Four New Species of Ursinia (Asteraceae, Anthemideae) from South Africa, with an Updated Key to the Genus in Namaqualand
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Phytotaxa 177 (3): 137–145 ISSN 1179-3155 (print edition) www.mapress.com/phytotaxa/ PHYTOTAXA Copyright © 2014 Magnolia Press Article ISSN 1179-3163 (online edition) http://dx.doi.org/10.11646/phytotaxa.177.3.1 Four new species of Ursinia (Asteraceae, Anthemideae) from South Africa, with an updated key to the genus in Namaqualand ANTHONY R. MAGEE1,2,*, JAMES S. BOATWRIGHT3 & LADISLAV MUCINA4,5 1Compton Herbarium, South African National Biodiversity Institute, Private Bag X7, Claremont 7735, Cape Town, South Africa 2Department of Botany and Plant Biotechnology, University of Johannesburg, P.O. Box 524, Auckland Park 2006, Johannesburg, South Africa 3Department of Biodiversity & Conservation Biology, Faculty of Natural Sciences, University of the Western Cape, Private Bag x17, Bellville, 7535, Cape Town, South Africa 4School of Plant Biology, University of Western Australia, 35 Stirling Hwy, Crawley WA 6009, Perth, Australia 5Department of Geography & Environmental Studies, Stellenbosch University, Private Bag X1, Matieland 7602, Stellenbosch, South Africa *Corresponding author; e-mail: [email protected]. Abstract Recent field and herbarium studies of the southern African genus Ursinia (Anthemideae, Asteraceae) in Namaqualand, South Africa, have revealed greater morphological variability than currently accommodated and a high percentage of mis- identified specimens. In an attempt to remedy this we herein describe four new species (Ursinia arida, U. glandulosa, U. kamiesbergensis and U. laciniata) and provide a key to the species in the region, together with illustrations of their involucral bracts and paleae. The species can be distinguished by a combination of their life history, vestiture, presence or absence of appendages on the paleae, and shape of the involucral bracts and their scarious apices. Key words: Compositae, Gariep Center of Endemism, Greater Cape Floristic Region, Kamiesberg Center of Endemism Introduction Namaqualand is a winter rainfall region within the Succulent Karoo Biome (Mucina et al. 2006) of South Africa, extending from the Orange River (ca. 28° S) southwards to the mouth of the Olifants River. Namaqualand is best known for the spectacular mass spring (July–September) flowering of annuals, largely from the Asteraceae. Ursinia Gaertner (1791: 462) (Asteraceae) is a prominent component of these spring floral displays. The genus is almost entirely southern African (one species extending to Ethiopia) and currently comprises ca. 39 species (Prassler 1967). They are easily recognized by their often large showy ray florets, paleate involucre, scarious involucral bracts and fruit crowned by a pappus of large, white spreading scales. It is the latter character which gives rise to the rather apt common name, Parachute Daisy. Ursinia is a member of tribe Anthemideae which has its origins in southern Africa (Watson et al. 2000, Oberprieler 2005, Himmelreich et al. 2008) and is placed within the early diverging subtribe Ursineae (Oberprieler et al. 2007). Ongoing field-based studies of Ursinia as well as herbarium studies revising the identity of the Namaqualand representatives (especially during the period of preparing the Ursinia treatment for Greater Cape Plants II; Magee et al. 2013), have revealed a broad spectrum of unaccommodated variability and a high percentage of misidentified specimens. Four unnamed species were discovered, two of which were recognized in Magee et al. (2013) as ‘sp. A’ and ‘sp. B’. Herein we formally describe these four species within a broader comparative context of all currently recognised Namaqualand Ursinia species and attempt to remedy the identification problems with a key to the species in Namaqualand, together with illustrations of the involucral bracts and paleae. Materials and Methods Herbarium material of Ursinia species from Namaqualand were studied at NBG and BOL, as well as extensive field collections over several years (2004–2013). Almost all of the taxa were observed in the field, providing crucial additional insight into the species studied. The recorded distributions of the two new species were ascertained and Accepted by Alexander Sennikov: 31 Jul. 2014; published: 29 Aug. 2014 137 mapped. The specimens examined are cited under each species treatment and arranged by Country, Province and then District. Within each District the specimens are organized according to geographical position, from west to east and north to south (using the Quarter Degree Reference System; Edwards & Leistner 1971, Leistner & Morris 1976). Results and Discussion Of the eleven species of Ursinia found in Namaqualand, four are from subgenus Sphenogyne (Aiton 1813: 142) Prassler (1967: 382), namely U. anthemoides (L.) Poiret (1808: 257), U. calenduliflora (Candolle 1836: 682) Brown (1887: 670), U. glandulosa and U. laciniata. They are easily distinguished by the truncate paleae, straight or slightly curved fruit and uniseriate pappus. However, U. anthemoides remains a difficult taxonomic complex in need of further study across its much broader distribution range. The remaining seven species are from subgenus Ursinia and can be easily identified by the ovate to round scale-like appendages on the paleae, as well as the geniculate fruit with a biseriate pappus composed of an outer series of broad scales and an inner series of setiform scales. The monophyly of these two subgenera was recently confirmed in a preliminary phylogenetic analysis of the genus using nrITS sequence data (Swelankomo 2008). With the exception of U. chrysanthemoides (Lessing 1832: 242) Harvey (1865: 152) (Fig. 1F), U. glandulosa (Fig. 1M) and U. laciniata, which are perennial subshrubs, all of the Namaqualand species are annual herbs. This is in contrast to the mostly perennial nature of the genus in the adjacent regions of the Greater Cape Floristic Region. As also found by Prassler (1967), the species are most easily distinguished by characters of the involucral bracts. The apices of the involucral bracts are prominently cuspidate (U. pygmaea Candolle (1836: 690), Fig 2F), acute to acuminate (U. arida, U. cakilefolia Candolle (1836: 690), U. nana Candolle (1836: 690)) or obtuse (U. kamiesbergensis, U. speciosa Candolle (1836: 690)). In the latter two species the scarious apices form broad apical appendages which are either transversely ovate, thin and transparent as in U. speciosa (Fig. 2I), or ovate, thick and opaque as in U. kamiesbergensis (Fig. 1H). Distinct plants with prominent scarious attenuate, recurved apices were found around Garies and Kamieskroon. However, upon further study these populations were found to form a continuum with more typical populations of U. cakilefolia from around Clanwilliam. The bracts may also bear diagnostic dark markings in many of the species. In U. pygmaea the entire cuspidate apex is purplish black (Fig. 2H), in U. arida (Fig. 1K) and U. cakilefolia (Fig. 1I) the margins are outlined purplish black and in U. nana (Fig. 1J) there is usually a black apical crescent-shaped mark. The paleae are also very important for distinguishing the species. As mentioned earlier, the presence or absence of rounded apical appendages is a prominent character to separate them into the two current subgenera. The shape and texture of the apical appendage is also very important. In U. cakilefolia the appendages are prominent and scale-like in texture with a lustrous, brownish-yellow to brownish-black colour. This gives the disc a prominent dark sheen where these appendages overlap over the developing florets (Fig. 1G, I). In contrast, the appendages of U. nana and U. arida are less conspicuous, membraneous in texture and somewhat undulate (Fig. 2M, N). Apical appendages are absent in U. anthemoides (Fig. 2A, B), U. calenduliflora (Fig. 2C, D), U. glandulosa (Fig. 2E) and U. laciniata (Fig. 2F). In these species, the apical margins of the paleae are typically repand to slightly erosulate, but in U. laciniata they are prominently and closely laciniate (Fig. 2F). Prassler’s (1967) separation of U. anthemoides and U. calenduliflora was based entirely on slight differences in the size of the membraneous tips of the involucral bracts. We found this character to be highly variable (Fig 2A–D) within these two species so that the separation was completely artificial. As a result different plants from the same population had often been identified as different species. Herbarium specimens of these two species appear superficially very similar as details of the ray florets are often lost. Ursinia anthemoides is a widespread and fairly variable species occurring throughout the winter rainfall region. It has whitish, yellow or apricot ray florets usually with a pinkish underside (Fig. 1C–E). On the other hand, Ursinia calenduliflora is restricted to Namaqualand occurring from the Richtersveld to Kamiesberg. The heads are quite spectacular with the ray florets orange on both surfaces (rarely yellow in the Richtersveld) and often with a purple or black spot at the base (Fig. 1A). The Namaqualand populations of Ursinia anthemoides are distinguished further by the pappus that exceeds the corolla limb in fruit and the paleae which extend far above the height of the florets soon after anthesis. An adventive population of U. calenduliflora growing along the National Road (N1) between De Doorns and Worcester was also identified (Mauve & Oliver 131, NBG; Magee & Boatwright 392, NBG—Fig. 1B), having likely been introduced from the cultivated spring flower plantings in and around Worcester. It should be noted, however, that