Ji-Dong Ya’s research while affiliated with Southwest University and other places

Two new species of Christisonia (Orobanchaceae), Christisonia hekouensis Gui L.Zhang, J.D.Ya & W.B.Yu and Christisonia dentosa J.D.Ya, Gui L.Zhang & W.B.Yu, found during botanical surveys in Southeast Yunnan, China, are described and illustrated. The two new species are similar to C. kwangtungensis bearing rose-red flowers and conspicuously inflated corolla tubes, and phylogenetic analyses strongly support the three species as monophyletic. However, C. hekouensis can be distinguished from C. kwangtungensis and C. dentosa by having externally puberulent calyces and corollas, corolla lobes with serrulate margins, styles that are pink and glabrous or sparsely capitate-glandular pubescent above, and with anthers less than 2 mm below the stigma. Christisonia dentosa differs from C. kwangtungensis and C. hekouensis by having dentate corolla lobe margins, internally capitate-glandular pubescent corollas, styles distinctly capitate-glandular pubescent above, and more than six anthers which are up to 10 mm below the stigma.

Cymbidium (Orchidaceae: Epidendroideae), with around 60 species, is widely-distributed across Southeast Asia, providing a nice system for studying the processes that underlie patterns of biodiversity in the region. However, phylogenetic relationships of Cymbidium have not been well resolved, hampering investigations of species diversification and the biogeographical history of this genus. In this study, we construct a plastome phylogeny of 56 Cymbidium species, with four well-resolved major clades, which provides a framework for biogeographical and diversification rate analyses. Molecular dating and biogeographical analyses show that Cymbidium likely originated in the region spanning northern Indo-Burma to the eastern Himalayas during the early Miocene (∼21.10 Ma). It then rapidly diversified into four major clades in East Asia within approximately a million years during the middle Miocene. Cymbidium spp. migration to the adjacent regions (Borneo, Philippines, and Sulawesi) primarily occurred during the Pliocene-Pleistocene period. Our analyses indicate that the net diversification rate of Cymbidium has decreased since its origin, and is positively associated with changes in temperature and monsoon intensity. Favorable hydrothermal conditions brought by monsoon intensification in the early Miocene possibly contributed to the initial rapid diversification, after which the net diversification rate was reduced with the cooling climate after the middle Miocene. The transition from epiphytic to terrestrial habits may have enabled adaptation to cooler environments and colonization of northern niches, yet without a significant effect on diversification rates. This study provides new insights into how monsoon activity and temperature changes affected the diversification dynamics of plants in Southeast Asia.

Thismia Griff. (Thismiaceae) is a holo-mycoheterotrophic genus with more than 100 species. In this study, phylogenetic analyses supported that T. malipoensis from Yunnan is a new species in T. sect. Glaziocharis. Morphologically, this new species can be distinguished from its phylogenetic sister species T. abei by having the annulus of the flower expanded and modified into a cucullate (hood-like) structure with zygomorphic symmetry with one opening on one side. Biogeographical inference showed that SW China to Indo-Burma and the Sunda Shelf region was suggested as the ancestral distribution region of Thismia s.s., then eastward to SE China and Japan, and southward to New Guinea to Australia, respectively. The Chinese species should have originated from at least two different ancestral sources, and geographical isolation caused the divergence between T. malipoensis and T. abei at 17.47 Mya.

A new species of Cylindrolobus (Orchidaceae), C. gaoligongensis J. D. Ya & H. Jiang from Gongshan county, northwestern Yunnan, China, is described and illustrated. It is morphologically similar to C. arunachalensis (A. N. Rao) A. N. Rao, but can be distinguished from it by having 5 veined lateral sepals, orange to pink and triangular-ovate lip mid-lobe and apex mucronate, yellow to white long hairs on the lip, 2 central calli and connected to a keel toward mid-lobe in the disk, 3 rows of white long hairs in the base of the disk. Additionally, a detailed description and illustration of its close species, C. arunachalensis, is also provided.

Two new species of Petrocosmea (Gesneriaceae), P. wangii M.Q.Han, J.Cai & J.D.Ya from Shiping County and P. yei M.Q.Han, C.Liu & Y.X.Gong from Mojiang and Zhenyuan Counties, Yunnan Province, China, are described and illustrated.

A new species of Gesneriaceae, Primulina hsiwenii Lei Cai, Ting Zhang & J.D.Ya from the karst regions in southeastern Yunnan, China, is described and illustrated. Its morphological relationship with a similar species is discussed, and a detailed description, colour photographs, distribution and habitat information and an IUCN conservation assessment are provided.

Vaccinium usneoides (Ericaceae), a new species from Fugong County of Yunnan Province, China is described and illustrated. This new species belongs to Vaccinium sect. Calcicolus and is most similar to V. brachyandrum , but differs in its branches hanging down, much smaller leaf blades, shorter inflorescences and pedicels, non-glandular tomentellate or densely pubescent inflorescence rachis and pedicels, densely white-pubescent hypanthium and pilose filaments.

Five new orchid species from southwestern China’s Yunnan Province and the Tibetan Autonomous Region, Neottia lihengiae, Neottia chawalongensis, Papilionanthe motuoensis, Gastrochilus lihengiae, and Gastrochilus bernhardtianus, are described and illustrated. To confirm their identities, and to resolve phylogenetic relationships, we sequenced the complete plastomes of these taxa with their congeneric species, adding new plastomes of three Neottia species, two Papilionanthe species and nine Gastrochilus species. Combined with published plastid sequences, our well-resolved phylogeny supported the alliance of N. lihengiae with the the N. grandiflora + N. pinetorum clade. Neottia chawalongensis is now sister to N. alternifolia, while P. motuoensis is closely related to P. subulata + P. teres. Conversely, phylogenetic analyses based on complete plastomes and plastid sequences showed inconsistent relationships among taxa in the genus Gastrochilus, but the two new species, G. lihengiae and G. bernhardtianus were supported by all datasets.

A new species of Cylindrolobus (Orchidaceae), C. gaoligongensis from the Gaoligong Mountain, northwestern Yunnan, China, is described and illustrated. It is morphologically similar to C. arunachalensis and C. gloensis , but can be distinguished from them by having orange to pink and triangular‐ovate lip mid‐lobe with mucronate apex, front margin of lateral lobes yellow to white and with short glandular hairs gradually transitioning to dense long hairs, two central calli connected to a keel toward mid‐lobe in the disk, and three rows of white long hairs at the base of the disk. Additionally, an improved description and illustration of the closely related species C. arunachalensis , is also provided.