Cryptomeria japonica var. sinensis is native in China with a few occurrences. Living Cryptomeria japonica shows a relic distribution after the demise of the European fossil representatives. However, no confirmed fossil record of Cryptomeria has been reported so far within its extant distribution area in southern China. Owing to the limited regional fossil record, little is known how Cryptomeria became restricted to its present refuge in China.
Researchers from Xishuangbanna Tropical Botanical Garden (XTBG) reported a new fossil species of Cryptomeria based on well-preserved leafy shoots collected from the Lühe Basin, Nanhua County, Yunnan Province, southwestern China (25°8.5′ N, 101°22.5′ E, 1, 882 m above sea level). They identified the fossils as Cryptomeria based on their macromorphology and cuticular micromorphology
The Lühe material shows morphological similarities to extant genera. Sterile shoots are assigned to Cryptomeria based on gross-morphological and cuticular (morphological) characters and are compared with extant and fossils species described so far. The shoots exhibit spirally arranged sessile subulate leaves, leaf cuticles show densely arranged and irregularly oriented monocyclic stomata, which are characteristic for the genus.
The fossils show macromorphological or cuticular differences from other fossil species assigned to Cryptomeria and from the extant Cryptomeria japonica.
Even though the fossils cannot completely be compared with C. japonica because the fossil specimens lack reproductive organs, both species are distinct based on the characters of the leafy shoots. Therefore, the researchers propose a new species, namely Cryptomeria yunnanensisW.N. Ding et Z.K. Zhou sp. nov.
The fossil is the earliest recorded fossil of Cryptomeria in East Asia. Deduced frommodern and fossil occurrences of Cryptomeria, the researchers conclude that palaeoclimate change, in particular, the decrease in precipitation in several parts of Eurasia, are crucial factors for shaping the present-day relic distribution pattern of Cryptomeria in East Asia.
The study entitled “A new fossil species of Cryptomeria (Cupressaceae) from the Rupelian of the Lühe Basin, Yunnan, East Asia: Implications for palaeobiogeography and palaeoecology” has been published online in Review of Palaeobotany and Palynology.
Contact
ZHOU Zhekun, Ph.D Principal Investigator
Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan 666303, China
Tel: 86-871-65109223
E-mail: zhouzk@xtbg.ac.cn
Cryptomeria yunnanensis sp. nov. compression material
and living Cryptomeria japonica
(Images by DING Wenna)
