ephedroids from the Early Cretaceous Yixian Formation in Liaoning ...

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248 C. Rydin et al.: Cretaceous ephedroids from China Figs. 9–11. Liaoxia acutiformis Rydin, S.Q. Wu et Friis sp. nov (PB20721). 9 Overview of this reproductive shoot. 10 The uppermost cone in close up. No remains of seeds or male structures have been observed in this specimen. 11 Close up of a node. Scale bars = 1 cm in Fig. 9; 0.3 cm in Figs. 10 and 11. L =leaf;B =branch served. The shoot is c. 4.5 cm long and represents the terminal reproductive part of one branch (Fig. 19). The stem is erect, 1.5 mm thick, and has distinct remnants of longitudinal striations. Leaves are not present in the preserved part of the shoot. Reproduc-
C. Rydin et al.: Cretaceous ephedroids from China 249 tive parts are positioned at two nodes separated by a short (6 mm) internode. Branching is opposite and with multiple axillary units. Cones are rounded, and vary in length between 3.5 and 4 mm (up to 15 mm long including the extended bract apex), and are 2–3 mm wide. Four cones are positioned axillary at the lowermost node (Fig. 20). They are sessile to shortly pedunculate. Each cone comprises only 1–2 pairs of bracts, which are reflexed and decussately arranged. Bracts are probably ovate, 10–15 mm long and 0.1–0.5 mm wide, and have a long pointed (setose) apex (Fig. 20). They have indistinct remains of two parallel veins (Fig. 20). The upper node comprises sessile cones, densely crowded into a head-like structure. Seeds are positioned in the axil of the bracts. They are poorly preserved, but appear elliptic, 2.5–4 mm long and c. 1 mm wide. This plant differs from the other species of Liaoxia in the multiple numbers of sessile cones at nodes, superficially forming head-like structures. Another obvious difference is the extended, very long and narrow apex of the cone bracts, 10–15 mm long. The bracts of other species described here are generally only 2–4 mm, (6–7 in L. robusta). Discussion The type species, Liaoxia chenii, was originally described as an angiosperm (Cyperaceae) by Cao et al. (1998). In the same work Cao et al. described another species, Eragrosites changii, also assigned to the monocots (Poaceae). The gnetalean affinity of these two species was, however, soon pointed out by several authors (Sun et al. 1998, Guo and Wu 2000). Both species are here assigned to Liaoxia. We have altered the terminology but basically followed the original interpretations made by Cao and Wu, with one exception. In the original description of Liaoxia it is stated that the cone bracts (‘‘glumes’’) are helically arranged (Cao et al. 1998), but according to our observations cone bracts are opposite and decussately arranged. Nomenclatural comments. In 2000, Liaoxia chenii and Eragrosites changii were re-described jointly as an ephedroid species, Ephedrites chenii (Guo and Wu 2000), based on the original material of Cao et al. (1998) and one additional specimen. This taxonomic treatment was followed by Sun et al. (2001), who based their description on the same specimens as well as new material. There are, however, problems with the approach of joining Liaoxia chenii and Eragrosites changii into a single species. The specimens originally described as Liaoxia chenii have a distinct ephedroid habit with opposite branching, long slender leaves in opposite and decussate arrangement at the nodes, and cone bracts with a distinctly pointed apex (referred to as an ‘‘awn’’ by Cao et al. 1998). Eragrosites changii (Cao et al. 1998) also represents a plant with an ephedroid habit, but it differs from Liaoxia chenii in that leaves are absent, cones have more bracts and the bracts are shorter, apparently with an acute to obtuse apex. We find these differences sufficiently marked to warrant a separation of the specimens into two different species. Further, the use of the genus Ephedrites is inappropriate for ephedroid fossils. The genus was originally described by Go¨ppert and Berendt (1845), based on stems with female reproductive units preserved in Baltic amber from the Early Cenozoic of Europe. Additional material, including male structures, convinced Go¨ppert that these plants belonged to Ephedra (Go¨ppert 1853) and he transferred the type species (Ephedrites johnianus) to the extant genus (Go¨ppert 1853, Go¨ppert and Menge 1883). A few years later, Conwentz (1886) argued that the male structures probably represented poorly preserved material of Castanea whereas the female structures (the type) belonged to the angiosperm family Loranthaceae and he transferred Ephedra (Ephedrites) johnianus to Patzea johnianus (Conwentz 1886). In 1891, Saporta made an emended diagnosis of Ephedrites (citing the Go¨ppert and Berendt type material from 1845). He included two species: one new species based on seeds
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ephedroids from the Early Cretaceous Yixian Formation in Liaoning ...

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