Morphological and molecular identification of natural hybridization between Begonia hemsleyana and B. macrotoma

• A natural hybrid of Begonia was found in southern Yunnan of China.
• The hybrid between Begonia hemsleyana (♀) and B. macrotoma (♂) was preliminarily identified based on geographic distribution, morphological intermediacy and overlapping flowering time of its parents.
• The hypothesis of the natural hybrid was supported by molecular information.
• The hybrid is the first generation (F1) and was named as Begonia × dashuigouensis D. K. Tian.

Several plants of a putative hybrid of Begonia were found in southern Yunnan of China during a field survey. They were preliminarily identified as the offspring of a natural hybrid between Begonia hemsleyana as the maternal parent and B. macrotoma as the paternal parent based on the following reasons: the putative hybrid grows sympatrically with B. hemsleyana and B. macrotoma, but more closely to the former; it shows some intermediate morphological characteristics between parents; and the flowering time of parents overlaps, at least partially. Molecular information of internal transcribed spacer (ITS), chloroplast spacer ndhF-rpl32 and SSR markers supported our hypothesis of the natural hybrid between B. hemsleyana (♀) and B. macrotoma (♂). The hybrid should be the first generation (F1) and was named as Begonia × dashuigouensis D.K. Tian based on the name of place where it was discovered.