Reinstatement of the Chinese endemic species Styrax zhejiangensis

Abstract Styrax zhejiangensis has been treated as a synonym of S. macrocarpus. Examination of herbarium specimens and observation of wild living plants demonstrates that S. zhejiangensis is a distinct species and is clearly distinguishable from S. macrocarpus through its flowering phenology in which leaves and flowers open simultaneously, its smaller corolla lobes and filaments, and its white-stellate-pubescent seeds. On this basis, we reinstate S. zhejiangensis as an accepted species. Photographic images and a distribution map of the two species are provided. A lectotype of S. zhejiangensis is also designated.


Introduction
Styrax zhejiangensis S.M. Hwang & L.L. Yu (Hwang 1983) (Styracaceae) was described on the basis of four specimens of one collection, X. Y. He 29344 (IBSC, HHBG, NAS; Fig. 1A), from Jiande, Zhejiang Province, China. In the protologue, the authors stated that this species was similar to S. macrocarpus Cheng (Cheng 1938) (Fig. 1B), but differed by its bush-like habit, broadly elliptic to ovate-oblong leaves, smaller fruits, and sparsely white-stellate seeds. It was recognized by later authors, including Hwang (1987), Li and Ding (1989), Fang (1992), and Hwang and Grimes (1996), but was synonymized with S. macrocarpus by Huang et al. (2003). Huang et al. (2003) purported that there were no essential morphological differences between the two species emphasized by Hwang (1983) other than the presence of stellate trichomes on the seeds in S. zhejiangensis versus their absence in S. macrocarpus, a difference which they regarded as taxonomically trivial. According to Huang et al. (2003), S. macrocarpus sensu lato is a species with a disjunct distribution between southeastern Hunan and western Guangdong (Fig. 2).
After critical examinations of the relevant Styrax specimens in major Chinese herbaria, combined with our field observations in the type localities of each entity, we find that S. zhejiangensis is a species distinct from S. macrocarpus, differing from it in a combination of taxonomically significant morphological characters. Here we provide updated detailed morphological descriptions of these two species, a table of their morphological character differences, a distribution map, photographic images, and conservation assessments.

Material and methods
Morphological comparisons were made through herbarium studies and field observations. Herbarium studies were conducted in AU, BNU, CSFI, HHBG, IBK, IBSC, JXAU, KUN, NAS and PE. Field observations were made in the type localities of Styrax zhejiangensis in Jiande, Zhejiang Province, and S. macrocarpus on Mang Mountain, Hunan Province. Moreover, we use IUCN Red List categories (IUCN 2012) to evaluate the conservation status of the two species.

Distribution and habitat. Styrax macrocarpus is distributed between southeastern
Hunan and western Guangdong (Fig. 2). It grows in sparse forests, valleys or at forest margins at elevations between 130 and 230 m a.s.l.
Distribution and habitat. Styrax zhejiangensis is only found in Jiande, Zhejiang Province, distributed in Taohuawu, Long River Forest Area (Fig. 2). It grows in sparse forests or at forest margins at elevations between 130 and 230 m a.s.l. Phenology

Conservation status of Styrax zhejiangensis and S. macrocarpus
Styrax zhejiangensis is a narrowly distributed species; it is only found in Jiande with a population of less than 100 individuals. Despite the wide distribution of S. macrocarpus, it is mainly distributed on Mang Mountain and is not common. According to our observation, the natural regeneration of both of the two species is very poor. Following IUCN Red List categories (IUCN 2012), we categorize S. zhejiangensis as critically endangered under criteria B and D and S. macrocarpus as endangered under criteria B.