Steudnera hoanglienica V.D.Nguyen, B.H.Quang & Bogner, 2018

Du, Nguyen Van, Quang, Bui Hong, Tien, Tran Van & Bogner, Josef, 2018, Steudnera hoanglienica (Colocasieae-Araceae), a new species from northern Vietnam, Phytotaxa 376 (5), pp. 223-226 : 223-226

Steudnera hoanglienica V.D.Nguyen, B.H.Quang & Bogner , sp. nov. ( Fig. 1 )

Steudnera hoanglienica is most similar to S. kerrii by sharing with it a purplish-brown to dark purple, triangular to lanceolate spathe, with sterile portion between male and female zone. It differs from S. kerrii by having a much longer cylindrical female zone, ca. 4.2 cm (vs. fusiform, ca. 2.5 cm long), with staminodes between ovaries at lower portion (vs. without staminodes); the staminate zone cylindrical, round at apex, purple (vs. ovate-oblong, obtuse at apex, pale cream or white); synandrium cubic shaped (vs. obconic); stigmas with 2 or 3 acute conical lobes (vs. 4 obtuse conical lobes).

Type: — VIETNAM. Lai Châu, Tam Duong distr., Sõn Bình commune, Chu Va , far from Chu Va fish station about 500 m, 22 o 35’15.34 N 103 o 70’99.72 E, 1,700 m alt. 21 April, 2017 ; Nguyen Van Du HN-UBC 401 (holotype HN!, isotype UBC!) .

Rhizomatous herbs, ca. 50 cm tall. Rhizome 10–20 cm long, ca. 2 cm diam., outside bright brown, covered by fibrous decayed cataphylls and leaf sheaths; roots all over few. Leaves 2, together on 1 shoot, peltate; petioles terete and tapering, 33–45 cm long, 7–8 mm diam. at base, 2.0– 2.2 mm diam. at apex, medium green to dark greyish-green, covered by dried and decayed cataphylls up to 10 cm from base, sheathing part at base, 2–5 cm long, ca. 9.5 mm wide, margin often dried; leaf bade ovate-elliptic, 23–27 cm long, 16–18 cm wide, acute and with a short acuminate tip, base slightly concave, green to dark green above in young leaves, dull green to yellow in mature leaves, young leaves grey or light brown beneath; lateral veins 4–6 each side of anterior lobe, 3 veins each side of posterior lobe, internal veins upward from lateral veins and midrib, abundant and prominent, small veins anastomosing. Inflorescence 1 or 2, arising from the leaf axils, not together at the same time; peduncles terete, ca. 14 cm long, ca. 3 mm diam., covered by 2 cataphylls; spathe ca. 10 cm long; spathe tube conical, ca. 5.5 cm long, ca. 2 cm wide at mouth, oblique, purplish-green outside, dark-purple inside, nearly completely open during anthesis, existent with fruits; spathe limb lanceolate to triangular, folded and narrowed at base during anthesis, ca. 6 cm long, ca. 4 cm wide at base, regularly acuminate at apex, dull light purple to purplish-brown outside and very dark purple inside surface. Spadix ca. 6 cm long; female zone cylindrical ca. 4.2 cm long, lower portion (2.5 cm long) adnate to spathe tube, covered by 2–3 rows of exposed pistils, with staminodes between, upper portion (ca. 12 mm long) free from spathe tube, cylindrical; male zone cylindrical, base (ca. 3 mm long) gradually narrowed, ca. 15 mm long, ca. 4 mm diam., rounded at apex, violet-brown when young, dark purple when mature, sometime stipitate, stipe ca. 2 mm long, covered by several short and sessile staminodes. Pistils bottle shaped and laterally compressed at lower half of female zone or subglobose to globose distally, dull white, ca. 0.8 × 1.0 mm; style conspicuous, short, ca. 0.1 mm long; stigma 2 or 3-lobed, lobes conical, acute, pointing up, triangular or nearly lozenge shape when viewed face on, reddish-brown when young and blackish when mature; staminodes obovate to subglobose, base narrowing to slender stipe, subequal to or much shorter than the pistils, milk white. Ovules many, parietal and orthotropous, with a short funicle. Male flowers with 3–4 connate stamens, forming a more or less cubic synandrium, surface rounded, obtuse or angled with many shallow lobes at margins, ca. 2 × 2 mm; anthers oblong to slightly conical, apex truncated, thickened and expanded, 2 lobes, dehiscence by oval pore at margin between 2 lobes at apex.

Notes: —In the genus Steudnera , S. assamica from Assam ( India) also has purple spathe, however it is distinguished from S. kerrii and S. hoanglienica from Indochina by having male zone cylindrical, equal in width and adnated to female zone, in contrast to S. kerrii with male zone ovate oblong and S. hoanglienica with male zone having base gradually narrowed, and by having a sterile zone (ca. 2 mm) between male and female zones unlike the latter two species.

Eponymy: —The specific epithet is derived from the name of Hoang Lien mountain belonging to Hoang Lien National Park the type locality of the species.

Phenology: —Flowering in March; fruiting in April.

Distribution: —Only known from Vietnam, Lai Chau province, Tam Duong district.

Habitat: —The plant grows on the shaded forest floor or under shady locations behind large rocks in evergreen disturbed dry forest on high mountains, close to streams, at an elevation of 1,700 m.

Conservation status: — S. hoanglienica is considered here as Data Deficient (DD) according to IUCN Red List Categories and Criteria ( IUCN 2018). The species is known only from a single collection, but the area where it was collected is still so poorly known that the true abundance of the species remains unknown.

Figures

FIGURE 1. Steudnera hoanglienica V.D. Nguyen, B.H. Quang & Bogner. A.—Habitat and habit in flowering; B.—Rhizome; C.— Beneath leaf blade surface; D.—Inflorescence; E.—Spadix in young; F.—Spadix in mature; G.—Male flower zone in young; H.—pistils; I.—surface of male flowers; J.—Male flower lateral view.—(All from the type specimens—Photographed by V.D. Nguyen).