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Sonerila erectifolia Phonep., Soulad. & Tagane, Sonerila souvannii Phonep. & Soulad., in Phonepaseuth, Souladeth, Souvannakhoummane, Vongthavone et Tagane, 2021. |
ABSTRACT
Two new species of Sonerila Roxb. (Melastomataceae), S. erectifolia Phonep., Soulad. & Tagane sp. nov. from southern Laos, and S. souvannii Phonep. & Soulad. sp. nov. from central Laos, are described and illustrated. Comparisons with morphologically similar species are presented, along with ecological information and preliminary conservation status. A key to the species of Sonerila in Laos is also provided.
Keywords: Bolaven Plateau, flora, Indochina, taxonomy, Vientiane Capital
Class Magnoliopsida Brongn.
Order Myrtales Juss. ex Bercht. & J.Presl.
Family Melastomataceae Juss.
Genus Sonerila Roxb.
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| Sonerila erectifolia Phonep., Soulad. & Tagane sp. nov. A. Habitat (on open moss-covered bedrock). B. Close-up of plant (left: pink flowers, common; right: white flowers, rare). C. Habit. D. Inflorescence (left: pink flowers; right: white flowers). E. Young fruits. F. Top view of young fruit. G. Cross sections of young fruit. H. Rhizome. I. Upper surface of lamina. J. Lower surface of lamina. Photos by P. Phonepaseuth on 17 September 2020. |
Sonerila erectifolia Phonep., Soulad. & Tagane sp. nov.
Diagnosis: Sonerila erectifolia sp. nov. is similar to Sonerila violifolia in its scorpioid or subumbelliform inflorescence, but it differs in the length of stem (ca 1 cm long in S. erectifolia sp. nov. vs 10–18 cm long in S. violifolia), the venation of the leaves (2 veins running from the base of lamina vs pinnately veined with 2–3 lateral primary veins), hairiness of leaves (sparsely covered with whitish hairs on veins abaxially vs glabrous), the length of the petiole (6–10 cm long vs 1–7 cm long), and number of flowers per inflorescence (5–12(–18) flowers vs 1–9 flowers). For further comparison see Table 1.
Etymology: The specific epithet refers to the plant having erect leaves.
Vernacular name: ຊີດິນໃບຕັ້ງ [ʻSeedin Baitungʼ
(meaning: ʻSonerila with erect leavesʼ)]
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| Sonerila souvannii Phonep. & Soulad. sp. nov. A. Habit. B. Front view of flower. C. Petals. D. Hypanthium and style, with portion of pedicel. E. Cross section of ovary. F. Stamens. G. Style and stigma. H. Capsule. I. Rachis and minute bracts. Line drawings from holotype (Phonepaseuth P012) by K. Souvannakhoummane. |
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| Sonerila souvannii Phonep. & Soulad. sp. nov. A. Habitat (on sandstone rock). B. Habit. C. Petiole densely covered withvillous hairs. D. Rhizome and stem with rudimentary leaves. E. Flowers. F. Inflorescence (scorpioid cyme). G. Lateral view of flower. H. Back view of flower. I. Longitudinal section of fruit. J. Top view of fruit. K. Cross section of fruit. L. Infructescence of the last season. Photos by P. Phonepaseuth on 12 September 2020. |
Sonerila souvannii Phonep. & Soulad. sp. nov.
Diagnosis: Sonerila souvannii sp. nov. is similar to S. cardamomensis, described from Cambodia, in its acaulescent habit and in the shape of its leaves, but it differs in the shape of its rhizome (cylindrical in S. souvanii vs bulbous in S. cardamomensis), larger leaves (8–10 × 6–9 cm vs 1–4 × 0.9–2.7 cm), petiole length and color (8–15 cm long and light green vs 0.4–2.5 cm long and reddish brown), greater number of flowers per cyme (20–25 vs 5–11), and petal length and pubescence (9–10 × 6–7 mm and glabrous vs 5.5–6 × 3.5–4 mm with glandular trichomes on midveins abaxially). Sonerila souvannii sp. nov.is also similar to S. dongnathamensis from Thailand in the shape of its inflorescences, but differs in the rhizome shape (cylindrical vs globose), the shape of the leaf base (cordate vs obtuse to rounded), pedicel length (10–25 mm long vs 1–4 mm long), the number of flowers per cyme (20–25 vs 5–12), and in the length and outline of the petals (9–10 × 6–7 mm, acute vs 3–5 × 3–4 mm, acuminate with long seta).The new species is also related to S. tuberosa from Cambodia, but distinguished in the rhizome shape (cylindrical vs slightly bulbous), the shape of the leaf base (cordate vs very broadly ovate to orbicular), pedicel length (10–25 mm long vs 5–6 mm long), the number of flowers per cyme (20–25 vs 4–8), and in the length and outline of the petals (9–10 × 6–7 mm, acute vs 5 × 2.7 mm, elliptic, apiculate, pink) (Table 2)
Etymology: The specific epithet honours Keooudone Souvannakhoummane (Centre for Development and Environment), a plant taxonomist who has greatly contributed to our understanding of plant diversity in Laos through the description of many new species in various families for the flora of Laos.
Vernacular name: ຊີດິນສຸວັນ [ʻSouvan’s Seedinʼ
(meaning: ʻSouvan’s Sonerilaʼ)].
Phongphayboun Phonepaseuth, Phetlasy Souladeth, Keooudone Souvannakhoummane, Thyraphon Vongthavone and Shuichiro Tagane. 2021. Two New Species of Sonerila Roxb. (Melastomataceae) from Laos. European Journal of Taxonomy. 755(1), 136-148. DOI: 10.5852/ejt.2021.755.1403
