Stipa dickorei M.Nobis, 2016

Nobis, Marcin, Nobis, Agnieszka, Klichowska, Ewelina, Nowak, Arkadiusz, Nowak, Sylwia & Gudkova, Polina D., 2016, Stipa dickorei sp. nov. (Poaceae), three new records and a checklist of feather grasses of China, Phytotaxa 267 (1), pp. 29-39 : 30-33

Stipa dickorei M.Nobis , sp. nov. ( Figs. 1–2)

Type:— CHINA. Xizang: E Tibet, upper Salween basin, Riwoqe—Dengqen, Da Qu, 31°10'N / 96°10'E, elev. ca. 4120 m, lower alp. Kobresia turf, limestone rocks, 8 July 1994, B. Dickoré 9083 (holotype MSB-152840!, isotypes KAS!—2 sheets, KRA!).

Perennial plant, densely tufted, with a few culms and numerous vegetative shoots; culms (12–) 19–40 cm tall, with 1(–2) node in the lower part of the culm. Leaves of vegetative shoots: sheaths glabrous or/and shortly pilose but only in the upper part near the margin and ligule; ligules membranous (0.3–) 0.5–1.6 mm long, obtuse, the apex shortly ciliate and setulose on the back; blades flat or convolute, green to pale green, 12–18 cm long, 0.5–1.0 mm in diameter or up to 2.2 mm wide when they are flat, adaxial surface densely covered with prickles up to 0.09 mm long, abaxial surface glabrous, at the apex glabrous or somewhat scabrous due to short prickles and spinules. Cauline leaves: sheaths glabrous, upper sheath of culms not inflated; ligules (1.5–)2.0–3.5(–4.5) mm long, acute or obtuse, with very short cilia at the apex, and shortly setulose on the back; blades convolute, green or pale green, up to 10 cm long, adaxial surface shortly pilose, abaxial surface glabrous, slightly scabrous at the apex due to short prickles and spinules. Panicle contracted, (5–) 10–16 cm long and 1–2 cm wide, with (8–)12–17 spikelets, exerted, branches erect, glabrous or somewhat setulose below spikelets. Glumes subequal, pale green to somewhat purple, lower glume 10.5–13.0 mm long, upper glume 10.0– 12.5 mm long, lanceolate, tapering into a delicate hyaline apex, glabrous on dorsal line. Anthecium 8.0– 9.2 mm long, 0.7–0.9 mm wide. Callus 1.0– 1.3 mm long, sharply pointed, densely long-pilose, hairs 0.5–0.9 mm long; base of callus dorsally flattened and long protruding, peripheral ring 0.25–0.30 mm in diameter, scar broadly elliptic. Lemma pale green, on dorsal surface covered by numerous hooks and scattered ascending hairs 0.4–0.7 mm long, top of lemma with coronula of hairs 0.4–1.0 mm long. Awn 20–26(–32) mm long, bigeniculate; column 5–7 mm long, twisted, 0.2(–0.3) mm wide, green or straw-coloured, pilose, hairs (0.2–)0.5–1.0(–1.3) mm long, gradually decreasing in length towards the geniculation; the middle segment of the awn 3–5 mm long, pilose, hairs (0.1–) 0.2–0.3 mm long; seta straight, green or purple, 11–15 mm long, hairs on seta 0.1–0.2 mm long. Palea equal to lemma in length, with scattered hairs on dorsal surface. Anthers yellow or purple, glabrous, 3–4 mm long.

Distribution and ecology:― Stipa dickorei is known from the eastern part of the Qinghai-Tibetan Plateau in southwestern China. It is probable that the species occupies neighbouring areas, where similar habitat occurs. The species grows in high mountain alpine swards, between elevation range of 3700 to 4300 m.

Etymology:―The species epithet honors the collector Dr. Wolf Bernhard Dickoré, the eminent German botanist, researcher of the flora and vegetation of Central Asian mountains.

Additional specimens studied (paratype): ― CHINA. Qinghai: Nangqên Xian, Bêca Xiang, just W of Bêca Forest Station, on road to the Bas Qu, SE of Bêcaka, 31°53'N / 96°32'E, 3750 m, on large rocks, slope below limestone cliffs with remnant Juniperus woodland, rock outcrops frequent, 9 September 1996, T.N. Ho, B. Bartholomew, M. Watson, M. Gilbert 3024 (PE-202793!).

Similar species:―Because of its contracted panicle, Stipa dickorei is morphologically very similar to S. regeliana Hackel (1884: 130) . However, the two species differ from each other in the character of ligules of vegetative shoots, which in S. dickorei are always shorter (0.3–1.6 vs. 4–6 mm) as well as by glabrous vs. slightly scabrous leaves, respectively.

Stipa dickorei is also similar to S. aliena Keng (1941a: 74) . These two species differ in the shape of their panicle which, in S. dickorei is contracted with straight, glabrous or somewhat setulose branches, whereas in S. aliena the panicle is lax with flexuous branches that are more or less densely setulose (hairs 0.3–0.6 mm long, sometimes present only below the glume). Additionally, S. dickorei has somewhat longer ligules of the vegetative leaves [(0.3–)0.5–1.6 vs. 0.1–0.5(–0.9) mm, respectively].

Stipa aliena is a polymorphic and variable taxon, particularly in the length of its culms, glumes, anthecia, calluses, awns, as well as in the number of spikelets per panicle ( Nobis et al. 2015a). Within the taxon, the variety S. aliena var. macrocarpa ( Martinovský 1970: 163) Nobis (in Nobis et al. 2015a: 238) has been distinguished, which differs from S. aliena var. aliena by having longer anthecia (9–12 vs. 6.5–8.5 mm) and slightly longer awns (23–30 vs. 15–26 mm). At the end of the last century, S. rohmooiana Noltie (1999: 287) was described from Sikkim. This taxon is morphologically very close to S. aliena , what was stressed also by Noltie (1999). Based on the description, S. rohmooiana differs from S. aliena generally by lower culms (3.5–12 cm) and smaller number of spikelets (5–7 non ca. 20) per panicle ( Noltie 1999). However, during our revision of Chinese specimens of S. aliena , specimens with culms 5–60(–84) cm tall and panicles with (2–)5–14(–20) spikelets were frequently observed. Probably, growth of plants from Sikkim could be limited by harsh conditions at the mountainous locality (elevation ca. 5000 m.), where these specimens were collected by Rohmoo in September 1912. Similar modifications in the habit of plants is observed for other high-mountains feather grasses, like S. glareosa Smirnov (1929a: 12) , S. tianschanica Roshevitz (1916: 149) , S. lipskyi Roshevitz (1916: 153) , S. zeravshanica Nobis (in Nobis et al. 2013: 667) or Ptilagrostis concinna ( Hooker 1896: 230) Roshevitz (1934: 75) , which at higher elevations, have smaller culms and sometimes reduced number of spikelets. Thus, we treat S. rohmooiana as conspecific with S. aliena .

Taxonomic synopsis of Stipa sect. Regelia :―Having awn setas with hairs up to 0.3 mm long as well as plumose columns with hairs up to 1.5 mm long, the new species described here is a typical member of the section Regelia , which currently comprises three species, namely:

1. Stipa regeliana Hack.

Type:—[ KYRGYZSTAN]. Issyk-kul, Musart, 2300–2650 m, August 1877, Regel (holotype W!).

≡ Achnatherum regelianum (Hack.) Tzvelev (2012: 22) .

= Stipa purpurascens Hitchcock (1930a: 95) . Type:— CHINA. Gansu: south of Sining, in the La Che Tze Mountains, elev. 3350 to 3900, R.C. Ching 686 (US-1245701).

2. Stipa aliena Keng

2.1 Stipa aliena var. aliena

Type:— CHINA. Gansu: Labrang, grassy swampy places, elev. 3000 m, 17 October 1934, C.W. Yao 502 [Herbarium Biological Laboratory, the Science Society of China, N 57946] (isotype PE-639926!)

= Stipa smithii Martinovský (1970: 162) nom. hom. illeg., non S. smithii Hitchcock (1930b: 382) . Type:— CHINA. Sichuan [Sina, prov. Sze-ch’uan]: reg. bor.-occid., Sankar-von-mâ, c. 45 km bor.-orient. versus in prato, c. 4100 m, 2 September 1922, leg. Harry Smith, Plantae sinenses 4287 (holotype UPS!, isotypes UPS!, PE!, LD)

= Stipa rohmooiana Noltie , syn. nov. Type:— Sikkim: Chugya, elev. c. 4900 m, 12 September 1912, Rohmoo 277 (holotype E!, isotype K!).

2.2 Stipa aliena var. macrocarpa (Martinovský) M.Nobis

Basionym:— Stipa smithii Martinovský var. macrocarpa Martinovský (1970: 163) . Type:— CHINA. Sichuan: reg. bor.-occid., Tsipula, in prato alpino graminoso, alt. c. 4000 m, 2 August 1922, leg. Harry Smith, Plantae sinenses 4148 (holotype UPS!, isotypes PE-2029699!, LD, MOIS!).

3. Stipa dickorei M.Nobis

Micromorphological variation:―The general pattern of the lemma micromorphology in Stipa dickorei is typical for the genus Stipa (cf. Barkworth & Everett 1987, Nobis 2013, 2014, Nobis & Nobis 2013, Nobis et al. 2013, 2014, 2015a, 2016a) ( Fig. 2E ). Fundamental long cells are elongated, rectangular to more or less square in shape. The side walls of the long cells are raised and undulate. Silica bodies are frequent, reniform to oblong or ovate, whereas cork cells are sparse or absent. Hooks are frequent, oriented towards the lemma apex, whereas prickles are sparse and present mostly near the apex of the lemma ( Fig. 2D–E ). Macrohairs are frequent on the whole surface of the lemma. They are straight, (0.1–) 0.4–0.7 mm long or geniculately bent near the base, cylindrical and/or string-like twisted, with bulbous base and needle-like apex. The adaxial surface of leaves of the vegetative shoots ( Fig. 2G ) is ribbed and covered by frequent prickles and papillae as well as less frequent stomata and rectangular to slightly 8-like constricted silica bodies. Abaxial surface of leaves is glabrous ( Fig. 2H ), with frequent elongated long cells and rounded to rectangular silica bodies.

Figures

FIGURE 2. Selected morphological characters of Stipa dickorei. A. General habit. B. Spikelets. C. Anthecia with awns. D. Lemma apex with basal part of the awn. E. Micromorphological structure of the lemma epidermis (lateral view). F. Callus. G.Adaxial surface of leaves. H. Abaxial surface of leaves. Scale bars: A: 1 cm, B–C: 5 mm.