﻿Carexlinanensis (sect. ﻿Mitratae), a new species of Cyperaceae from Zhejiang, East China

﻿Abstract Carexlinanensis X.D.Qiu & X.F.Jin, a new species in sect. Mitratae of the sedge family (Cyperaceae) from north-western Zhejiang is described and illustrated. We performed a statistical comparison of the new species with other closely-related species from the same section. Carexlinanensis is similar to Carexsachalinensis F.Schmidt, but differs in having leaf blades 1–2 mm wide (vs. 2.5–3.5 mm wide), utricles longer than pistillate glumes, with beak margin smooth (vs. barbate) and peduncles of lateral spikes enclosed in bract sheaths (vs. exserted from bract sheaths).


Introduction
Cyperaceae, the sedge family with more than 5600 species, is the third largest monocot family and has considerable economic and ecological importance (Larridon et al. 2021).Carex L., the largest genus of 95 genera in the Cyperaceae, is distributed across all continents, except Antarctica (Larridon et al. 2021).This morphologically diverse genus contains > 2000 species and species thrive in various habitats, such as forests, meadows or thickets, wetlands or swamps, mountain slopes or sandy areas (Dai et al. 2010;Jin and Zhang 2020).Kükenthal (1909) proposed an infrageneric classification of global Carex taxa, based on morphological characters, which has been challenged in recent phylogenetic studies (Jiménez-Mejías et al. 2016;Martín-Bravo et al. 2019;Roalson et al. 2021).Section Mitratae s.l. was established by Kükenthal's worldwide monograph.This group was established to group species having nutlets frequently discoid-annulate at the apex and a persistent style base (Kükenthal 1909;Lu and Jin 2023).Recent phylogenetic studies have revealed that the sect.Mitratae s.l. is a polyphyletic group organised in five different clades within subg.Carex: Sect.Cryptostachyae and clades Tristachya, Truncatigluma, Mitrata and Conica (Roalson et al. 2021) Recent ongoing field collections and specimen examinations of Carex in Zhejiang Province, China have resulted in the discovery and description of new species and subspecies (Lu and Jin 2018a), as well as some new distribution records (Lu and Jin 2018b;Lu et al. 2019;Zhang et al. 2020).These findings have contributed to revisions in the genus Carex for the new edition of Flora of Zhejiang (Jin et al. 2020;Jin et Lu 2021).Herein, we describe another new Carex species from north-western Zhejiang, which has nutlets discoid-annulate and thus belonging to sect.Mitratae s. l.

Delimitation of study group
Specimens of the new species were collected from Mount Daming of north-western Zhejiang, China.A review of the related literature (Koyama 1962;Egorova 1999;Tang 2000;Hoshino et al. 2011) and a careful comparison of type specimens revealed that the new species is similar to those of the Carex pisiformis complex.

Observation and analysis of macromorphological characters
Type specimens of the Carex pisiformis complex were critically examined including specimens at GH, K, KYO, LE, P, TI, WUK and ZJFC.Holotypes, syntypes or lectotypes of 15 species were measured and analysed.
A morphological exploration was conducted on eight diagnostic characters using PCoA (principal coordinate analysis) which was performed in RStudio software using 'vegan' and 'ape' packages.
Of these eight characters, five were binary (colour of basal sheaths: pale brown to brown vs. purple-brown; stolons: present vs. absent; indumentum on leaves and bracts: glabrous vs. pilose; lowermost bract: leaf-like vs. shortly leaf-like; and utricle beak: conspicuous vs. inconspicuous), one (leaf width) was continuous and two (colour of staminate spikes and indumentum on utricle bodies) were codified as ordered multistate using three or four categories (Table 1).According to the PCoA (see Results), the most morphologically similar species was the Japanese-Sakhalin endemic Carex sachalinensis.Accordingly, we performed subsequent statistical analyses focusing on comparing these two species.Twenty-four specimens from three known populations of the new species (holotype, isotypes and paratypes) and 12 specimens from Japan and Sakhalin of C. sachalinensis (see the note under Table 2) were measured.Based on our preliminary observations, we selected five characters: leaf width, length of staminate spikes, length of pistillate spikes, lowermost spike peduncle and utricles length.

Observation on nutlet sculpture micromorphology
Scanning electron microscopy (SEM) observations of nutlet surface of the new species and the similar species Carex sachalinensis were carried out.Mature nutlets were gathered from the specimens 'Y.F. Lu & X.F. Jin 23042601' for the new species and 'O.Yano s. n.' for C. sachalinensis, respectively.The nutlets were initially soaked in a solution of concentrated sulphuric acid and acetic anhydride (volume ratio = 1:9) for 12 hours, then rinsed in acetic acid for 10 min and water for 5 min and placed in a bath-type ultrasonic cleaner for 7 min with 70% ethanol to remove the cuticle and outer periclinal wall of the epidermis (Jin et al. 2014).After air drying, the nutlets were mounted on stubs using double-sided adhesive tape and coated with a layer of gold.The coated utricles and nutlets were observed and photographed under a GEMINI-300 scanning electron microscope.

Morphological study
Based upon the PCoA of diagnostic morphological characters, the new species is most closely related to C. sachalinensis (Fig. 1), although it seems smaller than this in all its parts.The morphological variation of five characters, viz.leaf width, length of staminate spikes, length of pistillate spikes, lowermost spike peduncle and utricles length are shown in Table 2. T-test revealed significant differences in length of staminate spikes, length of lowermost spike peduncles and leaf width between the new species and C. sachalinensis.Amongst them, length of lowermost spike peduncles and leaf width were discontinuous between the new species and C. sachalinensis (Fig. 2A, B), while overlapping in length of staminate spikes was detected.
Etymology.The specific epithet 'linanensis' refers to the type locality of this new species which was collected from Mount Daming of Lin'an District in Hangzhou.

Figure 1 .
Figure 1.PCoA (principal coordinate analysis) of the Carex pisiformis group, based on analysis of eight diagnostic characters of the type specimens.

Figure 2 .
Figure 2. Differences between Carex linanensis and C. sachalinensis A variation of leaf width B variation of lowermost spike peduncle C surface sculpture of C. linanensis D surface sculpture of C. sachalinensis.Scale bars: 20 μm.

Figure 3 .
Figure 3. Carex linanensis sp.nov.A, B habitat C lower part of habit, showing stolons D pistillate spike and bract E staminate spike and two pistillate spikes F, G utricle H, I nutlet.Scale bars: 1 mm.

Table 1 .
Comparison of diagnostic characters of the Carex pisiformis group.Note: the leaf width was measured and shown as Mean ± SD and the mean values were used for PCoA.The other values under the morphological characters were also used for PCoA, which have the same meaning in square brackets.

Table 2 .
The variation of five morphological characters between C. sachalinensis and the new species.