Haec species nova C. tastiensi (Franch.) Kük. affinis est, sed utriculis brevioribus, 3–3.2 mm longis, membranaceis, squamis pistillatis ovatis vel late ovatis, nucibus obovoideis, stigmatibus 2 vel 3 differt.

China. Tibet: Mêdog, Dayandong, 29°25'45.54"N, 95°02'58.37"E, in thickets on slope, alt. 2950 m, 7 Jun 2017, X.H. Xiong 999A (holotype: ZM; isotypes: ZJFC, ZM).

Rhizomes slender, long, woody, long-stoloniferous. Culms central, 14–30 cm tall, slender, obtusely trigonous, lower part smooth and upper part scabrous, base with red-brown fibrous sheaths. Leaves shorter than culms; blades flat, 1–2 mm wide, margin scabrous. Bracts shortly leaf-like or uppermost setaceous, shorter to longer than inflorescence, base with 0.5–2 cm long sheaths. Spikes 2–4, remote; terminal 1 or 2 spikes staminate, narrowly cylindrical, 1–3.5 cm long, 1–2.5 mm wide, base with 0.3–6 cm long peduncles; lateral spikes pistillate, single or rarely binate, cylindrical, 0.8–2.7 cm long, 2.5–4 mm wide, 8–18-flowered, peduncles erect, slender, 0.3–7.5 cm long, exserted from sheaths. Staminate glumes obovate-lanceolate, red-brown, 5–5.5 mm long, apex acute or emarginate, with yellow 3-veined costa excurrent into a mucro. Pistillate glumes ovate or broadly ovate, red-brown, 2.5–2.8 mm long, margin whitish hyaline, apex acute or emarginate, with yellow-brown 3-veined costa excurrent into a mucro. Utricles red-brown and yellow-green below, ellipsoid, obtusely trigonous, 3–3.2 mm long, membranous, obliquely patent, inconspicuously several thinly veined, base cuneate and shortly stipitate, apex gradually contracted into a ca. 1 mm long beak, orifice truncate or 2-lobed with minute teeth, margin barbate. Nutlets tightly enveloped, yellow, obovoid, trigonous, 1.8–2 mm long, apex with ca. 0.3 mm long curved beak; style base not thickened; stigmas 2 or 3.

The specific epithet ‘paratatsiensis’ refers to the similarity with Carextatsiensis.

Flowering and fruiting is in early June.

China. Tibet: Mêdog, Dayandong, 29°25'45.54"N, 95°02'58.37"E, in thickets on slope, alt. 2950 m, 7 Jun 2017, X.H. Xiong 999B, 999C (ZJFC, ZM).

Data Deficient (DD). There is inadequate information for distribution and population status and we could not make a direct assessment of its risk of extinction now (IUCN 2019).

This new species is similar to Carextatsiensis, which was placed in sect. Aulocystis, but differs in having utricles shorter (3–3.2 mm long), membranous, pistillate glumes ovate or broadly ovate and nutlets obovoid with 2 or 3 stigmas. Based on the phylogenetic hypotheses, the traditional taxonomic section Aulocystis was polyphyletic and clustered with some species of sect. Clandestinae, which made it a heterogeneous group (Roalson et al. 2021). In some descriptions of Carextatsiensis (Dai et al. 2000, 2010), the utricles were described as membranous, but our examination showed the utricles of C.tatsiensis are thin-coriaceous or coriaceous (Jin and Lu 2020).