NOMENCLATURAL NOTE

 

New infrageneric taxa in Leucospermum (Proteaceae) and Tetragonia L. (Aizoaceae) and a new name in Aizoon subgenus Galenia (Aizoaceae) in southern Africa

 

 

John C. Manning^{I, II}; Cornelia Klak^III

^IFoundational Biodiversity Science Directorate, Compton 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
^IIIBolus Herbarium, Department of Biological Sciences, University of Cape Town, Rhodes Gift 7707, South Africa

Correspondence

 

 

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ABSTRACT

New infrageneric taxa are described in Leucospermum R.Br. (Proteaceae) and Tetragonia L. (Aizoaceae) to accommodate species that are currently unplaced in the respective generic classifications. Leucospermum section Hamata J.C.Man-ning is described to accommodate the relatively recently described L. hamatum Rourke and L. harpagonatum Rouke, and L. section Secundifolia J.C.Manning for L. secundifolium Rourke, which was unplaced following the transfer of the type of L. section Xericola Rourke to the genus Vexatorella Rourke. In Tetragonia L., T. series Echinatae J.C.Manning & Klak is described for three species that were left unplaced following their exclusion from subgenus Tetragonoides DC. In addition, the three series T. series Chenopodinae, series Pedunculares and series Macran-thae are incorrectly attributed to Fenzl and are shown to be combinations by Adamson of unranked taxa published by Fenzl. In Aizoon L., we replace the illegitimate name, A. procumbens (L.f.) Klak, with the new name A. flavescens Klak.

Keywords: nomenclature; Leucospermum section Hamata; Leucospermum section Secundifolia; Tetragonia series Echinatae.

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Introduction

Advancements in our understanding of species relationships, either from increased phylogenetic insights or from additional discoveries, can result in modifications to existing generic taxonomies. These modifications may happen long after the original classifications were established, and their nomenclatural ramifications may not always be apparent at the time. Two such oversights in the South African flora were uncovered during the preparation of species lists for curatorial purposes. Both are the result of the transfer of the type species of a section or series to another taxon, whilst retaining the remainder of the species in the original section or series without making the necessary nomen-clatural changes to accommodate these species. These 'orphan' species thus lack any position within the existing formal classifications. This poses problems for both the curation of these genera and for future testing of the classifications, and also for increasing the democratisation of biological knowledge, which demands the rapid assimilation of new data within existing frameworks.

Here we describe new sections in the genera Leucospermum R.Br. (Proteaceae) and Tetragonia L. (Aizoaceae) that are required to accommodate a handful of species that are currently unplaced in these genera, following the transfer of the type species of the relevant section or series to some other taxon. In addition, in Aizoon L. (Aizoaceae) we propose a new name for the illegitimate Aizoon procumbens (L.f.) Klak, which was found to be an earlier homonym of A. procumbens Crantz.

 

Taxonomy

1. Leucospermum

R.Br. (Proteaceae: Proteoideae)

Leucospermum R.Br. (Proteaceae: Proteoideae) is a genus of 48 species from temperate southern Africa, where it is concentrated in the Greater Cape Floristic region, extending along the Eastern Escarpment into eastern Zimbabwe (Rourke 1972, 1994). The genus was monographed by Rourke (1972), at which time the 47 accepted species were segregated among nine sections. Since then an additional three species have been described (Rourke 1979, 1983, 1994) and two have been transferred to the genus Vexatorella Rourke (Rourke 1984).

The genus Vexatorella Rourke (1984) was established following the discovery of an undescribed species of Proteoideae that could not be accommodated within any of the existing genera. It resembled Leucospermum in floral morphology but differed from that genus in its terminal (vs. lateral) inflorescences. The accrescent, woody floral bracts were also anomalous in Leucospermum but were common in the genus Leucadendron R.Br. Both characters were also identified in two of the three species of Leucospermum section Xericola Rourke, and they were accordingly transferred to Vexatorella. One of them, L. alpinum (Salisb. ex Knight) Rourke, was the type of the section, leaving just L. secundifo-lium Rourke still in Leucospermum but now unplaced to section. We describe the new section Secundifolia to accommodate this species.

Two of the three species of Leucospermum that were described after the publication of the generic monograph by Rourke (1972), L. hamatum Rourke (1983) and L. harpagonatum Rourke (1994), constitute a pair of morphologically similar taxa that are interpreted as closely allied geographical vicariads (Rourke 1994). They cannot be accommodated within the existing classification of the genus and Rourke (1994) was explicit in stating that 'the two species should be placed within a distinct section of their own'. This section was not erected. Currently the two species are treated under the unpublished group name Hamatum in online resources (Identifying Pincushions, viewed on 28 October 2021, from https://www.proteaatlas.org.za/pin-cushid.htm). We describe the new section Hamata to accommodate these two species.

Finally, although the affinities of the third pincushion species to be described, L. winteri Rourke (1979), were not immediately evident, Rourke (1979) suggested an affinity to certain members in section Crinita Rourke and it can be satisfactorily accommodated here.

Leucospermum R.Br. in Transactions of the Linnean Society, London 10: 95 (1810), nom. cons. Type: L. hypophyllocarpodendron (L.) Druce.

Section Hamata J.C.Manning, sect. nov. Type: L. hamatum Rourke

Prostrate, mat-forming shrublets. Leaves gla-brescent, entire, obtuse or 3-toothed. Inflorescence turbinate, 15-30 mm diam. Perianth pink or off-white, tube inflated or utriculose. Style retrorsely barbed, recurved distally. Stigma conical.

Species: L. hamatum Rourke, L. harpagonatum Rourke

Section Secundifolia J.C.Manning, sect. nov. Type: L. secundifolium Rourke

Prostrate or decumbent, mat-forming shrublets. Leaves glabrous, thick and cartilaginous, entire, obtuse or rarely 3-toothed. Inflorescence small, globose, 10-15 mm diam.; bracteoles accrescent and woody. Perianth pink or whitish pink, tube subcylindric. Style glabrous, suberect. Stigma clavate.

Species: type only

2. Tetragonia L. (Aizoaceae: Aizooideae)

Tetragonia L. (Aizoaceae: Azooideae) as recently re-circumscribed, is a genus of ± 50 species from temperate and subtropical regions, mainly in the southern Hemisphere (Klak et al. 2017). The southern African taxa were last revised by Adamson (1955), and this remains the current treatment for the species in the region. In his classification, Adamson (1955) segregated the species among the four subgenera Tetragonia, Tetragonoi-des DC., Anisostigma (Schinz) Engl. and Tribulocarpus (S.Moore) Adamson, defined by several characters of the fruits and flowers. The recent molecular phyloge-netic analysis of the subfamily by Klak et al. (2017), however, uncovered some unexpected relationships among the species that necessitated realignments among several taxa in order to render them mono-phyletic. Among these was the removal of Tetragonia subgenus Anisostigma and subgenus Tribulocarpus to the new tribe Anisostigmateae Klak in subfamily Sesu-vioideae as the genera Anisostigma Schinz and Tribulo-carpus S.Moore respectively.

In addition to these changes, the circumscription of Tetragonia subgenus Tetragonoides was greatly altered by the removal from it of most of the southern African taxa previously included there by Adamson (1955). Tetragonia subgenus Tetragonoides is now understood to be essentially Australasian in distribution, with the exception of the cosmopolitan littoral species T. tetragonoides (Pall.) Kuntze, the type of the subgenus. Two additional subgenera, subgenus Tetragonella (Miq.) Klak and subgenus Americanae Klak were established to accommodate respectively the other Australasian and the American species (Klak et al. 2017).

The remaining four southern African species that were included by Adamson (1955) in subgenus Tetragonoides were retrieved by Klak et al. (2017) as a clade sister to subgenus Tetragonia and were accordingly included in it, with the observation that the 'series erected by Adamson (1955) should be maintained'. This alludes to the seven sections recognised by Adamson (1955) in subgenus Tetragonia. Although they included these additional four former members of subgenus Tetragonoi-des in subgenus Tetragonia, Klak et al. (2017) did not accommodate them within the existing classification.

Significantly, the removal of T. tetragonoides from this group renders it morphologically more homogenous. The four species share a prostrate, ± annual habit and half-inferior ovary, and differ from all other members of subgenus Tetragonia in having the stamens less than twice as many as the perianth segments vs. more than twice as many as the perianth segments (Adamson 1955). The new series Echinatae J.C.Manning & Klak is accordingly proposed here to accommodate them.

There are two other nomenclatural corrections required in subgenus Tetragonia. The first concerns the authorities for the infrageneric names that were published by Fenzl (1862). Adamson (1955) treats these as series, with Fenzl (1862) as author. However, examination of Fenzl (1862) reveals that they were published as third tier names two ranks below sectional level but without a definite rank. Although they are to be accepted as validly published by Fenzl (1862) they are to be treated as unranked (Turland et al. 2018: 'Art. 37.3. A name published before 1 January 1953 without a clear indication of its rank is validly published provided that all other requirements for valid publication are fulfilled; it is, however, inoperative in questions of priority except for homonymy. If it is the name of a new taxon, it may serve as a basionym or replaced synonym for subsequent new combinations, names at new ranks, or replacement names at definite ranks.'). Their later publication by Adamson (1955) with a clear indication of the rank of series serves as the first publication at that rank and they are therefore to be treated as combinations by Adamson (1955).

The second correction concerns the status of the series that includes the type of the genus, T. fruticosa L. Although the genus Tetragonia was only lectotypified by Britton (1918) after the treatment by Fenzl (1862), the name T. [unranked] Fruticulosae Fenzl. (1862) is to be treated as not validly published [Turland et al. 2018: 'Art. 22.2. A name of a subdivision of a genus that includes the type (i.e. the original type or all elements eligible as type or the previously designated type) of the adopted, legitimate name of the genus is not validly published unless its epithet repeats the generic name unaltered. For the purposes of this provision, explicit indication that the nomenclaturally typical element is included is considered as equivalent to inclusion of the type, whether or not it has been previously designated. ']. Similarly, the publication of this taxon at series rank (spelled Fruticosae) by Adamson (1955) is to be treated as not validly published. The correct name for this taxon is series Tetragonia (Turland et al. 2018: 'Art. 22.1. The name of any subdivision of a genus that includes the type of the adopted, legitimate name of the genus to which it is assigned is to repeat that generic name unaltered as its epithet, not followed by an author citation.').

The species of Tetragonia subgenus Tetragonia are thus distributed among eight series as follows:

Tetragonia L., Species plantarum 1: 480 (1753). Type: T. fruticosa L., lecto., designated by Britton, Flora of Bermuda: 125 (1918).

Series Tetragonia

Tetragonia [unranked] Fruticulosae Fenzl in Flora capensis 2: 460 (1892), nom. inval.

Tetragonia series Fruticulosae Adamson in Journal of South African Botany 21: 112 (1955), nom. inval.

Species: T. arbuscula Fenzl, T. arbusculoides Engl., T. calycina Fenzl, T. fruticosa L., T. glauca Fenzl, T. macroptera Pax, T. reduplicata Welw. ex Oliv., T. rangeana Engl., T. spicata L.f., T. vir-gata Schltr.

Note: The Chilean species T. macrocarpa Phil. was erroneously included in this series by Klak et al. (2017) instead of the southern African T. macroptera Pax.

Series Robustae Adamson in Journal of South African Botany 21: 123 (1955). Type: T. robusta Fenzl.

Species: T. distorta Fenzl, T. robusta Fenzl, T. sarcophylla Fenzl

Series Salignae Adamson in Journal of South African Botany 21: 127 (1955). Type: T. saligna Fenzl.

Species: T. erecta Adamson, T. haworthii Fenzl, T. lasiantha Adamson, T. saligna Fenzl

Series Decumbentes Adamson in Journal of South African Botany 21: 130 (1955). Type: T. de-cumbens Mill.

Species: T. decumbens Mill., T. namaquensis Schltr., T. verrucosa Fenzl

Series Macranthae (Fenzl) Adamson in Journal of South African Botany 21: 133 (1955). T. [un-ranked] Macranthae Fenzl in Flora capensis 2: 461 (1892). Type: T. hirsuta L.f.

Species: T. hirsuta L.f., T. rosea Schltr.

Series Pedunculares (Fenzl) Adamson in Journal of South African Botany 21: 135 (1955). T. [un-ranked] Pedunculares Fenzl in Flora capensis 2: 460 (1892). Type: T. herbacea L., lecto., designated by Adamson: 135 (1955).

Species: T. halimoides Fenzl, T. herbacea L., T. nigrescens Eckl. & Zeyh., T. portulacoides Fenzl, T. sphaerocarpa Adamson

Series Chenopodinae (Fenzl) Adamson in Journal of South African Botany 21: 141 (1955). T [un-ranked] Chenopodinae Fenzl in Flora capensis 2: 460 (1892). Type: T. chenopodioides Eckl. & Zeyh., lecto., designated by Adamson: 141 (1955).

Species: T. chenopodioides Eckl. & Zeyh., T. ga-lenioides Fenzl. T. pillansii Adamson

Series Echinatae J.C.Manning & Klak, ser. nov. Type: T. echinata Aiton.

Prostrate ± annual herbs. Flowers sessile or subsessile, solitary or in small groups. Stamens as many as and alternating with perianth segments, sometimes in pairs, or sometimes fewer. Ovary half-inferior. Fruit not winged, often with ridges or projections at top or sides.

Species: T. acanthocarpa Adamson, T. caesia Adamson, T. echinata Aiton, T. microptera Fenzl

Note: The accession identified as 'T microptera (voucher Klak 2430, BOL)' in Klak et al. (2017)

was subsequently found to be misidentified, and true T. microptera was thus never included in the analysis. This species is therefore placed in series Echinatae based on the morphological characteristics that it shares with the other species in this series (Adamson 1955).

3. Aizoon L. (Aizoaceae: Aizooideae)

The generic circumscription of Aizoon L. (Aizooideae, Aizoaceae) was recently enlarged to include those species previously treated in the genus Galenia L. (Klak et al. 2017). In its new circumscription, Aizoon is recognized by capsules with reduced expanding tissue, and leaves and/or stems covered by silvery hairs or hair-like to rounded papillae. The species previously placed in Galenia subgenus Galenia were transferred to Aizoon subgenus Galenia (L.) Klak, which now includes six species. Among these, the new combination A. procum-bens (L.f.) Klak proposed by Klak et al. (2017) for G. procumbens L.f. (1782) is, however, a later homonym of A. procumbens Crantz (1766: 135). Consequently, the proposed name is illegitimate (Turland et al. 2018: Art. 53.1 and 53.2), and a replacement name is required.

Although this species was originally described as 'procumbent', most forms are erect shrublets, some of which have been grouped under the manuscript name 'Galenia flavescens', which alludes to the yellow to orange colour of the leaves (Adamson, 1956: 96). Since a new name is required, this unpublished epithet is taken up here.

Aizoon flavescens Klak, nom. nov. pro Galenia procumbens L.f., Supplementum plantarum: 227 (1782). Aizoon procumbens (L.f.) Klak in Taxon 66: 1163 (2017), nom. illeg., non A. procumbens Crantz in Institutiones Rei Herbariae 1: 135 (1766).

 

REFERENCES

Adamson, R.S., 1955, 'The South African species of Aizoaceae. II. Tetragonia', Journal of South African Botany 21, 109-154.         [ Links ]

Adamson, R.S., 1956, 'The South African species of Aizoa-ceae. III. Galenia', Journal of South African Botany 22, 87-127.         [ Links ]

Britton, N.L., 1918, Flora of Bermuda, Charles Scribner's Sons, New York.         [ Links ]

Brown, R., 1810, 'Leucospermum', Transactions of the Linne- an Society, London 10, 95-104.         [ Links ]

Crantz, H.I.N., 1766, Institutiones Rei Herbariae juxta nutum Naturae Digestae ex Habitu 1, 135-136, Krauss, Vienna.         [ Links ]

Fenzl, E., 1862, 'Tetragonia L.', in W.H. Harvey & O.W. Sonder, Flora capensis 2, 460-469, L. Reeve & Co., Kent.         [ Links ]

Klak, C., Hanáček, P. & Bruyns, P.V., 2017, 'Disentangling the Aizooideae: New generic concepts and a new subfamily in Aizoaceae', Taxon 66, 1147-1170.         [ Links ]

Linnaeus, C., 1753, Species plantarum, Salvius, Stockholm.         [ Links ]

Linnaeus, C. (fil.), 1782 ['1781'], Supplementum plantarum, Orphanotropheus, Brunswick.         [ Links ]

Rourke, J.P, 1972, 'Taxonomic studies on Leucospermum R.Br.', Journal of South African Botany, Supplementary Volume No. 8.         [ Links ]

Rourke, J.P, 1979, 'Leucospermum winteri', Flowering Plants of Africa 45, t. 1781.         [ Links ]

Rourke, J.P, 1983, 'A remarkable new Leucospermum Pro-teaceae) from the southern Cape', Journal of South African Botany 49, 213-219.         [ Links ]

Rourke, J.P, 1984, 'Vexatorella Rourke, a new genus of the Proteaceae from southern Africa', Journal of South African Botany 50: 373-391.         [ Links ]

Rourke, J.P, 1994, 'A new species of Leucospermum (Proteaceae) from the southwestern Cape', Bothalia 24, 167-170.         [ Links ]

Turland, N.J., Wiersema, J.H., Barrrie, F.R., Greuter, W., Hawksworth, D.L., Herendeen, PS., Knapp, S., Kusber, W.-H., Li, D.-Z., Marhold, K., May, T.W., McNeil, J., Monro, A.M., Prado, J., Price, M. J. & Smith, G.F. (eds.), 2018, International Code of Nomenclature for algae, fungi, and plants (Shenzhen Code) adopted by the Nineteenth International Botanical Congress Shenzhen, China, July 2017, Regnum Vegetabile 159, Koeltz Botanical Books, Glashütten. https://doi.org/10.12705/Code.2018.         [ Links ]

 

 

Correspondence:
John Manning;
e-mail: J.Manning@sanbi.org.za

Submitted: 2 November 2021
Accepted: 2 June 2022
Published: 18 July 2022