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| Orophea sichaikhanii Damth., Aongyong & Chaowasku. in Damthongdee, Aongyong & Chaowasku, 2021. |
Abstract
Background and aims – Recent botanical expeditions in Ranong Province, southern Thailand yielded unidentifiable collections of Orophea subgenus Sphaerocarpon (Annonaceae). To elucidate the taxonomic status of these collections, detailed morphological examinations and comparisons with morphologically similar species are made.
Material and methods – This study followed standard practices of herbarium taxonomy. Specimens of Orophea spp. in BKF, CMUB, L, and QBG herbaria were studied. Digitised type specimens deposited in BM, E, G, K, and L herbaria were accessed. A stereo microscope was used for morphological observations and measurements.
Key results – A new species Orophea sichaikhanii is described and illustrated. The Peninsular Malaysian O. hastata and O. kingiana are the species most similar to the new species. Orophea sichaikhanii is different from O. hastata in several traits: indumentum on ovaries and young twigs; length of pedicels, inner petals, and inner petal claw; and inner petal colour and tip. The new species differs from O. kingiana by having dissimilar colour and tip of inner petals; lower number of stamens and carpels per flower; and glabrous ovaries. Additionally, a key to the species of Orophea in Thailand and notes on certain species are provided.
Keywords: Annonaceae, Miliuseae, morphology, new species, Orophea, subgenus Sphaerocarpon, systematics, taxonomy, southern Thailand
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| Figure 3 – Flower and floral organs of Orophea sichaikhanii Damth., Aongyong & Chaowasku. A. Flower with one inner petal removed. B. Outer petal: adaxial (below) and abaxial (above) sides. C. Inner petal: adaxial side (right), showing glands (paired slits), and abaxial side (left). D. Stamen: adaxial (left) and abaxial (right) sides. E. Flower with petals removed. F. Flower with petals and stamens removed. G. Carpel, showing glabrous ovary and globose stigma. H. Flower with petals, stamens, and carpels removed, showing torus and adaxial side of sepals. I. Same as (H), but showing abaxial side of sepals. All from Sichaikhan 6 (CMUB). |
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| Orophea sichaikhanii Damth., Aongyong & Chaowasku. A. Inflorescence and flowers. B. Infructescence and globose monocarp. C. Twig, showing upper leaf surface. D. Twig, showing lower leaf surface. Photographs by Kithisak Aongyong (A) and Geerawit Sichaikhan (B–D). |
Orophea sichaikhanii Damth., Aongyong & Chaowasku, sp. nov.
Etymology –This species is named after Geerawit Sichaikhan, who collected the specimens. He is an electrical engineer, but has a strong interest in plant diversity, especially in the area where he was born and has lived (Ban Khlong Ngoen).
Anissara Damthongdee, Kithisak Aongyong and Tanawat Chaowasku. 2021. Orophea sichaikhanii (Annonaceae), A New Species from southern Thailand, with A Key to the Species of Orophea in Thailand and Notes on Some Species. Plant Ecology and Evolution. 154(2); 307-315. DOI: 10.5091/plecevo.2021.1780
