Lectotypification of the name Premna wightiana Schauer (Lamiaceae) and notes on its distribution in India

The genus Premna Linnaeus (1771: 587) (subfamily Premnoideae) is one of the largest woody genera of the mint family (Lamiaceae) (Li et al. 2016). Premna has been recently transferred from the family Verbenaceae to Lamiaceae (Li & Olmstead 2017, Harley et al. 2004, Bramley et al. 2010, Olmstead 2010, 2012) based on molecular evidence. The genus is mainly distributed in Old World tropical and subtropical regions (Govaerts et al. 2008), and comprises about 129 species in the world (POWO 2023). Though some regional revisions of Premna have been done (Munir 1984, Ho 1999, Rajendran & Daniel 2002, Mabberley & de Kok 2004, Leeratiwong et al. 2009, de Kok 2013), the complete revision of the genus is missing. So it still ranks among the most taxonomically difficult and complicated genera of Lamiaceae (Tan & Li 2014). In India, the genus is represented by 32 species (Rajendran & Daniel 2002), out of which nine are recorded so far from Kerala region (Prabhukumar et al. 2013) with five endemics (Sasidharan 2013). In a floristic exploration trip, the authors collected an unknown species of Premna on the road sides of Bodymettu forest ranges of Idukki district, Kerala. The specimen is distinct from the other taxa distributed in Western Ghats in its thyrsus inflorescence. Perusal of literature (Wight 1849, Clarke 1885, Gamble 1924, Moldenke & Moldenke 1983, Rajendran & Daniel 2002) and types, its identity was confirmed as P. wightiana Schauer (1847: 635), which was earlier thought as endemic to southern part of Western Ghats until Rajendran and Daniel reported its occurrence from Sri Lanka based on the herbarium specimens housed at PDA (Daniel & Rajendran, 1993). In India, this species was earlier known to occur in Western Ghats of Kerala and Tamil Nadu and Eastern Ghats of Orissa (Balachandran et al. 2015) (Figure 1). While revising the family Verbenaceae for India, Rajendran and Daniel (2002) noted that "this species has never been re-collected in Kerala after Bourdillon who collected it in Quilon 1894". Hence the present collection of this specimen from Idukki District of Kerala is a re-collection after 123 years for the state (Figure 2). During the study, we realized the need of typification of the name P. wightiana and a lectotype was designated here according to the Art. 9.3 of Shenzhen Code (Turland et al. 2018).