Abstract:

To clarify the pollen morphology and the taxonomical status of Tibetia liangshanensis in Tibetia, a small genus endemic in the Hengduan Mountains of SW China, we reexamined the pollen morphology of all species of Tibetia (except for a plausible species, T.forrestii) using SEM in this study. The pollen data for T.liangshanensis was corrected and the others (T.himalaica, T.yunnanensis, T.tongolensis and T.yadongensis) were confirmed. The shapes of Tibetia’s pollen grains are spheroidal or subprolate with perforate surfaces. Two types of pollen grains were found (i.e., 3-colporate and 4-colporate), corresponding to two sections recognized in this genus. The results showed that the pollen grain of T.liangshanensis is 4colporate. However, it was reported as 3colporate pollens and treated as a synonym of T.forrestii. Morphologically, the two species are very distinct with T.liangshanensis in having leaflets 13-17, stipules free and corolla purple, while T.forrestii with leaflets 7-9, stipules connate at base and corolla yellow. The epidermal characters of the two species are also distinguished under SEM. Therefore, we suggested that T.liangshanensis should regain its taxonomical status at the species level.

Key words: Pollen morphology, Tibetia, Tibetia liangshanensis, 3-colporate, 4-colporate