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

Fei, Wen-Qun, Yuan, Qiong & Yang, Qin-Er, 2023, Ranunculus jiguanshanicus (Ranunculaceae), a new species from Sichuan, China, PhytoKeys 219, pp. 57-75 : 57

publication ID	https://dx.doi.org/10.3897/phytokeys.219.96266
persistent identifier	https://treatment.plazi.org/id/2BCA64EF-A813-5D77-97AD-83B236A8591D
treatment provided by	PhytoKeys by Pensoft
scientific name	Ranunculus jiguanshanicus W.Q.Fei, Q.Yuan & Q.E.Yang
status	sp. nov.

Treatment

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

Figs 1 View Figure 1 , 2 View Figure 2 , 3 View Figure 3 , 4 View Figure 4 , 5 View Figure 5

Diagnosis.

Ranunculus jiguanshanicus is readily distinguishable from all other Chinese species of Ranunculus by a unique array of characters, including small stature, glabrous and prostrate stems, 3-foliolate leaves with obvious petiolules (3-5 mm long), unequally 3-sected leaflets, lanceolate to linear ultimate leaflet segments, small flowers (5.2-6 mm in diameter), and long styles in the carpels and achenes (ca. 0.8 mm long).

Type.

China. Sichuan province: Chongzhou, Anzihe Nature Reserve, Jiguan Shan , 30°46'5.8"N, 103°10'21.93"E, alt. 2998 m, among moss on rocks or rocky cliffs in moist places in fir forests, 10 June 2022, W.Q. Fei 581 (holotype: IBSC; isotypes: IBSC, PE) GoogleMaps .

Description.

Herbs perennial, terrestrial or rupicolous. Roots 2-5, 6-10 cm long, fibrous, slender, slightly thickened at base. Stems 7-15 cm long, prostrate, glabrous, unbranched to few-branched. Basal leaves 2-5, 3-foliolate, long-petiolate; petioles 2-4 cm long, glabrous; blades 0.8-1 × 0.8-1.3 cm, suborbicular, thinly chartaceous, adaxially green, abaxially light green, both sides glabrous; leaflets 3, unequally 3-sected, petiolulate, petiolules 3-5 mm long, ultimate leaflet segments 3-4 × 0.8-1.2 mm, narrowly lanceolate to linear, margin entire, apex 1-2-denticulate to 1-2-cleft. Lower cauline leaves 2-3, similar to basal ones but smaller. Upper cauline leaves 1-2, 3-foliolate, subsessile or sessile, adaxially glabrous or sparsely puberulous, abaxially glabrous, central leaflet 4.5-5 × 1-1.2 mm, narrowly lanceolate to linear, margin entire, lateral leaflets entire, 1-2-lobate or 2-3-sected, ultimate leaflet segments 3-3.5 × 1-1.2 mm, narrowly lanceolate to linear. Inflorescences terminal, 1(-2)-flowered. Flowers 5.2-6 mm in diameter; pedicels 1-2 cm long, glabrous or sparsely puberulous; receptacles ca. 1.2 mm long, clavate, glabrous; sepals 5, 2.2-2.5 × 1.5-1.8 mm, elliptic to obovate, patent, green tinged with yellowish, concave, both sides glabrous; petals 5(-6), 3.2-3.5 × 1.8-2 mm, obovate, yellow, glabrous, apex rounded, nectary pit without a scale, claws ca. 0.4 mm long; stamens 6-8, ca. 2 mm long, filaments ca. 1.5 mm long, narrowly linear, anthers ca. 0.5 mm long, oblong; gynoecium subglobose; carpels 8-12, ovaries ca. 0.8 × 0.6 mm, ovoid, laterally flattened, biconvex, glabrous, styles ca. 0.8 mm long, glabrous, apex recurved. Aggregate fruit ca. 4 × 4.2 mm, subglobose; achenes ca. 1.2 × 1 mm, widely ovoid, laterally flattened, biconvex, glabrous, styles ca. 0.8 mm long, persistent, glabrous, apex recurved.

Etymology.

The specific epithet refers to the type locality of the new species, i.e. Jiguan Shan in the Anzihe Nature Reserve in Chongzhou, Sichuan province, China.

Phenology.

Flowering in early June; fruiting at the end of June.

Distribution and habitat.

Ranunculus jiguanshanicus is currently known from its type locality, i.e., Jiguan Shan in the Anzihe Nature Reserve in Chongzhou, and from the closely adjacent Xiling Xue Shan in Dayi, both in Sichuan province, China (Fig. 6 View Figure 6 ). It grows among moss on rocks or rocky cliffs in moist places in fir forests at altitudes of 2900-3150 m above sea level.

Conservation status.

Ranunculus jiguanshanicus is currently known only from two populations in Sichuan province, China. The Chongzhou population consists of ca. 150 individuals within an area of less than 10 m2. The size of the Dayi population remains unknown. The conservation status of R. jiguanshanicus should better be categorized as "Data Deficient (DD)" before adequate information of this species is acquired ( IUCN Standards and Petitions Committee 2022).

Discussion.

Ranunculus jiguanshanicus is readily assigned to R. sect. Ranunculus due to its swollen achenes with a distinct beak and receptacles hardly enlarged after anthesis. In his infrageneric classification of the Chinese Ranunculus , Wang (1995a, b) placed almost all the alpine species within this section under the name R. sect. Auricomus (Spach) Schur.

Morphologically, Ranunculus jiguanshanicus is somewhat similar to R. pegaeus (Figs 7 View Figure 7 - 10 View Figure 10 ), also a member of R. sect. Ranunculus , in having prostrate and glabrous stems (Figs 2A, B View Figure 2 , 8A, B View Figure 8 ), small flowers (Figs 3D View Figure 3 , 9D View Figure 9 ), subglobose aggregate fruit (Figs 3I View Figure 3 , 9I View Figure 9 ), and glabrous carpels (Figs 3H View Figure 3 , 9H View Figure 9 ), achenes (Figs 3G View Figure 3 , 9G View Figure 9 ) and receptacles (Figs 3K View Figure 3 , 9K View Figure 9 ). However, it differs by having 3-foliolate leaves with obvious petiolules (3-5 mm long), unequally 3-sected leaflets, lanceolate to linear, entire or 1-2-denticulate to 1-2-cleft ultimate leaflet segments (Fig. 3C View Figure 3 ), and styles in the carpels and achenes ca. 0.8 mm long (Fig. 3H, G View Figure 3 ). In R. pegaeus , the leaves are 3-partite, 3-sected or 3-foliolate with the central segment/leaflet rhombic or oblong, entire or 3-denticulate and the lateral segments/leaflets obliquely flabellate, entire or unequally 2-cleft (Figs 9C View Figure 9 , 10 View Figure 10 ), and styles in the carpels and achenes ca. 0.3 mm long (Fig. 9H, G View Figure 9 ). A detailed morphological comparison between R. jiguanshanicus and R. pegaeus is given in Table 1 View Table 1 .

As mentioned earlier, a gathering of Ranunculus jiguanshanicus , W.B. Ju, L. Zhang & D.K. Chen AZH01290 (CDBI), from Chongzhou in Sichuan, the type locality of this species, had been previously misidentified as R. glareosus (Figs 11 View Figure 11 - 14 View Figure 14 ). Morphologically, R. jiguanshanicus is very easily distinguishable from R. glareosus by having glabrous stems (vs. sparsely puberulous) (Figs 3B View Figure 3 , 13B View Figure 13 ), thinly chartaceous leaves (vs. fleshy), leaflets of the 3-foliolate leaves with obvious petiolules (3-5 mm vs. 0.5-2 mm long), unequally 3-sected, with the ultimate leaflet segments narrowly lanceolate to linear, entire or 1-2-denticulate to 1-2-cleft (vs. 3-sected or 3-foliolate, central segment/leaflet ovate or rhombic, entire or 3-lobed, and lateral segments/leaflets flabellate, unequally 2-partite) (Figs 3C View Figure 3 , 13C View Figure 13 ), smaller flowers (5.2-6 mm vs. 15-17 mm in diameter) (Figs 3D, E View Figure 3 , 13D, E View Figure 13 ), abaxially glabrous sepals (vs. puberulous) (Figs 3F View Figure 3 , 13F View Figure 13 ), smaller (3.2-3.5 × 1.8-2 mm vs. 9-10 × 7-8 mm) and obovate petals (vs. widely obovate) (Figs 3G View Figure 3 , 13G View Figure 13 ), subglobose aggregate fruit (vs. ellipsoid) (Figs 3J View Figure 3 , 13J View Figure 13 ), and longer styles in the carpels and achenes (ca. 0.8 mm vs. ca. 0.2 mm long) (Figs 3I, K View Figure 3 , 13I, K View Figure 13 ). In habitat, R. jiguanshanicus grows among moss on rocks or rocky cliffs in moist places in fir forests at altitudes of 2900-3150 m above sea level, whereas R. glareosus grows on alpine scree slopes at altitudes of 3900-4800 m above sea level. A detailed morphological comparison between R. glareosus and R. jiguanshanicus is given in Table 1 View Table 1 .