A semi-aquatic fern (Marsileaceae) from the mid-Cretaceous amber of northern Myanmar

The present study reports unique leaflets of a semi-aquatic fern (Marsileaceae) preserved in midCretaceous amber from Myanmar, and further describes the new species Marsileaceaephyllum ciliatum sp. nov. The new species has leaflets fan-shaped without a midvein, venation dichotomous and partially anastomosing, and possesses unique dense hairs from the dorsal base radiating to the upper 2/3. This occurrence represents the first record of semi-aquatic ferns of the Marsileaceae found in Myanmar amber. This record further demonstrates the species richness of ferns in the Cretaceous, and also reveals the ecological adaptability of Marsileaceae in the aquatic environments of the mid-Cretaceous. (c) 2021 Elsevier Ltd. All rights reserved.

Automated summary

The present study reports the discovery of unique leaflets of a semi-aquatic fern in mid-Cretaceous amber from Myanmar and describes a new species of Marsileaceae. The new species has fan-shaped leaflets without a midvein, dichotomous venation partially anastomosing, and dense hairs on the dorsal base radiating upward. This finding represents the first record of semi-aquatic ferns of the Marsileaceae in Myanmar amber and demonstrates their ecological adaptability in the aquatic environments of the mid-Cretaceous.