A revision of Anisochilus Wall. ex Benth. (Lamiaceae) Somran Suddee 1 & Alan Paton 2 Summary. Sixteen species of Anisochilus are reviewed. Full synonymy, information about types, distributions, and a key to species are given. The type of the little known A. adenanthus Dalzell has been found and the widely used A. verticillatus is a synonym. A. sericeus and A. dysophylloides var. purpureus are synonyms of A. dysophylloides. A. henryi,a recently published name is a synonym of A. robustus. Nine names are lectotypified. The genus occurs in South Asia, from the East Himalaya, North Thailand, and South China in the North to Sri Lanka and Peninsular Thailand in the South. Key Words. Anisochilus, Lamiaceae, lectotypes, Leocus, Plectranthus, taxonomy. Introduction Anisochilus (Lamiaceae) is an Asian genus of herbs and shrubs. It was first described by Bentham (1830a), the generic name refering to the unequal lips of the calyx. The genus belongs to subtribe Plectranthinae in tribe Ocimeae (Harley et al. 2004). It is characterised by the spike-like head, the sessile or subsessile fruiting calyx with posterior lobes decurved or deflexed and con- cealing the throat after anthesis, the decurved corolla tube, and the declinate stamens with confluent anthers. Bentham (1848) divided the genus into 2 sections, Anisochilus Benth. and Stiptanthus Benth., based on calyx characters. At present, the genus contains 16 species and is chiefly distributed in India, Sri Lanka, Himalaya, Burma, south China, Thailand and Indo-China. The southernmost distribution known so far is Peninsular Thailand (Trang Province). Fourteen species occur in India and Sri Lanka. Eight are endemic to the Deccan Peninsula (see Table 1). The genus Leocus A. Chev. is recognised by Harley et al.(2004). This is superficially similar to Anisochilus but it differs in having fused, rather than free stamens and a variety of different calyx structures. It is also restricted to Africa, whereas true Anisochilus is Asian. Perparatory work done for Flora of East Tropical Africa has revealed that the type of Leocus, L. lyratus A. Chev. is a synonym of Plectranthus betonicifolius Baker and that Leocus is better subsumed into Plectranthus. The names Anisochilus africanus Scott-Elliot, Leocus africanus (Scott- Elliot) J. K. Morton and A. erlangii Briq. should be considered synonyms of Plectranthus africanus (Scott- Elliot) A. J. Paton. Plectranthus africanus (Baker in Scott-Elliot) A. J. Paton (Paton et al. 2009: 308) Anisochilus africanus Baker in Scott-Elliot, J. Linn. Soc., Bot. 30: 94 (1894). Type: Sierra Leone, Freetown, Scott-Elliot 5033 (holotype K!) A. engleri Briq. (1894: 190). Type: Dem. Rep. Congo, between Nyangwe and Kibundo, Pogge 1019 (lecto- type K!, chosen here). Leocus africanus (Baker in Scott-Elliot) J. K. Morton (1962: 270). Anisochilus can be distinguished from Plectranthus by a combination of a spike-like head and a deflexed posterior lip of the calyx (Harley et al. 2004). A phylogeny of Plectranthus and related genera is pre- sented in Paton et al. (2004). Anisochilus nests within the ‘Coleus’ clade but better resolution and support are required before further changes to the generic circumscription within the Plectranthinae are made. Habitats Anisochilus species are most common in the rather dry and open habitats, including open rocky places, Accepted for publication July 2008. 1 The Forest Herbarium (BKF), National Park, Wildlife & Plant Conservation Department, Chatuchak, Bangkok 10900, Thailand. 2 Herbarium, Royal Botanic Gardens, Kew, Richmond, Surrey, TW9 3AB, UK. KEW BULLETIN VOL. 64: 235–257 (2009) © The Board of Trustees of the Royal Botanic Gardens, Kew, 2009