Lycoris insularis S.Y.Zhang & J.W.Shao, a new fertile diploid species from coastal provinces in eastern China is described. This new species is most similar to L. sprengeri in morphology and has been misidentified as the latter for a long time. However, it can be distinguished from the latter by the relatively longer perianth tube (1.5‒2.5 cm vs. less than 1.3 cm), a characteristic that was overlooked before. Phylogenetic analysis, based on complete plastid genome, showed that L. insularis is not genetically related to L. sprengeri in the genus. The former was a sister group of L. sanguinea, while the latter was closely related to L. longituba and L. chinensis and they were respectively located on different clades that were separated at the base of the phylogenetic tree. The chromosome number of L. insularis is 2n = 22. At present, as the new species is relatively widely distributed and the wild population can normally reproduce by seeds, we evaluate it as LC (Least Concern) according to criteria of the IUCN Red List.

Lycoris sprengeri, taxonomy, chloroplast genome, cryptic species

Lycoris Herb. (Amaryllidaceae) is a typical pan-East Asian genus, currently considered to have about 9 fertile diploid species, mainly distributed in China, Japan and South Korea (Hsu et al. 1994; Ji and Meerow 2000; Kim 2004; Hori et al. 2006; Lu et al. 2020; Zhang et al. 2021; Zhang et al. 2022). China is the centre of the distribution diversity of this genus, with about eight of these fertile diploid species being endemic to this country (Hsu et al. 1994; Lu et al. 2020; Zhang et al. 2021; Liu et al. 2022). Due to the special living habit of flowers and leaves not being able to co-exist, as well as the rich and beautiful flower patterns and colours, Lycoris plants are considered to have great horticultural value and have received extensive attention (Hsu et al. 1994; Zhang et al. 2022).

Lycoris sprengeri Comes ex Baker was first described in 1902, being only distributed in China. The type specimen was collected from around Xiangyang City, Hubei Province in Central China (Comes and Baker 1902; Traub and Moldenke 1949; Hsu et al. 1994). Due to extensive investigation of basic plant resources in China, many populations identified as L. sprengeri were found and most of them were located in the coastal areas of Zhejiang, Fujian and Jiangsu Provinces. However, there were few collections or photographic records of this species in the central or inland areas near the collection location of the type specimens.

Recently, we collected some populations of L. sprengeri from inland areas, including Guangshui City, Hubei Province (near the collection location of the type specimen) and the surrounding areas of Dabie Mountains in Anhui Province. In the field, we noticed that there was a certain difference in morphology between those plants (identified as L. sprengeri) occurring inland and those from the coastal area: the flower colour of the former varied from white to dark purple in a population and the length of the perianth tube is short (less than 1.3 cm), while the flower colour of the latter is relatively stable, generally pink and the perianth tube is long (usually about 2.0 cm). After further morphological observations, chloroplast sequence alignment and phylogenetic analysis and checking the related type specimens, we recognised that the plants found in the inland area were the genuine L. sprengeri, while those plants collected from the coastal area (identified as L. sprengeri) are actually an undescribed new species. Thus, we named it as Lycoris insularis S.Y.Zhang & J.W.Shao and describe it here.

Based on our research, especially the phylogenetic tree constructed by the complete chloroplast genome (Fig. 5), it can be clearly seen that those plants (identified as L. sprengeri) collected from the inland and coastal areas are two distinct entities (Comes and Baker 1902; Traub and Moldenke 1949). The original description and type specimen photos of L. sprengeri (in Kew, Sprenger K000901061, http://specimens.kew.org/herbarium/K000901061) both show that it has a short perianth tube (about 0.5 cm), which is consistent with those plants from inland populations collected by the authors. Therefore, we recognised that those inland plants with a short perianth tube (usually less than 1.3 cm) was the genuine L. sprengeri, while those coastal plants with a relatively long perianth tube (usually longer than 1.5 cm) is the new species, i.e. L. insularis.

The known karyotypes of fertile diploid species in Lycoris can be roughly divided into two categories: 2n = 12‒16 (such as L. traubii, L. aurea, L. chinensis and L. longituba) or 2n = 22 (such as L. sanguinea, L. radiata, L. wulingensis and L. sprengeri) (Kurita 1986; Hsu et al. 1994; Zhang et al. 2021; Zhang et al. 2022). Other sterile hybrid species are always with odd or allotriploid karyotypes. The chromosome number of L. insularis (2n = 22) is in line with the premise of being a fertile species. Furthermore, L. insularis has a relatively wide distribution area; its wild population can normally seed; and the seeds can develop into new plants at a high rate; thus, it can easily form a large population (more than 5,000 bulbs) and the individuals are scattered (i.e. do not show obvious clustering). All these factors indicate that L. insularis is a diploid fertile species and possibly has great value in the breeding and application of Lycoris.

Thanks to Zhang-jie Huang, Cheng-sheng Li and Miao Gao for their help in writing the first draft. Thanks to Yao Zhu and De-ying Liu for their help in the collection of experimental materials. This work was supported by National Natural Science Foundation of China (32070370) and China’s National Basic Science and Technology Program (2019FY101810).