TAXON 70 (2) • April 2021: 443–444 Siu & al. • (2813) Conserve Hedyotis diffusa (b) No other purple-flowered Dionysia is known within a 100 km radius. (c) It has leaves 1/4 inch long. (d) It has a calyx 1/3 the length of the corolla. (e) It has a 1/2 inch long corolla with a [pale] yellow tube, pale purple limb with a yellow naked mouth and obcordate lobes. (f) In size and appearance of flowers it resembles Primula minutissima Duby. Finally, although less decisive, the leaves of mature cushions are ± equal in size, entire in outline (although the revolute margin is usually obscurely crenate), and can appear ciliate (although the hairs are not confined to the margin). The only part of Watt’s description that disagrees is “calyx […] segments obovate”. In Dionysia archibaldii they are mostly oblong to lanceolate, obtuse to sub-acute. Wendelbo would possibly have reached a different conclusion, had Dionysia archibaldii been known to him when he wrote his 1961 monograph. However, he was not made aware of this species until 1966. Conclusions (1) The epithet sawyeri has, with very high probability, priority over the epithet archibaldii for a species of Dionysia that is common in the Bazoft and Koohrang Districts. This species is fairly widely cultivated in botanic gardens and by dedicated amateurs, as evidenced by a simple google images search for “Dionysia archibaldii”. (2) The names Primula sawyeri and Dionysia bachtiarica designate different species. The former name has thus been consistently used (1961 to present) for a taxon not including its type. Based on these two reasons, I suggest that the disruptive name Primula sawyeri G. Watt be disarmed by being listed among the suppressed names. Author information ML, https://orcid.org/0000-0001-6306-9353 (2813) Proposal to conserve the name Hedyotis diffusa (Oldenlandia diffusa, Scleromitrion diffusum) (Rubiaceae) with a conserved type Tin Yan Siu,1 Mavis Hong Yu Yik,2 David E. Boufford,3 Pang Chui Shaw2,4 & David Tai Wai Lau1,2 1 Shiu-Ying Hu Herbarium, School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong, China 2 Li Dak Sum Yip Yio Chin R & D Centre for Chinese Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong, China 3 Harvard University Herbaria, 22 Divinity Avenue, Cambridge, Massachusetts 02138, U.S.A. 4 School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong, China Address for correspondence: David Tai Wai Lau, lautaiwai@cuhk.edu.hk DOI https://doi.org/10.1002/tax.12488 First published as part of this issue. See online for details. (2813) Hedyotis diffusa Willd., Sp. Pl. 1: 566. Jul 1798, nom. cons. prop. Typus: “Oldenlandia capensis?”, Klein (B-W barcode B -W 02588 -01 0, right-hand specimen [“B”]), typ. cons. prop. The name Hedyotis diffusa Willd. (Sp. Pl. 1: 566. 1798) has been applied for nearly two centuries to a taxon with usually solitary white flowers (Smith in Rees, Cycl. 17: Hedyotis no. 14. 1811). More recently, the species has been treated as Scleromitrion diffusum (Willd.) R.J. Wang (Wang & al. in Trop. Subtrop. Bot. 22: 440. 2014) based on a taxon with solitary-flowered (or 2- or 3-flowered) inflorescences. Conservation is required to preserve this longstanding application of the name. When Willdenow (l.c.) described Hedyotis diffusa as “Flores axillares solitarii pedunculati”, he did not specify in the protologue whether “pedunculati” referred to the peduncle of a solitary flower or an inflorescence. His description was interpreted as referring to a solitary flower by subsequent authors, including Smith (l.c.) as “Flower axillary, solitary, stalked”. Roxburgh (Hort. Bengal.: 11. 1814) initially transferred H. diffusa to Oldenlandia, as O. diffusa, without comment or description, but later (Fl. Ind. 1: 444. 1820) described the species as “Peduncles axillary, solitary, one-flowered […].” Hooker (Fl. Brit. India 3: 65. 1880), circumscribing the species in a broader sense, published two varieties of O. diffusa, including O. diffusa var. extensa Hook. f., which he described as 1- or 2-flowered and with a longer peduncle. This application of the name H. diffusa to a solitaryflowered taxon gained widespread acceptance around the world (Makino, New Ill. Fl. Japan: 580. 1961; Chao in Li & al., Fl. Taiwan 4: 271–272. 1978; Lee, Ill. Fl. Korea: 693. 1979; Manilal & Sivarajan, Fl. Calicut: 139–141. 1982). The 1- or 2-flowered concept of Hedyotis/Oldenlandia diffusa was followed until Sivarajan & Biju (in Taxon 39: 665–674. 1990) © 2021 The Authors. TAXON published by John Wiley & Sons Ltd on behalf of International Association for Plant Taxonomy. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made. Version of Record 443 Siu & al. • (2813) Conserve Hedyotis diffusa TAXON 70 (2) • April 2021: 443–444 chose as lectotype, against the traditional application, Willdenow Herbarium no. 2588-01 A (material on left-hand side of sheet), which is a specimen of Hedyotis pseudocorymbosa Bakh. f. (Bakhuizen van den Brink & Koster in Blumea 12: 62. 1963) with a cymose inflorescence. Consequently, Oldenlandia diffusa (Willd.) Roxb. in the sense of Roxburgh, including Willdenow Herbarium no. 2588-01 B, was treated as Hedyotis brachypoda (DC.) Sivar. & Biju, based on Oldenlandia brachypoda DC. (Prodr. 4: 424. 1830). Hedyotis pseudocorymbosa was reduced to the synonymy of H. diffusa. Sivarajan & Biju’s (l.c.) lectotypification was based on the interpretation that “pedunculati” in the protologue should refer to a multiple-flowered, stalked inflorescence. They mentioned that Roxburgh “started the confusion by […] misreading […] ‘solitarii pedunculati’ […] as 1-flowered” and pointed out that the flowers of Willdenow Herbarium 2588-01 B are sessile. Therefore, going against traditional usage, they lectotypified the name with a taxon with a (1-) 3- to 7-flowered pedunculate cyme. However, in the description of other species in Willdenow’s Species plantarum, the word “pedunculati” was applied to both the stalk of a solitary flower, which is reflected in the description of Convolvulus pes-caprae L. as “pedunculis unifloris” (Willdenow, l.c.: 876), and also to multi-flowered inflorescences as “pedunculis multifloris” in Convolvulus vitifolius Burm. f. (Willdenow, l.c.: 864). The lectotypification by Sivarajan & Biju based on their interpretation of “pedunculati” was therefore not well grounded. Later, Dutta & Deb (Taxon. Revis. Hedyotis: 143–147. 2004) cited Willdenow Herbarium no. 2588-01 B with solitary flowers as the type of Hedyotis diffusa, describing the species as having “solitary sessile or pedicelled flower or pedunculate cyme of 2–3 flowers”. However, it was not an effective lectotypification because the phrase “designated here” or an equivalent was not included (Art. 7.11 of the ICN; Turland & al. in Regnum Veg. 159. 2018). The treatment also lacked priority over Sivarajan & Biju under Art. 9.19 of the ICN. In 2014, Wang & al. (l.c.) transferred Hedyotis diffusa in the sense of Dutta & Deb (l.c.), not of Sivarajan & Biju (l.c.), to Scleromitrion as S. diffusum. The treatment was based on the latest delimitation of the Scleromitrion clade, which was characterized by having homostylous flowers and exserted stamens and style (Guo & al. in Molec. Phylogen. Evol. 67: 110–122. 2013; Neupane & al. in Taxon 64: 299–322. 2015). The combination was applied to a solitaryflowered (or rarely 2- or 3-flowered) taxon. Although the combination is legitimate, the treatment is problematic due to misapplication of the name, which must be applied to a (1-) 3- to 7-flowered species according to the existing lectotype of the basionym. Despite Sivarajan & Biju’s (l.c.) lectotypification, the traditional concept of Hedyotis diffusa is still widely adopted in the literature, in taxonomic revisions (Dutta & Deb, l.c.), regional floras (Lo & al. in Lo, Fl. Reipubl. Popularis Sin. 71(1): 26–77. 1999; Chen & Taylor in Wu & Raven, Fl. China 19: 147–174. 2011), traditional Chinese medicine (Chang & But, Pharmacol. Applic. Chin. Mater. Med. 1: 395–403. 1986; Li & al. in Food Chem. 119: 1239–1245. 2010; Zhao & Xiao, Encycl. Med. Pl. 4: 342–347. 2010), and anti-cancer 444 research (Lee & al. in Amer. J. Chin. Med. 39: 201–213. 2011; Chen & al. in Molecules 21: 710. 2016). Chen & al. (l.c.) clearly defined the species with which they were dealing in a review of the phytochemistry, pharmacology, quality control, and pharmacokinetic characteristics of H. diffusa for clinical use based on the treatment in the Flora of China. To avoid further confusion, we propose to conserve the type indicated by Dutta & Deb (l.c.), Willdenow Herbarium no. 2588-01 B (material on right-hand side) (image available at https://herbarium. bgbm.org/object/BW02588010), representing a 1-flowered taxon, as a conserved type. This would preserve over 200 years of traditional and current usage. The species is, in a broad sense, a 1- to 3-flowered taxon, including in the sense of Smith (l.c.), Roxburgh (l.c. 1820), Dutta & Deb (l.c.), and Wang (l.c.). Conservation of Hedyotis diffusa with B-W no. 2588-01 B as type will affect the application of two names: Scleromitrion brachypodum (DC.) T.C. Hsu (Hsu & Chen in Taiwania 62: 151–156. 2017) (O. brachypoda DC.) will become a synonym of S. diffusum. Oldenlandia pseudocorymbosa (Bakh. f.) Raizada (Suppl. Fl. Gangetic Plain: 95. 1976) will apply to a distinct species, which matches its existing application (Dutta & Deb, l.c.; Nandikar & Kishor in Blumea 64: 225–230. 2019), instead of being included in synonymy under Hedyotis diffusa. Willdenow Herbarium no. 2588 includes two sheets of three individuals from three different taxa. Specimen B-W no. 2588-01 A will be Oldenlandia pseudocorymbosa and B-W no. 2588-02 is O. corymbosa L. (Sp. Pl.: 119. 1753). As the treatment by Sivarajan & Biju has not been adopted by other taxonomists, the conservation would not have a significant impact on the current application of the two names. The conservation will contribute to nomenclatural stability and prevent confusion in the widespread application of the name Hedyotis diffusa in traditional Chinese medicine and anti-cancer research. If the proposal is rejected, the name of the taxon currently known as H. diffusa would need to be changed to Scleromitrion brachypodum, as the name H. diffusa would have to be applied to a different taxon currently accepted as Oldenlandia pseudocorymbosa. Author information TYS, https://orcid.org/0000-0001-5725-3314 MHYY, https://orcid.org/0000-0001-5029-819X DEB, https://orcid.org/0000-0003-1483-9651 PCS, https://orcid.org/0000-0001-6848-5073 DTWL, https://orcid.org/0000-0002-3443-1808 Acknowledgements The authors would like to thank Prof. John McNeill and Dr. John Wiersema for the review of this manuscript. The project is funded by Wu Jieh Yee Charitable Foundation Limited. The authors would like to thank Harvard Herbaria staff for their technical support and hospitality during specimen check for this project. The first author would also like to thank Mr. Ying Wai Lam for his guidance on nomenclatural studies. Version of Record