Begonia circumlobata Hance, J. Bot. 21: 203, 1883 (Hance, 1883)

Tian, Dai-Ke, Xiao, Yan, Li, Yan-Ci & Yan, Ke-Jian, 2020, Several new records, synonyms, and hybrid-origin of Chinese begonias, PhytoKeys 153, pp. 13-35 : 13

Begonia circumlobata Hance, J. Bot. 21: 203, 1883 (Hance, 1883) Fig. 3

- Begonia lipingensis Irmscher, Mitt. Inst. Allg. Bot. Hamburg 6: 353, 1927 ( Irmscher 1927). syn. nov. Type: China, Kweitschou (Guizhou), Liping, alt. 600 m, 21 July 1917, Handel-Mazzzetti 10909 (holotype: WU0038812, WU!; isotype: E00265121, E!)

Type.

China, Canton (Guangdong), 05 Oct 1881, Rev. Benjamin Couch Henry s.n. (BM000944652, BM!).

Note.

Begonia lipingensis has been treated as a species differing from B. circumlobata in Flora Reipublicae Popularis Sinica ( Ku 1999) and Flora of China ( Gu et al. 2007). The species was based on small-sized mature plants that were collected from Liping County of Guizhou Province, China (Fig. 3A-C ). However, the species could not be separated when comparing the specimens and living plants in the wild. Many specimens stored in herbaria of China or other countries were identified with both names. After our careful review of type specimens and comprehensive field surveys on a large number of populations of both entities, it was confirmed that no differences could be found between them. Since B. lipingensis was described later, it should be considered as a synonym of B. circumlobata .

Begonia circumlobata displays significant variation in plant size, morphology of leaves, and flowers (Fig. 3E-H ). The leaves may be shallowly to very deeply lobed in the same population, even for the same individual and very few of the plants are shallowly double-lobed like B. jinyunensis C.I Peng, B.Ding & Q.Wang ( Ding et al. 2014) (Fig. 3G, H ). The leaves of most plants are pure green on two sides, while others may have deep green leaves with abxially red surface. Occasionally, variegated plants with white-spotted leaves could be seen in some populations such as in Huangsang National Nature Reserve of Suining, Hunan Province. Flowers can be white, whitish-pink, pink or nearly red (Fig. 3D, E ).

Distribution and phenology.

Begonia circumlobata is widely distributed in at least seven provinces of China, from western Hubei to Hunan, Jiangxi, Fujian, Guangdong, Guangxi and Guizhou, growing on flat areas, steep slopes or rock surfaces along or near stream and valley. Alt. 200-1230 m (Fig. 4 ). Flowering June to September, fruiting July to October.

Conservation status.

Least Concern (LC) due to wide distribution and usually large populations. However, in some places, a small number of plants with variegated leaves (adaxially white spots) have high value as ornamentals. Therefore, these variegated individuals may be over-collected by humans.

Remarks.

Begonia circumlobata has sparsely hairy leaf blades and outer tepals of male flowers (Fig. 3C ). It is most similar to B. jinyunensis and B. laminariae , particularly in the morphology of its leaves, flowers and fruits. Begonia circumlobata is also easily confused with some individuals of B. pedatifida Lév. ( Léveillé 1909), particularly when examining herbarium specimens. Unpublished morphological and molecular data (Tian et al.) suggests that B. jinyunensis should be treated as a subspecies of B. circumlobata . At the same time, a study is ongoing concerning the taxonomic relationship of B. circumlobata , B. laminariae Irmsch. ( Irmscher 1951) and B. pedatifida . Since plants with intermediate morphology amongst these three taxa exist in the wild, it appears that gene flow or natural hybridisation might occur between them.

Figures

Figure 3. Begonia lipingensis and B. circumlobata (E-H photos by Daike Tian) A-E Begonia lipingensis: A holotype (WU) (digitalised by Herbarium of Institut fur Botanik der Universitat Wien) B close-up view of type leaf C close-up of male flower from holotype, showing abaxial hairs on the middle of outer tepals D wild blooming plants E, F male flowers showing colour variation G, H Begonia circumlobata: adaxial (G) and abaxial (H) views showing variations of leaf lobes and colour in a single small population.

Figure 4. Distribution map of B. circumlobata (including syn. B. lipingensis) Triangles show distribution based on specimens and field surveys and red triangles indicate type locality of B. circumlobata (Guangdong) and B. lipingensis (Guizhou), respectively.