Ophiorrhizashiqianensis (Rubiaceae), a new species from Guizhou, China

Abstract A new species of the genus Ophiorrhiza L. (Rubiaceae), Ophiorrhizashiqianensis L.D.Duan & Yun Lin, is described, illustrated and photographed from Shiqian County, Guizhou Province, South-western China. This species was found growing at the side of streams in evergreen broad-leaved forests in mountains at elevations of 960–1100 m. The new species is morphologically similar to Ophiorrhizahunanica H.S.Lo, but differs from the latter by the glabrous, glabrescent or pilose stems, the 5–10 cm long subterranean stem internodes, the glabrous or pilose petioles, the 3–5 mm long stipules, the purple corolla lobes, the ca. 12 mm long style and included stigmas in long-styled flowers and the 3–4 × 8–10 mm, glabrous or glabrescent capsules.


Introduction
The Rubiaceae genus Ophiorrhiza L. includes more than 300 species worldwide (WC-SPF 2017) and is mainly distributed in tropical and subtropical Asia, Australia, New Guinea and the Pacific Islands (Darwin 1976, Chen andTaylor 2011). In China, Ophiorrhiza is represented by 70 species (Chen and Taylor 2011, Deng and Huang 2012, Wu et al. 2017a, b, Yang et al. 2018) and most of them are distributed in the region south of the Yangtze River, especially in the provinces of Yunnan and Guangxi (Lo 1999).
During three botanical explorations in Shiqian County, Guizhou Province, Southwest China, specimens of Ophiorrhiza were collected on the banks of streams in dense evergreen broad-leaved forests in valleys at elevations of 960-1100 m. After comparison of the newly collected specimens with material available in Chinese herbaria and careful consultation of literature, they were found to be most similar to Ophiorrhiza hunanica H.S.Lo, but sufficiently different to qualify as a new species, hitherto not reported from any region in China. We therefore describe it as new, under the name Ophiorrhiza shiqianensis L. D. Duan & Yun Lin.
Phenology. Plants were observed in full bloom on 18 March 2014 and with ripe fruits on 12 May 2014 and neither flowers nor fruits were seen on 12 August 2011. It can be expected that the flowering time of the new species is from March to April and that fruiting time is from April to June.
Habitat. The species grows on the banks of streams in dense broad-leaved forest in valleys at elevations of 960-1100 m.
Distribution. Ophiorrhiza shiqianensis is only known from two localities in Shiqian County, northeast Guizhou Province, southwest China, notably: Fudingshan Nature Reserve, Pingshan Town and Nishan Village, Ganxi Town.