Chen, W.-H., Y.-M. Shui & M. Möller (2014). Two new combinations in Oreocharis Benth. (Gesneriaceae) from China. Candollea 69: 179–182. In English, English abstract.
Recent molecular phylogenetic studies indicated that no less than ten genera of Gesneriaceae are nested in Oreocharis Benth., and the circumscription of the genus was extended accordingly. The enlarged genus has a distribution predominantly in China. On the basis of recent molecular phylogenetic studies, two further species are transferred to Oreocharis here : Briggsia speciosa (Hemsl.) Craib and Ancylostemon dimorphosepalus W. H. Chen & Y. M. Shui and the necessary new combinations are provided.
Introduction
The genus Oreocharis Benth. (Gesneriaceae), as newly circumscribed based on molecular phylogenetic studies ( Möller & al., 2011a; Möller & al., 2011b), contains over 80 species, predominantly distributed in China, with some outliers in Thailand, Myanmar, Bhutan, NE India, and Japan ( Möller & Clark, 2013). Nine genera had been in their entirety merged in the newly circumscribed Oreocharis: Ancylostemon Craib, Bournea Oliv., Dayaoshania W. T. Wang, Deinocheilos W. T. Wang, Isometrum Craib, Opithandra B. L. Burtt, Paraisometrum W. T. Wang, Thamnocharis W. T. Wang, and Tremacron W. T. Wang ( Möller & al., 2011b).
Another genus, Briggsia Craib, was only partly merged into Oreocharis, including its type species B. longifolia Craib ( Möller & al., 2011b). Briggsia s.s. includes caulescent and rosette-forming species. All the species nested in the “Oreocharis clade” in a molecular phylogenetic study were rosetteforming species and were formally transferred to Oreocharis (see Möller & al., 2011b). The species currently remaining in Briggsia s.s. (c. 12 rosette forming and three caulescent species) are currently the subject of lurther studies. Nevertheless, new molecular phylogenetic studies already revealed that at least Briggsia speciosa (Hemsl.) Craib and the recently described Ancylostemon dimorphosepalus W. H. Chen & Y. M. Shui ( Chen & al., 2012) belong to Oreocharis ( Chen & al., 2014). Those two species are here formally transferred to Oreocharis.
Taxonomy
While studying Didissandra C. B. Clarke specimens collected by G. Forrest in China as circumscribed by Clarke (1883), i.e. possessing four anthers cohering in pairs, Craib (1920b) recognised readily definable groups and moved species to three different genera, he had previously described: Ancylostemon, Briggsia, and Isometrum ( Craib, 1920a). Briggsia was characterized based on its large ventricose corolla with gradually inarching filaments (Fig. 1E), while the other two genera had medium sized corollas, which are slightly ventricose in Ancylostemon and not ventricose in Isometrum. He further described the filaments in the latter two genera as straight with a bent at almost right angle at the apex bringing the anthers in contact (Fig. 1I), with the corolla distinctly bilabiate in Ancylostemon, Briggsia and Didissandra (now Coralio discus Batalin), and equally lobed in Isometrum. In this concept, Didissandra speciosa Hemsl. (Fig 1A–E) fitted well into Briggsia and Craib (1920b) formally transferred the species to Briggsia as Briggsia speciosa (Hemsl.) Craib.
The recently described Ancylostemon dimorphosepalus ( Chen & al., 2012) holds morphological characters that do not allow an easy placement in any of Craib's three genera. The corolla is not strongly bilabiate and the tube not ventricose, a characteristic of Isometrum. The anthers of the abaxial pair are cohering but those in the abaxial pair are free (Fig. 1I). This is somewhat intermediate between Ancylostemon, Isometrum (where at least one species has free anthers, I. eximium K. Y. Pan) and Oreocharis (all anthers free). This indicates that the characteristic of anther coherence is rather labile and probably not a reliable generic character.
Recent molecular phylogenetic studies, showing that anther number and coherence are homoplastic ( Möller & al., 2011a; Möller & al., 2011b), resolved the problem of assigning taxa to the correct genus in this group of Gesneriaceae by merging these three (and seven further) genera to a newly circumscribed Oreocharis. It seems that vegetative characters, e.g. basal rosette, loculicidal capsule dehiscence of the upper suture, are more accurate in the systematic of this group ( Möller & al., 2011b).
Oreocharis speciosa (Hemsl.) Mich. Möller & W. H. Chen, comb, nova (Fig. 1A–E).
≡ Didissandra speciosa Hemsl. in J. Linn. Soc., Bot. 26: 228. 1890.
≡ Briggsia speciosa (Hemsl.) Craib in Notes Roy. Bot. Gard. Edinburgh 11: 264. 1920.
Lectotypus (designated here): China. Prov. Hubei (Hupeh): Hsingshan, A. Hemy 6411A (K [K000858093]!; iso-: E [E00396435]!).
Distribution and habitat. — Oreocharis speciosa is distributed in W Hubei (Enshi city), SW Hunan (Hongjiang county), and S Chongqing [previously E Sichuan] (Nanchuan county). The species grows on shady, damp rocks on slopes, at an altitude ranging from 300 to 1600 m.
Observations. — In the protologue of Didissandra speciosa, Hemsley (1890) lists A. Henry collections in Hubei from Patung, Nanto, Hsingshan and Tunghu, all deposited at K without designating an holotype. Four collections mounted on two herbarium sheets of A. Henry are currently deposited at K : A. Henry 6356 from Nanto [K000858092] and A. Henry 6411A from Hsingshan [K000858093], both mounted on one sheet, and A. Henry 3951 from Nanto [K000858094] and A. Henry 7668 from Patung [K000858095], mounted on another. The specimens of A. Henry 6411A [K000858093] and A. Henry 6356 [K000858092] are annotated by Skog as syntypes of D. speciosa. A slightly smaller and atypical plant mounted on the second sheet was annotated “Oreocharis ? sp. C. B. Clarke”. Another duplicate collection of A. Henry 6411A [E00396435] deposited at E is also annotated by Skog as a syntype of D. speciosa. Overall, A. Henry 6411A represents the more complete and accurate collection of this species and is here designated as the lectotype.
Conservation status. — Oreocharis speciosa has a wide distribution range across three provinces in South China. Only two populations have been observed by two of the authors (YMS, WHC), one situated in S Chongqing in the Jinfoshan Mountain and one in W Hubei in Enshi in the Suo Bu Ya Stone Forest park (Fig. 1F–H). There are around hundred mature individuals and many immature plants in each known population, and the total number of individuals would be around 5000. The “Extent of Occurrence” (EOO) in Suo Bu Ya is around 100m2 and both locations receive some protection due to their occurrence in National Parks. We have not enough information for a definitive conservation assessment, but the species has been proposed by Wei & al. (2010) to be categorized as “Vulnerable” [VU Alc] following IUCN Red List Categories and Criteria (IUCN, 2012).
Fig. 1. —
Oreocharis speciosa (Hemsl.) Mich. Möller & W. H. Chen (A–E) and Oreocharis dimorphosepala (W. H. Chen & Y. M. Shui) Mich. Möller (F–I). A–B. Habitat; C. Habit in situ; D. Top view, and E. Front view of flowers showing the arched filaments; F. Habit; G. Top view, and H. Front view of flowers; I. Cut-open view of a flower showing the straight filaments with a bent at almost right angle at the apex.
[photos: A–E: M. Möller; F–I: Y.-M. Shui]
Oreocharis dimorphosepala (W. H. Chen & Y. M. Shui) Mich. Möller, comb. nova (Fig. 1F–I).
≡ Ancylostemon dimorphosepalus W. H. Chen & Y. M. Shui in Ann. Bot. Fenn. 49: 391. 2012.
Typus: China. Prov. Yunnan: Yuanyang County, Shangxincheng Community, in broad-leaved forests along ravines, 23°03′45″N 102°56′56″E, 2368 m, 1.VIII.2010, fl., Y. M. Shui & al. 85333 (holo-: KUN [KUN0149160]!; iso-: PE!).
Distribution and habitat. — Oreocharis dimorphosepala occurs only in Yuanyang County in SE Yunnan. The plants grow at the foot of tree trunks in evergreen forests between 2270 and 2620 m.
Conservation status. — The situation of O. dimorphosepalus is precarious. YMS and WHC have observed only 13 mature individuals in the field during 2009–2012 surveys. The species usually grows on the foot of tree trunks with a very low frequency of occurrence. So far, only three trees have been observed harbouring the plant in Yuanyang County. Thus, we propose to provisionally assess O. dimorphosepalus as “Critically Endangered” [CR D] following IUCN Red List Categories and Criteria (IUCN, 2012).
Acknowledgements
We thank Hannah Atkins and John McNeill for input on nomenclatural issues and Mark Hughes on IUCN Red Listing. We are very grateful to Martin Callmander and Alain Chautems for their critical comments that significantly improved the manuscript. We greatly acknowledge support by the National Natural Science Foundation of China (grants no. 31000258, 31470306), and by the Open Project of the Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany (grant no. KLBB201304), and the Chinese Academy of Sciences (Visiting Professorship Scheme). The Royal Botanic Garden Edinburgh is supported by the Rural and Environment Science and Analytical Services division (RESAS) in the Scottish Government.
