Crotalaria menglaensis S. A. Rather, 2024

Rather, Shabir A., Radbouchoom, Sirilak, Wang, Kaikai, Xiao, Yunxue, Liu, Hongmei & Schneider, Harald, 2024, Molecular, morphological, and morphometric evidence reveal a new, critically endangered rattlepod (Crotalaria, Fabaceae / Leguminosae, Papilionoideae) from tropical China, PhytoKeys 242, pp. 333-348 : 333-348

Crotalaria menglaensis S. A. Rather sp. nov.

Fig. 4

Type.

China. Yunnan: Xishuangbanna Dai Autonomous Prefecture, Mengla County, Mengpengzhen ., 21 ° 26 ' 57.42 " N, 101 ° 18 ' 31.49 " E, alt. 577 m, 23 November 2022, SAR 202305 (holotype HITBC! isotypes KIB! PE! DUH! CAL!) .

Diagnosis.

The new species is similar to two sympatrically occurring species, C. incana L. and C. bracteata Roxb. ex DC. However , C. menglaensis S. A. Rather differs from the former and latter in its height, 0.5 m (vs 1 vs 60–1.20); stem surface, pubescent with white hairs (vs pubescent brownish vs densely brownish yellow); bract surface, pilose (vs glabrous vs glabrous); leaflet shape, ovate to oblanceolate (vs elliptic obovate, or suborbicular vs narrowly elliptic); leaflet surface, pubescent (vs glabrous vs sparsely pilose); standard shape, obovate-orbicular (vs elliptic vs oblong); planar callosities (vs ridge vs ridge); keel shape, angled (vs subangled vs subangled); keel beak, straight (vs spirally twisted up to 90 ° vs slightly incurved); pod shape, elliptic to oblong (vs fusiform vs ellipsoid-fusiform); and pod indumentum tomentose (vs rusty pilose vs densely rusty pubescent).

Description.

Stiff and erect herbs, ca. 0.5 m tall. Stems terete and densely pubescent. Stipules acicular. Leaves trifoliolate, alternate, petiole up to 30 mm long, lamina ovate to oblanceolate, 30–80 × 21–31 mm, terminal leaflet larger than the lateral ones, attenuated at the base, acute at apex, margin entire with puberulent indumentum, adaxial surface glabrescent, abaxial surface pubescent. Inflorescence a terminal or axillary raceme, a terminal raceme 80–120 mm bearing up to 12 flowers, and an axillary raceme 110–170 mm bearing up to 47 florets. Flower 10–11.9 × 3.3–4 mm. Bract lanceolate, 1.2–2 × 0. 6– 0.7 mm covered with white pilose hairs inserted at the base of a pedicel. Pedicel ca. 4.7 mm, pubescent, reflexed downwards; bracteole ovate to obovate with an asymmetric base, 2.7–3.1 × 1.6–1.8 mm, hirsute, margin entire. Calyx 5 - lobed, calyx tube ca. 2.4 × 2.9 mm, oblong-lanceolate, 2.2–2.9 × 0.4–0.71 mm, apex attenuate, densely ciliate along margins. Corolla primrose or strongly pale yellow, exserted beyond calyx, obovate-orbicular, ca. 8.8 × 7.4 mm, claw ca. 1.4 mm, with paired planar callosites at the base, ca. 0.6–0. 7 × 0. 7– 0.8 mm; wing petals 7.1–7.3 × 2.3–2.9 mm, claw 1.52–1.84 × 6.3– 0.77 mm, cavae 4.2–4.4 mm; keel angled, curvature below the middle, claw 3.4–3.6 × 1.2–1.4 mm, glabrous, beak straight. Staminal sheath 7.8 mm; filaments free, glabrous, shorter filament 3.7–6.7 mm, longer filament 7.7–8.0 mm; anthers dimorphic, basifixed ones longer, ensiform, ca. 1.2–1.5 mm, dorsifixed ones shorter, orbicular ca. 0.5–0.6 mm. Ovary sessile, linear, ca. 3.3 × 1.5 mm, inflated, style 8.2 mm long, geniculate, trichomes in a single row; stigma brush-like and contracted, ca. 0. 21 mm long, hairy. Pods elliptic to oblong, 14.2–15 × 6–7.7 mm, tomentose, with persistent style. Seeds 2.2–2.5 × 0.9–1.2 mm, bright citrine, smooth and glossy.

Phenology.

The plants were observed to bear flowers and fruits from October to January.

Etymology.

The specific epithet of the new species “ menglaensis ” is derived from the type locality of this species.

Distribution and habitat.

Crotalaria menglaensis S. A. Rather is found in grasslands and exposed areas of Mengpeng, Mengla County, within the Xishuangbanna Dai Autonomous Prefecture, Yunnan, China.

Uses.

Locals use the pods of this species as a food source. Additionally, its roots and seeds are utilized in traditional medicine to treat various digestive disorders.

IUCN Red List Category.

This species is exclusively documented in a single location where clustered populations of fewer than 100 mature individuals have been observed. Its habitat is adjacent to roads and agricultural land and is consistently affected by anthropogenic activities such as grazing, deforestation, cultivation, and landscape management. The potential degradation of its natural habitat and restricted geographical range significantly threatens its survival. Therefore, according to the IUCN Standards and Petitions Committee (2019), this species should be considered critically endangered under criteria A 4, B 2 a, C 2 a, and D 1. These criteria denote species facing a very high risk of extinction in the wild.

Additional specimens examined

(paratypes). China, Yunnan. Mengla , in forest, alt. 1600 m, 12 June 2012, Y. M. Shi & W. S. Chen 254655 ( KUN) . Xishuangbanna, Mengla , in the forest, 1650 m, 16 July 2014, Y. M. Shui & W. S. Chen 245266 ( KUN) . Xishuangbanna, Mengla , in the forest, 1450 m, 14 August 2016, Z. Y Wen & Z. A Wang 524694 ( KUN) . Hekou , on forest edges, 1459 m, 25 November 2005, Z. Y. Chang et al. 162458 ( KUN) . Xishuangbanna, Mengla , in grasslands, 1200 m, 3 August 2007, Z. Y. Chang 445123 ( KUN) . Xishuangbanna, Mengla , 1180 m, 25 August 2010, Z. Y. Chiang 2005387 ( HITBC) .

Figures

Figure 4. Crotalaria menglaensis S. A. Rather A habit B plant twigs with leaves and flowers C inflorescence with flowers D inflorescences with flowers and fruits E flower in dorsal, lateral, and ventral views F calyx showing the dorsal and ventral surfaces G standard adaxial surface H standard abaxial surface with paired planar callosity pairs at the base with white silky pubescence I wing petals with prominent cavae and a distinct claw J adaxial and abaxial surfaces of keel petals, beak not twisted, pubescence along the margins from the middle to the base of the keel petal K anthers monodelphous, 10 dimorphic anthers (common to all the species within the genus) L gynoecium showing the ovary, style, and stigma M pod in ventral, dorsal, and lateral views N pod splitted longitudinally with young seeds.