Helonias yunnanensis var. mesostyla N.Tanaka, 2019

Tanaka, Noriyuki, 2019, Taxonomy, evolution and phylogeography of the genus Helonias (Melanthiaceae) revisited, Phytotaxa 390 (1), pp. 448-450 : 448-450

2b. Helonias yunnanensis var. mesostyla N.Tanaka , var. nov. ( Figs. 8 , 9 ).

Differs from var. yunnanensis by the longer style with slightly shorter stigmatic segments, and stamens equaling or slightly exceeding (vs usually shorter than) tepals.

Type:― MYANMAR (BURMA). Myitkyina. Nr. Panwa Pass, alt. 7500 ft, 2 April 1938, Herb 4–5 inches high. Flowers pale blue-purple. Anthers purplish. Older flowers maroon. C.W.D. Kermode 17139 (Holotype, K-001235138!) .

– Ypsilandra alpina auct. non Wang & Tang (1936: 81): Chen (1980: 18) p.p., Chen & Tamura (2000: 87) p.p.

Rhizome (sub)cylindrical, closely annulate with many scars, to 3 cm long, 1.4 cm in diam. Root s filiform, to ca. 2 mm in diam., contractile. Leaves slightly hysteranthous, main fresh rosette leaves 4–7, oblanceolate, to 13. 5 cm long, to 2.2 cm wide, tapering to base, apex apiculate. Flowering stem (4–) 8–12.5 cm long incl. terminal raceme at anthesis, elongating to ca. 41 cm in fruit; peduncle to 11 cm long at anthesis, 33 cm long in fruit; scale-like leaves on peduncle several, becoming smaller and laxer upward, oblong-ovate or lanceolate, acute or acuminate, subherbaceous; inflorescence racemose, ovoid-ellipsoid, 2–2.5(–3) cm long, 1.2–1.5 cm in diam., becoming laxer with progression of anthesis due to elongation of rachis; rachis of inflorescence 0.5–1.5(–2.5) cm long at anthesis, to 8 cm long in fruit; pedicels 0.5–2 mm long at anthesis, 1–3.5 mm long in fruit, ebracteate or lowermost sometimes bracteate. Flowers few to many, crateriform-funnelform, 5.5–9 mm across, spreading horizontally or slightly ascending, deliciously fragrant, adichogamous. Tepals narrowly elliptic or narrowly elliptic-oblanceolate, 3.5–5.3(–7.5) mm long, (1.5–)1.8–2(–3) mm wide, subacute to obtuse, 3-veined, pale blue-purple, pale slaty violet, or white. Stamens equaling or slightly exceeding tepals, usually slightly longer than pistil; filaments (3–) 4.5–5.5 mm long; anthers reniform, unilocular, (0.4–) 0.7–0.8 mm long, purplish. Pistil 1, almost equaling or slightly shorter than tepals, (2.5–) 4–4.2 mm long; ovary globose, trilobed, apex concave, 1.5–2.3 mm long, 1.5–2(–3.3) mm across; style terete, (1–) 2–2.5 mm long; stigma trisected, segments oblong, (0.6–) 0.8–1 mm long, recurved. Capsules erect, broadly obpyramidal, tripartite, ca. 3 mm long, 6.5–7.8 mm across, apex depressed in center; lobes ovoid-conic, strongly divergent, apex obtuse. Seeds many, straw colored, narrowly fusiform, tailed at both ends, 4.2–4.8 mm long, 0.5–0.7 mm wide; body of seed narrowly oblong, 1.5–2.3 mm long, 0.5–0.6 mm wide, brownish.

Additional specimens examined (paratypes):― CHINA. Yunnan. Gongshan. Cikai. Yipsaka Lake, 3500 m, 12 August 2006, fr., Gaoligongshan Biodiversity Survey 32015 (GH-00292433); Salwin-Kiukiang Divide , Newahlung , 2950 m, 9 July 1936, fr., T.T. Yü 19283 (A, PE-00035447*, PE-00593847*, PE-00593848*); Salwin-Kiuking Divide , Tsukuei , 3850 m, 13 July 1938, fl., T.T. Yü 19337 (PE-00593985) . MYANMAR. Adung Valley, 28°20’N, 97°40’E ( Sources of the Irrawaddy), 8500–9000 ft, 27 May 1931, Kingdon-Ward 9557 (BM-001118041); ibid., 8500 ft, 23 May 1931, Kingdon-Ward 9522 (BM-001118042); Myanmar , opposite to Dazu in Gongshan County of China, 3100–3200 m, 30 July 2013, X.H. Jin et al. ST1434 (PE-02002621*). Distribution:― N Myanmar (border with China), SW China (NW Yunnan) (Fig. 15- Ym). Habitat:― Alpine wet meadows and margin of thickets at elevations 2286–3850 m. Conservation status:― This form is very local and the population size is supposedly small. Preliminarily assessed as DD according to the criteria set out in IUCN (2001). Flowering:― March – May (– July). Ripening:― Usually July – August. Etymology:― The varietal epithet refers to the medium-long style .

Remarks:―Plants collected by T.T. Yü (no. 19337, PE-00593985!) on a high peak in NW Yunnan (3850 m) appear to be dwarf alpine forms of Helonias yunnanensis var. mesostyla with short leaves (to ca. 4 cm long, 1 cm wide), short flowering stems (2.5–4 cm long, including flower-bearing portion), few flowers (4 to 6 per scape), short tepals (3.5–4 mm long) and short styles 1–1.5 mm long, obviously reflecting the harsh alpine habitat. These plants may represent the smallest extreme in size within H. yunnanensis var. mesostyla . This variety appears to be closely allied to both H. yunnanensis var. yunnanensis ( Fig. 7 ) and H. alpina ( Fig. 10 ). It differs from H. yunnanensis var. yunnanensis by the longer style and usually slightly shorter stigmatic segments ( Fig. 9A–C , Table 6). The anthers of H. yunnanensis var. mesostyla are usually slightly exserted beyond the tepals ( Figs. 8 , 9A ), while those of H. yunnanensis var. yunnanensis are usually shorter than the tepals ( Fig. 7B, D, E ). Helonias yunnanensis var. mesostyla differs from H. alpina by its shorter, narrowly elliptic or eliptic oblanceolate (vs oblong or oblong-oblanceolate) tepals, and shorter styles and filaments. It is viewed as an intermediate form between H. yunnanensis var. yunnanensis and H. alpina . The geographic range of var. mesostyla (Fig. 15-Ym) partly overlaps with that of H. yunnanensis var. yunnanensis (Fig. 15-Yy) and is close to that of H. alpina (Fig. 15-A). H. yunnanensis var. mesostyla is also close to Helonias jinpingensis , but distinguishable by the slightly shorter, ebracteate pedicels, usually slightly longer style ( Table 6) and vernal flowering.

Figures

FIGURE 7. Helonias yunnanensis var. yunnanensis. A. Habit and habitat (Y-1; photo on 24 May 2014). B. Closeup of inflorescence (Y-1 on 24 May 2014). C–E. Isolectotype (G. Forrest 12055, E-00115522). C. Habit. D, E. Closeup of inflorescence. F. Part of infructescence with dehisced capsules (G. Forrest 14961, E-00115516). G. Seeds (Gaoligongshan Biodiversity Survey 27019, GH-00293355). Photos A & B by Yang Niu.

FIGURE 8. Helonias yunnanensis var. mesostyla from N Myanmar (Kermode 17139, holotype, K-001235138). A. Habit. B, C. Closeup of inflorescence.

FIGURE 9. Helonias yunnanensis var. mesostyla. A. Flower with frontal tepal and stamen removed.B. Pistil.C. Fruit with persistent floral parts. One frontal tepal removed. D. Two seeds. A, B from N Myanmar (Kermode 17139, holotype, K-001235138). C, D from Yunnan, China (Gaoligongshan Biodiversity Survey 32015, GH-00292433). Scale on right corner for B and D. Drawn by Noriyuki Tanaka.

FIGURE 10. Helonias alpina from SE Tibet (F. Kingdon-Ward 7084). A, B. Habit. C–E. Closeup of inflorescence. A–D: Holotype (K- 000400242*). E: Isotype (E-00115520). Stigmas arrowed in E.