Asarum pubitessellatum, sp. nov. (sect. Heterotropa, Aristolochiaceae) from Taiwan based on morphological and palynological evidence.

Background: Recently, we discovered an unknown Asarum from Taiwan which is closely related to A. crassisepalum S.F. Huang, T.H. Hsieh and T.C. Huang and A. taipingshanianum S.F. Huang, T.H. Hsieh and T.C. Huang by sharing a thick leaf blade, spreading perianth-lobes and a conical to cylindrical perianth-tube. We compared it with other related species and identified this plant as a new species.

Results: This new species differs distinctly from the above two related species by having larger plant body, shortened rhizomes and an inner surface of the perianth-tube that is covered with numerous simple trichomes (vs. glandular trichomes). The pollen tectum in this new species is perforate, which differs from the incomplete reticulate with small supratectate granules in A. crassisepalum and the compact rugulate with small supratectate granules in A. taipingshanianum. Furthermore, these three species are geographically separated from one another.

Conclusions: Asarum pubitessellatum C.T. Lu & J.C. Wang, a new species is described and illustrated. The trichomes on the inner surface of the perianth-tube and pollen micromorphology were the valuable characters in the low-level classification of Heterotropa species in Taiwan.