Sphagneticola, Hoffmann, 1900

Li, Hui-Min, Ren, Chen, Yang, Qin-Er & Yuan, Qiong, 2015, A new natural hybrid of Sphagneticola (Asteraceae, Heliantheae) from Guangdong, China, Phytotaxa 221 (1), pp. 71-76 : 71-74

Sphagneticola × guangdongensis Q. Yuan, nothosp. nov. ( Figs. 1 & 2 )

Type:— CHINA. Guangdong: Guangzhou, Tianhe District, Longdong , South China Botanical Garden , 23°11´38.24´´N, 113°21´38.24´´E, 28 m, 8 July 2012, Q . Yuan & C . Ren 525 (holotype IBSC; isotype IBSC) .

Herbs, perennial, procumbent. Stems subglabrous or strigose. Leaves opposite, sessile or shortly petiolate; blade 3- lobed, oblong, (2−) 5−8 cm long, (0.8−) 1.5−2.5 cm broad, papery, sparsely strigose on both surfaces, base cuneate, apex acuminate, margin remotely serrulate. Capitula solitary on elongate peduncle, radiate; peduncle 6−15 cm long, strigose; involucre hemispheric, green; phyllaries 9−11, lanceolate, 2-seriate, subequal, 9−11 mm long, strigose, apex

acute. Ray florets 1-seriate, yellow; corolla 1.0− 1.2 cm long, 3−4 mm broad, 2- or 3-dentate. Disk florets numerous, yellow; corolla 4−5 mm long, 5-lobed. Achenes unknown.

Cytology: —One population from Guangzhou, Guandong, China (voucher: Q. Yuan & C. Ren 525, IBSC) was cytologically examined. Root tips were pretreated in 0.1% colchicine at about 20° for 3 h, fixed in Carnoy I (glacial acetic acid: absolute ethanol = 1: 3) at 4° for 30 min, then they were macerated in 1: 1 mixture of 1 M HCl and 45% acetic acid at 37° for 45 min, and stained and squashed in Carbol fuchsin. Karyotype formula was based on measurements of metaphase chromosomes of three cells. The symbols used to describe the karyotype followed Levan et al. (1964).

The chromosome number of Sphagneticola × guangdongensis was 2 n = 53 ( Fig. 3A ). The karyotype was formulated as 2 n = 53 = 21sm + 30m + 2st ( Fig. 3B ).

Distribution and habitat: — Sphagneticola × guangdongensis is currently known from Guangdong (Foshan, Guangzhou, Zhaoqing, Zhuhai) in south China ( Wu et al. 2013; this study) ( Fig. 4 ). It grows at riverbanks, coastlands and other moist habitats at lower elevations (20−160 m).

Phenology: —Flowering almost all year round, but in full blossom in April; fruiting plants not seen.

Etymology: —The specific epithet is derived from Guangdong, a province in south China where the new hybrid is currently known to occur.

Additional specimens examined (paratypes): — CHINA. Guangdong: Foshan, Shanshui District , riverbank, 5 m, 27 April 2011, Q . Yuan 22 ( IBSC), 23 ( IBSC), 36 ( IBSC); Guangzhou, Tianhe District , Longdong , pond side, 28 m, 26 May 2015, H. M . Li 5 ( IBSC) .

Discussion: — Sphagneticola × g uangdongensis is intermediate between S. calendulacea and S. trilobata in leaf shape ( Fig. 5 ). It differs from its parental species by the leaves 3-lobed and oblong (vs. often entire or sparsely serrulate, oblong to oblong-lanceolate in S. calendulacea and 3-lobed, ovate in S. trilobata , respectively).

Our cytological study lends strong support for the hybridity and parental origin of Sphagneticola × guangdongensis. The maternal parent S. calendulacea has 2 n = 50, the paternal parent S. trilobata has 2 n = 56 ( Ren et al. 2012), and the new hybrid has 2 n = 53 (this study), indicating that 25 chromosomes in the hybrid come from S. calendulacea while the remaining 28 come from S. trilobata .

Figures

FIGURE 1. Holotype sheet of Sphagneticola × guangdongensis.

FIGURE 2. Sphagneticola × guangdongensis in the wild. A. Habitat. B−C. Habit. D. Capitulum (top view). E. Capitulum (bottom view). F. Disk florets. G. Ray florets. Photos by Q. Yuan.

FIGURE 3. Mitotic metaphase chromosomes (A) and karyotype (B) of Sphagneticola × guangdongensis, both same scale.

FIGURE 4. Distribution of Sphagneticola × guangdongensis (▲).

FIGURE 5. Leaf morphology in Sphagneticola × guangdongensis (B) and its two parent species, S. trilobata (A) and S. calendulacea (C). A from H. M. Li 4 (IBSC), B from Q. Yuan & C. Ren 525 (IBSC), and C from Q. Yuan17.