[Botany • 2024] Marijordaania filiformis (Celastraceae: Cassinoideae) • A New monotypic Genus from South Africa

Marijordaania A.E.van Wyk & R.G.C.Boon, gen. nov.
Marijordaania filiformis (Davison) A.E.van Wyk & R.G.C.Boon, comb. nov.

in van Wyk et Boon, 2024. 

 DOI: 10.5091/plecevo.116544

Abstract

Background and aims – The species name Gymnosporia filiformis, validly published in a 1927 revision of South African Celastraceae, was based on syntypes representing both Maytenus cordata and a new species. Subsequent studies supported the distinction of Gymnosporia and Maytenus as separate genera. From 1984, this new species was provisionally referred to by the designation “Maytenus sp. A”. Maytenus in Africa comprises a diverse group of species not closely related to the New World members of Maytenus. Here, we clarify the taxonomic identity and generic placement of G. filiformis, and compare it with species with which it has historically been confused.

Material and methods – Descriptions and observations are based on extensive field work, supported by conventional taxonomic methods, including study of relevant literature and herbarium collections.

Key results – The name Gymnosporia filiformis is lectotypified using a syntype representing “Maytenus sp. A”. We describe a new monotypic genus, Marijordaania, to accommodate “Maytenus sp. A”, and propose the new combination, Marijordaania filiformis. An amended description is provided for the species. It is morphologically quite different from Maytenus cordata, but also from Maytenus acuminata and Maytenus abbottii, species with which it has been confused in the past. Marijordaania filiformis grows in the understorey of evergreen Scarp Forest and is relatively rare, known with certainty only from KwaZulu-Natal and the Eastern Cape provinces, South Africa. A preliminary conservation assessment suggests that M. filiformis should be classified as Endangered.

Conclusion – Marijordaania filiformis is a taxonomically isolated species with no apparent close relatives among African Celastraceae. While the generic status of other African members of Maytenus still needs to be resolved, it would not impact the taxonomic status of Marijordaania. In a recent key for Celastraceae genera based on morphology and geography, M. filiformis ran to the genus Euonymus, but this association lacks support from available molecular evidence.

Keywords: Celastreae, Celastroideae, gutta-percha, lectotypification, Maputaland-Pondoland-Albany Hotspot, new genus, Pondoland Centre, Scarp Forest, taxonomy

Marijordaania filiformis.
 A. Flowering branchlet, viewed from below; note distichous arrangement of leaves. B. Branchlet showing flowers borne on long, slender, and pendant pedicels; also present is a young developing fruit. C. Flowers; note each stamen inserted on a swollen discoid subunit of the disc. D. Flower viewed obliquely from the side. E. Flower, viewed from below. F. Fruit, intact and almost mature. G. Fruit, dehisced, showing a dark-coloured seed partly covered by a white aril.

Photographs A–C by Sharon Louw; D–G by Richard Boon.

Marijordaania A.E.van Wyk & R.G.C.Boon, gen. nov.

 

Diagnosis: A member of Celastraceae, subfamily Cassinoideae (sensu Simmons et al. 2023), belonging to a clade of African members of the family (sensu McKenna et al. 2011), but taxonomically isolated without obvious close relatives. Often confused with Maytenus cordata, but distinguished from this and other unarmed African species still placed in Maytenus by the following combination of characters: shrub or small tree, without elastic threads (gutta-percha; trans-1,4-polyisoprene); stems distinctly angular when young; inflorescences cymose, 1- or 2(3)-flowered; flowers 5-merous, with pedicel slender, pendant, usually 35–40 mm long, articulated ca 0.5 mm from the base; floral disc present, fleshy, distinctly divided into 5 discoid subunits (lobes), the latter raised and alternating with the petals; stamens 5, each inserted in the centre of a discoid subunit; filaments very short (ca 1 mm); anthers dorsifixed; ovary 5-locular, almost entirely included in and adnate to the disc, with 2 erect collateral ovules in each locule; style ca 0.5 mm long, stigma capitate; fruit a loculicidally dehiscing capsule; seeds lacking postchalazal vascular bundles, with the basal portion enveloped for ca two-thirds or more its length with a fleshy, white aril, the latter mostly smooth-surfaced, but sparsely puberulent towards the base.

Etymology: The generic name commemorates Dr Marie Jordaan (née Prins) [1948–], in recognition of her considerable contributions towards the taxonomy of the southern African flora in general, and the Celastraceae in particular.

Marijordaania filiformis (Davison) A.E.van Wyk & R.G.C.Boon, comb. nov.

Vernacular names: English vernacular names in use are “red-flowered false silkybark” and “red-flowered silkybark”, and Afrikaans names are “rooiblomvalssybas” and “rooiblomsybas” (Boon 2010; Van Wyk et al. 2011). The first mentioned of these English and Afrikaans names are the ones recommended by the Dendrological Society of South Africa (Von Dürckheim et al. 2014). No names have been recorded in any of the other local languages.

 Abraham E. van Wyk and Richard G.C. Boon. 2024. Marijordaania (Celastraceae: Cassinoideae), A New monotypic Genus from South Africa. Plant Ecology and Evolution. 157(1): 100-112. DOI: 10.5091/plecevo.116544