﻿Ranunculusluanchuanensis (Ranunculaceae), a new species from Henan, China

﻿Abstract Ranunculusluanchuanensis (Ranunculaceae), a new species from Laojun Shan in Luanchuan county, Henan province, central China, is here illustrated and described. It is morphologically similar to R.limprichtii in having 3-lobed and subreniform basal leaves, 3-lobed cauline leaves, and small flowers with reflexed and caducous sepals, but differs by having slender and basally slightly thickened roots (vs. fusiform), prostrate stems (vs. erect), obliquely ovoid and glabrous carpels and achenes (vs. widely ovoid and puberulous), longer styles in the carpels (ca. 1.2 mm vs. 0.6–0.8 mm) and achenes (ca. 1.8 mm vs. 0.6–0.8 mm), and glabrous receptacles (vs. sparsely puberulous). Ranunculusluanchuanensis, currently known only from its type locality, is geographically isolated from R.limprichtii, a species widely distributed in Gansu, Qinghai, Sichuan, Xizang (Tibet) and Yunnan, China. The distribution map of this new species and its putative closest ally, R.limprichtii, is also provided.

During our botanical expedition in June 2022 to Laojun Shan in Luanchuan county, Henan province, central China, we encountered an unusual population of Ranunculus (Figs 1-4). The plants grow in a shady area among boulders and have prostrate stems, 3-lobed and subreniform basal leaves, 3-lobed cauline leaves, small flowers with reflexed and caducous sepals, and glabrous carpels and achenes with long styles. They look like R. limprichtii Ulbr.     Table 1. Ranunculus limprichtii is widely distributed in Gansu, Qinghai, Sichuan, Xizang (Tibet) and Yunnan, China (Fig. 9). Therefore, we determined that the population in question represents a hitherto undescribed species, which we name R. luanchuanensis and describe below.

Materials and methods
For morphological comparison, we examined physical specimens or high-resolution specimen images of Ranunculus limprichtii at CDBI, HNWP, KUN, PE and WU (acronyms according to Thiers 2022). We also observed living plants in one population of R. limprichtii (Dawu in Sichuan province, the type locality) and one population of R. luanchuanensis (Luanchuan in Henan province). The morphological description of R. luanchuanensis was based on the observation of herbarium specimens and living plants in the wild. Diagnosis. The new species is morphologically similar to R. limprichtii in having 3-lobed and subreniform basal leaves, 3-lobed cauline leaves, and small flowers with reflexed and caducous sepals, but differs by having slender and basally slightly thickened roots (vs. fusiform), prostrate stems (vs. erect), obliquely ovoid and glabrous carpels and achenes (vs. widely ovoid and puberulous), longer styles in the carpels (ca. 1.2 mm vs. 0.6-0.8 mm) and achenes (ca. 1.8 mm vs. 0.6-0.8 mm), and glabrous receptacles (vs. sparsely puberulous).
Etymology. The specific epithet refers to the type locality of the new species, i.e., Luanchuan county in Henan province, central China.
Phenology. Flowering in early June; fruiting at the end of June. Distribution and habitat. Ranunculus luanchuanensis is currently known only from its type locality, i.e., Laojun Shan in Luanchuan county, Henan province, central China (Fig. 9). It grows in a shady area among boulders on a mountaintop at an altitude of 2077 m above sea level.
Conservation status. Ranunculus luanchuanensis is currently known only from one small population at its type locality, i.e., Laojun Shan in Luanchuan county, Henan province, central China. This population consists of ca. 100 individuals within an area of less than 3 m 2 . However, the threat risk seems low because this species is not economically valuable and grows in a secluded place. The conservation status of R. luanchuanensis is here categorized as "Data Deficient (DD)" before adequate information on this species is acquired (IUCN Standards and Petitions Committee 2022).
Notes. Since its description, Ranunculus limprichtii var. flavus Hand.-Mazz. has been known only from its type material from Songpan county in Sichuan province, China (Wang 1995b). Based on our observations of herbarium specimens and living plants in the wild, we agree with Liou (1980) that this variety should be reduced to the synonymy of R. limprichtii. We will deal with the identity of R. limprichtii var. flavus in detail elsewhere.
According to Tamura's (1995) infrageneric classification of Ranunculus, R. luanchuanensis should be assigned to R. sect. Ranunculus, which is characterized by having swollen achenes with a distinct beak and receptacles hardly enlarged after anthesis. Ranunculus limprichtii, the putative closest ally of R. luanchuanensis, was placed by Wang (1995b) in R. sect. Ranunculus, with the section being incorrectly treated by him as R. sect. Auricomus (Spach) Schur. We accept the sectional placement of R. limprichtii since it is in accordance with the current placement of our new species in the same section.