LEONARD E. NEWTON1 & JOACHIM THIEDE2
Rank adjustments for the infraspecific taxa of Sansevieria pinguicula P.R.O.Bally (Asparagaceae/Dracaenaceae) Summary
Considerations of morphology and geographical distribution suggest that two recently described infraspecific taxa of Sansevieria pinguicula P.R.O. Bally were given inappropriate ranks. It is proposed that subspecies disticha, occurring together with the type in habitat and differing in only one character, should be reduced to the rank of form. It is proposed that variety nana, which occurs at some considerable distance from the type and differs in three characters, should be raised to the rank of subspecies.
INTRODUCTION
DISCUSSION
Sansevieria pinguicula was described many years ago from eastern Kenya by Peter Bally (1964), based on the holotype Bally B 4275 (“14976”) collected January 1943 near Bura, at 393 feet altitude, and the paratype Bally B 9386 collected 12.x.1953 northeast of Garissa, at 755 feet altitude. The type of Sansevieria pinguicula is very distinctive, with very hard and stiff, mostly ± bluish, spine-tipped, rosulate leaves and short paniculate inflorescences bearing small white flowers with tepals with brownish mid-stripe (Figs. 1–3). Only recently, two infraspecific taxa were published: Sansevieria pinguicula subsp. disticha Pfennig ex Butler (2012) and Sansevieria pinguicula var. nana Chahinian (2013). However, the taxonomic ranks to which these two taxa were assigned are questionable.
Sansevieria pinguicula subsp. disticha Pfennig ex Butler (2012) is based on the holotype Bally [& Smith] B 14976 from east of Garissa, close to the paratype of subsp. pinguicula, and is stated to differ from the latter by its distichous, much shorter and upcurving leaves. Comments: According to the protologue, subsp. disticha differs by its shorter leaves (10–15 cm) from subsp. pinguicula with longer leaves (12–30 cm). This difference is based on misinformation on the label of the holotype (http://plants.jstor.org/specimen/ ea000002647?s=t) which reads “10–15 cm”, whereas the cm scale shows that the leaves are actually about 20–30 cm long and thus fall within the range of subsp. pinguicula. Photographs of flowering plants of the
1 Corresponding
1. Sansevieria pinguicula (fa. pinguicula) in cultivation in Nairobi (Powys 047; 1992). Photo: L. Newton.
author Dept. of Plant Sciences, Kenyatta University, Nairobi, Kenya. email:
[email protected]. 2 Schenefelder Holt 3, 22589 Hamburg, Germany. email:
[email protected]
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2. Sansevieria pinguicula (fa. pinguicula) in flower (Powys 047; 1992). Photo: L. Newton.`
3. Sansevieria pinguicula (fa. pinguicula). A fruiting specimen (Powys 047; 1992). Photo: L. Newton.
type collection of subsp. disticha of Pfennig (2014; Pfennig Pf 215 = Bally B 14976) are reproduced in the protologue as figures 2 and 3, but with the pot being cut off so that the size of the leaves does not become clear. The original photograph of Pfennig (in Pfennig 2014; reproduced here as Fig. 4) of a flowering plant with pot shows a leaf size within the range of subsp. pinguicula. Further published photographs of subsp. disticha from cultivation (p. 100 in Chahinian 2005) and from habitat (of P.R.O. Bally in Pfennig 2014, and of P.R.O. Bally, via S. Carter, in Chahinian 2013: Fig. 6) likewise show a leaf size in the range of subsp. pinguicula as well as straightly ascending and not upcurved leaves, which are present only on the plant in Pfennig‘s photograph (Fig. 4). A habitat photograph by P.R.O. Bally of subsp. disticha taken close to its paratype locality east of Garissa (in Chahinian 2013: Fig. 6; here as Fig. 5) shows on the right hand side plants with distichous, erect and not upcurved leaves, but in the foreground also a plant with rosulate leaves (entering from left), clearly indicating that plants with rosulate and distichous leaves occur in mixed stands at the same locality. Bally & Smith B 14976, the type of subsp. disticha, was also
included in the concept of S. pinguicula by Mbugua (1995, 2007) five years before subsp. disticha was published, and without noting distichous leaves. Chahinian (2005) stated that the distichous growth form is a mature plant, with rosulate leaves found only on juvenile plants. However, the mature plant shown in Fig. 1 has been grown by the first author for over 20 years without any sign of the leaf arrangement changing to distichous; and changes from rosulate to distichous leaf arrangement are not reported by other cultivators (Pfennig 1980, 2014). The distichous plant shown in Fig. 6 is a cutting from a plant grown for many years by Patricia Powys, in Kenya, after it was given to her by Peter Bally. It has retained the distichous leaf arrangement for at least 35 years.
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Sansevieria pinguicula var. nana Chahinian (2013) is based on the type collection Schwartz & LaFon s.n. in Chahinian 397 from southern Kenya, and is stated to differ by its compact growth and its shorter, dark green leaves. Comments: Fig. 3 in the protologue shows that var. nana may flower at a much smaller size / leaf length
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4. Sansevieria pinguicula fa. disticha, Pfennig Pf 215 (= Bally B 14976), flowering in cultivation with the late Dr. Horst Pfennig (Herford, Germany). Photo: H. Pfennig; courtesy D. Pfennig.
than subsp. pinguicula; it might represent a neotenic form (Fig. 7). Fig. 5 in the protologue shows that adult plants of var. nana may be as large as those of subsp. pinguicula. Green-leaved forms are also known in subsp. pinguicula, but these are never as dark green as in var. nana (Fig. 7). An additional difference not clearly mentioned in the protologue is that the flowers of var. nana are pure white without brownish midstripe on the tepals. Rank assignments: Whilst the International Code of Nomenclature, or ICN (McNeill et al. 2012), lists ranks in the hierarchy of classification, it does not define them. There is some confusion in the use of the terms subspecies and variety, and also form, as they have been used differently by different authors (Hamilton & Reichard 1992). It is generally held that the rank of subspecies should be used for populations of a species that have several morphological differences and are geographically and/or ecologically separated, whereas varieties, also with some morphological differences, overlap in their distribution, and forms differ usually by a single, conspicuous difference and their sporadic and sympatric occurrence (e.g. Beentje 2010; Stuessy 2013). The known localities of the original Sansevieria pinguicula at Bura and near Garissa are all within about 80 km of one another. Butler (2012) states that his new subspecies disticha was collected “close to the type locality of the species”. The comments given
5. Sansevieria pinguicula in habitat. Plants with rosulate leaves (fa. pinguicula; entering from left) and with dis-
tichous leaves (fa. disticha; on the right hand side) occur in mixed stands. Photo: P.R.O. Bally; courtesy S. Carter.
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7. Sansevieria pinguicula subsp. nana, in cultivation in Indonesia. Photo: J. Arbi.
6. Sansevieria pinguicula fa. disticha. Cutting from a plant grown for many years by Patricia Powys, in Kenya, after it was given to her by Peter Bally. The plant has retained its distichous leaf arrangement for at least 35 years. Photo: L. Newton. above show that it differs solely in its distichous leaves and occurs in mixed stands with rosulate plants (Fig. 5), thus clearly representing a mere form. Chahinian’s variety nana was found in similar vegetation more than 250 km distant from the type locality of the species, and differs constantly in three characters from the latter. Thus, it contradicts the definition of a variety as “largely allopatric with some overlap” and “one to few conspicuous differences” (Stuessy 2013: 158) and clearly qualifies as subspecies with “several conspicuous differences” and occuring “largely allopatric or peripatric” (Stuessy 2013: 158). To bring the rank assignments of the two heterotypic infraspecific taxa of S. pinguicula into line with common definitions and practice, rank adjustments are proposed below.
TAXONOMY Sansevieria pinguicula P.R.O. Bally, Candollea 19: 145(–147) (1964). Type: Bally B 4275 (K, digital image!). — The protologue cites “Bally B 14976” which was corrected in later treatments to Bally B 4275 (Pfennig 1980, Mbugua 1995, Newton 2001, Mbugua 2007).
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Rosettes forming stolons on vertical aerial roots; leaves rosulate or distichous, very hard and stiff, bluish to greenish or dark green, spine-tipped; inflorescences paniculate, short; flowers small, white, tepals white with brownish mid-stripe or pure white. Due to its paniculate inflorescences, S. pinguicula places in Sansevieria sect. Dracomima Jankalski (2009: 9) where it is easily distinguished from the remaining species by its stemless habit and short inflorescences. Sansevieria pinguicula P.R.O. Bally subsp. pinguicula Leaves rosulate or distichous, bluish to greenish, tepals white with brownish mid-stripe. Sansevieria pinguicula P.R.O. Bally subsp. pinguicula fa. pinguicula Leaves rosulate, bluish to greenish. Sansevieria pinguicula P.R.O. Bally subsp. pinguicula fa. disticha (Pfennig ex Butler) L.E. Newton & Thiede, comb. & stat. nov. Basionym: Sansevieria pinguicula subsp. disticha Pfennig ex Butler, Sansevieria 28: 17(– 18) (2012). Type: KENYA, [Northern Frontier Prov., Garissa Dist.,] 31 km E of Garissa [= 24 km on Garissa-Liboi road from junction with Mado Gashi road], on road to Kismayo [‚Kismajo‘, at the coast of Somalia], open mixed bushland on pale grey-pinkish
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soil. Bally B 14976, 28/1/1972 (EA, holo [digital image!], ZSS, para). - Bally B 14976 is also recorded as Pfennig Pf 215. Epitype (here designated): Sansevieria 28: fig. on p. 17 (2012). Leaves distichous, bluish. Typification: The holotype at EA consists of 2 detached leaves from which the distichous leaf arrangement cannot be inferred. The isotype at ZSS is, according to information provided by U. Eggli (ZSS), a small dried rosette with a few root stumps and 3 leaves that can be described “with a little good will as quite distichous (length 12 cm)”. The holotype is labelled 28/1/1972, while the “isotyp” at ZSS is labelled 17. Feb. 1972 and consequently it apparently represents a different gathering and thus a paratype. According to U. Eggli, however, the date of the paratype might be the accession date at ZSS and not the collecting date; Bally often preserved specimens from cultivated material on different dates thus causing notorious problems with his collections. Since neither the holotype nor the paratype unambiguously shows the characterizing distichous leaf arrangement, an epitype (ICN Art. 9.8, McNeill & al. 2012) is designated here from among Pfennig’s photographs in the protologue in order to fix the application of the name as intended by Butler. Sansevieria pinguicula subsp. nana (Chahinian) L.E. Newton & Thiede, comb. & stat. nov. Basionym: Sansevieria pinguicula var. nana Chahinian, Sansevieria 30: 15(–19) (2013). Type: [ex cult. Chahinian], coll. KENYA, Koni Airstrip, N. W. Galana Ranch, [s.d.], Schwartz & LaFon s.n. in Chahinian 397 (MO holo, NYBG iso).
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Mature (= flowering) plants smaller than in subsp. pinguicula, leaves rosulate, dark green, tepals pure white.
Acknowledgements The authors are indebted to Urs Eggli (ZSS) for information on Bally’s specimen at ZSS. We are also grateful to Susan Carter Holmes for permission to use Peter Bally’s habitat photograph, to Doris Pfennig for permission to use Horst Pfennig’s photograph, to Jusuf Arbi for the photograph of his plant of subsp. nana, and to Seta Kartika for providing this photograph. References Bally PRO. 1964. Miscellaneous notes on the flora of Tropical East Africa, including descriptions of new taxa, 16–22. Candollea 19: 145–166. Beentje H. 2010. The Kew Plant Glossary. Royal Botanic Gardens, Kew. Butler A. 2012. Sansevieria pinguicula ssp. disticha Pfennig ex Butler, a new subspecies from Kenya. Sansevieria 28: 17–18. Chahinian BJ. 2005. The Splendid Sansevieria. Published by the author, Buenos Aires. Chahinian BJ. 2013. Sansevieria pinguicula var. nana A new variety from Kenya. Sansevieria 30: 15–19. Hamilton CW, Reichard SH. 1992. Current practice in the use of subspecies, variety, and forma in the classification of wild plants. Taxon 41: 485–498. Jankalski S. 2009. The Sansevieria inflorescence and new sections proposed. Sansevieria 19: 8–10. Mbugua PK. 1995. Systematic studies of the genus Sansevieria Petagna (Dracaenaceae Salisb.). PhD. thesis, Reading University, School of Plant Sciences, Department of Botany. Mbugua PK. 2007. Sansevieria. In: Beentje, H.J & Ghazanfar, S.A. (eds.): Flora of Tropical East Africa. Dracaenaceae. Kew (GB): Royal Botanic Gardens, p. 10–43. McNeill J, Barrie FR, Buck WR, Demoulin V, Greuter W, Hawksworth DL, Herendeen PS, Knapp S, Marhold K, Prado J, Prud’homme van Reine WF, Smith GF, Wiersema JH, Turland NJ. (eds.) 2012. International Code of Nomenclature for algae, fungi, and plants (Melbourne Code) adopted by the Eighteenth International Botanical Congress Melbourne, Australia, July 2011. Koeltz Scientific Books, Königstein. [Regnum Veg. 154]. Newton LE. 2001. Sansevieria (Dracaenaceae). In: Eggli, U. (ed.), Illustrated Handbook of Succulent Plants Vol. I, Heidelberg (D): Springer, p. 261–272; pl. XXVII–XX. Pfennig H. 1980. Sansevieria pinguicula Bally. Kakt. and. Sukk. 31(7): 206–207. Pfennig D. 2014. Sansevierien: Die Sammlung Dr. Horst Pfennig. Published on the web at http://www.sansevieria-pfennig.eu/ (accessed 20-10-2014). Stuessy, T. (2013) Plant taxonomy: the systematic evaluation of comparative data. 2nd ed. New York, Columbia University Press.
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