A taxonomic revision of the Malesian species of Lasianthus (Rubiaceae)

Abstract

Based on herbarium collections, the Malesian species of the genus Lasianthus are revised. A total of 131 species including 5 subspecies and 6 varieties are recognized from the Malesian region, of which 41 species, 3 subspecies and 3 varieties are described as new, and 3 new combinations are made for varieties. 22 species names and 15 variety names are reduced to synonyms. Ten species names and 2 varieties are treated as dubious mainly because their types cannot be traced. Additionally, 11 species are further excluded from Lasianthus. All species are described and a key to Malesian Lasianthus is given. TAXONOMIC HISTORY Generic delimitationLasianthus Jack was established in 1823 based on two Sumatran species, Lasianthus cyanocarpus (later selected as the type of the genus; see below) and Lasianthus attenuatus. In the same year Blume (1823) listed several plant species under the genus name Mephitidia attributed to Reinwardt but described one species M. hexandra himself. The genus was redescribed two years later by Reinwardt (1825), but no species were mentioned by him. According to the International Code of Botanical Nomenclature (McNeill et al. 2006), the genus Mephitidia is attributed to Reinwardt ex Blume with M. hexandra Blume as type. Blume (1826Blume ( -1827 realized that Mephitidia was synonymous with Lasianthus Jack and provided accounts of the Javanese species. Mephitidia continued to be used by some authors because they were aware of an earlier publication of Lasianthus Adans. (= Gordonia) for a genus in the Theaceae. De Candolle (1830) was the most significant of these authors and Korthals (1851) was the last author to use Mephitidia for the Malesian species in taxonomic publications. Later, Lasianthus Jack has been conserved for the genus treated here. Blume (1823) described from Java a monotypic genus Lito santhes, which is closely related to Lasianthus. Inherently Ridley (1923a) reduced this genus to a section of Lasianthus, however Bakhuizen van den Brink (1965) retained Litosanthes as a separate genus based on three characters: imbricate corolla, forked stipules, and pedunculate inflorescences. Deb & Gangopadhyay (1991) transferred some Indian taxa to Litosan thes, but subsequently Gangopadhyay & Chakrabarty (1992) reduced these taxa of Litosanthes to a section of Lasianthus (see section below).The circumscription of Lasianthus Jack was more or less modified by later authors, especially referring to the number of ovary locules or pyrenes. In Jack's description Lasianthus has ovaries with 4 locules each with a single basal erect ovule, which normally develops into a drupe with 4 pyrenes. Blume (1826-1827) followed Jack's view, but described more variation based on more Malesian species: 4-9 locules and a drupe with 4-9 pyrenes. Wight (1846) modified the genus by adding a species with a 2-locular ovary and drupes with 2 pyrenes (L. foetens Wight = Saprosma foetens (Wight) K.Schum. (1891)). Korthals (1851) established a subgenus of Dysosmia based on a Javanese species Mephitidia dichotoma Ko...

Antibacterial Activity of Three Medicinal Lasianthus (Rubiaceae) Extracts on Human Resistant Pathogenic Bacteria

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Three New Taxa and a New Record of Lasianthus (Rubiaceae) in Thailand

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The Genus Lasianthus (Rubiaceae) in Wawonii Island, Southeast Sulawesi, Indonesia

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“…However, the centre of its diversity is concentrated in the Malesian region with 131 species enumerated (Zhu et al, 2012), with new species still being discovered as more botanical explorations were conducted in Southeast Asia.…”