New fossil endocarps of Sambucus (Adoxaceae) from the upper Pliocene in SW China

A new species of fossil endocarp is described from the Sanying Formation of the upper Pliocene at Fudong Village, Lanping County of northwestern Yunnan Province, Southwest China. The endocarps are elliptic, ovate or oblong elliptic, 2.1–2.5 mm long and 1.2–1.7 mm wide. The dorsal face is convex and the ventral is concave or more flattened. The endocarp surface is loosely, transversely or sinuously furrowed and ridged, forming a reticulate and alveolate pattern on the ridges, and the inner wall of the surface cells on the ridges is flaky and scaly. They are morphologically compared with selected extant genera of Adoxaceae and Caprifoliaceae. The interspecific comparisons show diagnostic differences of the fossil endocarps from the selected modern species and other fossil taxa, supporting their recognition as a new species: Sambucus alveolatisemina Huang, Liu et Zhou, sp. nov. Previous records of the reliable Sambucus fossils were from mid-high latitude regions in Europe, northeastern Asia and northern North America. Therefore, it is interesting to note that S. alveolatisemina represents a fossil record from a low latitude region. Sambucus apparently has existed at low latitudes in China at least since the upper Pliocene. A review of other Sambucus fossil occurrences indicates that plants of this genus have been living at higher latitudes in the geological past than they are at present.

► New Sambucus endocarps are described from the upper Pliocene in SW China. ► This is the first reliable fossil record of Sambucus at low latitude. ► Sambucus might have occurred in SW China at least since the upper Pliocene. ► This study provides new evidence of past biogeography of this genus.