Ixeridium dimorphifolium Y.L.Xu, Y.F.Lu & X.Cai, 2021

Lu, Yi-Fei, Xu, Yue-Liang, Xie, Wen-Yuan, Zhang, Hong-Wei, Zheng, Zi-Hong, Cai, Xin & Jin, Xiao-Feng, 2021, Two new species and a new combination from Zhejiang, East China, PhytoKeys 184, pp. 111-126 : 111

Ixeridium dimorphifolium Y.L.Xu, Y.F.Lu & X.Cai sp. nov.

Chinese name: 二型叶小苦荬 Figs 5 , 6

Latin diagnosis.

Species nova I. beauverdiano (H. Lév.) Spring. affinis est, sed planta stolonibus, foliis basilaribus dimorphis, involucris 8-10 mm longis, phyllis intimis 8, flosculis 7-10 differt.

Type.

China. Zhejiang (浙江): Suichang (遂昌), Jiulongshan National Nature Reserve (九龙山国家级自然保护区), Yangmei Keng (杨梅坑), in grasses along streams, alt. 550 m, 17 April 2020, Xiao-Feng Jin 4568 (holotype: ZM; isotypes: HTC, ZM) .

Description.

Herb perennial, glabrous totally. Stolons elongate, creeping. Stems erect, 20-35 cm tall, slender, with sparse branches from base. Basal leaves crowed, present at anthesis, dimorphic; blades of early ones nearly orbicular to long-elliptic, 0.9-2.5 cm long, 0.7-1.3 cm wide, apex obtuse and mucronate, base broadly cuneate to rounded, margin entire and with sparsely slender ciliate-teeth, with petioles 1-3 cm long; blades of later ones narrowly elliptic to lanceolate, 3-6 cm long, 0.6-1.1 cm wide, apex acute, base attenuate to a 2-3 cm long petiole, margin entire or with sparsely slender ciliate-teeth below. Cauline leaves 1-3; blades linear-lanceolate, 2.5-7.5 cm long, 0.4-0.7 cm wide, apex acuminate, base attenuate, margin entire and with/without sparsely slender ciliate-teeth below. Synflorescence corymbiform, with 6-16 capitulae; capitula with 7-10 florets, base with slender, long peduncle. Bracts small, broadly ovate-triangular, ca. 1 mm long, margin entire or with 1-pair ciliate-teeth. Involucre narrowly cylindrical, 8-10 mm long. Phyllaries 2 series, abaxially glabrous; outer phyllaries broadly ovate, 0.5-0.7 mm long, apex obtuse; inner phyllaries 8, linear-lanceolate, 7-9 mm long, apex obtuse, short-ciliate. Receptacle flattened, glabrous, alveolate. Florets 7-10, yellow, corolla 10-11 mm long, tube 3-3.5 mm long, ligule linear, apex 5-lobed. Achenes brown or pale brown, narrowly fusiform or linear-fusiform, slightly compressed, 4.5-5 mm, finely spiculate, with ribs finely spiculate, apex attenuate to a 1-1.5 mm long slender beak. Pappi pale brown, ca. 5 mm long, scabrid. Flowering and fruiting April- July.

Distribution and habitat.

Ixeridium dimorphifolium is currently known from only two localities in Suichang and Qingyuan counties, southwestern Zhejiang Province, East China. It grows in grassy roadside along stream or wetland at the elevation of 500-1450 m.

Phenology.

Flowering and fruiting from mid-April to mid-July.

Etymology.

The specific epithet ' Ixeridium dimorphifolium ' refers to two different shapes of basal leaves.

Conservation status.

Endangered, EN B2ab(iii) ( IUCN 2019). The new species is only known from two localities, and occupied less than 100 km2 with about 1000 mature individuals. This species is considered as Endangered (EN) according to IUCN Red List Categories and Criteria ( IUCN 2019) based on the current data.

Specimen examined.

Same locality as type, alt. 500 m, 5 May 2017, Yue-Liang Xu 234, 239, 274 (ZM), alt. 550 m, 17 April 2020, Xiao-Feng Jin 4569 (HTC, ZM). Qingyuan (庆元), Huangpi (黄陂), in wetland, alt. 1450 m, 12 July 2020, Xiao-Feng Jin, Yi-Fei Lu & Dan-Qi Liu 4600 (HTC, ZM).

Notes.

Ixeridium (A. Gray) Tzvel. is a moderatedly sized genus within the tribe Cichorieae . It contains 15 species and distributes in E and SE Asia, with eight species occurring to China ( Shi & Kilian, 2011). The genus Ixeridium is most morphologically similar to Ixeris (Cass.) Cass., but is distinguished in having achenes with 9-12 prominent but not wing-like ribs (vs. 10 prominent and wing-like ribs) ( Shih, 1997). Ixeridium dimorphifolium is similar to I. beauverdianum in having the cauline leaf blades linear to linear-elliptic, margin nearly entire, and pappi brown or pale brown, but differs from the latter in its dimorphic basal leaves, involucres longer, 8-10 mm long, inner phyllaries 8, florets 7-10, and plant with stolons.

Morphology of pollens and achenes of the species in Asteraceae has taxonomic significance and sometimes was used to identify similar species ( Biyiklioğlu et al. 2018; Joujeh et al. 2020; Nurgül et al. 2021). The micromorphology of achenes and pollen grains of Ixeridium dimorphifolium and I. beauverdianum was shown in Figure 7 and Table 2 . The new species, Ixeridium dimorphifolium , has the achenes narrowly fusiform or linear fusiform, with surfaces and ribs both finely similar spiculate, apex gradually narrow to a beak. While those of I. beauverdianum are fusiform, with spicules on surfaces shorter than those on ribs, apex abruptly narrow to a beak. The pollen grains of Ixeridium dimorphifolium and I. beauverdianum are similar to each other.

Figures

Figure 5. Ixeridium dimorphifolium sp. nov. A habit B bract C outer phyllary D inner phyllary E opened involucre (showing receptacle) F floret G achene (Illustrated by Xiao-Feng Jin; based on Xiao-Feng Jin 4568, ZM).

Figure 6. Comparison of Ixeridium dimorphifolium and I. beauverdianum A-E Ixeridium dimorphifolium sp. nov. A habit B basal part (showing dimorphic leaves and stolon) C cauline leaves D capitula (showing involucre) E capitula (showing florets) F-J Ixeridium beauverdianum F habit G basal part (showing monomorphic leaves) H cauline leaves I capitula (showing involucre) J capitula (showing florets).

Figure 7. Micromorphology of achenes and pollen grains of Ixeridium dimorphifolium and I. beauverdianum A-E Ixeridium dimorphifolium sp. nov. (from Suichang) F-J Ixeridium dimorphifolium sp. nov. (from Qingyuan) A and F achene shape (scale bar: 1 mm) B and G middle part (scale bar: 200 μm) C and H spicules on surfaces and ribs (scale bar: 50 μm) D and I pollen grains (scale bar: 20 μm) E and J surface sculpture (scale bar: 5 μm) K-O Ixeridium beauverdianum K achene shape (scale bar: 1 mm) L middle part (scale bar: 200 μm) M spicules on surfaces and ribs (scale bar: 50 μm) N pollen grains (scale bar: 20 μm) O surface sculpture (scale bar: 5 μm).