Oxytropis shennongjiaensis D.G. Zhang, J.T. Chen, T. Deng & H. Sun, 2020

Chen, Jun-Tong, Zhang, Dai-Gui, Lv, Zhen-Yu, Huang, Xian-Han, Liu, Peng-Ju, Yang, Jia-Ning, Yang, Jing-Yuan, Tojibaev, Komiljon, Deng, Tao & Sun, Hang, 2020, Oxytropis shennongjiaensis (Fabaceae), a new species from Hubei, Central China, PhytoKeys 149, pp. 117-128 : 117

Oxytropis shennongjiaensis D.G. Zhang, J.T. Chen, T. Deng & H. Sun sp. nov. Figures 1 , 2 , 3

Type.

China. Hubei: Shennongjia National Park, 31°26'39.96"N, 110°16'00.34"E, 2880 m elev., 9 June 2019, D.G. Zhang & Q. Liu 19060901 (holo: KUN barcode 1347953!; iso: JIU!).

Diagnosis.

Compared with the published species of Oxytropis in China, O. shennongjiaensis appears to be closely similar to O. sitaipaiensis , from which it can be distinguished by its stems with less conspicuous internodes and 5-15 mm internodes (stems with two or more conspicuous internodes in O. sitaipaiensis ); stipules ovate, 7-10 mm long, herbaceous (stipules narrowly triangular, 3-5 mm long, membranous in O. sitaipaiensis ); bracts ovate, 6-8 mm long (bracts subulate, ca. 2 mm long in O. sitaipaiensis ); calyx 9-11 × 2-4 mm (calyx ca. 4 × 3 mm in O. sitaipaiensis ); pale yellow to white corolla; beak 3 mm long (purplish corolla; beak ca. 1.5 mm long in O. sitaipaiensis ). Table 1 provides detailed morphological comparisons with similar species.

Description.

Perennial herbs, 10-15 cm tall. Yellowish-brown, cylindrical roots, up to 25 cm long, with lateral roots. Caulescent from a multi-headed caudex, slightly subterranean sometimes rhizomatous. Stems sprawling, 3-15 cm long, basally with persistent stipules; nodes of stems slightly swollen; internodes 5-15 mm long, invested with sparse, white trichomes. Leaves (4-) 6-9 (-11) cm long, 13-17 (-19)-foliolate; leaflets ovate, 5-11 × 2-4 mm, apex acuminate, with sparse, subappressed white trichomes, abaxially mid-vein slightly raised (obvious after drying), with denser trichomes along vein; dark purplish-red or green rachis, with sparse white trichomes; stipules ovate, 7-10 × 3-4 mm, herbaceous, basally connate, apex acuminate, abaxially sparsely hairy with white trichomes, adaxially glabrous, margins scarious, ciliate with black and white trichomes. Racemes rather lax, 3-6-flowered; peduncles 2.5-4.5 cm long, erect, villous, with white trichomes, sparsely intermixed with black trichomes below, with densely black trichomes above. Bracts ovate, 6-8 × 2-3 mm, membranous, with sparse, dark brown trichomes intermixed with white trichomes abaxially. Calyx campanulate, 9-11 × 2-4 mm, with dark brown trichomes sparsely intermixed with white trichomes outside; lobes subulate, 4-5 mm long, as long as or sometimes slightly shorter than tube. Pale yellow to white corolla; standard 16-18 mm long, lamina broadly ovate, 12-13 × 10-11 mm, apex emarginate to 2-lobed, margins slightly undulated entire or with irregular repand teeth; wings 12-15 mm, lamina obovate, 7 × 4 mm long, apex obtuse, claw 4-5 mm long; keel 15 mm long, beak 3 mm long. Ovary linear, with dense white trichomes. Legumes stipitate (stipe 5-7 mm long), oblong-ellipsoid, 20-25 × 5-7 mm, erect, inflated and slightly flattened, with sparsely white trichomes, beak 3-5 mm long.

Phenology.

Flowering from May-June and fruiting from July-August.

Etymology.

The specific epithet refers to the Shennongjia National Park to which the species is endemic. The Chinese name is 神农架棘豆, shén nóng jià jí dòu in Chinese phonetic transcription.

Distribution and habitat.

The new species is currently known only from the Shennongjia National Park (Figure 4 ), Hubei, China, at an elevation of 2,880 m. It grows in barren rock crevices at the top of a mountain together with Polygonum macrophyllum D.Don ( Polygonaceae ), Primula sp. ( Primulaceae ), Carex sp. ( Cyperaceae ), Chrysanthemum oreastrum Hance ( Asteraceae ), Dracocephalum rupestre Hance ( Lamiaceae ) and Meconopsis quintuplinervia Regel ( Papaveraceae ) etc.

Conservation status.

The new species was only discovered in Jinsiyanya, Shennongjia National Park, from our expeditions during the past few years. About 300 individuals were observed and the extent of occurrence is ca. 50,000 m2. The precise conservation status of the population(s) has not been determined, so further explorations are needed to assess its conservation status. Based on available data, the new species is assigned to the category 'Data Deficient’ (DD) of International Union for Conservation of Nature (IUCN 2019).

Molecular phylogenetic analysis.

Based on the combined datasets (ITS, trnL-F and psbA-trnH), BI, MP and ML trees were reconstructed and their topologies are quite similar. The ML tree is presented in Figure 5 and shows the posterior probability (PP), ML bootstrap support (MLBS) and MP bootstrap support (MPBS) values. Our phylogenetic analyses show Oxytropis shennongjiaensis to be nested within a polyphyletic Sect. Mesogaea Bunge. O. melanocalyx (Sect. Mesogaea Bunge) and O. latibracteata (Sect. Oxytropis Bunge) are shown to be sister to O. shennongjiaensis , with relatively high support (ML/BS = 75). This new species is shown to be separated from other species and, to some extent, it can be identified as a new species.

Figures

Figure 1. Photograph of the holotype of Oxytropis shennongjiaensis D. G. Zhang, J. T. Chen, T. Deng & H. Sun (KUN barcode 1347953).

Figure 2. Oxytropis shennongjiaensis D. G. Zhang, J. T. Chen, T. Deng & H. Sun A, B plant showing flowering branch and leaves C bract D calyx E-F wing G-H standard (view from inside) I keel J ovary K legume L stipules. (Drawn based on the holotype of D. G. Zhang & Q. Liu 19060901 by J. N. Yang).

Figure 3. Oxytropis shennongjiaensis D. G. Zhang, J. T. Chen, T. Deng & H. Sun A, B habitat C root D, E flowering branch and leaves F raceme (close-up) G, H floral parts (showing calyx, standard, wings, keel and stamens) I legume.

Figure 4. Known distribution of Oxytropis shennongjiaensis D. G. Zhang, J. T. Chen, T. Deng & H. Sun (The red dot represents the distribution site).

Figure 5. Maximum likelihood consensus tree of Oxytropis shennongjiaensis and related taxa. Numbers above branches indicate Bayesian posterior probability [PP], numbers below branches represent maximum likelihood bootstrap support [ML / BS] and maximum parsimony bootstrap support [MP / BS] values. Only bootstrap values> 50 % are shown. The new species is shown in bold.