Corydalis mianxianensis D.Wang, 2023

Wang, Dong, Xu, Xiaodong, Li, Niya, Sun, Qian & Wang, Liang, 2023, Corydalis mianxianensis (Papaveraceae), a new species from limestone cliffs in central China, and notes on the Shaanxi record of C. saxicola G. S. Bunting, Phytotaxa 609 (3), pp. 233-239 : 233-238

Corydalis mianxianensis D.Wang , sp. nov. ( Figs. 1–3 )

Diagnosis: —It resembles Corydalis moupinensis Franchet (1885: 198) , but it differs from the latter in 30–50(–70)-flowered racemes, spur being much shorter than the limb of the upper petal, linear fruits being arcuate to strongly contorted, and stigma with geminate papillae at the basal corners of the lobes.

Type: — CHINA. Shaanxi: Hangzhong City, Mianxian County, Yuanduan Town , limestone cliff crevices, 33°02′ N, 106°40′ E, elev. ca. 573 m, 13 April 2021, D. Wang et al. 210003 (holotype CCNU!, isotype PE!) .

Description: —Herbs, chasmophytic perennial, clustered, (sub-)scapose, glaucous, slightly fleshy and fragile. Taproot with persistent withered leaf residues apically. Leaves all crowded at base in a dense broad rosette, 10–35 × (2–) 2.5–4 cm; petiole longer than blade, 6–20 cm, vaginate at base; blade lanceolate, bipinnate; primary pinnae 4–6 pairs, distant, petiolulate; secondary pinnules 1(–2) pairs, shortly petiolulate to subsessile; terminal one larger, ca. 2 × 1.4–1.6 cm, deeply 3(–5)-divided; lateral ones ca. 10 × 4–8 mm, entire to bifid (rarely trifid); ultimate lobes oblong to ovate, apex obtuse. Flowering stems several, leafless, 20–30 cm (to 40 cm in shade-grown plants). Racemes densely 30–50(–70)- flowered (much less in late racemes), 15–25 cm, elongating and usually irregularly curved or spreading in fruit; bracts oblong-lanceolate, 3–4.5 mm, apex acuminate. Pedicels 5–8 mm, straight, erect-spreading in anthesis, elongating to 10–13 mm, suberect and usually arcuate in fruit. Flowers yellow, sometimes with a slight brownish tint toward keel of outer petals. Sepals ovate, 2.5–4 × 1.7–2 mm, dentate, apex acuminate. Outer petals mucronate, without crest; upper petal 15–16 mm (sometimes only 5–6 mm in cleistogamous flowers), upcurved, margin of limb usually upwardly reflexed; spur ascending-curved, 4–5.5 mm, obtuse; nectary extended through 2/3–3/4 of spur; lower petal 11–12 mm; inner petals 8–10 mm, only internally tipped with blackish purple, with dorsal crests shortly overtopping apex, claw shorter than or equaling limb. Stigma bifid, lobes reflexed-geniculate, each with 2 apical papillae and geminate lateral submarginal papillae and geminate papillae in basal corners (occasionally basal geminate papillae less developed). Capsule linear, 25–35 × 1–1.5 mm, arcuate to strongly contorted, subtorulose, not explosively dehiscent. Seeds in one row, black, 1.0–1.1 × 0.9–1.0 × 0.5–0.6 mm (length ×width × thickness), faintly colliculate; caruncle large, folded back over seed, covering ca. 1/3 of seed.

Phenology: —Flowering in April (probably late March) and fruiting from mid-April to May.

Distribution, Habitat and Ecology: — Corydalis mianxianensis is so far known from the Qinling-Daba mountains and southern Minshan mountains, central China. This species has a scattered distribution confined within about 32°31′– 33°32′ N and 104°3′– 106°40′ E and at elevational range of 570–1450 m ( Fig. 4 ). Plants grow strictly on limestone cliffs where they are well protected against rainfall. Occasionally, it is found colonized on shaded cliffs, where individuals can reach 40 cm high. In general, dry cliffs represent highly stressful environments, which have relatively limited habitats available for plants. It is therefore assumed that this species is restricted to a narrow ecological niche, adapting to specific condition of soil, pH and moisture. It is also noticeable that some plants can bear few-flowered racemes that developed late or in fruiting stage, when fruits of many-flowered racemes are close to mature.

Etymology: —The specific epithet mianxianensis is from the name of the county, where the type specimens were collected. The Chinese name is also suggested from this county name, mianxian huang jin (MBȒae).

Conservation status: — Corydalis mianxianensis should be classified as LC (Least Concern) according to IUCN Red List criteria ( IUCN 2012). It may be more common than indicated by the known localities since limestone cliffs are abundant in central China. Also, it may have been easily overlooked because of its superficial resemblance to C. saxicola G.S. Bunting (1965: 172) and C. wilsonii N.E. Brown (1903: 123) of C. sect. Thalictrifoliae ( Fedde 1924b: 359) Lidén (1986: 28) .

Discussion: —Judging from its general features (perennial, scapose; leaves bipinnate; flowers yellow, with obtuse spur; stigma 2-armed, arms reflexed-geniculate; capsules linear, not explosively dehiscent), our new species clearly belongs to Corydalis sect. Cheilanthifoliae Lidén (1986: 28) . This section currently comprises six species, namely C. cheilanthifolia Hemsley (1892: 302) , C. moupinensis Franchet , C. ophiocarpa J.D. Hooker & Thomson (1855: 259) , C. campulicarpa Hayata (1913:15) , C. giraldii Fedde (1924a: 50) and C. racemosa ( Thunberg 1801: 103) Persoon (1806: 270) ( Zhang et al. 2008). Our new species is most similar to C. moupinensis Franchet , but deviates considerably in a number of characters as diagnosed above ( Figs. 1 & 2 ). Besides, a closer examination on plants in the field revealed that C. mianxianensis has no special odor, which is quite different from C. moupinensis that smells like C. racemosa . The habitats of C. mianxianensis and C. moupinensis are also widely different, the former grows on apparently dry limestone cliffs, and the latter grows in mixed forest and stone crevices and non-limestone cliffs. Our new species further differs from C. cheilanthifolia by the very glaucous (vs. green) leaves and leaves with 4–6 pairs (vs. 6–12 pairs) of primary pinnae, and from all the other four species of the section in its perennial habit (vs. annual or biennial), leaves all crowded at base (vs. leafy throughout stem) and flowering stems leafless (vs. leafy).

One of the habitats that Corydalis thrive is cliffs. So far, a number of species have been recorded in cliff environments. But just a few species that grow on limestone cliffs, which are exemplified by some species of C. sect. Thalictrifoliae , such as C. wilsonii , C. saxicola , C. tomentella Franchet (1894: 292) , and C. fangshanensis W.T.Wang ex S.Y.He in He et al. (1984: 670). Corydalis mianxianensis is another species added to inhabit limestone cliffs. This study raises questions about the geographic distribution of C. saxicola in Shaanxi province as documented in the Chinese floras (Wu at al. 1999, Zhang et al. 2008). Perusal of specimens lead us to trace that the record of C. saxicola in Shaanxi (Mian Xian) was based only on one collection (Li Peiyuan 605, WUK, https://www.cvh.ac.cn/spms/detail. php?id=bfafef62). This specimen was collected from Yuandun Town, Mianxian County, Shaanxi; on the label of this specimen the habitat is given as cliffs and the collecting date is October 12, 1957. The collection only has leaves and part of taproot. Although it was identified as C. saxicola by C.Y. Wu in 1978, we do not find sufficient basis for identifying characters. More specifically, we found it does not fit in C. saxicola , as shown by its rather different foliage. After seeing species alive in Yuandun town and noting its different flowers and fruits, we confirmed that the specimen should be identical to C. mianxianensis . It is therefore concluded that the record of C. saxicola in Shaanxi was a misidentification.

Additional specimen examined (paratypes) — CHINA. Gansu: Longnan City, Huixian County, Yuguan Xiang , elev. ca. 872 m, 12 May 2017, D. Wang et al. 170056 (in fruit, CCNU) . Shaanxi: Hanzhong City, Mianxian County, Yuanduan Town , 12 October 1957, Li Peiyuan 605 (without flower and fruit, WUK) ; Lüeyang County, Lianghekou Town, Changba Cun , elev. ca. 734 m, 13 April 2018, D. Wang et al. 180024 ( CCNU) . Sichuan: Bazhong City, Nanjiang County, Guangwushan , 4 May 2020, photos taken by D. C. Meng ( PPBC id:6798844–6798864, http://ppbc.iplant. cn) ; Mianyang City, Pingwu County, Huya Tibetan Xiang , elev. ca. 1433 m, 19 August 2019, D. Wang et al. 190033 ( CCNU) ; 19 April 2021, D. Wang et al. 210010 ( CCNU) . Guangyuan City, Qingchuan County, Fangshi Town , Lihe Cun , elev. ca. 855 m, 20 April 2021, D. Wang et al. 210015 ( CCNU) .

Figures

FIGURE 1. Habitat, habit and morphology of Corydalis mianxianensis (D. Wang et al. 210003). A. habitat; B. inflorescence; C. fruits; D–G. flower showing the lateral view (D), front view (E), adaxial view of flower showing the apex of upper petal (F) and abaxial view of flower showing the apex of lower petal (G).

FIGURE 2. Corydalis mianxianensis (a–m) (D. Wang et al. 210003). a. bracts; b. flower with bract; c. sepals; d. upper petals; e. lower petals; f. spur and nectary; g. inner petals; h. stamens; i. pistil with attached sepals and bract and pedicel; j. stigmas showing variation among individuals; k. fruits; l. seeds; and m. dissected floral parts that are illustrated to the same scale bar.

FIGURE 3. The photo of the holotype sheet of Corydalis mianxianensis.

FIGURE 4. Distribution of Corydalis mianxianensis (●).