Ranunculus luanchuanensis W.Q.Fei, Q.Yuan & Q.E.Yang, 2023

Fei, Wen-Qun, Yuan, Qiong & Yang, Qin-Er, 2023, Ranunculus luanchuanensis (Ranunculaceae), a new species from Henan, China, PhytoKeys 220, pp. 17-29 : 17

Ranunculus luanchuanensis W.Q.Fei, Q.Yuan & Q.E.Yang sp. nov.

Figs 1 , 2 , 3 , 4

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).

Type.

China. Henan province: Luanchuan county, Laojun Shan , 33°43'3.62"N, 111°38'59.89"E, in shady place among boulders on mountaintop, alt. 2077 m, 17 June 2022, W.Q. Fei 588 (holotype: IBSC; isotypes: IBSC, PE) .

Description.

Herbs perennial, terrestrial or rupicolous. Roots 1-3, fibrous, slender, slightly thickened at base. Stems 12-20 cm long, prostrate, unbranched, glabrous. Basal leaves 2-6, 3-lobed, long petiolate; petioles 2-6 cm long, glabrous; blades 0.7-1.6 × 1-2.3 cm, subreniform in outline, thinly papery, adaxially green, glabrous or sparsely puberulous, abaxially light green, glabrous, base cordate, central segment 0.5-0.6 × 0.6-0.7 cm, widely obovate to rhombic-obovate, entire or 2-3-dentate, apex rounded or acuminate, lateral segments 0.5-0.7 × 0.7-1 cm, obliquely flabellate, inconspicuously 2-lobed, apex rounded or acuminate. Lower cauline leaves 2-3, similar to basal ones but smaller. Upper cauline leaves 1-2, 0.6-1.2 × 0.3-0.8 cm, 3-lobed, rarely entire, shortly petiolate or subsessile, oblate-ovate, flabellate or lanceolate, glabrous. Inflorescences terminal, 1(-2)-flowered. Flowers 6-7 mm in diameter; pedicels 0.5-2 cm long, glabrous or sparsely puberulous; receptacles ca. 1 mm long, clavate, glabrous; sepals 5, 2-2.5 × 1.5-1.8 mm, elliptic to obovate, reflexed, caducous, green tinged with yellowish, concave, adaxially glabrous, abaxially sparsely puberulous; petals 5(-6), 3-3.5 × 1.5-1.8 mm, narrowly obovate, yellow, glabrous, apex obtuse or acuminate, nectary pit without a scale, claws ca. 0.4 mm long; stamens 12-16, filaments ca. 1.5 mm long, narrowly linear, anthers ca. 0.5 mm long, oblong; gynoecium subglobose; carpels 14-18, ovaries ca. 0.8 mm long, obliquely ovoid, laterally flattened, biconvex, glabrous, styles ca. 1.2 mm long, glabrous, apex recurved. Aggregate fruit ca. 3.5 × 3.5 mm, subglobose; achenes ca. 1.8 × 1.2 mm, obliquely ovoid, laterally flattened, biconvex, glabrous, styles ca. 1.8 mm long, persistent, apex recurved.

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 m2. 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.

Figures

Figure 1. Ranunculus luanchuanensis sp. nov. in the wild (China, Henan, Luanchuan, Laojun Shan) A, B habitat C habit. Photographed by Wen-Qun Fei.

Figure 2. Ranunculus luanchuanensis sp. nov. in the wild (China, Henan, Luanchuan, Laojun Shan) A roots B portion of stem C leaves D flower with the sepals reflexed (lateral view) E flower with the sepals having fallen off (lateral view) F flower (top view) G sepal (left: abaxial side; right: adaxial side) H petal (left: adaxial side; right: abaxial side) I stamens J carpels K aggregate fruit L achenes M receptacle. Photographed by Wen-Qun Fei.

Figure 3. Holotype sheet of Ranunculus luanchuanensis sp. nov.

Figure 4. Isotype (A-D) sheets of Ranunculus luanchuanensis sp. nov.

Figure 9. Distribution of Ranunculus limprichtii (black circle) and R. luanchuanensis sp. nov. (black square). Black arrow indicates the type locality of R. limprichtii, i. e., Dawu in Sichuan province, China.