About the Author(s)


John C. Manning Email symbol
Compton Herbarium, South African National Biodiversity Institute, South Africa

Research Centre for Plant Growth and Development, University of KwaZulu-Natal, South Africa

Anthony R. Magee symbol
Compton Herbarium, South African National Biodiversity Institute, South Africa

Department of Botany and Plant Biotechnology, University of Johannesburg, South Africa

Citation


Manning, J.C. & Magee, A.R., 2018, ‘Additional new combinations in Sesamum L. (Pedaliaceae: Sesameae)’, Bothalia 48(1), a2363. https://doi.org/10.4102/abc.v48i1.2363

Nomenclatural Change

Additional new combinations in Sesamum L. (Pedaliaceae: Sesameae)

John C. Manning, Anthony R. Magee

Received: 26 Apr. 2018; Accepted: 30 May 2018; Published: 19 July 2018

Copyright: © 2018. The Author(s). Licensee: AOSIS.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Background: Ongoing systematic studies in the African flora necessitate periodic nomenclatural adjustments and corrections.

Objectives: To effect requisite nomenclatural changes.

Method: Relevant literature was surveyed and requisite nomenclatural transfers provided.

Results: The new combination Sesamum byngianum Christenh. proposed for Josephinia africana Vatke is superfluous as an available synonym exists.

Conclusions: The new combination Sesamum rosaceum (Engl.) J.C. Manning & Magee is also provided for Josephinia africana Vatke. Three new sectional combinations are provided to accommodate the species previously placed in Ceratotheca Endl., Josephinia Vent. and Dicerocaryum Bojer in the current infrageneric classification of Sesamum.

Introduction

Pedaliaceae are a family of 60–70 species from the Old World tropics and subtropics, mainly in sub-Saharan Africa, with 13 genera traditionally recognised (Christenhusz, Fay & Chase 2017a; Ihlenfeldt 1988). Recent molecular phylogenetic analyses of the family confirm that the tribes Pedalieae Dumort., Sesameae (Endl.) Meisn. and Sesamothamneae Ihlenf. are monophyletic, but that the genus Sesamum L. is not (Gormley, Bedigian & Olmstead 2015).

Tribe Sesameae is recognised by its axillary flowers with obliquely campanulate, pink to purple corolla; anthers with parallel, oblong thecae; and the development of false-septa dividing the ovary and fruit locules (Ihlenfeldt 1988). It has traditionally been treated as comprising the four genera Ceratotheca Endl. (2 spp.), Dicerocaryum Bojer (4 spp.), Josephinia Vent. (6 spp.) and Sesamum (21 spp.), essentially separated, like many of the genera in the family, by characters of the fruit. Thus, both Dicerocaryum and Josephinia are characterised by indehiscent fruits with the locules completely divided by false-septa, whereas Ceratotheca and Sesamum share dehiscent capsules with incompletely divided locules (Bruce 1953; Ihlenfeldt 1988). The development and position of spines on the fruits serve to separate the genera within these two groups: Dicerocaryum has flattened, discoid fruits bearing paired horns on a central disc; Josephinia has ovoid or subglobose fruits densely covered with small spines; Ceratotheca has obtuse or truncate capsules usually with a pair of horns on the distal angles; and Sesamum has acute, beaked capsules. These carpological developments are associated with modes of seed dispersal, with the indehiscent fruits adapted for zoochory and the capsular fruits adapted for anemochory.

Phylogenetic analyses of plastid (ndhF and trnLF) and nuclear (ETS) sequence data by Gormley et al. (2015) show convincingly that Sesamum is paraphyletic with respect to the remaining genera in the tribe, which fall within a clade including members of S. sect. Aptera and possibly also sect. Sesamum. This finding is borne out by both plastid and nuclear analyses, although sampling in the latter is not as comprehensive as in the former. Morphological support for this relationship is evident in the simple leaves of Ceratotheca, Dicerocaryum and Josephonia, a condition shared with S. sect. Aptera (some of the other sections have palmate leaves) and in the seeds of Ceratotheca (the only one of the three genera with dehiscent fruits), which are consistent with those of S. sect. Aptera in lacking wings but with a well-developed double fringe on the margins and with rugose-reticulate testal sculpturing. The molecular topology reproduced in Gormley et al. (2015) suggests an increasing shift in this clade from anemochory towards zoochory through the development of lateral horns, accompanied by shortening (or depression) of the capsule and loss of dehiscence.

On the basis of these findings, Sesamum can be rendered monophyletic only by splitting it into smaller segregates or by enlarging its circumscription to include the remaining three genera and 12 species in the tribe. The former option has no historical precedent, and Christenhusz, Fay and Byng (2017b) adopted and partially implemented the second option. Unfortunately, the new name Sesamum byngianum Christenh. that was proposed for Josephinia africana Vatke to avoid a later homonym for S. africanum Tod. (1866) is superfluous as an earlier available synonym exists and should have been used (McNeil et al. 2012: Art. 11.4). We provide the relevant combination here. We also provide three additional combinations at sectional level in order to integrate these taxa into the infrageneric classification of Sesamum, which currently includes the four sections Aptera Seidenst., Chamaesesamum Benth., Sesamopteris Endl. and Sesamum (Ihlenfeldt 1988).

Materials and methods

We examined the relevant literature and implemented the necessary nomenclatural changes following McNeil at al. (2012).

Results

Sesamum L., Sp. Pl.: 634 (1753).

Existing sections (see Ihlenfeldt 1988): sect. Aptera Seidenst., sect. Chamaesesamum Benth., sect. Sesamopteris Endl. and sect. Sesamum.

New sections:

Sect. Ceratotheca (Endl.) J.C. Manning & Magee, comb. et stat. nov. Ceratotheca Endl. in Linnaea 7: 5, tt. 1, 2 (1832). Type: C. sesamoides Endl. = S. sesamoides Byng & Christenh.

Sect. Josephinia (Vent.) J.C. Manning & Magee, comb. et stat. nov. Josephinia Vent., Jard. Malm. 2: 67, t. 67 (1804). Type: J. africana Vatke = S. rosaceum (Engl.) J.C. Manning & Magee.

Sesamum rosaceum (Endl.) J.C. Manning & Magee, comb. nov. Pretreothamnus rosaceus Endl. in Bot. Jahrb. 36: 228 (1905). Type: Kenya, ‘Northern Frontier Province, Jeroko’, Ellenbeck 2199 (B, holo.?).

Josephinia africana Vatke in Linnaea 43: 541 (1882). Sesamum byngianum Christenh. in GLOVAP Nomenclature 1, 4: 145 (2017b), as nom. nov. [non S. africanum Tod. (1866)]. Type: Kenya, ‘Teita District, Tsavo River’, Hildebrandt 2586 (B, holo.?).

Sect. Dicerocaryum (Boj.) J.C. Manning & Magee, comb. et stat. nov. Dicerocaryum Bojer in Ann. Sci. Nat., sér. 2, 4: 268 (1835). Type: D. sinuatum Bojer = S. zanguebarium (Lour.) J.C. Manning & Magee

Acknowledgements

The authors are grateful to the anonymous referees for valuable comments.

Competing interests

The authors declare that they have no financial or personal relationships that may have inappropriately influenced them in writing this article.

Authors’ contributions

J.C.M. and A.R.M. both contributed to all aspects of the research.

Funding

This research was supported by a grant from the National Research Foundation.

References

Bojer, W., 1835, ‘Descriptiones et icons plantae rariores quas in insulis Africae orientalis detexit anno 1824’, Annales des Sciences Naturelles, sér. 2, 4, 262–269.

Bruce, E.A., 1953, ‘Pedaliaceae’, in W.B. Turrill & E. Milne-Redhead (eds.), Flora of Tropical East Africa Pedaliaceae, pp. 1–23, Westminster, Crown Agents for the Colonies.

Christenhusz, M.J.M., Fay, M.F. & Chase, M.W., 2017a, Plants of the world, Kew Publishing, Kew and University of Chicago Press, Chicago, IL.

Christenhusz, M.J.M., Fay, M.F. & Byng, J.W., 2017b, GLOVAP Nomenclature Part 1, 4: 1–155, Plant Gateway, Bradford.

de Loureiro, J., 1790, Flora Cochinchensis, Ullyssipone, Lisbon.

Engler, A., 1905, ‘Pedaliaceae africanae III’, Botanische Jahrbücher 36, 228, 229.

Endlicher, S., 1832, ‘Ceratotheca, eine neue Pflanzengattung aus der Ordnung der Sesameen’, Linnaea 7, 1–42.

Gormley, I.C., Bedigian, D. & Olmstead, R.G., 2015, ‘Phylogeny of Pedaliaceae and Martyniaceae and the placement of Trapella in Plantaginaceae’, Systematic Botany 40, 259–268. https://doi.org/10.1600/036364415X686558

Ihlenfeldt, H.-D., 1988, ‘Pedaliaceae’, in E. Launert (ed.), Flora zambesiaca 8, 3, pp. 86–113, Flora Zambesiaca Managing Committee, British Museum, London.

Linnaeus, C., 1753, Species plantarum, Salve, Stockholm.

McNeil, J., Barrie, F.R., Buck, W.R., Demoulin, V., Greuter, W., Hawksworth, D.L. et al. (eds.), 2012, ‘International code of nomenclature for algae, fungi and plants (Melbourne Code)’, adopted by the Eighteenth International Botanical Congress Melbourne, Australia, July 2011, Regnum Vegetabile 154, Koeltz Scientific Books, Königstein.

Vatke, W., 1882, ‘Plantas in itinerere africano ab J.M. Hildebrandt collectas determinare pergit’, Linnaea 43, 507–541.

Ventenant, É.P., 1804, Jardin de la Malmaison, vol. 2, Crapelet, Paris.



Crossref Citations

No related citations found.