed in tropical and subtropical regions of eastern and south eastern Asia and Central and South America. The most diverse and widely distributed genus in the family is Meliosma (Figure 1). The number of species within Meliosma is uncertain and between different publications varies considerably from 25 species (Van Beusekom, 1971) to 80 species (Stevens, 2017) or even 124 species (World Checklist of Selected Plant Families, 2021). In China, 29 species are currently known (Law and Wu, 1982; Guo and Brach, 2007) and over 70 species are estimated for the Neotropical region (Cornejo, 2008, 2009; Ramos and Cornejo, 2012).

Methods

Discussion

Conclusion