A taxonomic revision of the twelve-scaled species of struthiola (thymelaeaceae: thymelaeoideae): the struthiolamundiig roup
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Date
2025
Journal Title
Journal ISSN
Volume Title
Publisher
Elsevier
Abstract
Struthiola L. (Thymelaeaceae: Thymelaeoideae) is a genus of approximately 40 species (Wright, 1915; manning and goldblatt, 2012) largely endemic to South Africa, but with four species in tropical Africa (Peterson, 1958, 1978, 2006). the Greater Cape Floristic Region (GCFR) is the centre of diversity for the genus, as well as for several other related southern African Thymelaeoideae, including Gnidial., Lachnaea l. and Passerina l. Almost all of the South African species of Struthiola are restricted to the GCFR (manning and goldblatt, 2012; Snijman, 2013), with only three of the South African species occurring beyond the region in the grasslands of KwaZulu-Natal (Wright, 1915; hilliard and burtt, 1986; Hilliard, 1993).
Struthiola l. was established by Linnaeus (1767) in his Systema Naturae ed. 12 for two species of Thymelaeaceae that were characterised by flowers with just four anthers and petaloid scales (incorrectly described as nectary glands) and subsequently conserved against the earlier name Belvala Adans. (1763) with the conserved type S. erecta l. The genus was last revised more than a century ago by Wright (1915), and as the taxonomy of the southern African species remains poorly understood it has been identified as one of the priority groups for taxonomic revision (Victor et al., 2015; Victor, 2020). Meisner (1857), in his global treatment of Thymelaeaceae, subdivided the genus into three morphological groups based on the number of petaloid scales in the mouth of the hypanthium, viz. four, eight or 12. All subsequent authors have retained these informal subdivisions.
The molecular analyses by Makhoba (2024) recovered the species with four scales (the Struthiola striata group) and those with 12 scales (the Struthiola mundii group) as two independent clades nested within the remaining species of the genus, all with eight scales. This confirms the value of the putatively derived scale-numbers of four and 12 in identifying relationships in the genus. The four-scaled S. striata group was recently revised (Makhoba et al., 2019) as a first step towards a comprehensive revision of the genus. As the next step we present a revision of the twelve-scaled species comprising the S. mundii group.
Twelve species and three varieties were recognized in the S. mundii group at the onset of this study. Characters such as habit, flower colour, presence or absence of hairs on the hypanthium, hypanthium length, shape of the petaloid scales and the colour of the associated hairs, bracteole length, and presence or absence
Description
Keywords
Hypanthium, Southern Africa, Struthiola, Taxonomy, Typification
Citation
Makhoba, Thuli & Boatwright, James & Magee, Anthony & Manning, John. (2025). A taxonomic revision of the twelve-scaled species of Struthiola (Thymelaeaceae: Thymelaeoideae): the Struthiola mundii group. South African Journal of Botany. 183. 202-217. 10.1016/j.sajb.2025.05.044.