NOMENCLATURAL NOTE

 

The new combination Coleus leemannii (N.H.Hahn) A.J.Paton for Rabdosiella leemannii N.Hahn (Lamiaceae: Nepetoideae: Ocimeae)

 

 

John C. Manning^{I, II}; Alan J. Paton^III

^ICompton Herbarium, South African National Biodiversity Institute, Private Bag X7, Claremont 7735, South Africa
^IIResearch Centre for Plant Growth and Development, School of Life Sciences, University of KwaZulu-Natal, Pietermaritzburg, Private Bag X01, Scottsville 3209, South Africa
^IIIHerbarium, Royal Botanic Gardens, Kew, Richmond TW9 3AE, United Kingdom

Correspondence

 

 

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ABSTRACT

The new combination Coleus leemannii (N.Hahn) A.J.Paton is provided for Rabdosiella leemannii N.Hahn (Lamiaceae: Ocimeae) from South Africa, a species that was overlooked in the recent synopsis of subtribe Plectranthinae.

Keywords: new combination; nomenclature; South Africa; taxonomy

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Introduction

The genus Rabdosiella Codd (1984) was established for two species of Lamiaceae: Ocimeae that differed from other genera in the tribe in their densely paniculate synflorescences with ascending branches; erect, shortly cylindrical and distinctly 10-nerved fruiting calyx with suberect or incurved teeth; and declinate, basally saccate corolla. Rabdosiella was considered to be allied to both Plectranthus L'Hér. and Isodon (Schrad. ex Benth.) Spach (Codd 1975, 1985). In addition to the type species R. calycina (Benth.) Codd from southern Africa, the genus also included the southeast Asian R. ternifolia (D.Don) Codd.

A later morphological and cytological analysis (Ryding 1993) concluded not only that Rabdosiella was polyphyletic, but that its continued recognition was not justified; the southern African species being best returned to Plectranthus as P. calycinus Benth. and the Asian species readily accommodated in the genus Isodon under the name I. ternifolius (D.Don) Kudô.

These findings were supported by the subsequent molecular phylogenetic analyses of plastid DNA regions in Ocimeae by Paton et al. (2004) and Paton et al. (2018), which retrieved I. ternifolius deeply embedded among other species of Isodon and P. calycinus nested in the genus Plectranthus sensu lato in a subclade that included species of Pycnostachys Hook. and Holostylon Robyns & Lebrun. It was clear from these analyses that substantial changes in generic circumscriptions in Ociminae-Plectranthinae were required to render the genera monophyletic. As a result of these findings, Paton et al. (2018) proposed that Coleus be expanded to include all species in the clade containing the type of the genus, Plectranthus be restricted to the clade sister to Thorncroftia N.E.Br. plus Tetradenia Benth., and the new genus Equilabium Mwany., A.J.Paton & Culham be described for the clade containing the mainly tropical African species and Indian species formerly included in Plectranthus.

This taxonomic proposal was followed by a nomenclatural synopsis of the genera Coleus, Equilabium and Plectranthus (Paton et al. 2019). Rabdosiella (type species only) was among several genera that were included in the expanded circumscription of Coleus, and the new combination C. calycinus (Benth.) A.J.Paton for R. calycina was among the 130 new combinations that were provided in that genus. In its expanded circumscription, Coleus is a genus of 295 species of the Old World tropics and subtropics, diagnosed by an oblique-based calyx with the pedicel attached asymmetrically to the base of the tube opposite the posterior lip, and a strongly zygomorphic corolla with the upper lip mostly shorter than the cymbiform lower lip enclosing the declinate stamens (Paton et al. 2019).

Paton et al. (2019), however, overlooked the existence of a third species of Rabdosiella that had been described from southern Africa several decades after the revision of the genus by Codd (1985). Rabdosiella leemannii N.Hahn (Hahn & Bredenkamp 2007) is a narrow endemic of quartzitic substrates on the Sout-pansberg and Blouberg in Limpopo, South Africa. It is morphologically very close to R. calycina and the two species are evidently an edaphic-allopatric species-pair. It falls within the currently expanded circumscription of Coleus, and we provide the necessary new combination for R. leemannii in Coleus here.

Coleus leemannii (N.Hahn) A.J.Paton, comb. nov. Rabdosiella leemannii N.Hahn in Hahn & Bredenkamp in Bothalia 37(1): 37 (2007). Type: South Africa, Limpopo, 2329 (Polokwane): Soutpansberg, Lejuma, (-AB), 13 Apr 2005, N. Hahn 2086 (ZPB, holo.; PRE!, PRU, iso.).

 

References

Codd, L.E., 1975, 'Plectranthus and allied genera in southern Africa', Bothalia 11, 371-442.         [ Links ]

Codd, L.E., 1984, 'The genus Isodon (Schrad. ex Benth.) Spach in Africa and a new genus Rabdosiella Codd', Bothalia 15, 7-10.         [ Links ]

Codd, L.E., 1985, 'Lamiaceae', in O.A. Leistner (ed), Flora of southern Africa 28(4), 1-247, Botanical Research Institute, Pretoria.         [ Links ]

Hahn, N. & Bredenkamp, G.J., 2007, 'Rabdosiella leemannii (Lamiaceae), a new species from the Limpopo Province of South Africa', Bothalia 37(1), 37-40.         [ Links ]

Paton, A.J., Springate, D., Suddee, S., Otieno, D., Grayer, R.J., Harley, M.M., Willis, F., Simmonds, S.J., Powell, M.P & Savolainen, V., 2004, 'Phylogeny and evolution of basils and allies (Ocimeae, Labiatae) based on three plastid DNA regions', Molecular Phylogenetics and Evolution 31, 277-299, https://doi.org/10.1016/j.ympev.2003.08.002.         [ Links ]

Paton, A.J., Mwanyambo, M. & Culham, A., 2018, 'Phylogenetic study of Plectranthus, Coleus and allies (Lamiaceae): Taxonomy, distribution and medicinal uses', Botanical Journal of the Linnean Society 188(4), 355-376, https://doi.org/10.1093/botlinnean/boy064.         [ Links ]

Paton, A.J., Mwanyambo, M., Govaerts, R., Smitha, K., Suddee, S., Phillipson, P.B., Wilson, T.C., Forster, P.I. & Culham, A., 2019, 'Nomenclatural changes in Coleus and Plectranthus (Lamiaceae): a tale of more than two genera', PhytoKeys 129, 1-158, https://doi.org/10.3897/phytokeys.129.34988.         [ Links ]

Ryding, O., 1993, 'A reconsideration of the genus Rabdosiella (Lamiaceae, Nepetoideae, Ocimeae)', Plant Systematics and Evolution 185(1/2), 91-97.         [ Links ]

 

 

Correspondence:
John C. Manning
E-mail: j.manning@sanbi.org.za

Submitted: 15 June 2022
Accepted: 11 November 2022
Published: 10 January 2023