Agapetes interdicta var. flaviflora Y. H. Tong, B. M. Wang & X. L. Guo, 2024

Tong, Yi-Hua, Guo, Xiang-Long, Wang, Bing-Mou, Wang, Zi & Guo, Yong-Jie, 2024, Two new varieties of Agapetes (Ericaceae) from Xizang, China, PhytoKeys 249, pp. 1-11 : 1-11

1 b. Agapetes interdicta var. flaviflora Y. H. Tong, B. M. Wang & X. L. Guo var. nov.

Fig. 1

Type.

China • Xizang Autonomous Region: Medog County, Beibeng Xiang, De’ergong Village ; 2300–2700 m elev.; 3 April 2024 (fl.); Xiang-Long Guo TYH- 2898 (holotype IBSC, isotype PE) .

Diagnosis.

This new variety differs from the nominate variety in having a yellow and smaller (1.3–1.8 cm) corolla with shorter (2–2.5 mm) lobes and anthers with shorter (ca. 0.2 mm) appendages at the base.

Etymology.

The variety epithet is derived from its striking yellow flowers. The Chinese name is given as 黄花中型树萝卜 (Chinese pinyin: huáng huā zhōng xíng shù luó bo).

Distribution and habitat.

This species is currently known only from the type locality, i. e. Medog County, Xizang, China. It grows on the tree trunks under broadleaved forests at elevations of 2300–2700 m.

Phenology.

The new variety flowers in March to April.

Taxonomic notes.

Compared to this new variety, the nominate variety, Agapetes interdicta var. interdicta , has a much wider distribution including southeast Xizang and northwest Yunnan of China, and north Myanmar ( Fang and Stevens 2005) (Fig. 2 ). Although the two varieties differ markedly in the colour, size and lobes of corollas, their vegetative parts are nearly the same so that it is difficult to identify them if the material is sterile. It is worth noting that Agapetes interdicta var. interdicta also rarely bears yellow-green flowers, but the differences in corolla size and lobes remain consistent (Fig. 3 ). The same kind of corolla colour variation also occurs in other Agapetes species, such as A. hosseana , which usually bears red or orange flowers, but some populations have green flowers ( Watthana 2015). Except for the corolla colour variation, the differences between this taxon and A. interdicta are mainly presented in some quantitative characters, viz. the size of corollas and the length of appendages at the base of anthers, which seem not significant enough to differentiate them as distinct species. Thus, we recognise this taxon ( A. interdicta var. flaviflora ) as a new variety rather than a new species. Another variety with narrower calyx lobes, A. interdicta var. stenoloba (W. E. Evans) Sleumer , was merged with the nominate variety by Fang and Stevens (2005). We agree with this treatment because the shapes of calyx lobes of this species can vary from narrowly laceolate to ovate even in a population, such as the Dulongjiang population. A lectotype for this name was designated here incidentally, since two collections were cited in the protologue without clear type designation ( Evans 1927). Due to the striking yellow corollas, A. interdicta var. flaviflora has high ornamental value.

Figures

Figure 1. Agapetes interdicta var. flaviflora A flowering plant B root tuber C leafy branch D flower E longitudinal section of flower with corolla and stamens removed to show style and ovary F androecium, abaxial view G androecium, adaxial view H calyx and disc, top view I calyx, bottom view J transection of ovary. Scale bars: 1 cm (D – G); 5 mm (H – I); 3 mm (J). A, B, E, G and I by Zi Wang, others by Xiang-Long Guo.

Figure 2. Distribution map of Agapetes interdicta var. interdicta (black circle), A. interdicta var. flaviflora (white circle), A. forrestii var. forrestii (black triangle) and A. forrestii var. parvifolia (white triangle).

Figure 3. Agapetes interdicta var. interdicta A flowering plant B leafy branch C inflorescence D variation of yellow-green corolla. All by Yi-Hua Tong. A – C from Gongshan County of Yunnan Province D from Tengchong City of Yunnan Province.