Volutaria capillifolia

Patzelt, Annette, Pinter, Michael & Martínez-Azorín, Mario, 2021, A new endemic species of Vera-duthiea (Hyacinthaceae subfam. Urgineoideae) from Oman, Phytotaxa 524 (1), pp. 45-52 : 46-49

Vera-duthiea capillifolia A.Patzelt, M.Pinter & Mart.-Azorín sp. nov. ( Fig. 1 )

Vera-duthiea capillifolia approaches V. zebrina in general morphology, especially in the basally contracted filaments, though the former species shows very thin leaves to 0.7 mm wide (not 4‒9 mm wide), less flowered racemes with (1)2‒3(5) flowers (not 5‒13 flowers), shorter tepals, filaments and gynoecium and presents a long disjunction in distribution.

Type:— OMAN. Jabal Qamar , Wadi Kharfut, 22 m of elevation, 13 February 2012, A. Patzelt, D. Lupton , L. Al Harthy, I. Al Rashdi & A. Al Hinai AP 4963 ( OBG holo.). Specimens collected from this accession are in cultivation in Oman Botanic Garden ( OBG) .

Herbaceous, perennial, bulbous plant. Bulb hypogeal, solitary, 2‒3 × 1‒2.2 cm (excl. neck), ovoid to spherical, frequently tapering into a neck; outer tunics pale brown, dry, membranous; inner scales whitish, compact, fleshy, adherent; basal plate elongated; roots whitish-cream, fleshy, thickened, contractile, widest parts to 5 mm in diam. Leaves (2)4‒9, in a basal rosette, mostly hysteranthous, becoming dry to withered at anthesis, filiform, canaliculate, tapering gradually towards a terete acute apex, arching, spreading, 6‒20 cm long, 0.2‒0.7 mm wide, glabrous, glossy, mid to dark green, with darker green maculations forming horizontal stripes abaxially, especially prominent at the base for the lowest 4‒5 cm, usually unspotted adaxially or weakly maculate. Inflorescence a stalked raceme, arching to erect, 1 per bulb, overtopping the leaves; scape slender, up to 25 cm long, ~ 1 mm in diam. at the base, light green to greenish-brown, slightly mottled at base; raceme lax, 3−6 cm long, with (1)2‒3(5) flowers, secund; bracts small, ca. 1.2 mm long, narrowly triangular, clasping, acute, yellowish-brown with a membranous whitish margin, basal spur up to 2 mm long, those from the upper part of the inflorescence showing very short or inconspicuous spurs; bracteoles absent; pedicels 20‒25 mm long at anthesis, slender, arching down, light green with a pale purple tinge, elongating and erect in fruit. Flowers short-lived, lasting only one day, opening in succession, pale yellow to yellowish brown, pentacyclic, trimerous, stellate, nodding, opening in the late afternoon to early evening and closing during night, without a discernible scent; perigone strongly reflexed; tepals 6, biseriate, almost free, only connate for <1 mm at the base, outer tepals lanceolate, 11‒12 × 3‒4 mm, with subobtuse apex, inner tepals lanceolate, 11‒12 × 2.5‒3 mm, with subobtuse apex, tepals with lighter margins and a greenish-brown longitudinal median stripe better defined on the adaxial side. Stamens 6, curved; filaments free, adnate to tepals for ca. 1 mm, incurved along the lower half, almost connivent to style in middle section and spreading distally, ca. 6.5‒7 mm long, proximally attenuated; anthers narrowly oblong, yellow, subbasifixed, ca. 2.5 × 1 mm in pre-dehiscence, dehiscing longitudinally along the whole length. Ovary 3-locular, subellipsoidal, light green with white markings around the septal nectaries, shallowly 3-angled, ca. 2.5 × 2 mm, ovules numerous in each locule; style well differentiated, yellowish, clavate, becoming gradually broader distally, deflexed and somewhat curved, ca. 5.5 mm long, 0.5 mm wide proximally to 1 mm wide distally; stigma trigonous, subcapitate, shortly papillate. Capsule ovoid, 7–8 × 5–8 mm in lateral view, triloculate, loculicidal, with valves splitting to the base, papyraceous. Seeds flattened, widely winged with prominent embryo, blackish, ca. 9 × 7 mm.

Etymology:—The species is named V. capillifolia based on the very thin leaves, a character previously unknown in the genus.

Biology:— Vera-duthiea capillifolia flowers from September to March in the wild. All parts of the plant are toxic to livestock, and it can be fatal to small or sickly animals ( Miller & Morris 1988). On the Salalah plain, livestock would occasionally accidentally eat the species while grazing, as its leaves are found amongst grasses. The toxin produced brings on symptoms of tremor, distention of the belly, and staggers ( Miller & Morris 1988). The swelling of the stomach can persist over a period of some days, but it is rarely fatal in larger animals. Animals overall avoid the plant on their own accord when the leaves are clearly visible ( Miller & Morris 1988).

Ethnobotany:—No uses have been recorded. The local Jibbali name of the plant is ‘heysir‘ or ‘hubsir‘. The alternative name, ‘edahin esebera’, meaning little tubers of the spirits, refers to the toxicity of the plant ( Miller & Morris 1988).

Habitat:— Vera-duthiea capillifolia is found along the coastal plains, extending to rocky outcrops, dominated by xerophytic shrubs up to an elevation of about 700 m. In these habitats a Vachellia -Commiphora woodland is found supporting a rich flora with many endemic species ( Patzelt 2014, 2015).

Distribution:— Vera-duthiea capillifolia is restricted to south-western Oman. It is found in the Dhofar province, from Mirbat westwards towards Wadi Kharfut, along the coastal area west of Mughsayl, which is reduced to a rather narrow area for most of Jabal Al Qamar with only a small number of larger coastal bays. It is known from ten localities over ca. 100 km ( Fig. 2 ). The precise geographical locations have been omitted for conservation reasons.

We studied material resembling a Vera-duthiea species in fruit from Yemen (Lahij Governorate, 40-48 km north of Lahij town, along the road to Dhala, north of Jebel Marif, alluvial soil, 650 m of elevation, 09 June 1987, L. Boulos et al. E00345423: http://psimg.jstor.org/fsi/img/size2/alukaplant/e/phase_01/e0003/e00345423.jpg), being probably the first record of the genus in that country and the second out of Africa. The pressed specimen comprises a single infructescence with three ripe capsules and seeds. The capsules are ca. 12–13 mm long, differing from the capsule size from the Omani V. capillifolia (ca. 8 mm long). Based on the considerable disjunction in distribution, the more inland habitat of the Yemeni plant and the different capsules size, we preliminary exclude the Yemeni material from V. capillifolia . Further studies are needed to elucidate the identity of the Yemeni plant.

Taxonomic relationships:—The new species shares the distinctive morphological characters of Vera-duthiea, such as the transversally maculate leaves, the nodding nocturnal flowers with reflexed free tepals, the sigmoid filaments that approach the style at the middle and spread above, and the declinate style. However, it represents the only record of this genus out of Africa and differs from any other known species in the genus by the very narrow, filiform leaves, and the overall small plant size with few flowered racemes. Moreover, flowers are comparatively small with regards to the remaining species in the genus.

The East African species Vera-duthiea macrocarpa ( Stedje 1987: 664) Speta (2016: 155) (≡ Drimia macrocarpa Stedje (1987: 664) = Ornithogalum laikipiense Newton (2003: 18) and other taxa from southern Africa ( V. reflexa (K.Krause & Dinter in Krause 1914: 445) Martínez-Azorín et al. (2019b: 296); V. senegalensis ( Kunth 1843: 334) Speta (2016: 155) ; V. vespertina ( Manning & Goldblatt 2018: 65) Martínez-Azorín et al. (2019b: 296) ; V. zambesiaca ( Baker 1873b: 223) N.R.Crouch & Mart. -Azorín in Crouch et al. (2020: 261)) differs from V. capillifolia in a distinct feature, such as the flattened and dilatated filaments at the basal portion apart from their much larger sizes. The closest taxon to V. capillifolia seems to be V. zebrina Mart. -Azorín et al. (2018b: 285), based on its narrowed filaments at the basal portion and the overall morphology. However, the latter species differs in the much larger leaves, inflorescences, flowers and capsules and their disjunct distribution, the latter being restricted to eastern southern Africa (Martínez-Azorín et al. 2018b). Moreover, our phylogenetic studies also show clear genetic distance between the two latter species (Martínez-Azorín et al., in prep.)

Conservation Status:—Today, the coastal plain in Oman around Salalah is heavily developed, severely overgrazed, significantly impacted by the indiscriminate use of off-road vehicles, and populated by the invasive mesquite Prosopis juliflora ( Swartz 1788: 85) De Candolle (1825: 447) . The coastal plain once supported a rich flora under open woodlands ( Miller & Morris 1988). This is largely gone, however, after exceptional monsoon rains, such as those of 2016 and 2018, the entire plain turns green with a covering of ephemeral grasses and herbs. It is likely that the species is more common than currently known, as the plant is inconspicuous, and all plant parts quickly disappear underground after the end of the moist monsoon season. In addition, the short-lived nature of the flowers contributes to the inconspicuous nature of the species.

Using IUCN Red List Categories and Criteria, Version 3.1 (2012), Vera-duthiea capillifolia has been assessed as Vulnerable, under the name of Drimia sp. ( Patzelt 2014) . This species is provisionally re-assigned a threat assessment of Endangered, with the following justification EN B2ab(ii,iii), reflecting the limited extent of occurrence and area of occupancy of V. capillifolia as well as the recent substantial residential and commercial development in its area of distribution. Population numbers always seemed to be small, e.g. population in Wadi Kharfut ca. 20 plants seen (A. Patzelt, in 2010 and 2012), 4 plants from west of Mirbat (M. Pinter, in 2018), 3 plants in Wadi Hinna (M. Pinter, in 2018) and 1 plant from Mughsayl to Shaat (M. Pinter, in 2018). The species is threatened by development of housing and urban areas, habitat degradation, and by human intrusion and disturbance via recreational activities. There has been an observed decline in the quality and extent of habitat, and as such, a decline in the number of individuals is inferred. The continuing pressure on this fragile habitat renders the species susceptible to extinction.

Additional material studied (paratypes):— OMAN. Dhofar: Jabal Al Qamar, Wadi Kharfut, 14 m of elevation, 08 March 2010, A. Patzelt, I. Al Rashdi, L. MacKinnon AP 3940 ( OBG!) ; Sewerage outlet Wadi 5 km west of Salalah , 20 m of elevation, 26 July 1985 (in leaf), A.G. Miller 7117 ( E00345425 digital image!) ; 5 km west of Salalah , 2 m of elevation, 09 September 1985 (in flower), A.G. Miller 7550B ( E00345369 digital image!) ; Wadi Afal , 0-250 m of elevation, 27 September 1993 (in flower), I. McLeish 2700 ( E00106879 digital image!) ; Mughsayl, 0-250 m of elevation, 27 September 1993, I. McLeish 2713 ( E00106875 digital image!) ; Wadi Aful , 180 m of elevation, 24 September 1993, I.S. Collenette 8904 (ON!) ; ca. 12 km W Mirbat along rd. 49, 44 m of elevation, 22 January 2018, M. Pinter s.n. (photo) ; ibidem, 20 June 2019 in leaf ex cult., M. Pinter ( ABH!) ; S of Wadi Hinna , 256 m of elevation, 22 January 2018, M. Pinter s.n. (photo!) ; ibidem, 20 June 2019 in leaf ex cult., M. Pinter ( ABH!) ; ibidem, 16 July 2019 inflorescence ex cult., M. Pinter s.n. ( ABH!) ; ca. 5,4 km E of military post along rd. 47 ; hillside, 672 m of elevation, 26 January 2018, M. Pinter s.n. (photo!) .

Figures

FIGURE 1. Vera-duthiea capillifolia A. Patzelt et al. A. Habitus of a plant at vegetative stage; B. Details of the canaliculate leaves (right) and apex (left); C. Inflorescence; D. Flower in lateral view; E. Dissected flower in lateral view; F. Flower in apical and dorsal view; G. Tepals and stamens; H. Gynoecium; I. Dehisced capsules. Scale bars: A, C: 1 cm; B: 2 mm; D–I: 5 mm.

FIGURE 2. Distribution map of Vera-duthiea capillifolia A. Patzelt et al. in the Dhofar province of Oman.