Ethesia tanquana ( Ornithogaloideae , Hyacinthaceae ) , a new species from the Tanqua Karoo ( South Africa ) , with notes on E . haalenbergensis

Martínez-Azorín, M. & Crespo, M.B. 2012. Ethesia tanquana (Ornithogaloideae, Hyacinthaceae), a new species from the Tanqua Karoo (South Africa), with notes on E. haalenbergensis. Anales Jard. Bot. Madrid 69(2): 201-208. As a part of a taxonomic revision of Ethesia Raf., a new species, E. tanquana Mart.-Azorín & M.B.Crespo, is described from the Tanqua Karoo in South Africa. This new species is at first sight similar to E. haalenbergensis (U.Müll.-Doblies & D.Müll.-Doblies) Mart.-Azorín, M.B.Crespo & Juan and also E. xanthochlora (Baker) Mart.-Azorín, M.B.Crespo & Juan, but it differs in floral and vegetative characters as well as in its ecology and isolated distribution. A complete description, data on biology, habitat, and distribution of the new species are presented. An identification key for Ethesia and new data on the rare Namibian E. haalenbergensis are also given.

Ornithogaloideae are distributed through Europe, SW Asia and Africa. In recent decades a number of morphological and phylogenetic studies were made on the group, focusing on circumscriptions of the genera. As a consequence, at least three very different taxonomic arrangements at generic level have been proposed for the Ornithogaloideae by Speta (1998) and Manning & al. (2004Manning & al. ( , 2009, all based exclusively on plastid DNA regions. The latest comprehensive study of the subfamily, including for the first time nuclear DNA regions, accepts 19 independent genera (Martínez-Azorín & al., 2011). These genera are based on monophyletic clades supported by a clear syndrome of morphological characters and distinct biogeographic patterns (cf. Martínez-Azorín & al., 2011), thus making this treatment highly consistent.
Ethesia was overlooked by modern taxonomic revisions in the Ornithogaloideae (Leighton, 1945;Obermeyer, 1978;Müller-Doblies & Müller-Doblies, 1996), and its four currently accepted species were placed in the morphologically heterogeneous Ornithogalum subg. Urophyllon (Salisb) Baker. The concept of this subgenus has proved to be artificial, with a mixture of taxa of the tribes Ornithogaleae and Albuceae (cf. Manning & al., 2009;Martínez-Azorín & al., 2011). Manning & al. (2009) haalenbergense that is endemic to a small area in the surroundings of Haalenberg in SW Namibia. This species is closely related to E. prasina, but it differs in the colour of the tepals and the number and morphology of the leaves. It is remarkable that no complete morphological description of this new species was presented, and no holotype or isotypes appear to have been deposited in the herbaria cited in the protologue ('holotypus: WIND; isotypi: B, BTU, K, PRE') since its description in 1996. As a consequence, a clear understanding of the taxonomic status of E. haalenbergensis is still lacking.
It is the aim of this paper to enhance our knowledge of the taxonomy of Ethesia. The study of living populations and herbarium collections of Ethesia from southern Africa reveals the existence of clear morphological differences that allow the description of a new species, Ethesia tanquana Mart.-Azorín & M.B.Crespo. This taxon appears to be closely related to E. xanthochlora and E. haalenbergensis from SW Namibia and Namaqualand. Data on morphology, biology, habitat, and distribution of E. tanquana and the rare and poorly known E. haalenbergensis are provided, together with a tentative key for the identification of Ethesia species.

MATERIAL AND METHODS
Morphological studies were mainly undertaken on living material from natural populations, usually within a few hours after collection, as described in detail by Martínez-Azorín & al. (2007 for other related groups of Ornithogaloideae. These data were complemented with studies of dried material conserved in the herbaria BOL, BNRH, GRA, J, K, KEI, KMG, NBG, NH, NU, PEU, PRE, PUC, UFH, and WIND (acronyms according to Thiers, 2012). Authors of the cited taxa follow the IPNI (2012).

RESULTS AND DISCUSSION
Species of Ethesia are characterized by tepals ovate-oblong, free, all spreading, greenish, with branched outer nerves, sometimes with white margins; staminal filaments showy, pure white, and also spreading; capsule obcordate or widely globose and truncate to retuse at the apex, about equal or wider than long (cf. Martínez-Azorín & al., 2011). From a phylogenetic point of view, Ethesia is monophyletic and considered sister to the Galtonia clade (including O. saundersiae Baker) (cf. Martínez-Azorín & al., 2011). Galtonia is easily differentiated from Ethesia by the large leaves sheathing the stem; racemose inflorescence, with flowers nodding; tepals fused into a campanulate tube for about half of their length; filaments cylindrical, adnate, and included; and capsule oblong-cylindrical and acute, usually longer than wide. Only G. saundersiae (Baker) Mart.-Azorín, M.B. Crespo & Juan shows a disruptive flower structure in the genus, it having the tepals almost free and spreading, and the ovary globose and shining black. Further studies, including molecular data, are needed to elucidate its final taxonomic position. Galtonia and Ethesia show different biogeographic patterns since species of the former genus occur in summer-rainfall, high-altitude regions of the Drakensberg, Low Drakensberg, Southern Berg and Natal Midlands (South Africa and Lesotho), whereas Ethesia species occur in winterrainfall, sub-arid regions in western and central South Africa and southern Namibia.
Four species are currently accepted in Ethesia (cf. Martínez-Azorín & al., 2011). Among them, E. xanthochlora is probably the most well-known species of the genus, perhaps because of its large size and abundance in Namaqualand, NW South Africa (Fig. 1). This species was described in Ornithogalum by Baker (1897) based on a Harry Bolus collection from 'Western region: Little Namaqualand; Kaus Mountain, 2500 ft., Bolus 6598!'. The original description includes the following characters: '… raceme dense, 6-8 in. long; pedicels stout, erecto-patent, lower 1-1¼ in. long, … perianth yellowish-green, ½ in. long …'. In summary, this species is characterized by the long and narrow, dense, inflorescence with short and stout pedicels, and flowers with uniformly yellowgreen tepals. A similar concept was followed by Leighton (1945) 'Inflorescence many flowered, dense … pedicels 2-3 cm long … perianth green …'. Later Obermeyer (1966) illustrated this species in Flowering Plants of Africa. The description and figure showed plants with a long and cylindrical inflorescence with pedicels short and stout, all of similar length, and greenish flowers. The specimen figured was collected by A. Amelia Obermeyer 'about 21 miles north of Springbok near the road to Steinkopf, not far from the type locality'. She gave interesting distribution data on this species, saying that it 'has been collected fairly often in the Namaqualand area, while a few records come from Calvinia and Ceres'. A few years later, Obermeyer (1978) characterized the same species again as having 'Inflorescence … with a long, dense, many flowered, cylindrical raceme … pedicels arcuate, lengthening and hardening in fruit, up to 30 mm long … Perianth green …'. She also cited a list of herbarium collections distributed from the Richtersveld in the north to near Ceres in the south. Müller-Doblies & Müller-Doblies (1996), in their revision of Ornithogalum in southern Africa accepted O. xanthochlorum, though with no new morphological data, and only citing Obermeyer s distributional information. Moreover, these authors described a new species O. haalenbergense, here accepted as E. haalenbergensis, which was known from a single locality in the surroundings of Haalenberg in SW Namibia. It was considered to be related to O. prasinum, but it differs by the tepals green with a white marginal region and the 2-3 narrowly oblong and decumbent leaves. No complete morphological description of E. haalenbergensis has been published to date and no types are available in any southern African or European herbaria.
Etymology. Named after its confined distribution to the Tanqua Karoo in South Africa (tanquana = from Tanqua Karoo).
Flowering time. August-October, fruits appear in late September-November.
Habitat. Flats with dry open karroid shrubby vegetation (Succulent Karoo Biome), over clayey soils on shale mudstones or red-brown sandy and slightly stony soils derived from shale arenites.
Distribution and biogeography. It is confined to the Tanqua Karoo in the inland areas of SW South Africa, from south of Calvinia to north of Ceres (Fig. 5). This region comprises the lowlands located south west of the Hantam-Roggeveld Centre Hartmann & Liede, are also found in the same geographic area, thus emphasizing the fact that the Tanqua Karoo is a remarkable biogeographical unit in terms of endemicity.
Diagnostic characters and relationships. Ethesia tanquana is easily identified by the tepals olive-green with a broad white margin and dark nerves, the bracts up to ¾ the length of fruiting pedicels, and the leaves mostly withered at the full anthesis. Ethesia xanthochlora can be related to E. tanquana on the basis of its robust habit, with stout inflorescence peduncle and flower pedicels, but it differs in its uniformly green-yellowish tepals, the cylindrical narrow inflorescence with bracts longer than pedicels in fruit (Table 1). On the other hand, E. haalenbergensis shares with E. tanquana the tepals green with a white margin, but differs in its smaller flowers and inflorescence, with only 2-3 leaves per flowering stem, among other characters (Table 1). It is also notable that despite its floral similarities with E. haalenbergensis, E. tanquana occurs in continental  Ornithogalo prasino affine, sed differt foliis solum 2-3, planis, humo appressis, anguste oblongis.
Etymology. Named after the type locality near Haalenberg (haalenbergensis = from Haalenberg) in SW Namibia.
Chromosome number. Unknown. Flowering time. July-September (January), fruits appear in late September-October.
Habitat. Deep sandy soils on flats and rocky outcrops of the Succulent Karoo Biome.
Distribution. Endemic to the coastal regions of SW Namibia, from Haalenberg near Lüderitz in the north, to Klinghardtsberge Mts. in the south (Fig. 5).
Diagnostic characters and relationships. This species is easily identified by the presence of 2-3 lorate and spreading leaves, the short, subglobose inflorescence, the widely ovate-lanceolate and white-membranous bracts and the tepals olive-green with white margins. It appears to be akin to E. tanquana on the basis of flower morphology, but strongly differs by leaf number, and size of inflorescence, flowers and pedicels (Table 1).
No type specimens of E. haalenbergensis have been found in WIND, PRE and K, which together with the very poor description in the protologue, made a priori understanding of this species difficult. However, the photograph in the protologue shows features that undoubtedly match the materials studied here (Fig. 6) from sites south to the type locality, which supports the placement of this species in Ethesia as proposed by Martínez-Azorín & al. (2011). This situation raises a question that should be addressed by botanical nomenclature authorities, with regard to a requirement for a time limitation for the deposition of types after description of new taxa.   (37) cm 5-6.5 cm Bulb 7-12 × 4-10 cm 4-9 × 2.5-6 cm 4-7 × 2-3 cm Leaves (7)9-12(15) 5-11 2-3 mostly coetaneous with the flowers completely or mostly withered coetaneous with flowers in full flower (15)20-37 (46)

Flowering time August-September
August-October July-September (January)