Equisetum yenbaiense A.T.Aung, T.Su, T.V.Do & Z.K.Zhou, 2020

Aung, Aye Thida, Huang, Jian, Do, Truong Van, Song, Ai, Liu, Jia, Zhou, Zhe-Kun & Su, Tao, 2020, Three new fossil records of Equisetum (Equisetaceae) from the Neogene of south-western China and northern Vietnam, PhytoKeys 138, pp. 3-15 : 3

Equisetum yenbaiense A.T.Aung, T.Su, T.V.Do & Z.K.Zhou sp. nov.

Holotype.

XTBGVNMN4001 (Fig. 2D ).

Paratypes.

XTBGVNMN4002-4004 (Fig. 2C, E-F ).

Locality.

Hop Thanh Village, Tuy Loc Commune, Yen Bai Province, northern Vietnam (21.725N, 104.849E).

Age.

The late Miocene.

Repository.

Paleoecology Collections, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences and Vietnam National Museum of Nature, Vietnam Academy of Science and Technology.

Etymology.

The species name ' yenbaiense ' means that fossils are from Yen Bai Province, northern Vietnam.

Diagnosis.

Rhizomes with internodes and nodes, node round; Four bunches of tubers arranged in a whorl on a node (Fig. 2D ); most tubers elongate in shape, with one to two tubers in each bunch (Fig. 2C-D ); longitudinal ridges on the surface of tuber; the tip of tuber mucronate (Fig. 2F ).

Description.

Rhizomes have both internodes and nodes (Fig. 2D ). The internode is ~0.2-0.3 cm in width, the length could not be observed, three longitudinal ridges are on the surface of the internode (Fig. 2D ). The node is round and ~0.2 cm in diameter (Fig. 2D ). Four bunches of tubers attach to one node and arrange in a whorl (Fig. 2D ). Only one tuber is preserved on each bunch, but it is likely that there are more than one tuber on each bunch (Fig. 2E-F ). Most tubers are elongate (Fig. 2D ); few are elliptical (Fig. 2F ), being~ 0.8 to 3.0 cm long and 0.4 to 1.0 cm wide. Two to four ridges are on the surface of each tuber (Fig. 2D ). The tip of tuber is mucronate (Fig. 2F ).

Figures

Figure 2. A-B Equisetum cf. pratense Ehrhart C-F Equisetum yenbaiense A. T. Aung, T. Su, T. V. Do & Z. K. Zhou, sp. nov. Specimen numbers: A-B XTBGSZTF 0001 (counterparts) C XTBGVNMN 4002 D & nbsp; XTBGVNMN 4001 E XTBGVNMN 4003 F XTBGVNMN 4004. n = node; r = ridge. Scale bars: 1 cm.