Eriobotrya condaoensis X.F.Gao, M.Idrees & T.V.Do., 2018

Idrees, Muhammad, Do, Truong Van & Gao, Xin-Fen, 2018, A new species of Eriobotrya (Rosaceae) from Con Dao National Park, southern Vietnam, Phytotaxa 365 (3), pp. 288-294 : 290-293

Eriobotrya condaoensis X.F.Gao, M.Idrees & T.V.Do. , sp. nov. ( Figs. 2 & 3 )

Type:— VIETNAM. Ba Ria-Vung Tau Province: Con Dao National Park , growing on slope of hill under tropical evergreen forest, elev. 20 m, 8°41′30″N, 106° 38′ 00″E, 21 March 2017, Do Van Truong VNMN_CN 633 (holotype VNMN!; isotype CDBI!) .

Diagnosis:—The new species resembles E. bengalensis ( Roxburgh 1832: 510) J.D. Hooker (1878: 371) and E. stipularis Craib (1929: 109) , mainly by leaf blade glabrous on both surfaces and style number, but differs greatly from the former by leaf blade oblong-oblanceolate, 8–12 × 4–6 cm, leaf margins crenate, petioles 1–2.5 cm long, lateral veins 6–7 pairs, alternate, looped near the margin, panicle 3–7 cm long, flowers yellowish and sessile, petals elliptic and 6–7 × 4–5 mm, styles 2, free at base and 5 mm long, and ovary glabrous and differs from the latter by stipules deciduous, leaf blade smaller, oblong-oblanceolate 8–12 × 4–6, leaf base rounded or cuneate, leaf margin crenate, lateral veins 6–7 pairs, alternate, flower yellowish and sessile, pedicels and peduncle brown tomentose, petals elliptic and 6–7 × 4–5 mm, styles free at base, and ovary glabrous.

Description:—Small to medium size tree, 8–12 m tall. Branchlets grey, rough and glabrous. Leaves in cluster at the apices of the branches; stipules deciduous, not seen; petioles 1–2.5 cm long, glabrous; leaf blade oblong-oblanceolate, 8–12 × 4–6 cm, thickly coriaceous, midrib prominent on both surfaces, lateral veins 6–7 pairs, conspicuous craspedodromous, looped near the margin, tertiary veins conspicuous reticulate, both surfaces glabrous, base rounded or cuneate, margin crenate or nearly entire at base, glabrous, apex rounded or obtuse. Panicle 3–7 cm in diam., many flowered; peduncle 5 mm long, brown tomentose; bracts persistent, 2–3 mm, free, apically dentate with 3 parallel veins, margin dentate, abaxially brown tomentose, adaxially glabrous, bracteoles ovate, 1.5 mm, abaxially brown tomentose, adaxially glabrous. Flowers sessile, yellowish, 1–1.5 cm in diam. Hypanthium funnel-shaped, 4 mm, abaxially brown tomentose. Sepals ovate-lanceolate, 3 mm, apex subacute, abaxially brown tomentose, adaxially glabrous. Petals yellowish, elliptic or ovate, 6–7 × 4–5 mm, base slightly pilose or glabrous, apex subacute or obtuse. Stamens 20, free, filament 3 mm long, anthers 1 mm long. Ovary glabrous, 2-loculed, with 2 ovules per locule; styles 2, 5–6 mm, free and villous at base. Pome elliptic, 1–1.5 cm in diam., exocarp brown tomentose, green when young, dark (in dry state), mesocarp thin, endocarp membranous and glabrous; fruiting sepal persistent, brown tomentose; seed 1, testa papery thin with thick cotyledon.

Distribution and Habitat:— Eriobotrya condaoensis is currently only known from the type locality, Con Dao National Park, Ba Ria-Vung Tau province, southern Vietnam. It grows on slope of hill under tropical evergreen forest, at elevation ca. 20 m.

Etymology:—The specific epithet referring to the type locality.

Discussion:—The new species Eriobotrya condaoensis is similar to E. bengalensis in having leaf blade glabrous on both surfaces, styles number, fruits shape and size, but can be distinguished from the latter by combination of various morphological characters, such as leaf blade size and shape, leaf margins, length of petioles, pairs of lateral veins, size of panicle, length of pedicels and peduncle, flower colour, petals size and colour, styles shape, and indumentum of ovary. E. condaoensis has leaf blade oblong-oblanceolate, 8–12 × 4–6 cm, leaf margins crenate; petioles 1–2.5 cm long; lateral veins 6–7 pairs, alternate, looped near the margin; panicle 3–7 cm long; flowers yellowish and sessile; petals elliptic and 6–7 × 4–5 mm; styles 2, free at base and 5 mm long, and ovary glabrous. In contrast, E. bengalensis has leaf blade oblong elliptic or lanceolate, 10–20 × 4–8 cm, leaf margins shallowly or incised serrate; petioles 2–4 cm long; lateral veins 10 pairs, opposite, extend toward margins; panicle 8–12 cm; flowers white and with pedicels 3–5 mm long; petals obovate, 4–5 × 3–4 mm; styles 2–3(–4), connate at base and 2–3 mm long, and ovary apically pubescent.

E. condaoensis is also similar to E. stipularis in having leaf blade glabrous on both surface, petioles size, length of panicle and styles number, the latter occurs in Thailand and Cambodia ( Vidal 1965), and also recorded recently from Vietnam ( Zhang & Lin 2015). The new species can be distinguished from the latter by stipules deciduous, leaf blade smaller, oblong-oblanceolate, 8–12 × 4–6; leaf base rounded or cuneate; leaf margins crenate; lateral veins 6–7 pairs, alternate; flower yellowish and sessile; pedicels and peduncle brown tomentose; petals elliptic and 6–7 × 4–5 mm; styles free at base; and ovary glabrous. In contract, E. stipularis has stipules larger (6–12 × 4–10 cm) and persistent, leaf blade larger, oblong-lanceolate, 12–18 × 4–5 cm; leaf base acuminate or cuneate; leaf margins shallowly serrate; lateral veins 10 pairs, opposite; flowers white and with pedicels 1–4 mm long; pedicels and peduncle rusty tomentose; petals obtuse oval and 4 × 3 mm; styles connate at base and ovary apically pubescent. The three species are compared with one another in Table 2.

Our phylogenetic analysis resolved E. condaoensis in a separate clade with long branch indicating its isolated phylogenetic position in the genus. In our tree, the new species formed a trichotomy with E. malipoensis , E. seguinii , and with the rest of the genus.

TABLE 2. Morphological comparison of E. condaoensis , E. bengalensis and E. stipularis

Figures

FIGURE 2. Eriobotrya condaoensis. A) Habit, branch leaves with inflorescence; B) Venation; C) Flower in front view; D) Style in front view; E) Petal in front view; F) Portion of inflorescence with flower bud and floral bract and G) Fruit. Illustration by Jian Gu from the holotype.

FIGURE 3. Eriobotrya condaoensis. A) Habitat; B) Top view of flower and fruit; C) Adaxial leaf surface; D) Abaxial leaf surface and E) Type specimen. Images designed by Zhang Cheng.