Lectotypification of Sida asiatica L. (Malvaceae)

Abstract

Sida asiatica L. was proposed in the dissertation of Tomer (Linnaeus, 1756), having previously been mentioned in Species Plantarum (Linnaeus, 1753: 685) as Sida abutilon var. 13. As fully explained by Borssum Waalkes (1966: 175), the elements actually cited, Zeyl..'520.1747, which is linked to a drawing in the Hermann Herbarium, and Pluk. phyt. 126. f. 5. 1692 as well as a specimen in the Linnaean Herbarium (LINN 866.27), do not agree with Linnaeus' actual description. Linnaeus (1762: 963) points out how his Sida asiatica and Sida indica differ, yet the three elements mentioned in 1756 all clearly belong to Sida indica. Both species are now placed in Abutilon, and A. asiaticum (L.) Sweet has long been used for a taxon which agrees with Linnaeus' description of S. asiatica. Borssum Waalkes treated this taxon as a subspecies of A. indicum (L.) Sweet but avoided using the epithet asiaticum and instead adopted that of a taxon described from West Africa Sida guineensis Schumach. & Thonn., 1827, which he considered taxonomically indistinguishable from A. asiaticum auctt. If one accepts Borssum Waalkes' classification of the group, i.e., a single species, A. indicum (L.) Sweet, divided into subsp. indicum and subsp. guineense (Schumach. & Thonn.) Borssum Waalkes (as, for example, has Philcox, 1997: 340), then the problem of the typification of Sida asiatica is of little practical consequence. All recent workers on African Malvaceae, however, have treated A. guineense (Schumach. & Thonn.) Bak. f. & Exell as a separate species, as also has Fryxell (1989: 206). By treating A. asiaticum as a synonym of his A. indicum subsp. guineensis, Borssum Waalkes in effect typified Sida asiatica by the description and rejected the cited elements and the Linnaean specimen-something that has not been possible since the option of typification by a description was removed from the ICBN at the Sydney Congress in 1981. It is clear that some definite action must be taken. C. Jarvis (BM) has informed me that he knows of no formal typification of Sida asiatica nor of the existence of any original elements in any other Linnaean herbaria, He suggested that lectotypification of Sida asiatica by one of the original elements was probably the best solution; S. asiatica would then become a synonym of A. indicum and the epithet guineense would be the correct one at both specific and subspecific rank. In his recent list of Abutilon species Fryxell (2002: 83) has stated under A. asiaticum Type: specimen unknown. Since it seems probable that specimen LINN 866. 27 was not in Linnaeus' herbarium at the time of the description of Sida asiatica (Fosberg, 1966: 148), I formally select the Hermann drawing illustrating Fl. Zeyl. 520 as lectotype of Sida asiatica L. Consequently, Abutilon asiaticum (L.) Sweet becomes a synonym of A. indica (L.) Sweet and the correct name for the species to which the name A. asiaticum has been applied is A. guineense (Schumach. & Thonn.) Bak. f. & Exell. This accords with current usage and the treatment I have written for the Flora of Tropical East Africa fascicle on Malvaceae (a multiauthored account which will not be published for many years).