﻿Lysimachiaailaoshanensis (Primulaceae), a new species from Yunnan, China

﻿Abstract A new species, Lysimachiaailaoshanensis is described and illustrated. In gross morphology it is evidently allied to subgen. Palladiasect.Chenopodiopsis and is most similar to L.chenopodioides and L.remotiflora, but is distinguished from L.chenopodioides by narrower lanceolate leaf blade and longer pedicel, and longer stamens and styles, and from L.remotiflora by narrower leaf blade and longer stamens.


Introduction
Ailao Mountain, located in central Yunnan, China, has rich plant diversity and was designated as a national natural reserve in 1988.In August 2020, Dr. H.F. Yan and colleagues of South China Botanical Garden made a botanical excursion to Ailao Mt., collecting plants of this area for systematic study on Primulaceae.A putatively new species of Lysimachia was secured.A subsequent field trip was conducted to confirm its entity.Careful examination revealed that the plant is distinct from all other Lysimachia species and represents an undescribed taxon.

Materials and methods
Earlier taxonomic literature has been consulted (e.g.Handel-Mazzetti 1928;Chen and Hu 1979;Chen et al. 1989;Hu 1985Hu , 1992Hu , 1999;;Hu and Kelso 1996) to infer allied species and relatedness.The new species was examined in the field and at the herbarium, and measurements of morphological features were conducted with fresh specimens.Flowers were dissected and measured in the laboratory.Morphological comparison with similar species was performed based on living plants and specimens from IBSC, KUN, PE, IBK and from the images of specimens from the JSTOR Global Plants (http://plants.jstor.org/).The conservation status of the new species was assessed following the guidelines for using the IUCN Red List Categories and Criteria (IUCN Standards and Petitions Committee 2024).Diagnosis.Lysimachia ailaoshanensis is most similar to L. chenopodioides Watt ex Hook.f. and L. remotiflora C.M. Hu, but differs from L. chenopodioides in narrower lanceolate leaf blade and longer pedicel, and longer stamens and styles, and from L. remotiflora in narrower leaf blade and longer stamens.
Distribution and habitat.The new species is presently known only from the type locality in Yunnan Province, Jingdong Yi Autonomous County (Map 1).It grows at the edge of secondary mixed-evergreen forests.Phenology.Flowering from June to August, fruiting from July to August.Etymology.The new species is named referring to the type locality where the new species occurs, Ailaoshan National Nature Reserve, Yunnan, China.
Conservation status.Based on our field investigations in Jingdong Yi Autonomous County and adjacent areas in the past three years, only one population with only five individuals of the new species have been found in an area of 10 km 2 in Jingdong Yi Autonomous County.Moreover, the local habitat is under threat by road construction and tourism development.Therefore, the conservation status of the new species is assessed as Critically Endangered (CR) (B2a & bi, iii), according to the guidelines for using the IUCN Red List Categories and Criteria (IUCN Standards and Petitions Committee 2024).
Relationship with similar species.Based on the classification of Lysimachia by Handel-Mazzetti (1928) and Chen and Hu (1979), the new species clearly belongs to Lysimachia subg.Palladia sect.Chenopodiopsis Hand.-Mazz., which is characterised by leaves alternate, racemes sparsely flowered or solitary in   Chen et al. 1989;Hu and Kelso 1996).The new species is morphologically similar to L. chenopodioides and L. remotiflora, but is distinctive in its leaf shape and heights of stamens and styles (see Table 1, Figs 1-3).

Map 1 .
Location of the population of Lysimachia ailaoshanensis in Jingdong, Yunnan.

Figure 1 .
Figure 1.Lysimachia ailaoshanensis G.Hao & Y.F.Yan, sp.nov.A habit B abaxial (right) and adaxial (left) surfaces of a leaf C flower D calyx lobes E dissected corolla F pistil and its stigma (enlarged) G young fruit with persistent calyx.Drawn by Yun-Xiao Liu from the holotype.

Figure 2 .
Figure 2. Living plant of Lysimachia ailaoshanensis G.Hao & Y.F.Yan, sp.nov.A habitat B habit C leaves on abaxial (right) and adaxial (left) surfaces D flower (lateral view) E corolla F pistil G abaxial (left) and adaxial (right) sides of a calyx lobe.Photographed by Hai-Fei Yan.
leaves, filaments free, adnate to middle of corolla, and styles usually shorter than corolla.Approximately eight species were recognized in this section, mainly distributed in southwestern China and adjacent regions (e.g., Bhutan, India, Kashmir, N. Myanmar, Nepal, Pakistan), and a few outliers in Thailand, the Mediterranean coast, and southeastern Africa(Handel-Mazzetti 1928;

Figure 3 .
Figure 3. Holotypes of Lysimachia ailaoshanensis and two of its allies A L. ailaoshanensis B L. chenopodioides C L. remotiflora.

Table 1 .
Main morphological differences between Lysimachia ailaoshanensis and two similar species.