Journal of Systematics and Evolution >

2024 , Vol. 62 >Issue 1: 164 - 180

DOI: https://doi.org/10.1111/jse.12952

Exceptionally well-preserved seed cones of a new fossil species of hemlock, Tsuga weichangensis sp. nov. (Pinaceae), from the Lower Miocene of Hebei Province, North China

  • Ya Li , 1,2,3 ,
  • Carole T. Gee 4,5 ,
  • Zhen-Zhen Tan 6 ,
  • Yan-Bin Zhu 1 ,
  • Tie-Mei Yi , 2,7 ,
  • Cheng-Sen Li , 2
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  • 1. State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology and Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Nanjing, 210008 China
  • 2. State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093 China
  • 3. MNR Key Laboratory of Stratigraphy and Palaeontology, Institute of Geology, Chinese Academy of Geological Sciences, Beijing, 100037 China
  • 4. Division of Paleontology, Institute of Geosciences, University of Bonn, Bonn, 53115 Germany
  • 5. Huntington Botanical Gardens, San Marino, CA, 91108 USA
  • 6. College of Agro-Grassland Science, Nanjing Agricultural University, Nanjing, 210095 China
  • 7. Beijing Institute of Science and Technology Information, Beijing Academy of Science and Technology, Beijing, 100044 China
yali@nigpas.ac.cn
yitm@bjstinfo.ac.cn
lics@ibcas.ac.cn

Received date: 20 Nov 2022

Accepted date: 19 Feb 2023

Copyright

2023 2023 Institute of Botany, Chinese Academy of Sciences.
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Abstract

Tsuga (hemlock) is a small genus of 10 extant species in the Pinaceae, with a disjunct distribution in East Asia and eastern and western North America. Reliable species-level identification of Tsuga fossils depends on the discovery of seed cones with intact bracts, but such cones are rare in the fossil record. Here we describe a new fossil species of hemlock as T. weichangensis sp. nov. based on exquisitely preserved seed cones with nearly complete bracts from the Lower Miocene of Weichang, Hebei Province, North China. This fossil species displays a mosaic of characters between Tsuga and Nothotsuga. The well-developed and slightly exserted bract scales of T. weichangensis are reminiscent of Nothotsuga, but other characters, such as nonleaved peduncles and tongue-shaped bract scales, in addition to monosaccate pollen found at the same fossil locality, suggest an affinity closer to Tsuga. Cladistic analysis based on 15 morphological characters and a molecular backbone constraint supports the assignment of these fossil cones to Tsuga rather than Nothotsuga, and places the fossil species of T. weichangensis in an unresolved polytomy within the genus Tsuga. The occurrence of Tsuga seed cone fossils indicate the paleoclimate in the Miocene of Weichang was warmer and more humid than today's climate, which is consistent with the paleoclimate reconstructed by paleopalynology.

Key words： Hannuoba Formation; micro-CT; Nothotsuga; phylogenetic analysis

Cite this article

Ya Li , Carole T. Gee , Zhen-Zhen Tan , Yan-Bin Zhu , Tie-Mei Yi , Cheng-Sen Li . Exceptionally well-preserved seed cones of a new fossil species of hemlock, Tsuga weichangensis sp. nov. (Pinaceae), from the Lower Miocene of Hebei Province, North China[J]. Journal of Systematics and Evolution, 2024 , 62(1) : 164 -180 . DOI: 10.1111/jse.12952

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