Crown Group Lejeuneaceae and Pleurocarpous Mosses in Early Eocene (Ypresian) Indian Amber

PLoS One. 2016 May 31;11(5):e0156301. doi: 10.1371/journal.pone.0156301. eCollection 2016.

Abstract

Cambay amber originates from the warmest period of the Eocene, which is also well known for the appearance of early angiosperm-dominated megathermal forests. The humid climate of these forests may have triggered the evolution of epiphytic lineages of bryophytes; however, early Eocene fossils of bryophytes are rare. Here, we present evidence for lejeuneoid liverworts and pleurocarpous mosses in Cambay amber. The preserved morphology of the moss fossil is inconclusive for a detailed taxonomic treatment. The liverwort fossil is, however, distinctive; its zig-zagged stems, suberect complicate-bilobed leaves, large leaf lobules, and small, deeply bifid underleaves suggest a member of Lejeuneaceae subtribe Lejeuneinae (Harpalejeunea, Lejeunea, Microlejeunea). We tested alternative classification possibilities by conducting divergence time estimates based on DNA sequence variation of Lejeuneinae using the age of the fossil for corresponding age constraints. Consideration of the fossil as a stem group member of Microlejeunea or Lejeunea resulted in an Eocene to Late Cretaceous age of the Lejeuneinae crown group. This reconstruction is in good accordance with published divergence time estimates generated without the newly presented fossil evidence. Balancing available evidence, we describe the liverwort fossil as the extinct species Microlejeunea nyiahae, representing the oldest crown group fossil of Lejeuneaceae.

Publication types

  • Historical Article

MeSH terms

  • Amber / history
  • Bryophyta / anatomy & histology
  • Bryophyta / classification*
  • Bryophyta / genetics
  • DNA, Plant / genetics
  • DNA, Plant / history
  • Evolution, Molecular
  • Extinction, Biological
  • Fossils / anatomy & histology
  • Fossils / history
  • Hepatophyta / anatomy & histology
  • Hepatophyta / classification*
  • Hepatophyta / genetics
  • History, Ancient
  • India
  • Phylogeny
  • Time Factors

Substances

  • Amber
  • DNA, Plant

Grants and funding

This work was supported by the German Research Foundation (grant HE 3584/6 to JH) and the Alexander von Humboldt Foundation (research fellowship to GEL): The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. It also received support from the Open Access Grant Program of the German Research Foundation (DFG) and the Open Access Publication Fund of the University of Göttingen: The publication fee in an open access publication will be covered by the funders.