古生态研究组知识库

Salvinia, a free-floating aquatic, rootless fern, has a rich fossil record in Cenozoic sediments of Southeast Asia, Europe, and North-South America. However, none have been reported from the Cenozoic sediments of India, until now. Here, we report the occurrence of vegetative remains (both impressions and compressions), along with trichome bases, resembling both morphologically and anatomically those of the extant genus Salvinia Seguier from the Late Paleocene-Early Eocene of the Subathu Formation in the Mandi District of Himachal Pradesh, northwestern India. These newly discovered fossils are characterized by round, elliptical, or elongate fronds, with small hexagonal or quadrangular areolaes, usually 8-16 tubercles in a row between adjacent lateral veins, and craspedodromous lateral veins lacking marginal loops. Anatomically, epidermal cells are quadrangular or polygonal with diacytic stomata composed of two guard cells and numerous conical, filiform, slightly enlarged, and curved non-glandular trichomes. We describe these Eocene specimens as a new species, namely Salvinia indica A. Ali & M. A. Khan sp. nov. The discovery of this species suggests that the Eocene Subathu Formation represents sediments deposited in mostly calm freshwater bodies such as very low-energy meandering rivers, streams, or wetland ponds.