Agapetesheana, a new species of A.ser.Longifiles (Ericaceae) from Yunnan, China

Abstract Agapetesheana Y. H. Tong & J. D. Ya (Ericaceae), a new species from Lüchun Xian, Yunnan Province, China is described and illustrated. This new species is assigned to Agapetessect.Agapetesser.Longifiles Airy Shaw. It is closest to A.inopinata Airy Shaw and A.oblonga Craib, but differs in having bead-like tubers, leaf blade with a wholly serrulate margin, subulate and much longer calyx lobes, much larger corollas that are carmine, green at the apex and maroon on angles, and longer stamens without spurs on the back.


Introduction
A general introduction to Agapetes D. Don ex G. Don, focusing on the species in China was given in previous papers published by the first author and is not repeated here (Tong 2016;Tong et al. 2019). With 17 species and two varieties of Agapetes in-cluding the recently published A. yingjiangensis Y. H. Tong, B. M. Wang & N. H. Xia, Yunnan Province, after Tibet, harbors the second most species of this genus in China (Huang and Fang 1991;Fang and Stevens 2005;Tong 2014). During one recent field trip to Huanglian Shan National Nature Reserve, Yunnan Province, China, an unknown Agapetes species was discovered. The combination of its ovate to ovate-lanceolate leaf blades, inflorescence with glandular hairs and elongated filaments immediately reminded us of two other similar species from the same province, viz. A. oblonga Craib and A. inopinata Airy Shaw. However, the latter two species have very differently colored corollas. After examining the specimens of similar species and referring to the related literature (Hiep 2003;Kress et al. 2003;Fang and Stevens 2005;Banik and Sanjappa 2014;Watthana 2015), we concluded that this unknown species is a new one to science, which is described and illustrated below.

Materials and methods
Specimens were collected from Huanglian Shan National Nature Reserve, Yunnan Province, China during two field expeditions in March and April 2021, respectively. All descriptions were based on dried specimens, which were deposited at the herbaria of Kunming Institute of Botany, Chinese Academy of Sciences (KUN) and South China Botanical Garden, Chinese Academy of Sciences (IBSC). Diagnosis. Agapetes heana is similar to A. inopinata Airy Shaw and A. oblonga Craib in the leaf blade shape, the glandular hairy inflorescence and the filaments that are longer than thecae, but can be distinguished from the latter two by its bead-like tubers (vs. spindle-shaped), leaf blade with a wholly serrulate margin (vs. entire, or inconspicuously serrate beyond middle, or sparsely denticulate at apex), subulate (vs. triangular) and much longer (7-8 mm vs. ca. 1 mm and 1.5-2.0 mm, respectively) calyx lobes, much larger (ca. 3.5 cm vs. ca. 0.8 cm and 1.3-1.9 cm, respectively) corollas that are carmine, green at the apex and maroon on angles (vs. red, crimson or carmine), and longer (ca. 3.6 cm vs. ca. 0.7 cm and 1.0-1.5 cm, respectively) stamens that are without spurs on the back (vs. with 2 obvious short spurs) ( Table 1).
Etymology. The species epithet is named in honor of Ms. Jiang-Hai He, a local staff in Huanglian Shan National Nature Reserve, who has worked there for almost 30 years and made a big contribution to the knowledge of biodiversity of this nature reserve, and is also the discoverer of this new species. Distribution and habitat. This species is currently known only from the type locality, i.e. Huanglian Shan National Nature Reserve, Yunnan, China. Since this locality is very close to the border of China and Vietnam and the habitat is similar and continuous, this species is probably also distributed in Vietnam. It grows on the trunks of trees like Schima wallichii (DC.) Korth. or Lithocarpus sp. under broadleaved forests at an elevation of ca. 1800 m.

Conservation status.
Agapetes heana seems to be very rare in the type locality, since only a population of fewer than 10 individuals has been found for now, but the threat risk seems to be low because it is not economically valuable and the conservation condition of the reserve is good. Because no population assessment of this species in the field of China or adjacent area of Vietnam has been made, it is best classified as 'Data Deficient' (DD) (IUCN Standards and Petitions Committee 2019).

Discussion
According to Airy Shaw's infrageneric system, A. heana fits well with the circumscription of Agapetes sect. Agapetes ser. Longifiles Airy Shaw due to its slender stems, flowers arranged into a short raceme, and elongated filaments (longer than anthers) (Airy Shaw 1935Shaw , 1959, except that its anthers are not spurred, while almost all the species of that series own spurred anthers. Both spurred and unspurred anthers occur in other series, such as ser. Agapetes and ser. Pteryganthae (Airy Shaw 1935Shaw , 1948Shaw , 1959Huang 1991). Thus, this character appears to have evolved more than once in this genus. Besides this new species, there are another two species of Agapetes distributed in the same mountain (Huanglian Shan), viz. A. lobbii C. B. Clarke (S. K. Wu et al. 652, PE!, KUN0230909!) and A. rubrobracteata R. C. Fang & S. H. Huang (S. K. Wu et al. 253,PE!). However, these two species are distantly related to our new species due to their very different vegetative and productive characters, such as habits, leaf blade shapes, indumentum on branches and inflorescences, various floral characters, and so on.