Carex radicalispicula Tang & F.T.Wang ex Y.F.Lu & X.F.Jin, 2023

Lu, Yi-Fei, Lu, Zhao-Cen, Duan, Yu-Hao, Zhang, Kun & Jin, Xiao-Feng, 2023, Notes on Carex (Cyperaceae) from China (IX): three new species of section Mitratae s. l., PhytoKeys 225, pp. 153-164 : 153

3. Carex radicalispicula Tang & F.T.Wang ex Y.F.Lu & X.F.Jin sp. nov.

Fig. 4A-G

Diagnostic description.

This new species is similar to Carex truncatirostris S.W.Su et S.M.Xu, but differs in having staminate spikes clavate, 1.5-2 mm wide, pistillate glumes pale yellow-white, 3-3.2 mm long, acuminate or short-awned at apex, nutlets with 3 angles shallowly constricted at middle.

Type.

China. Sichuan: Kangding County, Erdaoqiao , on roadside, alt. 2650 m, 26 May 1940, K. L. Chü 6963 (holotype: PE!; isotypes: IBSC0654521!, PE!) .

Description.

Perennial herbs. Rhizomes short, woody. Culms central, loosely turfed, 8-30 cm tall, slender, trigonous, smooth, base with grey-brown sheaths. Leaves shorter than or rarely equal to culms, blades 1.5-2 mm wide, flat, leathery, scabrous on margins. Lowermost bract leaf-like, others setaceous, base with 4-6 mm long sheath. Spikes 3 or 4; terminal spike staminate, clavate, (5-)9-12 mm long, 1.5-2 mm wide; lateral spikes pistillate, with the lowermost arising from the base of culms, shortly cylindrical or cylindrical, 7-15 mm long, 3.5-4 mm wide, 4-12-flowered, with the lowermost peduncle slightly exserted from the sheath. Staminate glumes elliptic-lanceolate, yellow-brown, 4.5-5.5 mm long, apex obtuse, with 1-veined yellow costa. Pistillate glumes broadly ovate, pale yellow-white, 3-3.2 mm long, apex acuminate or with a ca. 0.5 mm long scabrous awn, with 3-veined green costa. Utricles yellow-green, rhombic-ovoid, obtusely trigonous, ca. 3.8 mm long, ca. 1.3 mm wide, longer than pistillate glumes, membranous, obliquely patent, distinctly thinly veined, sparsely pubescent, base gradually cuneate, short-stipitate, apex gradually contracted into a 0.8-1 mm long beak, orifice 2-lobed with short teeth. Nutlets tightly enveloped, pale yellow, rhombic-ovoid, trigonous, ca. 2.5 mm long, with 3 angles shallowly constricted at middle, lateral sides slightly concave above and below, base shortly curved-stipitate, apex abruptly contracted into a discoid-annulate style-base; style base thickened; stigmas 3.

Etymology.

The specific epithet ' radicalispicula ' refers to the lowermost spike arising from the base of culm.

Phenology.

Flowering and fruiting occur in late May.

Conservation status.

Least Concern (LC). The new species was collected by Kuei-Ling Chü (K. L. Chü 6963) from the type locality, including two sheets deposited in PE and one in IBSC. The authors carried out a field trip to the type locality in 2019, but failed to locate and collect any similar specimens. The type locality has been disturbed and the quality of the habitat appears to be continuously declining now ( IUCN 2019).

Notes.

With rhombic-ovoid nutlets abruptly contracted into a discoid-annulate style-base at the apex, 3 angles constricted at the middle, and the lowermost spike arising from a culm base, Carex radicalispicula is similar to C. truncatirostris . A taxonomic revision of C. chungii Z.P.Wang and the allied species has been conducted ( Jin 2017), and these very closely related species can be distinguished from each another using the following key.

1a	Lowermost spikes exserted from the basal sheaths of culms; lowermost bract sheaths <6 mm long	2a
2a	Terminal staminate spikes 1.5-2 mm wide; nutlets shallowly constricted at middle angles; pistillate glumes pale yellow-white, 3-3.2 mm long, acuminate or short-awned at apex	Carex radicalispicula
2b	Terminal staminate spikes 0.6-1 mm wide; nutlets constricted at middle angles; pistillate glumes pale brown or yellow-brown, 2-2.5 mm long, emarginate or obtuse at apex	Carex truncatirostris
1b	Lowermost spikes exserted from the middle sheaths of culms; lowermost bract sheaths> 1 cm long	3a
3a	Terminal spikes 1-3 cm long; pistillate glumes long-awned at apex; staminate glumes short-awned or mucronate at apex	Carex chungii
3b	Terminal spikes 3.5-6 cm long; pistillate glumes mucronate at apex; staminate glumes acute at apex	Carex nanpingensis

The new species is closed to Carex truncatirostris , and the species have nutlets apex abruptly contracted into a discoid-annulate style-base which were divided into two clades in the recent phylogenetic scaffold for the Carex classification ( Roalson et al. 2021). The species in the Mitrata Clade have shorter lateral spikes and smaller plants, and the new species is temporarily placed in the Mitrata clade.

Figures

Figure 4. Carex radicalispicula sp. nov. A habit B lowermost spike C staminate glume D, E pistillate glume F utricle G nutlet. (Drawn by Xiao-Feng Jin; based on the holotype: K. L. Chue 6963 in PE).