(1532) Proposal to Conserve the Name Hydrocera against Tytonia (Balsaminaceae)

Abstract

In publishing the name Hydrocera, Blume (Bijdr.: 241. 1825) gave only a family description of Hydrocereae. Although Hydrocera Blume ex Wight & Am. was frequently accepted as a genus (e.g., GreyWilson in Dassanayake & Fosberg (eds.), Rev. Handb. Fl. Ceylon 5: 77. 1985), it was not validly published as noted by Backer & Bakhuizen van den Brink (Fl. Java 1: 251. 1963). When Blume (l.c.) effectively published Hydrocera angustifolia, he referred to his earlier Impatiens angustifolia Blume, Catalogus: 49. 1823 (there validated by his diagnosis pedunculis multifloris solitariis; foliis lineari-lanceolatis 7-pollicaribus serrulatis). If the generic name Hydrocera were validly published in 1825, Blume would have validated his new combination by this reference to its basionym. However, neither the generic name nor the species name was validly published under Art. 43 of the ICBN (Greuter & al., Regnum Veg. 138. 2000). Subsequently, the former was validated by Wight & Amott (Prodr. Fl. Ind. Orient. 1: 140. 1834). Meanwhile, G. Don (Gen. Syst. 1: 749. 1831) had published another name for the same genus of Balsaminaceae: Tytonia, the legitimate and correct name for the genus, as currently circumscribed. Hydrocera Blume ex Wight & Am. is, in fact, currently illegitimate because Wight & Amott (l.c.) mentioned Tytonia in synonymy (Art. 52). Greuter & al. (in Regnum Veg. 129: 548. 1993) cited, following ING (Farr & al., Regnum Veg. 101: 848. 1979), Hydrocera angustifolia (Blume) Wight & Am. as the type of Hydrocera. This is incorrect since Amott (in Wight & Amott, 1.c.) explicitly stated that Impatiens natans Willd. is the type of Hydrocera, not Hydrocera angustifolia (Blume) Wight & Am. Hydrocera, being an illegitimate superfluous renaming of Tytonia, would automatically be typified on the type of Tytonia but for this explicit type indication of Amott (Art 7.5). Don (l.c.) mentioned two species under Tytonia, T natans (Willd.) G. Don (Impatiens natans Willd.) and T madagascariensis G. Don, but failed to designate a type. We here designate T natans as lectotype, a sensible choice since T madagascariensis is a true Impatiens, no longer considered as belonging to either Tytonia or Hydrocera. The two genera thereby become nomenclatural synonyms. There is an urgent need to conserve the superfluous name Hydrocera against its legitimate counterpart Tytonia. While C. E. Wood (in J. Amold Arbor. 56: 413. 1975) appears to be the single author who took up the name Tytonia, most recent authors have failed to realize that Hydrocera was not validly published in 1825 and continue to attribute it to Blume, not to Wight & Amott. Although unispecific, the genus is important as the only genus of Balsaminaceae other than Impatiens. Its acceptance was noted in 21 important floristic works, including the following: Bentham & Hooker, Gen. Pl. 1: 278. 1862; Hooker, Fl. Brit. India 1: 483. 1875; Venkateswarulu & Dutt, J. Bombay Nat. Hist. Soc. 58: 545. 1961; Subramanyan, Aquatic Angiosperms: 12, fig. 7. 1962; Airy Shaw in Willis, Dict. Flow. Pl. Ferns, ed. 8, 577. 1973; Brummitt, Vasc. Pl. Fam. Gen.: 214. 1992; Gunn & al., Fam. Gen. Spermatoph.: 107. 1992; Vivekananthan & al., Fl. India 4: 96-99, fig. 33. 1997. In addition, the name has been used in specialized studies of cytology and embryology (Venkateswarlu & Lakshminarayana, Phytomorphology 7: 194-203. 1957), floral and fruit anatomy (Narayana, J. Jap. Bot. 40: 104-116. 1965; 49: 315-320. 1974; Grey-Wilson, Kew Bull. 35: 213-219. 1980; Ramadevi & Narayana in Trivedi & al., P1. Sci. Res. India: 707-713. 1989 & in Proc. Indian Acad. Sci. (P1. Sci.) 100: 43-49. 1990; Raghuveer & al.,