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Reinstatement of the Chinese endemic species Styrax zhejiangensis
expand article infoYu-Qing Ruan§, Yu-Long Yu|, Fen Yu§, Guo-Xing Deng, Yu-Lin Liu§, Xue-Hui Wu§, Ming Tang§
‡ Key Laboratory for Bamboo Germplasm Resources and Utilization, Nanchang, China
§ Jiangxi Agricultural University, Nanchang, China
| Jiande Forest Farm of Zhejiang, Jiande, China
¶ Hunan Mangshan National Nature Reserve, Yizhang, China
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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.

Keywords

Flowering phenology, Styracaceae, Styrax zhejiangensis, S. macrocarpus, synonym

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.

Figure 1. 

Lectotype sheet of Styrax zhejiangensis, China, Zhejiang, Jiande, X. Y. He 29344 (IBSC) (A) and holotype sheet of S. macrocarpus, China, Hunan, Yizhang, Mang mountain, W. C. Cheng s.n. (PE) (B).

Figure 2. 

Distribution map of Styrax zhejiangensis ([INSERT FIGURE 003]) and S. macrocarpus.

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.

Results and discussion

Styrax zhejiangensis differs from S. macrocarpus in a combination of morphological characters (Table 1, Figs 35). S. zhejiangensis produces flowers and leaves simultaneously (vs. flowers before the leaves in S. macrocarpus), has smaller flowers (4.0–5.5 cm vs. 6.0–7.5 cm in diameter) with shorter corolla lobes (1.8–2.7 cm vs. 2.8–3.8 cm) and stamens (10–12 cm vs.14–16 cm), and has a seed surface with sparse to dense white-stellate trichomes (vs. glabrous). Furthermore, S. zhejiangensis is shrub-like, 1.5–3 m (only one individual reaches 7 m in our observation), with multiple branches from the base, whereas S. macrocarpus is tree-like, often over 7 m and with single stem. The pubescence on the corolla also helps to distinguish the two species, with S. zhejiangensis having inconspicuous pubescence or being glabrous, and S. macrocarpus having conspicuous pubescence.

Figure 3. 

Styrax zhejiangensis (Jiande, Zhejiang, China) A habitat and habit B inflorescence C leaf blades D flower (top view) E flower (back view) F flower (side view) G opened flower H corolla lobes I sepals (two sepals pulled apart at the lobe margins of one calyx) J stamens. Photographed by Yu-Qing Ruan and Ming Tang.

Figure 4. 

Styrax macrocarpus (Yizhang, Hunan, China) A habitat and habit; red arrow indicates S. macrocarpus B inflorescence C leaf blades in adaxial (left) and abaxial (right) view D flower (top view) E flower (back view) F flower (side view) G corolla lobes H sepals (two sepals pulled apart at the lobe margins of one calyx) I stamens. Photographed by Yu-Qing Ruan and Ming Tang.

Figure 5. 

Morphological comparison between Styrax zhejiangensis (A1, B1, C1, D1) and S. macrocarpus (A2, B2, C2, D2). A1, A2 Flower B1, B2 corolla lobes C1, C2 stamens D1, D2 seed (Note the enlarged stellate trichomes in the red circle in figure D1). Photographed by Yu-Qing Ruan and Ming Tang.

Morphological differences between Styrax zhejiangensis and S. macrocarpus.

Taxonomic traits Styrax zhejiangensis Styrax macrocarpus
Stem 1.5–3 (–7) m, shrub-like habit 6–9 (–12) m, tree-like or small tree-like habit
Petiole Upper 1–3 mm, middle nearly absent Both upper and middle 2–5 mm
Flowering phenology Leaves and flowers open simultaneously Flowers open before leaves
Flower diameter 4.0–5.5 cm 6.0–7.5 cm
Corolla lobe length 1.8–2.7 cm 2.8–3.8 cm
Corolla lobe pubescence inconspicuous or absent Conspicuous
Stamens, number 13 to 16 11 to 15
Stamen, length 10–12 mm 14–16 mm
Seeds with stellate trichomes without stellate trichomes

Li and Ding (1989) and Hwang and Grimes (1996) described the flowering phenology for Styrax zhejiangensis and S. macrocarpus and they have been confirmed in our field observation, and undoubtedly serve as a diagnostic character. Li and Ding (1989) also pointed out that the species can also be distinguished by the size of the corolla lobes and numbers of stamens. We observed a substantial difference in the size of their corolla lobes, but no distinct difference in the numbers of their stamens, with 13 to 16 stamens for S. zhejiangensis and 11 to 15 for S. macrocarpus. Huang et al. (2003) pointed out that the number of stellate trichomes distributed on the seed surface of S. zhejiangensis varies from several to dozens, which is consistent with our observation, and they considered that this character by itself cannot be used to distinguish S. zhejiangensis from S. macrocarpus. However, it should be noted that the seed surface of S. macrocarpus is glabrous by our observation, never with stellate trichomes. Thus, combined with the other differences observed, warrant the treatment of S. zhejiangensis as an accepted species distinct from S. macrocarpus.

Taxonomic treatment

Styrax macrocarpus Cheng (Cheng 1938: 398)

Fig. 1B, 4, 5 A2, B2, C2, D2

Type

CHINA. Hunan: Yizhang, Mang Mountain, 800 m, 21 August 1937, W. C. Cheng 7000 [from protologue] (holotype PE00027927!; isotype PE 00027979!)

Description

Trees 6–9(–12) m tall, with a single stem, deciduous. Branchlets subterete, densely gray-brown stellate-pubescent, glabrescent. Leaves alternate, two most proximal leaves on each shoot subopposite to opposite; leaf blade broadly elliptic to ovate-oblong, 5.5–15.0 × 3.0–6.0 cm, papery, glabrous but veins stellate-pubescent, elliptic to obovate-elliptic; apex acute; base cuneate, broadly cuneate or rounded; margin subentire or apically slightly serrate; secondary veins 6 to 10 pairs, tertiary veins subparallel; adaxially plane or slightly sunken, abaxially raised. Petiole 2–5 mm long. Pedicel 9–13 mm long, densely white-stellate-tomentose; bracteoles 6–10 mm long, ovate-lanceolate. Flowers solitary, axillary, opening before leaves. Calyx 5–8 × 6–9 mm, membranaceous, densely gray-stellate-tomentose and sparsely stellate-pubescent; teeth 5 or 6, deltoid, unequal, 2–3 mm, subglabrous. Corolla diameter 6.0–7.5 cm, white, tube 3–4 mm long; lobes 6 or 7, elliptic-obovate, 2.8–3.8 × 1.5–2.5 cm. Stamens 11 to 15, 14–16 mm long, shorter than corolla; filaments 7–10 mm long, basally densely white-stellate-pubescent; anthers 5–7 mm long. Fruit solitary, axillary, ovoid, 2–3 × 2.0–2.5 cm, densely gray-stellate-pubescent, apex shortly pointed. Seeds ovoid-ellipsoid, irregularly rugose, glabrous.

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.

Phenology

Flowering from mid- to late April and fruiting in August and September.

Additional specimens examined

CHINA. Hunan: Yizhang, S.H. Chun 2889 (AU, IBK, IBSC, KUN, PE), 5408 (IBSC), Central South Forestry Institute internship team 02-3 195 (CSFI), M.S Huang 112743 (IBSC), H.S. Liao 15727 (CSFI), P.H. Liang & X.H. Xu 85107 (IBK, IBSC), S.R. Lin & K.W. Liu 50285 (CSFI), X.Q. Liu 28884 (IBK, IBSC, NAS, PE), Y.Q. Ruan & Y.L. Liu 34 (JXAU), J.G. Xiao 4142 (CSFI), anonymous 137 (IBSC), anonymous 1017 (CSFI). Guangdong: Fengkai, G.L. Shi 14815 (IBSC), Q.S. Yue 5185 (IBSC); Ruyuan, L. Wu & Y. Tong 3192 (IBSC), Z.L. Chen 30610 (IBSC).

Notes

The two specimens collected from Mengla County, Yunnan (Y. M. Xia 245, HITBC) and Yulin, Guangxi (Y.S. Wu 0289, IBK) respectively, which were also designated as Stytax macrocarpus on the sheets, are confirmed to be wrongly identified and should be S. chinensis (Liang 1980: 230), a widely distributed species in the southernmost provinces of China such as Guangdong, Guangxi, Yunnan, Fujian, as well as Southeast Asia. S. chinesis could be easily distinguished from S. macrocarpus by its bigger (8–23 × 3–12 cm vs 5.5–15.0 × 3.0–6.0 cm), thick-leathery leaves (vs papery) leaves.

Styrax zhejiangensis Hwang (Hwang 1983: 75)

Fig. 1A, 3, 5A1, B1, C1, D1

Type

CHINA. Zhejiang: Jiande, northeast of Long River, along stream, 27 June 1958, X. Y. He 29344 (lectotype, here designated, IBSC0002732!; isolectotype IBSC0497542!; isolectotype HHBG-HZ044271!; isolectotype NAS00072216!).

Description

Shrubs, 1.5–3(–7) m tall, often branched at base, deciduous. Branchlets subterete, brown to grayish brown, glabrous. Leaves alternate but subopposite on basal part of branchlet; leaf blade broadly elliptic to ovate-oblong, 2.5–8.0 × 2.0–5.0 cm, papery, adaxially glabrous, abaxially glabrous but veins sparsely stellate-villous, base broadly cuneate to rounded, margin denticulate to subentire, apex acute, secondary veins 5 to 10 pairs, tertiary veins reticulate; adaxially plane or slightly sunken, abaxially raised. Petiole: those of upper leaves 1–3 mm, those of middle nearly sessile. Pedicel 7–13 mm long, densely white-stellate-tomentose; Flowers solitary, axillary, opening simultaneously with leaves. Calyx 5–8 × 5–10 mm, membranaceous; teeth 5 or 6, deltoid, unequal, 1.0–2.5 mm, apex white-glandular-dotted. Corolla diameter 4.0–5.5 cm, white, tube 3–4 mm long; lobes 6 to 8, elliptic-obovate, 1.8–2.7 × 1.0–1.6 cm. Stamens 13 to 16, 10–12 mm long, shorter than corolla; filaments 5–8 mm long, basally densely white-stellate-pubescent; anthers 4–5 mm long. Fruit solitary, axillary, ovoid, 1.8–2.0 × 1.0–1.2 cm, densely gray-stellate-pubescent, apex shortly pointed. Seeds ovoid-ellipsoid, irregularly rugose, sparsely or densely white-stellate-pubescent.

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

Flowering in early April and fruiting in August and September.

Additional specimens examined

CHINA. Zhejiang: Jiande, G.Y. Li et al. L 0150 (PE); G.Y. Li et al. L 0154 (PE); Y.Q. Ruan & Y.L. Liu RL 31 (JXAU); Y.Q. Ruan & Y.L. Liu RL 46 (JXAU).

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.

Acknowledgements

We are grateful to Dr. Chen Ren, Dr. Peter W. Fritsch and Dr. Yasen Mutafchiev for their valuable comments on the manuscript. We also thank the curators of AU, BNU, CSFI, HHBG, IBK, IBSC, JXAU, KUN, NAS and PE for access to their specimens and allowing us to use their scanned images of specimens. This work was supported by the National Natural Science Foundation of China (grant no 31960043, 31500166) and the Science and Technology Research Project of Jiangxi Education Department (grant no. GJJ170255).

References

  • Cheng WC (1938) A new Chinese Styrax. Contributions from the Biological Laboratory of the Science Society of China 10(3): 242–243.
  • Fang YY (1992) Styrax. In: Zhang CF, Zhang SY (Eds) Zhejiang Zhiwuzhi, Tomus 5. Zhejiang Science and Technology Press, Hangzhou, 88–95. [In Chinese]
  • Huang YL, Fritsch PW, Shi SH (2003) A revision of the imbricate group of Styrax series Cyrta (Styracaceae) in Asia. Annals of the Missouri Botanical Garden 90(4): 491–553. https://doi.org/10.2307/3298541
  • Hwang SM (1983) New taxa of Styrax from China. Acta Botanica Austro Sinica 1: 75–77. [In Chinese]
  • Hwang SM (1987) Styracaceae. In: Zhang CF, Zhang SY (Eds) Flora Reipublicae Popularis Sinicae, Tomus 60(2). Science Press, Beijing, 79–121. [In Chinese]
  • Hwang SM, Grimes J (1996) Styrax L. In: Wu ZY, Raven PH (Eds) Flora of China, Vol. 15. Science Press, Beijing & Missouri Botanical Garden Press, St. Louis, 253–263.
  • Li GY, Ding L (1989) Revision and supplement of morphological characteristics of Styrax zhejiangensis. Journal of Zhejiang Forestry College 6(4): 443–444. [In Chinese]