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| Wikstroemia fragrans W.B.Liao, Q.Fan & J.R.Chen, in Chen, Lee, Guo, Jin, Fan et Liao, 2022. |
Abstract
A new species, Wikstroemia fragrans (Thymelaeaceae, Daphneae), from Danxiashan National Park, Shaoguan, Guangdong of China is described and illustrated. It is similar to the sympatric W. trichotoma, but can be differentiated easily from the latter by its shorter racemose inflorescences, yellowish green calyx tube, and smaller leaves. It also resembles the allopatric W. fargesii, but differs from it by its strigose-pubescent ovary and disk scale that is 2- or 3-dentate apically. Phylogenetic analysis using the nuclear DNA internal transcribed spacer (ITS) region revealed that W. fragrans falls within the Wikstroemia clade; based on current sampling, W. fragrans is closely-related to W. capitata. It is also the first species of Wikstroemia known to be endemic to the Danxia landform and is classified provisionally as Critically Endangered according to the IUCN Red List Categories and Criteria.
Keywords: Danxia landform, flora, internal transcribed spacer (ITS), IUCN Redlist, phylogenetics, taxonomy, Wikstroemia
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Wikstroemia fragrans W.B.Liao, Q.Fan & J.R.Chen, sp. nov. A flowering branch B flower C subgynoecial disk scale opened out D dissected flower showing the normal condition of 10 stamens E strigose ovary and glabrous disk scale A–E DNPC 1597 deposited in SYS. Drawn by Rong-En Wu. |
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Habitat and morphological features of Wikstroemia fragrans W.B.Liao, Q.Fan & J.R.Chen, sp. nov. A, B habitat, hillsides thickets of Danxiashan National Park C flowering branches D immature fruits E densely racemose inflorescence F, G flowers, showing 5-lobed calyx. (A–C, E–G photographs by Jing-Rui Chen of unvouchered plants in the original habitat in April 2022 D photograph by Jian-Qiang Guo taken in April 2021). |
Wikstroemia fragrans W.B.Liao, Q.Fan & J.R.Chen, sp. nov.
Diagnosis: Wikstroemia fragrans differs from W. trichotoma, by its smaller leaves (1.2–1.6×0.5–0.9 vs. 1.2–3.5(-8) × (0.5-)1–2.2(-4) cm), densely racemose to nearly capitate inflorescence (vs. loose panicle), yellowish green calyx (vs. white), and strigose-pubescent ovary (vs. apically strigose ovary). Wikstroemia fragrans differs from W. fargesii by its strigose-pubescent ovary (vs. apically strigose) and a disk scale 2- or 3-dentate apically (vs. entire or slightly retuse apically).
Distribution and habitat: Wikstroemia fragrans is currently known only from the type locality, Danxiashan National Nature Reserve (Ba Zhai, Mount Shaoshi, Shuang He Zhai, Yu Nv Lan Jiang), Guangdong, China. It occurs in xerophytic hillside thickets on sandstone and conglomerate based soil at 100–300 m elevation. In this habitat, the most common shrubby and herbaceous species are Lagerstroemia indica Linn. (Lythraceae), Symplocos tanakana Nakai (Symplocaceae), Decaspermum gracilentum (Hance) Merr. et Perry (Myrtaceae), Viola hybanthoides W. B. Liao & Q. Fan (Violaceae) and Salvia scapiformis Hance (Lamiaceae).
Etymology: Latin fragrans, smell or odor, alluding to sweet-scented flowers. The Chinese name is given as 香花荛花 (xiāng huā ráo huā).
Jing-Rui Chen, Shiou Yih Lee, Jian-Qiang Guo, Jie-Hao Jin, Qiang Fan and Wen-Bo Liao. 2022. Wikstroemia fragrans (Thymelaeaceae, Daphneae), A New Species from Mount Danxia, China based on Morphological and Molecular Evidence. PhytoKeys. 213: 67-78. DOI: 10.3897/phytokeys.213.91116
