Koenigia hedbergii B. Li & W. Du, 2016
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publication ID |
https://doi.org/ 10.11646/phytotaxa.272.2.2 |
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persistent identifier |
https://treatment.plazi.org/id/A814CF10-6019-E82C-FF76-FA15FE2E26BE |
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treatment provided by |
Felipe |
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scientific name |
Koenigia hedbergii B. Li & W. Du |
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sp. nov. |
Koenigia hedbergii B. Li & W. Du View in CoL , sp. nov. ( Figs. 1 View FIGURE 1 , 2 View FIGURE 2 , 3A View FIGURE 3 1 & B1 View FIGURE 1 ).
Type:— CHINA. Hubei Province, Shennongjia National Nature Reserve, Shennongding Peak, on the open and grassy slope, elev. 2611 m, 31º27’ 32.92’’ N, 110º13’25.96’’ E, 22 July 2014, W.Du 2129 (holotype WH!, isotypes A!, IBSC!, JXAU!, K!).
Diagnosis: — Koenigia hedbergii is related to K. pilosa , but differs in stems lenght (25–72 cm vs. 5–30 cm long in K. pilosa ), leaves shape (lanceolate or lanceolate-ovate vs. ovate or narrowly ovate in K. pilosa ) and size (2.2–5.5 × 0.9–1.9 cm vs. 0.8–2.5 × 0.5–1.0 in K. pilosa ), number of leaves lateral veins (6–11 pairs vs. 2–5 pairs in K. pilosa ) and blade margins (obviously undulate and sparsely minutely ciliate vs. not undulate and sparsely or densely ciliate in K. pilosa ), hairness of the ocreae (glabrous but sparsely puberulent around bases vs. sparsely pilose around base in K. pilosa ), tepals lenght (1.8–2.4 mm vs. 1–1.6 mm in K. pilosa ) and achenes size (2.4–3.3 × 1.5–2.4 mm vs. 1–2.2 × 0.5–1.6 mm in K. pilosa ) and surface (achenes with three pronouncedly keeled edges in K. hedbergii vs. achenes without keeled edges in K. pilosa ).
Description:— Herbs annual. Stems erect, 25–72 cm tall, slender, slightly angulate, branched mainly in its upper parts, internodes glabrous but sparsely minutely pubescent below nodes. Leaf blades lanceolate or lanceolate-ovate (2.2–5.5 × 0.9–1.9 cm), lateral veins 6–11 pairs, both surfaces sparsely strigose to glabrous; petioles 0.3–1.9 cm long, slightly winged, glabrous; base subtruncate or broadly cuneate, slightly decurrent; margin entire, obviously undulate, sparsely minutely ciliate; apex subacute or acuminate. Ocreae distinctly bipartite, 2.3–3.1 mm long, yellow-brown to brown, membranous, slightly hyaline, base sparsely around by reflexed minute hairs but glabrous above, apex acute. Inflorescence terminal, erect, fascicled with 3–15 flowers; peduncle short, glabrous; bracts ochrea-like, narrowly campanulate, about 1 mm long, glabrous, each 1–2-flowered. Flowers white; perianth 5-parted, subequal, broadly obovate, 1.8–2.4 mm long, apex obtuse to rounded. Stamens 8, about 1 mm long, all fertile; thecae dark purple, distinctly separated. Styles 3, erect, very short, about 0.1 mm; stigmas capitate. Achenes exceeding persistent perianth, ovoid (2.4–3.3 × 1.5–2.4 mm), yellow-brown, sharply trigonous with three pronouncedly keeled edges and concave sides, surface smooth, shiny. Seed with straight embryo and copious endosperm.
Etymology:— The specific epithet “ hedbergii ” is named in honor of Pro. Olov Hedberg (1923–2007), a muchadmired international botanist with a wide range of interests. He has contributed a lot in palynological studies of Polygonaceae and carried out a taxonomic monograph of the genus Koenigia in 1997 ( Hedberg 1997).
Pollen morphology:— Pollen grains of K. hedbergii are spheroidal (19–22 μm in diameter) with 12(–15)- pantoporate apertures (the pores are circular with diameter of 1.8–2.4 μm), and prominently spinulose exine ornamentation (spinules are 0.9–1.7μm in length) ( Fig. 4 View FIGURE 4 ). Zhou et al. (2004) recognized three types of pollen grains in Koenigia based on the features of apertures: 1) Delicatulum - type with 7(–8)-zonocolpate aperture, 2) Forrestii - type with 12-pantocolpate apertures, 3) Koenigia - type with 12(–15) or 20(–30)-pantoporate apertures. Accordingly, the pollen grains of K. hedbergii are Koenigia - type.
Distribution, habitat, and phenology:— Koenigia hedbergii can be considered endemic to Shennongjia Mountains, and it is currently recorded only from two adjacent localities (Shennongjia National Nature Reserve in western Hubei Province and Wuxi County in eastern Chongqing Municipality; Fig. 5 View FIGURE 5 ). The new species frequently occurs in Shennongding Peak, Banbiyan, Taiziya, Mirentang, etc., common under the subtropical montane dwarf forests, or on the open and grassy slope at elevations of 2400–2650 m ( Fig. 1A View FIGURE 1 ). Flowering time is July–September, fruiting time is August–October.
Taxonomical notes:— With the extremely short styles and the prominently spinulose exine ornamentation for pollen grains, K. hedbergii is a certainty member of the genus Koeni gia. After examining herbarium specimens of other taxa of Koenigia (uncorrectly identified as Polygonum spp. ), as well as consulting relevant literatures (e.g., Don 1825, Meisner 1856, Maximowicz 1882, Gross 1913b, Steward 1930, Haraldson 1978, Hedberg 1997, Li et al. 2003), we found out that K. hedbergii can be treated as a distinct species. Among the six species recognized by Hedberg (1997) or the five restricted by Fan et al. (2013), K. delicatula and K. islandica are delicate or minute and usually entirely glabrous annual herbs ( K. hedbergii has stems sparsely pubescent), while K. forrestii and K. nummularifolia are prostrate perennial herbs ( K. hedbergii is annual). Only K. nepalensis and K. pilosa show some morphological features which resemble K. hedbergii , such as erect or ascending stems, dense or sparse pubescences on stems and leaves, loose capitate inflorescences, 5-parted perianth, and trigonous achenes. Pollens of K. nepalensis and K. pilosa are also Koenigia - type ( Zhou et al. 2004), indicating their close relationships with K. hedbergii . However, detailed morphological comparison reveal clear differences between the three species ( Fig. 2 View FIGURE 2 , Fig. 6 View FIGURE 6 , Table 1). K. hedbergii is much taller than K. nepalensis and K. pilosa , and has larger leaf blades, more paris of leaf lateral veins and longer perianth and achenes. Besides, K. nepalensis also differs from K. hedbergii by its stems, leaves and ocreae densely to sparsely covered by stiffly erect and appressed hairs, and by its ocreae funnel-shaped. K. pilosa is additionally different from K. hedbergii by its weak and short stems, by its leaves ovate or narrowly ovate. As to distribution area, K. hedbergii was only known from two adjacent localities in Shennongjia Mountains which are far distant from the main distribution ranges of K. nepalensis and K. pilosa in alpine areas of the Qinghai-Tibet Plateau, the Himalaya and the Hengduan Mountains in southwest China ( Fig. 5 View FIGURE 5 ).
Conservation status:— Population of Koenigia hedbergii can be found easily in the Shennongding area at elevations of 2400–2650 m; moreover, specimens were also collected from Wuxi Country, which is near the Shennongjia Forest Zone, based on the specimen checking.According to the results of the population survey (1m × 1m), the average individuals of each population were 78 ± 23 (n = 10), there are 114.5 km 2 area above 2000 m elevation in Shennongjia National Nature Reserve ( Liao 2011). Lots of mature seeds can be produced in the populations. Thus, we suggest evaluating the species as Least Concern (LC) according to the IUCN Red List Categories and Criterion C (IUCN 2012).
Additional specimens examined (paratypes):— CHINA. Hubei: Shennongjia National Nature Reserve, 2600 m elev., 31º27′32′.92″ N, 110º13′25.96″ E, 22 July 2014, Du 2129 (WH!); at the same place, 31°30′ N, 110°30′ E, ca. 3000 m a.s.l., 26 August 1980, 1980 Sino-American Botanical Expedition 41 (WH!), labeled as Polygonum pilosum (Maximowicz) Hemsley (1891: 345) ; at the same place, August 1993, Anonymous 93035H (PE00384085! labeled as P. cyanandrum ); Chongqing: Wuxi County, Hongchi Town, 22 August 1958, Yang 59243 (KUN0124810!, labeled as P. cyanandrum ); at the same place, September 1958, Yang 59523 (NAS00169032!, labeled as P. filicaule ; KUN0124809!, labeled as P. cyanandrum ).
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