Sunday, October 4, 2015

[Botany • 2011] Impatiens qingchengshanica • A Unique New Species (Balsaminaceae) from Southwestern China and its Phylogenetic Position


Impatiens qingchengshanica 
Y.-M. Yuan, Y. Song & X.-J. Ge

ABSTRACT
 Impatiens qingchengshanica Y.-M. Yuan, Y. Song & X.-J. Ge, sp. nov. is described and illustrated. It was collected from a broad-leaved forest on Sichuan Province’s Qingcheng Shan, Southwestern China. This species is unique in the genus for its specialized nodular (moniliform) and horizontal rootstock with conspicuously enlarged knots (1-3 cm in diameter) and long (3-5 cm), thin (2-3 mm in diameter) string. It resembles I. clavigera Hook. f. in terms of gross floral morphology. Impatiens qingchengshanica has oblong, elliptic or widely elliptic leaves and showy pink flowers. The lower sepal is funnel-form, ca. 4-4.5 cm deep, abruptly narrowed into a subulate spur ca. 2.5-3 cm long, straight, and only occasionally incurved in young buds. The left and right pairs of the lateral united petals are unequal in size thus the whole flower is oblique and asymmetrical. The lower petals of the lateral united petals are oblong and oblique unlike I. clavigera, which has obovate, lanceolate or oblanceolate leaves and bright yellow flowers. Its lower sepal is subsaccate, 2-3 cm deep, abruptly contracted into a narrow tubular spur which is 5-6 mm long, conspicuously incurved when flowering. The left and right pairs of the lateral united petals are almost equal in size, thus the whole flower is nearly symmetrical. The lower petals of the lateral united petals are dolabriform. The new species is also similar to I. omeiana Hook. f. and I. pritzelii Hook. f. in terms of rhizome, leaf and stem morphology, but the flower shape and bauplan are conspicuously different. Impatiens omeiana has enlarged tuberous rhizomes, yellow or pale yellow flowers with subsaccate to saccate lower sepals that gradually narrow into a short incurved spur, and dolabriform lower petals of the lateral united petals. Impatiens pritzelii has a procumbent tortuous subterranean stem with enlarged nodes, yellow or yellow-white flowers with saccate to widely saccate lower sepals which gradually narrow into a short incurved spur, and oblong or subdolabriform lower petals having a rounded apex. The new species is nested in the basal clade of the phylogentic tree of the genus, and thus represents one of the ancestral forms with important implications for understanding the evolution within the genus. Molecular phylogeny further indicated that nodular (moniliform) and tuberose rootstocks may have undergone multiple independent origins and parallel evolution within the genus adaptive to the seasonal dry habitats of the species.

Keywords: Balsaminaceae; Evolution; Impatiens qingchengshanica; New species.


Phenology. Flowering in July to September; fruiting in September to October.
Ecology. Under stories of sparse and dense broad-leafed forests on slopes, forest margins in moist places in valleys; 700-1,400 m.
Distribution. Sichuan, Southwestern China. It is so far known only from the type location and its vicinity, sparsely found in both front and rear hills of Qingchengshan Park.


Yong-Ming YUAN, Yi SONG and Xue-Jun GE. 2011. Impatiens qingchengshanica (Balsaminaceae), A Unique New Species from China and its Phylogenetic Position. Botanical Studies. 52: 225-230.

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