Trimelopter craibii Mart.

Martínez-Azorín, Mario, Crespo, Manuel B. & Dold, Anthony P., 2013, Trimelopter craibii (Hyacinthaceae, Ornithogaloideae), a new species from the North West Province of South Africa, Phytotaxa 87 (3), pp. 50-60 : 52-57

Trimelopter craibii Mart. -Azorín, M.B.Crespo & A.P.Dold, sp. nov. ( Figs. 1−2 )

Planta insignis , omnibus speciebus generis distincta et facile distinguitur. Folium solitarium ad solum appressum, coriaceum, oblongum, subconvexum, supra pilis validis erectis 0.6−0.8 mm longis dense vestitum, margine albido, incrassato, papillis minutis usque ad 0.05 mm longis densissime obsito, subtus glaberrimum. Scapus 1−5 cm longus; racemus brevissimus, usque ad 2.5 cm longus, 1−5-florus. Tepala 8.5−13 mm longa, albicantia, in dorso fascia longitudinali media viridi instructa. Ovarium ovatum , trilobatum, costis longitudinalibus vix prominentibus, infirme carinatis; stylus 3−3.5 mm longus. Habitu cum T. dyeri primo adspectu congruens sed illa valde differt quae folium supra et ad marginem papillis minutis dense obsitum, tepala minora (5−7 mm longa), ovarium globosum vel obovatum carinis longitudinalibus magis prominentibus, et stylum brevius (usque ad 2 mm longum) habet. A T. unifolio multo discrepat quae folium longius (usque ad 12 cm longum), non coriaceum, subconcavum, supra pilis tenuioribus brevioribusque (0.05−0.4 mm longis) laxiore dispositis, in margine breviter laxeque papillosum, et inflorescentiam majorem floribus plus numerosis exhibet.

Type: — SOUTH AFRICA. North West Province: Mafikeng (2525DD), Lichtenburg district, ca. 25 km northwest of Lichtenburg to Zeerust on R505, west of Molopo Oog , Trekdrift Farm , in soil pockets of low dolomite outcrops, 1450 m, flowered ex hort. 20 August 2011 in Grahamstown , C. Craib s.n. (holotype GRA!, isotypes ABH! n. 59467, K!) .

Deciduous bulbous plant up to 5 cm tall. Bulb solitary, hypogeal, ovoid, 1.5−3 × (0.5) 1−2 cm, with soft pale brown outer tunics, terminating in a hypogeal neck, 2−3 × 0.3−0.5 cm. Roots fleshy, branched, white, up to 50 × 1−2 mm. Leaf solitary, ovate-oblong, dark green, flat on the ground, slightly convex, 3−7 × 1−2 cm, firm, leathery, with whitish-coloured thickened margins densely covered by short papillae (up to 0.05 mm), covered on the adaxial side with translucent, erect, stout, conical bristles of ca. 0.6−0.8 mm (collapsed, flattened and narrowly triangular when dry), glabrous on the abaxial side, clasping the stem at base, starting to wither to mostly withered at the anthesis. Inflorescence an erect raceme with (1)2−4(5) flowers, 1−2.5 cm long; lowermost pedicels 3−6 mm long, erect-patent; peduncle 1−2.5 cm long; bracts ovate-lanceolate to triangular, abruptly acuminate in the upper part, 4−7 × 2−4 mm, green with white membranous margins, withering soon and becoming papery white with brownish nerves, nearly as long as pedicels. Flowers suberect; tepals white with a green median stripe 1−1.5 mm wide, clearly visible in the abaxial side and undefined in the adaxial side associated to the central nerves, slightly fleshy, with minutely glandulous apex; outer tepals ovate-oblong, 10− 13 × 2.5−3.5 mm; inner tepals ovate, 8.5−10 × 3−4 mm. Stamens monomorphic; anthers ca. 1.3 × 0.7 mm; filaments strap-like, wider in the lower half, outers narrowly oblong, 6–7.5 × 1.5−2 mm; inners ovate oblong, 6.5−8 × 2−2.5 mm. Ovary ovate, green, 3.2−3.5 × 1.5−2.8 mm, trigonous in section, with two prominent longitudinal keels on each carpel; style filiform, 3−3.5 × 0.5−0.8 mm, stigma punctiform. Capsule broadly ovate to subglobose, ca. 5 × 5 mm, trigonous to subsphaerical in section, pale-brown when mature. Seeds flat, ca. 3 × 2.5 mm, dark brown to black, flattened and semidiscoidal ( Figs. 1−2 ).

Biology:— Trimelopter craibii remains dormant underground at the hottest time of the year, from November until early February. Leaves appear in autumn from early February, and become fully developed in April ( Craib 2001b) and are covered with erect, short, white or ivory coloured bristles that impart a silvery or shiny appearance when the leaves are in strong direct sunlight. The leaf is cryptic and blends in very well with the rough and shiny black and grey dolomite pebbles and rocks which surround it ( Craib 2001a). Bud development starts in June until early August, when heavy frosts occur. The flowering season lasts from the end of June to the middle of August, with a peak in late July and the beginning of August. Seeds develop from mid- to late August. Late August and early September are dry and windy creating ideal conditions for seed dispersal ( Craib 2001b). The bulbs occur singly or in scattered groups of two to forty plants, rarely more. The species is plentiful at some localities particularly where there are pockets of deep soil that remain moist for longest after rainfall ( Craib 2001c).

Habitat:— Trimelopter craibii grows in the summer rainfall area of South Africa with most of the rainfall occurring between November and early April, in open short grassland in very hot and arid habitat with interesting associated succulent flora ( Craib 2001c). It occurs in cracks in exposed dolomite sheets, shallow soil over sheets of exposed rock and patches of dolomite grit in depressions on bare rocks ( Fig. 1 ) ( Craib 2001a, 2001b). The endemic T. craibii is confined to vegetation classified as the Carletonville Dolomite Grassland ( Mucina et al. 2006).

Distribution: —This species is only known from a single locality in the Lichtenburg district of the North West Province of South Africa, in an area of about 4 square kilometres (Charles Craib, pers. comm., July 2010) ( Fig. 3 ).

Diagnostic characters and relationships:— Trimelopter craibii is easily identified by the solitary oblong convex leaf, with erect thickened bristles of 0.6−0.8 mm long only on the upper side, and thickened and densely papillate margin, the tepals 8.5−13 mm long, and the ovate ovary with scarcely prominent longitudinal keels ( Figs. 1−2 & 4−5 ). These characters are not present as a whole in any known taxa of this genus.

The new species appears to be closely related to T. dyeri but the latter shows the leaf with the upper surface and margins only minutely papillate, the tepals shorter (5−7 mm, up to 8.5 mm under cultivation; ABH! n. 58825), the ovary globose to obovate with larger and more prominent longitudinal keels, and the style shorter, ca. 2 mm long ( Table 1, Figs. 4−5 ).

Trimelopter unifolium shows some resemblance to T. craibii , though it differs by the leaf commonly longer (up to 12 cm), slightly concave, with margins covered with short laxly arranged papillae (neither whitish nor thickened as in the latter), and the larger and many flowered inflorescence ( Table 1). In particular, some individuals of this species with hairy leaves, which were named Ornithogalum unifolium var. vestitum Müller-Doblies & Müller-Doblies (1996: 471) , resemble in some extent T. craibii by the patent hairs on the upper side, but they are shorter and thinner, 0.05−0.4 mm (not 1 mm as cited in the protologue, cf. Müller- Doblies & Müller-Doblies 1996: 477), and evenly distributed ( Table 1, Fig. 5 ). They are regarded here as a distinct variety T. unifolium var. vestitum (see the Appendix).

Relationships between T. craibii and other species of the genus with hairy leaves are weaker. Trimelopter monarchos ( Müller-Doblies & Müller-Doblies 1996: 476) Martínez-Azorín et al. (2011: 26) produce a much bigger leaf (15–33 cm long), with long and thin hairs of ca. 0.5−1 mm long on both sides of the leaf and margins, and a longer style, ca. 4−5 mm long. Furthermore, this species is only known from a single locality 7 km W of Steinkopf in the Northern Cape Province of South Africa. It is worth mentioning that the ovary of T. monarchos was described by Müller-Doblies & Müller-Doblies (1996) as being smooth and lacking ornamentation “ovario levi (haud sculptato).” However, plants collected at the type locality (ABH! n. 59600) showed constantly the ovary with the typical Trimelopter structure, it being deeply three-lobed, with six rounded angles, though in this case not markedly keeled.

The Namibian Trimelopter etesiogaripense (U.Müll.-Doblies & D.Müll.-Doblies) Martínez-Azorín et al. (2011: 26) shows a canaliculated, narrowly lanceolate leaf, with an involute tip, with rows of stiff hairs or papillae of 0.3−3 mm long on both sides and margins. It is only known in winter-rainfall Namibia along the mountains at the eastern border of the Namib, from Dikwillem in the north to the Orange River near Rosh Pinah and to the Richtersveld in the Cape (cf. Müller-Doblies & Müller-Doblies 1996). A related species, Trimelopter strigosulum ( Müller-Doblies & Müller-Doblies 1996: 480) Martínez-Azorín et al. (2011: 26) , has a narrowly ovate leaf, 2.5−3.5 cm long (up to 8 cm in cultivation), densely covered with adpressed hairs of 0.5−1 mm long, which are somewhat medifixed with a very short retrorse arm. The indumentum in this species seems to be unique in the genus. It is also restricted to SW Namibia, near Pockenbank (cf. Müller- Doblies & Müller-Doblies 1996).

Etymology:—Named after botanist Charles Craib, author of several botanical books and numerous articles, who passed away in March 2012. Together with Trimelopter craibii he is commemorated in Aloe craibii Smith (2003: 26) and Ceropegia craibii Victor (2001: 212) .

Observations:— Ornithogalum dyeri var. leistneri Müller-Doblies & Müller-Doblies (1996: 476) was described and illustrated from a single herbarium specimen (Holotype: Leistner 849 KMG) collected near Postmasburg, Northern Cape Province of South Africa. The authors related that plant to Trimelopter dyeri , a species with a glabrous, convex leaf, but noted that “the indument is so striking that it deserves taxonomic recognition. Parallel to O. unifolium var. vestitum the rank of variety was chosen”. Unfortunately, the holotype of that variety remains on loan to U. and D. Müller-Doblies since 1980 (A. van Heerden, pers. comm.) and therefore we are unable to study it. However, the illustration presented by Müller-Doblies & Müller-Doblies (1996) and the very brief description suggests that T. craibii and O. dyeri var. leistneri are closely related. Further studies are needed to elucidate this hypothesis, including studying living plants of Ornithogalum dyeri var. leistneri from the type locality near Postmasburg.

Figures

FIGURE 1. Trimelopter craibii Mart.-Azorín M.B. Crespo & A.P. Dold at the type locality (Trekdrift Farm, North West Province, South Africa). Photographs by Connall Oosterbroek.

FIGURE 2. Trimelopter craibii Mart.-Azorín, M.B. Crespo & A.P. Dold. North West Province (holotype: Craib s.n. GRA). A. Flowering plant. B. Flower, frontal and dorsal views. C. Tepals and stamens, outer ones (left) and inner ones (right). D. Gynoecium, lateral views. E. Mature capsule with dry tepals; a valve capsule and seed. F. Bract. G. Leaf. Scales A–C, E, G: 1 cm; D, F: 5 mm.

FIGURE 3. Known distribution of Trimelopter craibii Mart.-Azorín, M.B. Crespo & A.P. Dold in South Africa.

FIGURE 4. Flowers and gynoecia of Trimelopter. A. T. craibii Mart.-Azorín, M.B. Crespo & A.P. Dold from the type locality: South Africa, North West Province, Trekdrift Farm, C. Craib s.n. (GRA Holo.; ABH59467, K Iso.). B. T. dyeri (Poelln.) Mart.-Azorín, M.B.Crespo & Juan from the type locality: South Africa, Eastern Cape, N of Grahamstown, Table Farm, Martínez-Azorín et al. MMA486 (GRA, ABH58825). C. T. unifolium var. vestitum from the type locality: South Africa, Western Cape, E of Matjiesfontein, near Laingsburg, Martínez-Azorín et al. MMA847 (GRA, ABH59634). Scale bars: flowers = 1 cm, gynoecia = 2 mm.

FIGURE 5. Leaf details of Trimelopter. A. T. craibii Mart.-Azorín, M.B. Crespo & A.P. Dold from the type locality: South Africa, North West Province, Trekdrift Farm, C. Craib s.n. (GRA Holo.; ABH59467, K Iso.). B. T. dyeri (Poelln.) Mart.-Azorín, M.B.Crespo & Juan from the type locality: South Africa, Eastern Cape, N of Grahamstown, Table Hill Farm, Martínez-Azorín et al. MMA486 (GRA, ABH58825). C. T. unifolium var. vestitum from the type locality: South Africa, Western Cape, 800 m from first gate to Whitehill, E of Matjiesfontein, near Laingsburg, Martínez-Azorín et al. MMA847 (GRA, ABH59634).