﻿Notes on Carex (Cyperaceae) from China (IX): three new species of section Mitratae s.l.

﻿Abstract Carexsect.Mitratae s.l. was established by Kükenthal in 1909 and can be distinguished from the closely related sections in having nutlets frequently discoid-annulate at the apex and a persistent style base. Based on field surveys and specimen examination, three new species of sect. Mitratae are described and illustrated here. Carexfatsuaniana was collected from Yunnan and differs from C.truncatigluma in having the utricles nearly glabrous, the nutlets with a ca. 0.5 mm long beak at the apex, the staminate spikes cylindrical, 5–7.5 cm long, 4–5 mm wide, and the pistillate glumes acuminate at the apex. Carexdamingshanica was collected from Guangxi and differs from C.breviscapa and C.rhynchachaenium in having 3 or 4 spikes, the lateral spikes cylindrical, the pistillate glumes, utricles and nutlets all shorter than in the other two species. Carexradicalispicula was collected from Sichuan and differs from C.truncatirostris in having the staminate spikes clavate, 1.5–2 mm wide, the pistillate glumes pale yellow-white, 3–3.2 mm long, acuminate or short-awned at the apex, and the nutlets with 3 angles shallowly constricted at the middle.


Introduction
Carex L. (Cyperaceae), a morphological diverse genus with about 2,000 species, is one of the largest genera of angiosperms and is distributed on all continents except Antarctica (Reznicek 1990;Govaerts et al. 2021;Pender et al. 2021). The main characters of this genus that distinguish it from the other genera in the Cyperaceae are flowers unisexual, the female ones contained within a prophyllar structure called a perigynium, which is referred to as a utricle when its margins are fused and closed (Dai et al. 2010;Jiménez-Mejías et al. 2016). Following an increasing number of samples and molecular markers, the systematic framework of Carex has become more robust, six strongly supported distinct main lineages were detected, viz. the Siderostictae, Schoenoxiphium, Unispicate, Uncinia, Vignea and core Carex clades (Villaverde et al. 2020;Roalson et al. 2021). A large number of new species of the core Carex clade were described during, or soon after, the preparation of the "Flora of China" (Dai et al. 2010;. Carex sect. Mitratae Kük. s.l. (Kükenthal 1909), containing 80+ species, was traditionally divided into three sections: Cryptostachyae Franch., Lageniformes (Ohwi) Nelmes and Mitratae s.s. These are mainly distributed from E and SE Asia to Australia and New Zealand, with a few species reaching Europe, as well as into western and northern Asia (Akiyama 1955;Dai et al. 2010;Roalson et al. 2021). Recent phylogenetic studies revealed the sect. Mitratae s.l. is a polyphyletic group, and five clades which were named as Sect. Cryptostachyae, Tristachya Clade, Truncatigluma Clade, Mitrata Clade and Conica Clade in the core Carex clade are recognized (Roalson et al. 2021).
Etymology. The specific epithet 'fatsuaniana' is in honour of Prof. Fa-Tsuan Wang (Fa-Zuan Wang, 1899-1985, the taxonomic founder of Chinese monocots. Phenology. Flowering and fruiting occur in early April. Conservation status. Data Deficient (DD). Only four sheets (C. W. Wang 88293) of the new species were collected by Chi-Wu Wang in 1940 from the type locality. Adequate information is lacking on its distribution and population status to make a direct or indirect assessment of the risk of extinction (IUCN 2019).
Notes. Carex fatsuaniana has nutlets contracted distally into a ca. 0.5 mm long cylindrical beak at the apex, which morphologically belongs to sect. Lageniformes and is similar to C. truncatigluma (Dai et al. 2010). In sect. Lageniformes, the species has terminal staminate spikes thinly linear-clavate, whereas those of the new species are cylindrical, 5-7.5 cm long, 4-5 mm wide. The characters distinguishing the new species from C. truncatigluma are shown in Table 1.
Etymology. The specific epithet 'damingshanica' refers to the type locality of this new species.
Phenology. Flowering and fruiting occur from late March to late May.

Conservation status. Least Concern (LC).
The new species is known from four localities in Damingshan National Nature Reserve of Guangxi. These populations are in protected areas where they are not really threatened but need attention at ordinary times (IUCN 2019).
Notes. Carex damingshanica belongs to sect. Lageniformes in having terminal spikes staminate and nutlets apex contracted into a prominent long cylindrical beak (Dai et al. 2010). It is similar to C. breviscapa and C. rhynchachaenium, but differs from these two species in the characters of spikes, pistillate glumes, utricles and nutlets. The morphological differences of C. damingshanica, C. breviscapa and C. rhynchachaenium are shown in Table 2.
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.  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.