Pontederia plantaginea Roxb., Fl. Ind. (ed. 1832) 2: 123. 1832.

Pellegrini, Marco O. O., Horn, Charles N. & Almeida, Rafael F., 2018, Total evidence phylogeny of Pontederiaceae (Commelinales) sheds light on the necessity of its recircumscription and synopsis of Pontederia L., PhytoKeys 108, pp. 25-83 : 25

2.8. Pontederia plantaginea Roxb., Fl. Ind. (ed. 1832) 2: 123. 1832.

Monochoria vaginalis var. plantaginea (Roxb.) Solms, Monogr. Phan. 4: 524. 1883.

Monochoria plantaginea (Roxb.) Kunth, Enum. Pl. 4: 135. 1843. Lectotype (designated here). NEPAL: Nathpur, fl., Aug. 1821, N. Wallich 5096 (K barcode K001104737!; isolectotypes: K barcodes K001104733!, K001104734!, K001104735!, K001104736!, K001104738!, K001104739!, K001104740!).

Monochoria vaginalis var. angustifolia G.X.Wang, Acta Phytotax. Sin. 41: 569. 2003. Type. THAILAND. Koksung: in a marshy place, fl., 18 Sep 1984, N. Fukuoka T-36166 (holotype: KYO!; isotypes: A n.v., BKF n.v., L n.v.). Syn. nov.

Boottia mairei H. Lév., Cat. Pl. Yun-Nan 131. 1916. Type. CHINA. Yunnan: Dongchuan [Tangdan], fl., Aug 1912, E.E. Maire s.n. (holotype: E barcode E00386692!). Syn. nov.

Monochoria junghuhniana Hassk., Flora 35: 115. 1852. Lectotype (designated here). INDONESIA. Java, Yogyakarta, Djokjakarta, prope Samas ad affim Opar, fl., s.dat., Junghuhn s.n. (L barcode L0041652!). Syn. nov.

Monochoria linearis (Hassk.) Miq., Fl. Ned. Ind. 3: 549. 1859.

Pontederia linearis Hassk., Flora 25(2, Beibl.): 4. 1842. Type (not found). INDONESIA. Java (L?). Syn. nov.

Monochoria ovata Kunth, Enum. Pl. 4: 665. 1843.

Pontederia ovata Hook. & Arn., Bot. Beechey Voy. 218 1837, nom. illeg. non P. ovata L. Lectotype (designated here). SRI LANKA. Canton, fl., s.dat., Millet s.n. (G barcode G00164757!; isolectotype: E n.v.).

Pontederia cernua L. ex B.D.Jacks., Index Linn. Herb.: 129. 1912, nom. nud.

Pontederia alba Buch.-Ham. ex Wall., Numer. List: 5095 D. 1831, nom. nud.

Pontederia racemosa Buch.-Ham. ex Wall., Numer. List: 5095C. 1831, nom. nud.

Pontederia lanceolata Wall. ex Kunth, Enum. Pl. 4: 135. 1843, pro. syn.

Distribution.

Australia, Bangladesh, Cambodia, China, India, Indonesia, Myanmar, Nepal, Sri Lanka, Thailand and Vietnam.

Nomenclatural notes.

Cook (1989) cites that no suitable specimens, collected by Roxburgh, were found. Nonetheless, according to Stafleu and Cowan (1983) and Forman (1997), many of Roxburgh’s new species described after 1831 were based on specimens at the Wallich Herbarium (currently housed at K). After visiting Kew, we came across a series of specimens at Wallich Herbarium (Wallich 5096), collected in the Bengal region (Bangladesh, Myanmar, Nepal and India), that perfectly matched the protologue of P. plantaginea . One of the herbarium sheets contained several complete flowering specimens in perfect condition. Thus, we designate the gathering under the barcode K001104737, as the lectotype for P. plantaginea .

Hasskarl (1852), when describing M. junghuhniana , makes no reference to any specimens. However, the author does mention that his new species is native to Sumatra, near Samas and Opar. After analysing the collection at L, we came across a specimen from exactly the same locality as indicated in the protologue and most likely collected by Junghuhn. Thus, it is designated by us as the lectotype for M. junghuhniana .

Taxonomical notes.

Monochoria vaginalis , in its current circumscription ( Cook 1989), is widely morphologically variable and distributed. However, recent studies ( Wang et al. 2003; Tungmunnithum et al. 2016) have highlighted the need to revisit the species boundaries in this taxon. Recently, Tungmunnithum et al. (2016) published a thorough morphometric study on M. vaginalis s.l. from Thailand and showed that two taxa are easily recognisable. The authors informally recognised M. vaginalis Burm.f. var. vaginalis and M. vaginalis var. angustifolia G.X.Wang as representing each of the recovered morphotypes. Nonetheless, after studying all the names treated as synonyms of M. vaginalis s.l. by Cook (1989), we concluded that M. vaginalis var. angustifolia and M. junghuhniana are conspecific to P. plantaginea Roxb. Thus, P. plantaginea is here re-established and M. vaginalis var. angustifolia and M. junghuhniana are treated as synonyms of the latter.