Parasenecio anhuiensis Y. S. Chen & L. S. Xu, 2016

Xu, Lian-Sheng & Chen, You-Sheng, 2016, Parasenecio anhuiensis (Asteraceae, Senecioneae), a new species from eastern China, Phytotaxa 283 (2), pp. 188-194 : 188-192

Parasenecio anhuiensis Y. S. Chen & L. S. Xu , sp. nov. ( Figure 1.A–C ; Figure 2.A, C, E & G ; Figure 3.A & C )

Type:— CHINA. Anhui Province: Huangshan City, Huangshan Mountain , Taohuafeng, in sparse forest in ravine, 1000 m, 12 August 2006, Y. S. Chen 6229 (holotype PE ; isotypes PE ).

Perennial herbs up to 100 cm tall. Rhizome short, elongate with numerous fibrous roots. Stem solitary, erect, striate, glabrous, 3–4 mm in diameter. Leaves usually 3–4, long-petiolate (uppermost one shortly petiolate); petiole up to 9 cm long, glabrous, not winged; basal leaves withered at anthesis; lower and middle leaf blade cordate-reniform or orbicular-reniform, 12–19.5 × 13–19 cm, palmately 3–5-veined, veins prominent on both surfaces, paper-thin, green, abaxially sparsely arachnoid to glabrescent, adaxially glabrous, margin 5–7-lobed, cartilaginous mucronulatedenticulate, apex acute, base cordate to truncate. Upper leaves gradually decreasing in size toward stem apex, oblong, lanceolate to subulate, margin usually entire. Capitula discoid, many, terminal or in upper leaf axils, arranged in nearly cylindrical panicles 11–27 cm long, 4–8 cm wide; peduncles nearly absent (up to 3 mm long); rachis shortly glandular-hairy; bractlets 5–7 at base of heads, triangular-ovate, ca. 1.5–2 mm long. Involucres cylindrical, 2–3 mm in diameter, 7–8 mm high; phyllaries in one series, linear, 7–8 mm long, 1.5–2 mm wide, outer surface glabrous, apex acute, margin membranous. Florets bisexual, 5; corolla white, tube ca. 5 mm long; limb broadly tubular, 5–6 mm long, with 5 lanceolate lobes ca. 1 mm long. Anthers exserted from corolla, ca. 5 mm long, anther apical appendages ovate, anther collars typically cylindrical, 0.6–0.7 mm long, anther base tails 0.4–0.5 mm long. Style ca. 11 mm long, style arms excurved, apically truncate, densely covered with papillae. Immature achenes brown, cylindrical, ca. 2.5 mm long, glabrous, longitudinally ribbed. Pappus of capillary bristles, white, ca. 8 mm long.

Phenology:—Flowering in August.

Etymology:—The specific epithet is derived from the type locality name, Anhui.

Distribution and habitat:— Parasenecio anhuiensis is currently known only from two localities: Huangshan Mountain in Anhui Province and Lushan Mountain in Jiangxi Province ( Figure 4 ). The new species grows in sparse forest in ravine at an altitude of about 1000 m.

Discussion:—According to Shen (1991), there are three species of Parasenecio [listed under the generic name Cacalia Linnaeus (1753: 834) ] in Anhui Province, including P. rubescens (Moore 1875: 228) Chen (1999: 49) , P. ainsliaeiflorus ( Franchet 1894: 361) Chen (1999: 47) and P. hwangshanicus ( Ling 1937: 11) Chen (1999: 75) . However, in Anhui P. ainsliaeiflorus is found to occur only in Jinzhai county in the west of that province ( Zhang et al. 2006). Parasenecio anhuiensis is similar to P. ainsliaeiflorus in its habit, leaf shape, corolla white, florets and phyllaries being 5 in number, peduncles usually absent, corolla lobes reflexed, style arms densely covered with papillae, but differs by its capitula arranged in short, compound corymbs which together form a terminal panicle, and 5–7 triangular-ovate bractlets at the base of a head, involucre 2–3 mm in diameter, middle leaves 3–4, phyllaries 6–7 mm long, 2–2.5 mm wide, anthers ca. 5 mm long, anther apical appendages ovate, anther collars typically cylindrical, 0.6–0.7 mm long, anther base tails 0.4–0.5 mm long, style ca. 11 mm long. In contrast, P. ainsliaeiflorus is characterized by its simple or compound racemose synflorescence, usually 1 linear bractlet at base of a head, involucre 1.5–2 mm in diameter, middle leaves 5–8, phyllaries ca. 5.9 mm long, ca. 1.2 mm wide, anthers ca. 4 mm long, apical anther appendages acute, anther collars subcylindrical, 0.4–0.5 mm long, anther base tails 0.3–0.4 mm long, style ca. 9 mm long ( Figs. 2–3 ). Moreover, the two species are somewhat separate in distribution. Parasenecio ainsliaeiflorus occurs in Anhui, Chongqing, Guizhou, Hubei, Hunan, Sichuan and Shaanxi provinces of China, whereas P. anhuiensis occurs only in southern Anhui and northern Jiangxi provinces of China ( Figure 4 ), with its distribution being situated on the border of the former species.

A similar case of differences in synflorescence and bractlets was also found between P. delphiniifolius ( Siebold & Zuccarini 1846: 190) Koyama (1995: 49) and P. delphiniiphyllus ( Leveille 1915: 18) Chen (1999: 79) ( Ren et al. 2015). The two species were treated as conspecific by Chen et al. (2011). According to Ren et al. (2015), however, P. delphiniifolius , a Japanese species, is characterized by its longer peduncles (4–9 mm long), capitula arranged in short, compound corymbs which together form a terminal panicle, involucre longer (8–10 mm long), anther collars subcylindrical and much shorter (ca. 0.2 mm long), anther bases only slightly tailed with the tails less than half the length of the anther collars, and a chromosome number of 2 n = 60; and P. delphiniiphyllus , a species occurring in Guizhou and Yunnan, China, differs from P. delphiniifolius by the shorter peduncles (less than 2 mm long), involucre shorter (5–6 mm long), anther collars typically cylindrical and longer (ca. 0.6 mm), and anther bases conspicuously tailed with the tails 1.5–2.0 times the length of the anther collars, and a chromosome number of 2 n = 52. However, the difference in style arms as observed between P. delphiniifolius and P. delphiniiphyllus was not found between P. anhuiensis and P. ainsliaeiflorus ; in both species the style arms are densely covered with papillae. The chromosome number in P. anhuiensis needs to be counted in the future.

Parasenecio anhuiensis is also somewhat similar to the Japanese P. kiusianus ( Makino 1910: 228) Koyama (1995: 49 ; “ kiusiana ”) in its numerous bractlets at the base of heads, and in the corolla and pappus length as well, but it differs by its smaller involucre (2–3 mm vs. ca. 5 mm), floret number (5 vs. 6–7) and pappus color (white vs. brownish red).

Additional specimen examined (paratype):— CHINA. Jiangxi province, [Jiujiang], Lushan , [Xiufeng], Xiangshansi, in shady places, 1931, Y. G. Xiong 76 ( LBG 00025947 ) .

Figures

FIGURE 1. Parasenecio anhuiensis and P. ainsliaeiflorus. A & B. Living plant of P. anhuiensis (Y. S. Chen 6229, collected from Anhui, Huangshan). C. Holotype of P. anhuiensis [Y. S. Chen 6229 (PE)]. D. Holotype of P. ainsliaeiflorus [Farges 663 (P)].

FIGURE 2. Capitula, bractlets, phyllaries and achenes of Parasenecio anhuiensis (A, C, E, G) [Y. S. Chen 6229 (PE), collected from Anhui, Huangshan] and P. ainsliaeiflorus (B, D, F, H) [1980 Sino-Amer. Exped. 1162 (PE), collected from Hubei, Shennongjia]. A & B. Floret. C & D. Bractlets. E & F. Phyllaries. G & H. Achenes.

FIGURE 3. Anther micro-morphology of Parasenecio anhuiensis (A & C) [Y. S. Chen 6229 (PE), collected from Anhui, Huangshan] and P. ainsliaeiflorus (B & D) [1980 Sino-Amer. Exped. 1162 (PE), collected from Hubei, Shennongjia].A & B. Anther bases. C & D. Apical anther appendages.

FIGURE 4. Distribution of Parasenecio anhuiensis (*) and P. ainsliaeiflorus (●) (based on specimen records from Chinese Virtual Herbarium and Nature Museum website).