A tough nutlet to crack: Resolving the phylogeny of Thesium (Thesiaceae), the largest genus in Santalales Author García, Miguel A. Ladislav Mucina & Real Jardín Botánico-CSIC, Plaza de Murillo Author Mucina, Ladislav & Daniel L. Nickrent & 28014 Madrid, Spain & Harry Butler Institute, Murdoch University, 90 South Street, Murdoch 6150, Perth, Australia & & Daniel L. Nickrent & Department of Geography and Environmental Studies, Stellenbosch University, Stellenbosch, South Africa Author Nickrent, Daniel L. Plant Biology Section, School of Integrative Plant Science, 332 Emerson Hall, College of Agriculture and Life Science, text TAXON 2024 2024-02-29 73 1 190 236 http://dx.doi.org/10.1002/tax.13123 journal article 10.1002/tax.13123 1996-8175 14047584 0. Lacomucinaea clade (BIPP 1). — Lacomucinaea lineata (L.f.) Nickrent & M. A .García ( Fig. 3A ), previously known as Thesium lineatum , was classified as a distinct genus by Nickrent & García (2015) based on molecular and morphological evidence. This genus is sister to Osyridicarpos and that clade is sister Thesium , relationships with the highest support from both ITS and the chloroplast genes ( Fig. 2A ). One may ask why Lacomucinaea was not included within Osyridicarpos . These two genera share several morphological features, e.g., primary phloem fiber bundles near the stem surface, bisexual flowers, lack of a swollen pedicel, and fleshy fruits with smooth exocarps. They differ in other characters such as habit (shrub vs. scrambling subshrub), leaf morphology, leaf persistence, inflorescence structure, presence of external floral gland, style length and ribbing on ovary. Four species have been described in Osyridicarpos although it is frequently treated as monotypic ( O. schimperianus ). Further studies might prove that several species should be recognized in the genus, all of them very different from Lacomucinaea . Thus, the preponderance of molecular and morphological evidence justifies recognition of two genera.