Billburttia Magee

Rakotonandrasana, Stéphan R., Oskolski, Alexei A., Tilney, Patricia M., Kotina, Ekaterina L. & Wyk, Ben-Erik Van, 2017, The rediscovery of Billburttia vaginoides, with notes on the morphology, anatomy, traditional uses and conservation status of the genus Billburttia (Apieae, Apiaceae), Phytotaxa 321 (3), pp. 265-276 : 271-275

Billburttia Magee & B.-E.van Wyk in Magee et al. (2009a: 223); Van Wyk et al. (2013: 114).

Type:— B. capensoides Sales and Hedge

A detailed description of the genus is given by Magee et al. (2009a).

Billburttia is a genus of two species, endemic to Madagascar and restricted to the central part of the country.

Diagnostic characters:— Billburttia can be distinguished from other peucedanoid species by its leaflets lacking a prominent midrib, but with well-developed lateral venation. Fruit characters are also distinct, especially the six commissural vittae (vs. the normal two), the ribs with vascular bundles located near the tips (vs. near the base of the ribs), and the presence of acicular crystals in sheaf-like and spherical aggregates. The width of the commissure is also a very important diagnostic character according to Magee et al. (2009a). It extends only to the base of each marginal wing/rib (and not to the tip of each wing as in peucedanoids).

Key to the species

1. Stems erect; leaflets broad, more than 4 mm (up to 15 mm) wide, obovate, linear-elliptic to elliptic, with 3 to 5 veins.................... ........................................................................................................................................................................ Billburttia capensoides

- Stems spreading; leaflets narrow, usually less than 2 mm (up to 4 mm) wide, linear-filiform, with a single vein ............................ ........................................................................................................................................................................... Billburttia vaginoides

Billburttia capensoides Sales & Hedge in Magee et al. (2009a: 242); Van Wyk et al. (2013: 114). Type:— MADAGASCAR, Ouest du massif d’Andringitra, Sept 1911, Perrier de la Bâthie 6807 (holoype P!) .

Shrub or subshrub. Stems 1–2 m, erect, c. 20 mm thick at base. Leaves 1- to 3-pinnate; rachis 60–150 mm; leaflets in 3–5 pairs; basal leaflets sometimes not divided, lateral leaflets elliptic to linear elliptic, 20–63(–70) × 5–15 mm, terminal leaflet obovate, 25–40 × 3–15 mm; margins weakly serrate; base narrow to broad and cuneate, with 3–5 basal veins; apex acute to mucronulate. Primary umbel 70–130 mm wide; rays 12–28(–40), 10–55 mm long; bracts 3–16 mm long; raylets 15–30, 4–8(–14) mm long; bracteoles 1.5–3.0(–12) × 1.0–1.5(–3) mm. Petals ovate, 2.0–2.1 × 1.1–1.5 mm; stamens up to 3 mm. Fruit ovate to narrowly ellipsoid, 3.5–4.5 × c. 1.5 mm, ribbed, but not winged.

Diagnostic characters:— Billburttia capensoides is distinguished from B. vaginoides by the erect (not spreading) habit and the much broader, obovate or linear-elliptic to elliptic shape of the leaflets, each with three to five well-developed basal veins (not linear-filiform, with a single midrib).

Distribution and habitat:— Known only from the central part of Madagascar, B. capensoides is apparently rare and localized. It occurs from Andringitra to the Arivonimamo massif, at elevations of 1 000–2 658 m ( Fig. 6 ). The species grows in fertile red clay soil on volcanic rock or in infertile lateritic clay soil. The habitat is undisturbed areas in the rocky evergreen sclerophyllous woodland and open grassland, with Leptolaena Thouars (1807: 41 , t11) spp., Uapaca bojeri Baillon (1874: 176) and Helichrysum Miller (1754 : [462]) spp. It can also withstand low levels of anthropogenic disturbance and sometimes grows in open rocky grassland in competition with Helichrysum species.

Phenology:— Flowering occurs in July to September and fruiting from September to October.

Vernacular names:— Tsilaninosy (Bara dialect), Hazompitatra (Merina dialect).

Uses:— Our ethnobotanical survey showed that a leaf decoction is traditionally used to stimulate lactation and to treat abdominal pains. A decoction of the whole plant may also be inhaled to treat influenza and headache. Decoctions of the aerial parts are taken to prevent neonatal jaundice. According to Boiteau et al. (1999), a decoction of the plant is reputed to be effective in treating colic.

Conservation status:— Based on 14 specimens collected in 14 different localities, nine subpopulations were investigated, four of which are inside three protected areas. These are Andringitra National Park and two newly protected areas (Itremo and Manjakatompo). The extent of occurrence (EOO) area is 25 178 km ² ( IUCN 2001). However, subpopulations outside the protected areas are subjected to anthropogenic pressure (agriculture and grazing by livestock). In addition, the area of occupancy (AOO) is low (only 126 km ²) ( IUCN 2001). The proposed conservation status is NT (Near Threatened).

Specimens examined:— MADAGASCAR, Antananarivo: without locality, without date, Baron 340 ( P) ; Central Madagascar , Oct 1882, Baron 2021 ( BM) ; Faratsiho, Ankaratra , Jan 1955, Bosser 7563 ( P) ; Ankaratra , pente rocailleuse [rocky slope], 2200 m, Nov 1955, Bosser 8623, ( P) ; Ankisatra , 27 May 1889, Catat 420 ( P) ; Station forestière de Manjakatompo [Manjakatompo Forest Station] near sommet Nosiarivo, in massif l’Ankaratra [Ankaratra massif], 27 Jan 1975, Croat 28892A ( P) ; Massif du Tsiafajavona [ Tsiafajavona massif], 2200–2600 m, 16 May 1938, Decary 13400 ( P) ; Nord Betsileo, Antsirabe [north of Betsileo, at Antsirabe], Aug 1880, Hildebrandt 3571 ( BM, K, P) ; Pentes nord de Vohitra, Antsirabe [north slope of Ivohitra, Antsirabe], March 1934, Jard. Bot. Tananarive 82-1 ( P) ; Tsiafajavona , 10 May 1938, Jard. Bot. Tananarive 3644 ( P) ; Env. d’Antsirabe , 1500 m, Oct 1913, Perrier de la Bâthie 6792 ( P) ; Manjakatompo Station Forestière [Manjakatompo Forest Station], 2320 m, 28 Oct 2003, Phillipson, Schatz, Schmidt & Rabehevitra 5636 ( P, TAN) ; Ambatobe , 6 km ouest de la ville de Manalalondo [6 km west of the town of Manalalondo], 1685 m, 19 Sept 2015, Rakotonandrasana et Ratrimosaona 1494 ( TAN, CNARP) ; Ankaratra, Rousson s.n. 1890 ( P) ; Distr. Betafo, sommet du pic de Vohimalaza près Betafo [summit of Vohimalaza], 1700 m, 18 Nov 1912, Viguier & Humbert 1357 ( P) ; Distr. Betafo , dans la coulée de laves de l’Iantsifitra [in the lava flow of Iantsifitra], c. 1450 m, 18 Nov 1912, Viguier & Humbert 1386 ( P) ; Betafo, monts Vararata [Vararata mountains], c. 2000 m, 19 Nov 1912, Viguier & Humbert 1617 ( P) ; Prov. Itasy, distr. Kitsamby, sur le flanc ouest de l’Ankaratra , entre Ambatofotsy et le Tsiafajavona [on the western slope of Ankaratra, between Ambatofotsy and Tsiafajavona], c. 2200 m, 17 Nov 1912, Viguier & Humbert 1727 ( P) ; Antsirabe, Dec 1913, Waterlot s.n. ( P). Fianarantsoa: 6 km ouest Itremo [6 km, west of Itremo], 14 Feb 2009, Andriamahay & Rakotoarisoa SNGF 2219 ( TAN) ; Ambatofinandrahana, sur la valée d’Ananiloha [in Ananiloha valley], 1475 m, 7 Feb 2001, Andriamihajarivo et al. 37 ( TAN) ; Ambositra to Ambatofinandrahana on R.N. 35, 1600 m, 11 March 1992, Clement, Phillipson & Rafamantanantsoa 2009 ( TAN) ; Itremo, Vicinity of col de l’Itremo, massif de l’Itremo [Itremo massif], 1300–1400 m, 27 Jan 1975, Croat 29892 ( P, TAN) ; Route de l’Itremo [on the way to Itremo], 7 July 1966, Debray 2015-D ( CNARP) ; Environs d’Ambatofinandrahana [around Ambatofinandrahana], 1600–1700 m, 17 Feb 1938, Decary 13035 ( P) ; Ambositra , dans les bois de Tapia [in the Tapia wood], 2 Feb 1942, Decary 17248 ( P) ; Ambatofinandrahana , 3 Feb 1942, Decary 17356 ( P) ; East margin of Itremo massif, 1290 m, 24 Nov 1993, Du Puy, Labat & Andriantiana M 660 ( P, TAN) ; Andringitra, plateau d’Andohariana [Andohariana plateau], c. 2000 m, 14 Nov 1970, Guillaumet 3588 ( P) ; Andringitra, Riambavy , près du cascade [next to the waterfall], 2000 m, 1934–1935, Heim s.n. ( P) ; Riviere Menaloha [Menaloha River], 11 Dec 1944, Homolle s.n. ( P) ; Env. de Miarinarivo , SE d’Ambalavao [Around Miarinarivo, south eastern of Ambalavao], 1000–1400 m, 23 Nov 1923, Humbert 3634 ( P) ; Env. d’Ambatofinandrahana [Around Ambatofinandrahana], 1400–1500 m, 16 Jan 1955, Humbert & Capuron 28129 ( P) ; Env. d’Ambatofinandrahana [around Ambatofinandrahana], March 1960, Keraudren 218 ( P) ; W du massif d’Andringitra [west of Andringitra massif], 1000 m, Sept 1911, Perrier de la Bathie 6807 ( P) ; Itremo massif, W of Ambatofinandrahina, along road to Col d’ltemo, 1540 m, 9 Nov 2002, Porter P. Lowry II et al. 5841 ( TAN) ; Réserve Naturelle Intégrale no. 5, près de la montagne rocheuse Vangomena , plateau de Sonindrana [near the rocky mountain Vangomena, Sonindrana plateau], 2010 m, 23–24 Sept 1994, Rakotovao 52 ( P, TAN) ; Itremo , 7 June 1966, Rakotozafy 631 ( P, TAN) ; Ambalavao, Sendrisoa, Antanifotsy , pic Boby d’Andringitra [Boby summit of Andringitra], 2658 m, 29 Oct 1994, Razafindrabe 193 ( P, TAN) ; Imaitso , June 1973, Razafindrambao 824 ( CNARP) ; Distr. Ambalavao, canton Sendrisoa [District of Ambalavao, Sendrisoa], 2278 m, 20 Oct 1957, Resérves Naturelles 2278 ( P) ; Eastern margin of the Itremo massif, 1580–1700 m, 10 March 2000, Schatz et al. 3962 ( TAN) .

Billburttia vaginoides Sales & Hedge in Magee et al. (2009a: 243); Van Wyk et al. (2013: 114). Type :— MADAGASCAR, Flanc E du Mt. Tsiafajavona, March 1921, Perrier de la Bâthie 13557 (holotype P!; isotype P!) .

Shrub or subshrub. Stems spreading, 1.0– 1.5 m, c. 15 mm thick at base. Leaves 1- to 3-pinnate; rachis 70–130(–140) mm; leaflets in 4–6 pairs; basal leaflets always divided, lateral leaflets linear, 25–45 × 2(–4) mm, terminal leaflet linear (15–)20–35 × 1.5–2.0(–4) mm; margins weakly serrate; base narrow to broad and cuneate; with a single midrib; apex acute to mucronulate. Primary umbel 50–100 mm wide; rays 12–30(–80), 15–50 mm long; bracts 3–15 mm long; raylets 15–30, 4–12 mm long; bracteoles 1.5–10.0 × 1–2 mm. Petals ovate, 1.8–2.0 × 1.0– 1.2 mm; stamens 2.5–4.0 mm. Fruit narrowly ellipsoid, 3.0–3.5 × 1.5 mm, prominently ribbed, but not winged.

Diagnostic characters:— Billburttia vaginoides is easily distinguished from B. capensoides by the spreading habit, and the linear-filiform leaflets occurring in 4 to 6 pairs, each with a single vein (midrib).

Distribution and habitat:— The species is stated to be in danger of extinction, according to notes by Perrier de la Bâthie on his specimen collected on Ankaratra summit in 1921. The last collection cited by Magee et al. (2009a) was made in 1939 and is housed at the Paris herbarium (P). A full investigation at the TAN herbarium showed that Bosser deposited a specimen of that species collected around Behenjy in 1957. The species was recently rediscovered by botanists of CNARP during field collecting of aromatic plants around Arivonimamo. One of us (BEVW) helped to identify the specimen. The field work revealed that only a few individuals are currently known to occur at Ambohitrambo (Arivonimamo district) and at Ankotrokotroka (Faratsiho district) ( Fig. 6 ). The habitat at Arivonimamo and Behenjy comprises rocky, evergreen, sclerophyllous woodland, which is highly disturbed and currently dominated by Leptolaena pauciflora Baker (1883: 96) and Uapaca bojeri . However, at Faratsiho, B. vaginoides grows in volcanic soil in open, rocky grassland.

Phenology:— Flowering occurs in April to June; fruiting in May to August.

Vernacular name:— Volotaratsintsina (Merina Dialect).

Uses:— According to local people, the plant is used to reduce fever, and decoctions of the stems and leaves are taken to treat convulsions. A decoction of the plant is said to be soporific (i.e. it induces drowsiness or sleep).

Conservation status:— The species is rare and was previously known only from a few herbarium collections made between 1890 and 1957. Based on five specimens collected in five different localities, five subpopulations were investigated and all of them occur outside protected areas. The extent of occurrence (EOO) is 2081 km ² and the area of occupancy (AOO) is 45 km ² ( IUCN 2001). The total known population is less than 250 mature individuals. Populations are subjected to anthropogenic pressure, including agriculture, grazing by livestock and wildfires. The proposed conservation status is CR (Critically Rare) [c2 (aii)]. Conservation of the natural ecosystem in which this species occurs should be encouraged. Transplantation of seedlings into protected areas is needed in order to improve seedling survival and increase the chance of future successful germination. Ex situ cultivation and research on propagation are also of great importance.

Specimens examined:— MADAGASCAR, Antananarivo: Prov. Emirina , without date, Bojer s.n. ( P) ; Route du sud, pseudo steppe sur rocaille [on the way to the south, pseudo steppe on rock], June 1957, Bosser 13204 ( TAN) ; Vallée de l’Ikopa NO d’Ankazobe [Ikopa valley, northwest of Ankazobe], 13 March 1930, Decary 7564 ( P) ; Tampoketsa , au NE de Fenoarivo [Tampoketsa, northeast of Fenoarivo], 16 March 1930, Decary 7583 ( BM, P) ; Behenjy ( Imerina ) sur rocaille humide [on wet rock], 11 March 1930, Decary 13893 ( P, TAN) ; Ambohimasimbola , 27 April 1939, Jard. Bot. Tananarive 4261S ( P) ; Ankaratra , vers 2200 m, April 1914, Perrier de la Bâthie 6795 ( P) ; Mt Tsiafajavona , 2000 m, April 1914, Perrier de la Bâthie 6799 ( P) ; Flancs est de mt Tsiafajavona , vers 2200 m, type de l’espèce [east slope of Tsiafajavona mountain, around 2200 m, typus], April 1914, Perrier de la Bâthie 13557 ( P) ; Ambohitrambo, 8 km au N d’Arivonimamo [Ambohitrambo, 8 km north of Arivonimamo], 1406 m, 13 Aug 2014, Rakotondrafara et al. 1424 ( TAN, CNARP) ; Ankotrokotroka, Faratsiho , 1454 m, 19 Sept 2015, Rakotonandrasana et Ratrimosaona 1496 ( TAN, CNARP) ; Région centrale d’Ankaratra [Central region of Ankaratra], Rousson s.n. 1890 ( P) .

Figures

FIGURE 6. The known geographical distribution of Billburttia capensoides (dots) and B. vaginoides (triangles).