Persicaria wugongshanensis B. Li 2014, sp. nov.
Creators: name: Li, Bo
Publisher: name: Zenodo
Year: 2014
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Polygonales
Polygonaceae
Persicaria
Persicaria wugongshanensis

description: Persicaria wugongshanensis B. Li, sp. nov.
Type:— CHINA. Jiangxi Province, Luxi County, Wugongshan Mountain, Longwangtan Village, 460 m a.s.l., 27°28′41″N, 114°08′11″E, 7 October 2009, Bo Li LB-0093 (Holotype: IBSC!; Isotypes: IBSC!, JXAU!) (Figs. 1−2).
Diagnosis: — A Persicaria odorata foliis ovatis vel ovato-lanceolatis, nervis 7–9, ochreis dense hirsutae, pedicellis 9.1–15.5 mm longis, pedicellis bracteis multo longiores, acheniis dense foveolatis differt.
Description: —Herbs annual, intensely odoriferous. Stems erect, 50–120 cm tall, robust, much branched, without rhizomes, glabrous, sparsely glandular, swollen at nodes. Petiole short or nearly absent, sparsely pubescent; leaf blade ovate, ovate-lanceolate, or rarely broadly lanceolate, 3.5–7.5 cm long, 1.2–2.2 cm wide, lateral veins 7–9 pairs, abaxially densely glandular, adaxially sparse, both surfaces sparsely pubescent, densely so along midvein; base broadly cuneate, slightly decurrent; margin entire, shortly sparsely ciliate; apex acute or acuminate. Ocrea tubular, 7.0– 13.1 mm, membranous, densely appressed pubescent, apex truncate, fimbriate, cilia 4.2–9.3 mm long. Inflorescence terminal or axillary, spicate, numerous, 4.5–8.9 cm, erect or slightly nodding, usually interrupted at base; peduncle sparsely glandular, glabrous; bracts green, funnel-shaped, sparsely pubescent and glandular, margin submembranous, ciliate, each 4–7-flowered. Pedicel much longer than bracts, 9.1–15.5 mm. Flowers dimorphic; perianth 5-parted, minutely goldenly punctate; long-styled flowers (L-morph) usually pinkish or pinkish-white, stamens 8, 2.1–2.4 mm, styles 3, 4.2–4.5 mm, exserted; short-styled flowers (S-morph) usually white or whitish, stamens 8, 4.6–4.9 mm, exserted, styles 3, 2.1–2.3 mm; stigmas capitate; nectaries 8, arranged at the base of each ovary. Achenes included in persistent perianth, black, opaque, ovoid, trigonous, 2.9–3.5 mm long, 1.8–2.2 mm wide, densely pitted.
Distribution, habitat, and flowering/fruiting times:—The species is endemic to western Jiangxi, eastern of China, currently known only from Wugongshan Mountain of Luxi County. The new species is frequent around Longwangtan, Dajiangbian and Xiongling villages, common near riverside and paddy fields, in swamp grassy places at elevations of 200–600 m a.s.l. Flowering time is August–October, fruiting time is September–November.
Etymology: —The specific epithet refers to the locus classicus Wugongshan Mountain.
Conservation status: —The species is restricted only in three locations (Longwangtan, Dajiangbian and Xiongling villages). Though individuals in these locations now widely disperse near riverside and paddy fields, or in swamp grassy places, they are threatened by local agricultural activities, such as weeding and grazing, as well by large number of construction projects (such as roads, hotels, stores and hydropower stations) induced by rapid development of tourism in this region (known as Wugongshan national forest park and Wugongshan national scenic spot). It is plausible that these direct or indirect threats will increase a risk of population decline of the species in a very short time in future. Persicaria wugongshanensis is here assessed as Vulnerable (VU) under Criterion D2 of the IUCN (2012) for China.
Uses: —Known from local people, the leaf blades and stems are used as one of the principal ingredients of medicinal liquor “pers. obs.”.
Cytology: —The somatic chromosome at mitosis metaphase of P. wugongshanensis is 2 n = 20 (Fig. 3A) which is congruent with that of most taxa reported in the genus (Löve & Löve 1956, Doida 1960, Wolf & McNeill 1987), and the karyotype formula is reported as 2 n = 14 m + 6 sm (Fig. 3B).
Discussion: — Persicaria wugongshanensis is clearly distinctive because its intensely odoriferous smell [just like Houttuynia Thunberg (1783: 149)] and distyly are rare in Persicaria (Tutin et al. 1991, Li 1998, Li et al. 2003, Qaiser 2005). Measurements of floral morphology revealed that P. wugongshanensis possesses a typical distylous floral syndrome. The heights of the stigmas (4.33 ± 0.190 mm vs. 2.18 ± 0.069 mm, pin vs. thrum) and anthers (2.23 ± 0.062 mm vs. 4.73 ± 0.078 mm, pin vs. thrum) of the two morphs are shown in Table 1 and Fig. 4. The tepal length in the long-style morph (L-morph) flowers is smaller than those of the short-style morph (S-morph) flowers (Table 1; F (LTL, STL) = 38.47, P <0.001). The stigma height in the L-morphs is significantly greater than those in S-morphs (Fig. 2D; F (LSH, SSH) = 1120.47, P <0.001), whereas the anther height in the S-morphs is significantly greater than those in the L-morphs (Fig. 2E; F (SAH, LAH) = 6383.46, P <0.001). In both morphs, the stigmas are capitate with dry papillate. The papillae of L-morphs are frequently longer and less crowded than those of the Smorphs, but the stigmas in S-morph flowers are wider than those in L-morph ones (Table 1; F(SSW, LSW) = 57.74, P <0.001). The pollen grains of the two morphs are both spheroidal with reticulate surface ornamentation, but pollens of the S-morphs have larger meshes and more papillates in every mesh than those of the L-morph flowers. In addition, the S-morph flowers produce significantly bigger and more pollen grains than the L-morph flowers (Table 1; pollen size: F(SM, LM) = 138.32, P <0.001; pollen number: F(SM, LM) = 77.79, P <0.001).
Up to now, a similar characteristic of the intensely odoriferous smell appears only in P. odorata (Loureiro 1790: 243) Soják (1974: 154), a Southeast Asian taxa known as “Vietnamese coriander”. Other similar features between P. wugongshanensis and P. odorata are: the glandular leaf blades and tepals, erect or slightly nodding tight inflorescences usually interrupted at base, dimorphic flowers and the pedicels longer than bracts (Fig. 5). In order to confirm the relationship of the two taxa, a preliminary phylogenetic analysis based on a dataset of internal transcribed spacer (ITS) of the nuclear ribosomal DNA which included 80 GenBank accessions and covered 55 Persicaria ingroup taxa and four outgroup taxa was carried out. The results suggested that P. wugongshanensis clusters with P. odorata and P. hydropiper (Linnaeus 1753: 361) Spach (1841: 536) form a well-supported monophyly (Bootstrap value = 96, Bayesian posterior probabilities = 1.00) (Li et al., in prep.). P. hydropiper (“Water Pepper”) does not have odoriferous smell, but its characterized peppery taste of leaves is similar to that of P. odorata, indicating that the clade may be supported by some organic compounds.
Since P. hydropiper is morphologically far different from P. wugongshanensis (Table 2), detailed comparative studies were mainly conducted for the group P. wugongshanensis / P. odorata (Table 2; Figg. 2, 5, 6). P. wugongshanensis is an annual herb without rhizomes, whereas P. odorata is a well-known perennial potherb with well-developed rhizomes. Morphologically, Persicaria wugongshanensis is obviously differs from P. odorata by its ovate or ovate-lanceolate leaf blades (vs. lanceolate or narrowly lanceolate leaf blades) (Fig. 2B vs. Fig. 5B), densely appressed pubescent ocreae (vs. glabrous ocreae) (Fig. 2B vs. Fig. 5D), pedicels much longer than bracts (vs. pedicels slightly longer than bracts) (Fig. 2C vs. Fig. 5E) and opaque pitted achenes (vs. shinny achenes) (Fig. 6, A vs. E). Additionally, there are also many micromorphological characters of achenes, leaves, pollen grains and tepals which can be used to distinguish the two species with no difficulty (Table 3; Figure 6).
Distyly has been also reported in P. japonica (Nishihiro & Washitani 1998) and P. jucunda (Meisner 1826: 71) Migo (1939: 142) (Chen & Zhang 2010). P. japonica is a perennial plant with developed rhizomes and differs from P. wugongshanensis in having lanceolate thinly leathery leaf blades with 10–13 pairs lateral veins, much longer ocreae and shorter pedicels, and biconvex or rarely trigonous achenes with smooth surface (Table 2). Besides, the mitotic chromosomes number of P. japonica have been reported as 2 n = 40 (Doida 1960, Iwatsubo et al. 2003, Li et al., unpublished), 49 or 50 (Iwatsubo et al. 2003), while that of P. wugongshanensis is 2 n = 20 (Fig. 3). Persicaria jucunda obviously differs from P. wugongshanensis in having elliptic-lanceolate leaf blades, smaller flowers, uninterrupted and more slender inflorescences, shorter pedicels, and shiny achenes (Table 2).
In Persicaria, a significant number of hybrid speciation events have been observed in many cases, and a hybridized taxon usually exhibites intermediate characters between its parent species (Kim & Donohgue 2008b, Kim et al. 2008). In P. wugongshanensis, its annual habit, ovate to ovate-lanceolate leaf blades, and opaque pitted achenes are similar to those of P. hydropiper, while its odoriferous smell is exactly similar to that of P. odorata, and its dimorphic flowers, and tight and robust inflorescences are similar to those of P. japonica and P. odorata. These intermediate characters of P. wugongshanensis may indicate that this new specific population is originated from the combination between two of the three related taxa. From a geographic view of point, P. odorata is native to peninsular Southeast Asia (Indo-china) (http://gernot-katzers-spice-pages.com/engl/Pers_odo.html#part) which is far away from the locations of P. wugongshanensis. While P. hydropiper and P. japonica are widely distributed in subtropical regions of China (Li 1998, Li et al. 2003), and both of the taxa are frequently observed around the locations of the new species, making a combination between them available. However P. japonica is a tetraploid (Doida 1960, Iwatsubo et al. 2003, Kim et al. 2008, Li et al., unpublished) and P. hydropiper is a diploid (Zakirova & Nafanailova 1990, Nakata & Nagai 1998, Gervais 2000, Probatova 2000, Li et al., unpublished), so their hybrid offspring are likely triploid or hexaploid followed by polyploidization, but impossible a diploid like the new species. So if P. wugongshanensis is originated from hybridization, P. hydropiper and another unknown or extinct diploid species with dimorphic flowers are probably the parents. Otherwise it may share a common ancestor with P. hydropiper or P. odorata, or both of them.
Additional specimens examined (paratypes):— CHINA, Jiangxi Province, Luxi Country, Wugongshan Mountains, Longwangtan village, near paddy fields, 30 September 2006, Li & Zhang W1001 (IBSC!).
description: Published as part of Li, Bo, 2014, Persicaria wugongshanensis (Polygonaceae: Persicarieae), an odoriferous and distylous new species from Jiangxi, eastern China, pp. 133-144 in Phytotaxa 156 (3) on pages 134-141, DOI: 10.11646/phytotaxa.156.3.4, http://zenodo.org/record/5127800