Thesium hispidifructum (Santalaceae), a New Hispidulous Species from Limpopo, South Africa and Notes on Enigmatic T. celatum

• Published in: Taxonomy (Basel, Switzerland) Vol. 3; no. 1; pp. 95 - 108
• Main Authors: Lombard, Natasha, Le Roux, M. Marianne
• Format: Journal Article
• Language: English
• Published: Vienna MDPI AG 01.03.2023
• Subjects: Blouberg; endemic; Flowers & plants; hemi-parasite; Leaves; Morphology; new species; Psilothesium; Software; Taxonomy; Thesiaceae; South Africa; Botswana
• ISSN: 2673-6500; 2673-6500
• DOI: 10.3390/taxonomy3010009

Two shrub-like Thesium species (subgenus Psilothesium) from the Limpopo and North West Provinces in South Africa are treated. Using morphological information from the literature, herbarium material (including types) and geographic information, specimens of the little-known T. celatum N.E.Br. and a new species, T. hispidifructum N.Lombard and M.M.leRoux sp. nov., are treated. A first comprehensive description of the Waterberg–Magaliesberg endemic, T. celatum, is provided along with diagnostic characters to distinguish it from its morphologically most similar-looking species, T. burchellii A.W.Hill. It has hitherto been classified as data deficient due to taxonomic reasons by the International Union for Nature Conservation (IUCN) but a status of Vulnerable is suggested. Thesium hispidifructum is recognised for the first time here and is endemic to Blouberg and Mount Letsjume. It is morphologically most similar to T. disparile N.E.Br. Its name was chosen with reference to its hispidulous to hispid indumentum covering the entire plant including the outside of the flowers and fruit. A threat status of vulnerable is proposed. Treatments of both species include detailed morphological descriptions, information on their distribution and habitat, comparisons and an identification key with morphologically similar species and photo plates.