Siliquamomum phamhoangii Luu & H.Đ.Tr

Trư ờng, Lưu H ồng, Đăng, Tr ần H ữu, Toàn, Tr ần Ng ọc, Hoan, Nguy ễn Văn & Bình, Ph ạm Ng ọc, 2017, Siliquamomum phamhoangii, a new species of Zingiberaceae from the Central Highlands, Vietnam, Phytotaxa 314 (1), pp. 135-139 : 135-137

Siliquamomum phamhoangii Luu & H.Đ.Tr ần, sp. nov. ( Fig. 1 )

Diagnosis: — Most similar to S. alcicorne in having mostly light yellow flowers with 3-lobed white calyx but differs in having 0.8–1 m long leafy shoots, 5–7 petiolate and ovate to narrowly elliptic leaves per shoot, ovate labellum, ca. 2 mm long anther crest and lateral staminodes connate to labellum in basal 1/3 (vs. up to 2 m long leafy shoots, 8–11 inconspicuous and elliptic to narrowly elliptic leaves, obovate labellum, 3–7 mm long anther crest and lateral staminodes connate to labellum in basal 2/3).

Type: — VIETNAM. Gia Lai Province: Kon Ka Kinh National Park, Ranger Station Two, 14°9’46.88”N, 108°20’13.54”E, 865 m elevation, 20 March 2015, Trần Ngọc Toàn, Nguyễn Văn Hoan & Phạm Ngọc Bình KKK/P-404 (holotype SGN!, isotypes SGN!, VNMN!).

Herb terrestrial, rhizomatous, forming loose clumps. Rhizome cream-yellow internally, greenish cream externally.

Leafy shoots 2–3 cm apart, 0.8–1 m long, leafless 35–40 cm from the base with 5–7 leaves per shoot; sheaths green with maroon patches, reticulate, margin papery, black; ligule bilobed, 3–4 mm long, dark maroon to black, papery. Petiole 2–4 cm long, 3–3.5 mm in diam., canaliculate, green, glabrous; lamina ovate to narrowly elliptic, 16–34 × 6–8 cm, green above, pale green below, glabrous on both sides, margin entire. Inflorescence terminal; peduncle enclosed in leaf sheaths, thyrse with 8–10 flowers; first bract boat-shaped, ca. 5 × 0.8 cm long, caducous, light green; fertile bracts minute, ca. 2.7 mm long to completely reduced, glabrous; cincinni 1–2 flowered; bracteoles absent; pedicels 4.5–7 mm long, ca. 1.2–1.5 mm in diam., green, glabrous. Flowers 5.5–6.5 cm long; calyx tubular, 20–25 mm long, 7–8 mm in diam., unilaterally slit 12 mm long, translucent cream-white, turning brown and papery towards age, 3-toothed at apex, teeth 7–9 mm long, glabrous; floral tube 13–14 mm long, pale greenish cream-white, glabrous; staminal tube 3 × 5.5 mm, cream-white, glabrous; dorsal corolla lobe ovate, slightly concave, apex rounded, ca. 2 × 1 cm, translucent yellowish white, glabrous on both sides; lateral corolla lobes ovate, apex rounded, ca. 2 × 0.8 cm, translucent yellowish white, glabrous on both sides; labellum ovate, 3-lobed, with undulate and serrulate margins, glabrous, ca. 24 × 16 mm (ca. 22 mm wide including staminodes), light yellow at periphery with dark green to yellowish green patch at apical free part and yellow patch in the center. Lateral staminodes connate to basal 1/3 of labellum, oblong-obovate, apex with serrate margin, 12–14 × 3–4 mm. Stamen 16–17 mm long, filament ca. 4.5 × 2.6 mm, cream-white, glabrous; anther 14 × 4.5 mm, attached to filament at an 180º angle, light yellow, paler to the base and the connective and green to the crest, covered with short glandular hairs at margin, glabrous at back, apex divided ca. 2.5 mm, each lobe ending in an anther crest; anther crest ca. 2 × 1.4 mm, bilobed, lobes 0.6–0.8 mm long, translucent green, covered with glandular hairs at base; anther thecae ca. 12 mm long, light cream, dehiscing longitudinally for their entire length, glabrous. Epigynous glands two, triangular, ca. 2 mm long, ca. 1 mm in diam. at base, cream. Style 27–28 mm long, cream, glabrous; stigma club-shaped, ca. 1.5 × 1.8 mm, ostiole ciliate, ca. 1 mm wide, facing front. Ovaries narrowly cylindrical, 12–18 mm long, ca. 2 mm in diam. at base, up to 4 mm at apex, green, glabrous, trilocular, placentation exile. Fruits 6–10 cm long, 5–8 mm in diam.; seeds 3–6 mm long, ca. 2 mm in diam.

Phenology:— Flowering seen in March and fruiting in April.

Distribution and ecology:— So far known only from the type locality in Kon Ka Kinh National Park, Gia Lai Province, Central Highlands, Vietnam. This species grows in moist soils under the broad-leaved evergreen montane forest.

Etymology:— Named after Phạm Hoàng Hộ (1929–2017), the late Professor of biology at the University of Science in Sài Gòn/Hồ Chí Minh City (1965–1984), for his enormous contribution to our understanding of the Vietnamese flora.

Other specimens examined (paratypes):— VIETNAM. Gia Lai Province: Kon Ka Kinh National Park, Mang Yang, 1424 m elevation, 14°13’43.76”N, 108°20’21.34”E, 23 April 2016, Lưu Hồng Trường, Đặng Minh Trí, Nguyễn Hiếu Cường, KKK-517 (SGN!).

Notes:— Siliquamomum phamhoangii is most similar to S. alcicorne in having mostly light yellow flowers with 3- lobed white calyx but the latter is distinct from the new species in having more robust habit (up to 2 m tall leafy shoots), 8–11 sessile elliptic to narrowly elliptic leaves per shoot, obovate labellum with round apex and hairs adaxially, up to 18 mm long anthers with much larger anther crest (3–7 × 3–6 mm) and longer lateral staminodes (up to 24 mm long) connate to labellum in basal 2/3.

Siliquamomum phamhoangii is also similar to S. tonkinense in having similar sizes of leafy shoots and leaf laminae and, especially, petiolate leaves but S. tonkinense is different in having about 3 leaves per shoot, entire calyx, yellowish white, orbicular labellum of ca. 12 mm in diam., 23–25 mm long floral tube, 8 mm long filament and 16 mm broad lateral staminodes that are almost free from the labellum. In addition, S. oreodoxa looks like the new species as both species have similar leafy shoot sizes and petiolate leaves but S. oreodoxa is readily distinguishable by its 9–13 leaves per shoot, smaller and elliptic to narrowly ovate leaf laminae, mostly white flowers, 19–21 mm long floral tube, unlobed obovate labellum, 19–21 mm long lateral staminodes and 6–8 mm long filament.

The morphological differences between S. phamhoangii and the other Siliquamomum species are summarized in Table 1.

seed. F. Flower. G. Flower dissection (from top, left): dorsal corolla lobe, lateral corolla lobes, labellum, stamen, ovary and epigynous glands, calyx. H. Anthers (front, back and side views). I. Stigma. Photos: Nguyễn Lê Xuân Bách (A, C, D, F, G, H), Trần Ngọc Toàn (B,

E).

Figures

FIGURE 1. Siliquamomum phamhoangii. A. Habit. B. Leaf laminae. C. Inflorescence. D. Ligules (side and front views). E. Fruit and