横断山区高山豆属的花粉形态及凉山高山豆的分类学地位

Pollen Morphology of Tibetia (Fabaceae) from the Hengduan Mountains, with Emphasis on the Taxonomical Status of Tibetia liangshanensis

为澄清我国西南横断山区特有属高山豆属(Tibetia)中凉山高山豆(T.liangshanensis)的花粉粒形态及其分类学地位,用电子显微镜重新扫描了本属的花粉粒。报道了除一个可疑种中甸高山豆(T.for-restii)外所有5个种的花粉形态,即高山豆(T.himalaica),云南高山豆(T.yunnanensis),凉山高山豆(T.liangshanensis),黄花高山豆(T.tongolensis)和亚东高山豆(T.yadongensis)。结果纠正了凉山高山豆的花粉粒形态,而另外4个种的花粉粒与之前的研究基本一致,仅在形状和大小上稍有差别。本属的花粉粒呈圆球形或近长球形,表面有穿孔凹陷,3-孔沟和4-孔沟两种花粉类型与高山豆属分为两个组相吻合。但我们发现凉山高山豆的花粉是4-孔沟类型,而不是之前报道的3-孔沟类型。另外,凉山高山豆与中甸高山豆的形态差异明显,凉山高山豆茎长,小叶13～17片,托叶分离,花冠紫色;而中甸高山豆茎短,小叶7～9片,托叶基部合生,花冠黄色,叶片下表皮细胞形态差异明显,因此我们认为应该将凉山高山豆独立作为一个种,而不是作为中甸高山豆的异名。

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 Ti- betia （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 hav- ing 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 sugges- ted that T. liangshanensis should regain its taxonomical status at the species level.