Sterculia konchurangensis C.N.Kieu, D.B.Tran & B.H.Quang, 2023

Kieu, Cam Nhung, Tran, Duc Binh, Le, Ngoc Han, Duong, Thi Hoan, Bui, Thu Ha, Nguyen, Thu Thuy, Bui, Hong Quang & Tran, The Bach, 2023, A new species of Sterculia (Malvaceae) from Vietnam, PhytoKeys 227, pp. 1-8 : 1

Sterculia konchurangensis C.N.Kieu, D.B.Tran & B.H.Quang sp. nov.

Figs 1 , 2 , 3

Type.

Vietnam. Tay Nguyen: Gia Lai province, Kon Chu Rang reserve , 1016 m a.s.l., 19 June 2022 (lf, f. fl.), Bui Hong Quang et al. BHQ 576 (holotype HN!, isotypes: HN!, VNM!) .

Diagnosis.

Sterculia konchurangensis is most similar to S. lanceolata Cav. due to the number of veins on each side of midrib, length of inflorescence, deeply divided calyx, globose, hairy ovary and curved style. They are separated by morphology of leaf blades (obovate or elliptic in S. konchurangensis vs. elliptic, lanceolate or elliptic-lanceolate in S. lanceolata ); petioles are shorter (7.0-9.5 mm vs. 25-35 mm in S. lanceolata ), leaf blades are shorter (6-8 cm vs. 9-20 cm in S. lanceolata ) and calyx lobes are longer (11-12.5 mm vs. 4-6 mm in S. lanceolata ).

Description.

Shrubs, ca. 3 m tall. Branches gray brown. Leaves alternate, apically clustered; petiole 7.0-9.5 mm long, glabrous, base and apex of petiole swollen; leaf blade simple, entire, glabrous, obovate, elliptic, base attenuate, apex shortly acuminate or obtuse, 6-8 × 3-4 cm, both surfaces glabrous; lateral veins 6-8 on each side of midrib. Stipules linear, ca. 1-2 mm long. Inflorescence slender, racemose, axillary, 8 cm long, few-12 flowered. Pedicel slender, 9.5-12.0 mm long, densely villous. Flowers 5-merous, functionally unisexual. Flowers: Flower bud lanceolate, 6.3 × 2.3 mm. Calyx divided almost to base, 5-lobed, pink, adaxial surface nearly glabrous to sparsely pubescent, abaxial surface pubescent; tube 1.3-1.7 mm long; lobes linear-lanceolate, 11-12.5 × 2.5-2.8 mm. Petals absent. Androgynophore slender, curved, ca. 2 mm long, glabrous. Staminodes at top of androgynophore in whorl around base of carpels; anthers of staminodes ovate, 0.22 × 0.18 mm. Carpels 5; ovary globose, densely pubescent, 1.3-1.8 mm in diameter; style curved, 2-3 mm long, sparsely pubescent; stigma glabrous, 0.3-0.6 mm in diameter. Fruits and seeds not observed.

Etymology.

The specific epithet refers to the type locality, Kon Chu Rang reserve in Vietnam.

Distribution and ecology.

Sterculia konchurangensis is only found in Vietnam, Gia Lai province, Tay Nguyen area, Kon Chu Rang reserve where it grows in primary evergreen forest at an altitude of 1016 m a.s.l. Flowering time is June; fruiting time is unknown.

Conservation status.

Data Deficient (DD; IUCN 2019). Sterculia konchurangensis is known only from the type locality within Kon Chu Rang reserve. A comprehensive botanical survey of the Sterculia has not been carried out to date.

Discussion.

Sterculia konchurangensis is morphologically similar to S. lanceolata Cav. due to the number of veins on each side of midrib, length of the inflorescence, deeply divided calyx, globose, hairy ovary, and curved style; furthermore, to be noted that both species have the same flowering time (June). However, S. konchurangensis differs from S. lanceolata by the morphology of length of petiole, shape of leaf blade, size of leaf blade and length of calyx lobe.

The identified key of 23 species of Sterculia in Vietnam was constructed. Sterculia konchurangensis differs from 22 species of Sterculia by having some characters such as simple, entire, glabrous leaves and length of petiole (less than 12 mm long). In addition, the comparison with the similar species ( S. lanceolata ) confirms that S. konchurangensis is a new species. Diagnostic characters separating the two species are listed in Table 1 .

Figures

Figure 1. Sterculia konchurangensis C. N. Kieu, D. B. Tran & B. H. Quang A flowering branch B, C, D leaf blade E inflorescence F open flower showing androgynophore, ovary, style, stigma G androgynophore, staminodes, ovary, style, stigma H ovary, style, stigma I section ovary, style, stigma (Photos by D. B Tran).

Figure 2. Sterculia konchurangensis C. N. Kieu, D. B. Tran & B. H. Quang A flowering branch B, C, D leaf blade E apex branches and stipules F inflorescence G flower H flower I open flower showing androgynophore, ovary, style, stigma J androgynophore, ovary, style, stigma, staminodes K section ovary, style, stigma (Drawn by Le Kim Chi).

Figure 3. Map indicating the type locality of Sterculia konchurangensis C. N. Kieu, D. B. Tran & B. H. Quang (Made by D. B Tran & T. B. Tran).