Research Article |
Corresponding author: Rafael F. Almeida ( dealmeida.rafaelfelipe@gmail.com ) Academic editor: Alexander Sennikov
© 2019 Rafael F. Almeida, Isabel R. Guesdon, Marcelo R. Pace, Renata M.S. Meira.
This is an open access article distributed under the terms of the CC0 Public Domain Dedication.
Citation:
Almeida RF, Guesdon IR, Pace MR, Meira RMS (2019) Taxonomic revision of Mcvaughia W.R.Anderson (Malpighiaceae): notes on vegetative and reproductive anatomy and the description of a new species. PhytoKeys 117: 45-72. https://doi.org/10.3897/phytokeys.117.32207
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A taxonomic revision of Mcvaughia is presented, including the description of a new species from the state of Piauí, Brazil, and notes on wood, secondary phloem, leaf, and floral morpho-anatomy. We present a key to the species, full morphological descriptions, a distribution map, and notes on distribution, ecology, etymology, and conservation status for each species.
Atlantic Forest, Brazil, Caatinga, Malpighiales , Neotropical flora
Mcvaughia W.R.Anderson is a genus of Malpighiaceae comprising three species endemic to the Atlantic Forest and Caatinga domains in northeastern Brazil (
The first phylogenetic studies for Malpighiaceae demonstrated that a clade comprising the genera Burdachia, Glandonia, and Mcvaughia made the Byrsonimoideae paraphyletic (
During recent visits to Brazilian herbaria, we found a third species of Mcvaughia endemic to seasonally dry forests from the state of Piauí, Brazil. We present a taxonomic revision of Mcvaughia, including full morphological descriptions, a distribution map, illustrations, and notes on conservation, distribution, and etymology of all species accepted in the genus. Additionally, we present a detailed anatomical description of wood, bark, leaves, and flowers for the genus. This is the first of a series of joint studies focusing on the biosystematics of Malpighiaceae by the Malpighiales Biosystematics Working Group (
Morphological and phenological data were based on herbaria samples (ALCB, ASE, CEN, CEPEC, F, FLOR, G, HST, HUEFS, K, MBM, MICH, NY, P, RB, SP, TEPB, U, UB, US, and VIC; herbaria acronyms according to Thiers, continuously updated). The indumentum terminology follows
Fresh samples of leaves, inflorescence, and stems were fixed in the field with FAA (formaldehyde, acetic acid and 50% ethyl alcohol; 1:1:18, by volume) for 48h (
For wood and bark anatomy, Mcvaughia sergipana stems [specimen Amorim 8393 (HUEFS)] were boiled in water and glycerin for a month to soften its extremely stiff wood (
Micromorphological data were obtained using a scanning electron microscope (SEM) at the Center for Microscopy and Microanalysis, Universidade Federal de Viçosa. Fixed samples were dehydrated in an ethanol series, submitted to the critical point technique (CPD 020; Bal-Tec, Balzers, Liechtenstein), sputter coated with gold (
Mcvaughia bahiana W.R.Anderson
Shrubs to subshrubs, perennial, growing in sandy soils. Branches cylindrical, densely sericeous or lanate-velutinous, generally glabrescent at age. Stipules epipetiolar, completely connate, persistent. Leaves opposite; petiole eglandular; blade bearing 2–many glands abaxially. Thyrsi terminal, pedunculate, many-branched; cincinni alternate to subopposite, 1–14-flowered; bracts persistent; bracteoles persistent, one of them 1-glandular, the other eglandular, gland green in bud turning yellow in anthesis. Flowers zygomorphic; floral buds slightly flattened at middle; pedicel stout, straight in bud. Sepals leaving petals exposed in pre-anthesis, all 2-glandular. Petals bright to golden yellow, glabrous, the anterior two remaining cupped one inside the other; lateral petals with the margin erose; posterior petal bearing several marginal glands. Stamens 7–8, staminodes 2–3 (stamens opposite the posterior-lateral sepals and the posterior petal); filaments glabrous, those opposite the posterior-lateral petals slightly curved towards the apex; connectives inconspicuous; anthers horseshoe-shaped, glabrous, outer locules confluent at apex, reduced to antherodes in staminodes. Ovary 3-carpellate, 3-locular, 2 locules ± anterior, apparently collapsed lacking ovules, 1 locule almost posterior, fertile, 1-ovulate; styles 3, slender, truncate to uncinate at apex; stigma minute, lateral. Drupes rugose, twisted, asymmetric, 1-locular, proximal chamber thick-walled, 1-seeded, distal chamber thin-walled, filled with a viscous secretion (allowing the fruit to float and to be dispersed by water).
The epithet pays tribute to Dr. Rogers McVaugh (*1909–2009†), an American botanist, expert in the Mexican flora.
Mcvaughia is restricted to sandy soils within sedimentary basins of Northeastern Brazil, with different species being endemic to each sedimentary basin: Mcvaughia bahiana – Tucano basin, M. piauhiensis – Parnaiba basin, and M. sergipana – Sergipe-Alagoas basin (
Mcvaughia is the sister-group of Burdachia and Glandonia, comprising a lineage (Mcvaughia clade) of early diverging Malpighiaceae with water-dispersed fruits, most commonly found growing along wetland floodplains and upland forest throughout the Amazon Basin (
Heartwood and sapwood indistinct light brown; grain straight to slightly wavy. In anatomical sections, the heartwood appears with abundant cell contents (bottom of Fig.
Wood anatomy of Mcvaughia sergipana. A–B transverse sections: Growth rings marked by radially narrow fibers (arrowheads) and a discontinuous line of axial parenchyma (in B); vessels are narrow and abundant, arranged in radial rows of 4 or more cells; some solitary vessels present; parenchyma rare, paratracheal scanty or at the growth ring limits; heartwood vessels in the bottom with content C radial section: Rays 2–3 cells wide, non-storied; prismatic crystals present in ray cells (arrows); parenchyma with 3 cells per strand (arrowhead) D ray heterocellular with procumbent, square and upright cells mixed throughout the ray. Scale bars: 150 μm (A), 100 μm (B–C), 60 μm (D).
Growth rings are indistinct, phloem non-stratified (Fig.
Secondary phloem of Mcvaughia sergipana. A–C Transverse section: A Phloem non-stratified, with scattered fiber-sclereids (arrows); Rays dilating slightly B Crystalliferous axial parenchyma arranged in diffuse-in-aggregate narrow bands (arrowhead) C Crystalliferous axial parenchyma with druse crystals, forming diffuse in aggregate bands, isolated fiber-sclereids present (arrowhead) D A ray 3 cells wide, fiber-sclereids and axial parenchyma in tangential section E Bands of crystalliferous parenchyma with druses evident also in radial section; Rays heterocellular mixed. Scale bars: 200 μm (A), 100 μm (B–C, E), 50 μm (D).
The leaf anatomy in the species of Mcvaughia is quite similar. The vascular system of petioles is arranged as a curved arc with two conspicuous accessory bundles. The most distinctive leaf character is the distribution pattern of glands (Fig.
Leaf morphoanatomy of Mcvaughia species. A patterns of leaf glands distribution on the abaxial leaf surface of M. bahiana B patterns of leaf glands distribution on the abaxial leaf surface of M. piauhiensis C patterns of leaf glands distribution on the abaxial leaf surface of M. sergipana D transverse section of leaf base showing the basilaminar pair of stalked glands (white arrows) E basilaminar leaf gland with a stalk (black arrow) in M. piauhiensis F basilaminar gland in M. sergipana showing a sessile position (SE= anatomical arrangement with secretory epidermis, SP= vascularized secretory parenchyma) G–H laminar glands on the apex of cleared leaves of M. sergipana and M. bahiana respectively, note the apical tooth (G) I sessile laminar glands in M. sergipana J stalked laminar gland in M. piauhiensis K–L transverse sections of the leaf blade; mesophyll with uniserial palisade-like parenchyma and spongy parenchyma composed by several or few layers in M. sergipana and M. bahiana, respectively; note the idioblast with druse crystals at the mesophyll (white arrow) and the stomata distribution at the abaxial leaf surface (black arrow) M–N adaxial epidermis surface of M. piauhiensis and M. sergipana, showing scars of malpighiaceous trichomes O abaxial epidermis surface of trichomes abundance in M. bahiana P–Q outline of the anticlinal epidermal cell walls: straight in M. sergipana (P) and sinuous in M. bahiana (Q). Laminar scale bars: 1 cm (A–C), 100 μm (D, F–K, N–O), 150 μm (E), 50 μm (L–M, P–Q).
Observations during field trips revealed that sepal and petal glands are yellow in M. sergipana and M. bahiana (Fig.
Reproductive morphoanatomy of Mcvaughia species. A inflorescence during development, showing a bracteole gland (BG) and Sepal glands (SG) B ten sepal glands encircling the calyx C Petal glands (PG) along the margin of posterior petal D–F transverse section of bracteole glands in M. sergipana, M. bahiana and M. piauhiensis, respectively G anatomical arrangement of bracteole gland, with a palisade-like secretory epidermis (SE) and secretory parenchyma (SP) H–I transverse section of floral bud and anthesis flower in Mcvaughia bahiana and M. sergipana; calyx gland pair displaced at the anterior sepal J calyx gland structure, showing a secretory epidermis (SE) and vascularized secretory parenchyma (SP) K–L petal glands on the margin of petals in M. sergipana and M. bahiana respectively M–N detail of the petal glands at the apex of the petal limb in M. sergipana, cleared and in SEM image O–Q petal glands positioned at the base, M. bahiana on SEM image, M. bahiana and M. piauhiensis cleared R–T conspicuous and stalked petal glands at the base of M. sergipana, in SEM image, cleared and longitudinal section. Scale bars: 200 μm (D), 150 μm (E–F), 50 μm (G), 500 μm (H–I), 100 μm (J, P–S), 300 μm (L–M), 200 μm (N, T).
1 | Leaf blades sericeous, margins revolute, several conspicuous and sessile glands near the midvein, straight outline of the wall in anticlinal epidermal cells, mesophyll with more than 4 layers of spongy parenchyma; cincinni 1–2-flowered; margins of posterior petal entirely glandular, staminode opposite the posterior petal with stout filament; restinga and coastal dunes | Mcvaughia sergipana |
– | Leaf blades tomentose to lanate-velutinous, margins plain, conspicuous and stalked glands only near base and apex, sinuous outline of the wall in anticlinal epidermal cells, mesophyll with fewer than 4 layers of spongy parenchyma; cincinni (2–)3–7-flowered; margins of posterior petal glandular at base only, staminode opposite the posterior petal with slender filament; inland caatinga | 2 |
2 | Shrubs 1–3 m tall; leaf blades tomentose; flowers 1–1.2 cm diam., staminode opposite the posterior petal shorter than fertile stamens, apex of styles truncate; state of Bahia | Mcvaughia bahiana |
– | Subshrubs ca. 50 cm tall; leaf blades lanate-velutinous; flowers 1.5–2 cm diam., staminode opposite the posterior petal as long as fertile stamens, apex of styles uncinate; state of Piauí | Mcvaughia piauhiensis |
BRAZIL. Bahia: Conceição do Coité, road from Coité, 12 km to Santaluz, fl. Fr., 6 Mar 1976, W.R. Anderson 11740 (holotype: MBM barcode MBM59835!; isotypes: F barcode F0062743F!, G barcode G00352842!, K barcode K000426948!, MICH barcode MICH1102251!, NY barcode NY00067680!, P barcode P02429273!, RB barcode RB00540751!, SP barcode SP000249!, U barcode U0003826!, UB barcode UB1950!, US barcode US00108758!).
Mcvaughia bahiana. A shrub habit B subshrub habit C inflorescence showing glandular bracts D inflorescence showing flowers in anthesis E inflorescence showing immature and mature fruits F detail of mature fruits G drupe indumentum H glabrescent drupe. A, D–H by W.R. Anderson B–C by I.R. Guesdon.
Shrubs 1–3 m tall. Branches densely sericeous, glabrescent at age. Stipules 2.5–5 mm long, adaxially glabrous, abaxially sericeous. Leaves opposite; leaf blades 4.5–8.8 × 2–5 cm, chartaceous to subcoriaceous, elliptic to obovate, base cuneate to rotund, margins plain, entire, apex acute to apiculate, adaxial side initially tomentose, glabrous at age, abaxial side densely tomentose, a pair of conspicuous glands at base abaxially, on each side of the midrib, a few inconspicuous glands scattered over the blade, with 1–3 glands near the apex; petiole 0.3–0.7 cm long, canaliculate, densely tomentose, eglandular. Thyrsi of 2–7-flowered cincinni; rachis 3–10 cm long, smooth, densely tomentose, with brown hairs; lateral cincinni 12–24, subopposite; bracts 2–7 mm long, narrowly-triangular, appressed to the peduncle, eglandular, tomentose; peduncle 1.5–4.5 mm long, tomentose; bracteoles 1.5–2.5 mm long, narrowly triangular, opposite, appressed to the peduncle, tomentose, one of each pair bearing a conspicuous gland at base, 1–1.2 mm long. Flowers 1–1.2 cm diam. at anthesis, floral buds 3–3.2 mm long, pedicel 0.5–1.7 mm long, tomentose. Sepals 2–3 × 1.5–2.5 mm, straight, keeled, covering most of the androecium, apex acute, margin glabrous, adaxial side glabrous, abaxial side tomentose, glabrescent near the margin; 10-glandular, glands 1.5–2.5 × 0.7–0.8 mm, yellow, elliptic. Petals yellow, both sides glabrous, soon deciduous; anterior lateral petals orbicular, cucullate, nested inside one another, limb 3–3.3 × 4.5–4.7 mm, margin denticulate, 2-glandular at base, claws 1.2–1.5 × 0.2–0.25 mm, glabrous; posterior lateral petals obovate, spreading, limb 5.5–6.5 × 6–7 mm, margin erose, 2-glandular at base, claws 1.8–2 × 0.3–0.35 mm, glabrous; posterior petal obovate to orbicular, erect, limb 6–7 × 7–8 mm, margin erose, 3–5 pairs of rounded glands at the base of limb, proximal pair larger, claws 3–4 × 0.7–0.9 mm, both sides glabrous. Stamens free at base, filaments 2–3 × 0.2–0.4 mm, cylindrical, thicker at base; connective inconspicuous, glabrous; anthers 0.7–1 × 0.4–0.45 mm; staminodes opposite the posterior-lateral sepals covered by sepals, filaments ca. 1 mm long, long-triangular, anthers ca. 0.2 mm long, oblong, locules lacking; staminode opposite the posterior petal not covered by sepals, exserted, diverging from styles, filament 2–2.1 × 0.2–0.4 mm long, anther 0.25–0.3 mm long, oblong, locules reduced. Ovary 1–1.3 × 1–1.3 mm, ovoid, densely sericeous; styles 3, erect, ca. 2.5–2.7 × 0.5–0.6 mm, cylindrical, parallel, glabrous, apex truncate, anterior style slightly smaller than posterior ones; stigma lateral, circular. Drupes 7–8.5 × 4–5 mm, cylindrical, slightly twisted, apex with persistent styles, sparsely tomentose, with two chambers, proximal chamber containing the seed, distal chamber containing an oily substance; seed globose, smooth. Embryo not seen.
BRAZIL. Bahia: Itiúba, 20 km de Camaleão para Cansanção, 330 m, fl., 26 Feb 2000, A.M. Giulietti 1827 (CEN, FLOR, HUEFS, RB, UB); 20 Km East Camaleão, Rod. Itiúba/Cansanção, 21 Feb1974, fl., R.M. Harley 16465 (CEPEC, MICH, NY, P, RB). Monte Santo, Fazenda Bom Jesus, fl. fr., 11 Oct 2000, C.M.L. Aguiar 17, 18, 19, 27, 28, 30, 31 (HUEFS); fl. fr., 12 Jan 2006, M.L. Guedes 12148 (ALCB). Quijingue, Serra das Candeias, 5 Km W povoado Quixabá do Mandacaru, near Tucano, fl. fr., 15 May 2005, D. Cardoso 529 (HUEFS); fl. fr., 8 Jul 2006, D. Cardoso 1311 (HUEFS). Tucano, povoado Bizamum, 23 km from Tucano, fl. fr., 6 Jun 2004, D. Cardoso 57, 99 (HUEFS, SP); povoado Marizá, 13 km from Tucano, fl. fr., 6 Jan 2006, D. Cardoso 958 (HUEFS, RB); distrito de Caldas do Jorro, estrada entre Caldas do Jorro e rio Itapicurú, fl. fr., 1 Mar 1992, A.M. Carvalho 3863 (CEPEC, HUEFS, MBM, NY, SP); fl., 15 March 2008, G. Costa 341 (HST, HUEFS); povoado Bizamum, fl., 6 Feb 2004, L.P. Queiroz 9017 (HUEFS); povoado Bizamum, fl. fr., 22 Sep 2015, I.R. Guesdon 300, 301 (VIC).
Mcvaughia bahiana is known only from sandy caatingas (seasonally dry forests) within northeastern state of Bahia, Brazil (Fig.
Mcvaughia bahiana shows an extent of occurrence of 2,527 km2, and an area of occupancy of 16.000 km2 within the northeastern state of Bahia, Brazil. Its restricted distribution associated with an accelerated habitat degradation categorizes it as Endangered (EN). Mcvaughia bahiana is the only species in the genus not protected within the limits of a conservation unit.
The epithet refers to the distribution of M. bahiana, which is restricted to the state of Bahia, Brazil.
Leaf glands are distributed throughout the leaf blade. Two basilaminar glands are typically positioned in pairs and visible to the naked eye (Fig.
Mcvaughia piauhiensis differs from M. sergipana Amorim & R.F.Almeida due to its leaf blades abaxially lanate-velutinous (versus sericeous), margins plain (versus revolute), conspicuous and stalked glands only near base and apex (versus throughout the leaf blade), cincinni 3–7-flowered (versus 2-flowered), margins of posterior petal glandular at base only (versus entirely glandular), and staminode opposite the posterior petal with slender filament (versus with stout filament). It also differs from M. bahiana W.R.Anderson due to its subshrub habit (versus shrub habit), leaf blades lanate-velutinous (versus tomentose), flowers 1.5–2 cm diam. (versus 1–1.2 cm diam.), staminode opposite the posterior petal as long as fertile stamens (versus shorter than fertile stamens), and the apex of styles uncinate (versus truncate).
BRAZIL. Piauí: Guaribas, Parque Nacional da Serra das Confusões, Barreiro, fl., 28 Mar 2007, R. Barros 2922 (holotype: HUEFS barcode HUEFS135774!; isotype: CEPEC!, TEPB!).
Subshrubs ca. 50 cm tall. Branches densely lanate-velutinous, glabrescent at age. Stipules 4–4.5 mm long, adaxially glabrous, abaxially densely lanate-velutinous. Leaves opposite; leaf blades 6–11 × 3–6 cm, chartaceous to subcoriaceous, elliptic to obovate, base cuneate, margins plain, entire, apex acute to apiculate, adaxial side light green in sicco, initially lanate-velutinous to glabrescent, abaxial side dark green in sicco, initially lanate-velutinous to glabrescent, except from midvein at base, a pair of conspicuous glands at base abaxially, on each side of the midrib, a few inconspicuous glands scattered on the blade, with 2 conspicuous glands near apex; petiole 0.8–1 cm long, canaliculate, densely lanate-velutinous, eglandular. Thyrsi of 5–8-flowered cincinni; rachis 6.5–7 cm long, smooth, densely tomentose-velutinous, with rusty hairs; lateral cincinni 14–15, alternate; bracts 1.5–2.5 mm long, triangular, appressed to the peduncle, eglandular, tomentose-velutinous; peduncle 3–4 mm long, tomentose-velutinous; bracteoles 1.5–2 mm long, triangular, subopposite, appressed to the peduncle, tomentose-velutinous, one of each pair bearing a conspicuous gland at base, 1.3–1.8 mm long. Flowers 1.5–2 cm diam. at anthesis, floral buds 3–3.5 mm long, pedicel 2–3 mm long, tomentose-velutinous. Sepals 2–2.5 × 1–1.3 cm, straight, keeled, covering most of the androecium, apex rounded, margin short ciliate, adaxial side glabrous, abaxial side tomentose, glabrescent near the margin; 10-glandular, glands 1–1.2 × 0.7–0.8 mm, yellow, elliptic. Petals yellow, soon deciduous; anterior lateral petals orbicular, cucullate, nested inside one another, limb 2.9–3.2 × 4–4.3 mm, margin erose, eglandular, claws 1–1.2 × 0.2–0.25 mm, glabrous; posterior lateral petals obovate, spreading, limb 4–5 × 4–4.5 mm, margin erose, eglandular, claws 1.5–2 × 0.3–0.35 mm, glabrous; posterior petal obovate to orbicular, erect, limb 5–5.5 × 5–5.5 mm, margin erose, 2–3 pairs of reniform glands at the base of limb, proximal pair larger, claws 2.5–3 × 0.6–0.8 mm, adaxially pubescent. Stamens free at base, filaments 2–3 × 0.2–0.4 mm, cylindrical, thicker at base; connective inconspicuous, glabrous; anthers 0.3–0.45 × 0.4–0.45 mm; staminodes opposite the posterior-lateral sepals covered by sepals, filaments ca. 1 mm long, long-triangular, anthers ca. 0.2 mm long, oblong, locules lacking; staminode opposite the posterior petal not covered by sepals, exserted, diverging from styles, filament 2–2.1 × 0.2–0.4 mm long, anther 0.25–0.3 mm long, oblong, locules reduced. Ovary ca. 1 × 1 mm, ovoid, densely tomentose; styles 3, erect, ca. 3 × 0.5 mm, cylindrical, parallel, tomentose at base, uncinate at apex, anterior style slightly smaller than posterior ones; stigma lateral, circular. Drupes (immature) 5–6 × 2–3 mm, cylindrical, slightly twisted, apex with persistent styles, rusty tomentose, with two chambers, proximal chamber containing the seed, distal chamber containing an oily substance; seed (immature) globose, smooth. Embryo not seen.
Mcvaughia piauhiensis is known only from sandy caatingas (seasonally dry forests) within Serra das Confusões National Park in state of Piauí, Brazil (Fig.
Mcvaughia piauhiensis is known only from a single population within the limits of the Serra das Confusões National Park in state of Piauí, Brazil. Until additional fieldwork can be done in seasonally dry forests from Piauí, this species is best categorized as data deficient (DD).
The epithet refers to the distribution of M. piauhiensis, which is restricted to the state of Piauí, Brazil.
This new species resembles M. bahiana in several aspects. The distribution pattern of leaf glands is quite similar, with both showing only one pair of conspicuous glands at base and a few conspicuous glands scattered over the blade (Fig.
BRAZIL. Sergipe: Pirambu, estrada para lagoa redonda, restinga sobre tabuleiro, 10°41'79"S, 36°50'90.2"W, 96 m, fl. fr., 7 Oct 2013, A.M.A. Amorim et al. 8393 (holotype: CEPEC barcode CEPEC142146!; isotype: ASE barcode ASE0035770!, HUEFS barcode HUEFS226853!, MBM!, NY barcode NY02859382!, MICH!, P barcode P01168074!, RB barcodes RB01190994!, RB01191408!, RB01191409!, SP barcode SP003291!).
Shrubs 1.5–2 m tall. Branches densely lanate-velutinous, glabrescent at age. Stipules 3–5 mm long, adaxially glabrous, abaxially sericeous. Leaves opposite; leaf blades 8.4–12 × 2.7–6.5 cm, chartaceous to subcoriaceous, elliptic to ovate to elliptic-lanceolate, base acute to cuneate, margins slightly revolute, entire, apex acute to slightly acuminate, adaxial side green in sicco, initially sericeous to glabrescent, abaxial side metallic green in sicco, densely sericeous to glabrescent, 1–4 pairs of conspicuous glands at base abaxially, on each side of the midrib, with many conspicuous glands scattered distally; petiole 0.3–1.5 cm long, canaliculate, densely sericeous to glabrous at age, eglandular. Thyrsi of 1–2-flowered cincinni; rachis 6.5–11.4 cm long, striated, densely sericeous, with brown hairs; lateral cincinni 15–30, opposite to subopposite; bracts 5–6.5 mm long, lanceolate, spreading, eglandular, sericeous; peduncle 4–5 mm long, sparsely sericeous; bracteoles 2.5–3 mm long, triangular, subopposite, spreading to the peduncle, sericeous, one of each pair bearing a conspicuous green gland at base, 1.3–1.8 mm long. Flowers 1.5–2 cm diam. at anthesis, floral buds 3–3.5 mm long, pedicel 2–3 mm long, tomentose-velutinous. Sepals 2–2.5 × 1–1.3 cm, straight, keeled, covering most of the androecium, apex rounded, margin short ciliate, adaxial side glabrous, abaxial side tomentose, glabrescent near the margin; 10-glandular, glands 1–1.2 × 0.7–0.8 mm, yellow, elliptic. Petals yellow, soon deciduous; anterior lateral petals orbicular, cucullate, nested inside one another, limb 2.9–3.2 × 4–4.3 mm, margin erose, eglandular, claws 1–1.2 × 0.2–0.25 mm, glabrous; posterior lateral petals obovate, spreading, limb 4–5 × 4–4.5 mm, margin erose, eglandular, claws 1.5–2 × 0.3–0.35 mm, glabrous; posterior petal obovate to orbicular, erect, limb 5–5.5 × 5–5.5 mm, margin glandular, 2–3 pairs of stalked reniform glands at the base of limb, proximal pair larger and with many sessile glands scattered distally at the margin, claws 2.5–3 × 0.6–0.8 mm, adaxially pubescent. Stamens free at base, filaments 2–3 × 0.2–0.4 mm, cylindrical, thicker at base; connective inconspicuous, glabrous; anthers 0.3–0.45 × 0.4–0.45 mm; staminodes opposite the posterior lateral sepals covered by sepals, filaments ca. 1 mm long, long-triangular, anthers ca. 0.2 mm long, oblong, locules lacking; staminode opposite the posterior petal not covered by sepals, exserted, diverging from styles, filament 2–2.1 × 0.2–0.4 mm long, anther 0.25–0.3 mm long, oblong, locules reduced. Ovary ca. 1 × 1 mm, ovoid, densely tomentose; styles 3, erect, ca. 3 × 0.5 mm, cylindrical, parallel, tomentose at base, uncinate at apex, anterior style slightly smaller than posterior ones; stigma lateral, circular. Drupes 5–6 × 2–3 mm, cylindrical, slightly twisted, apex with persistent styles, rusty tomentose, with two chambers, proximal chamber containing the seed, distal chamber containing an oily substance; seed globose, smooth. Embryo not seen.
Mcvaughia sergipana. A sandy dune where M. sergipana occurs B detail of epipetiolar stipules C detail of leaf venation patterns D abaxial surface of a leaf E inflorescence showing buds and flowers F detail of glandular bracts G floral bud H flower in frontal view I fruit in side view. Photos by R.F. Almeida.
BRAZIL. Sergipe: Japaratuba, povoado Sambaíba, fl. fr., 9 Sep 2013, B.C.A. Lima 37 (ASE); povoado Bonito, fl. fr., 24 Nov 2014, S.A. Damasceno 73 (ASE). Pirambú, estrada para Lagoa Redonda, fl. fr., 20 Dec 1978, M.R. Fonseca s.n. (ASE671); fl. fr., 17 May 2011, Santana 911 (ASE); fl. fr., 1 Nov 2011, E.A. Melo 13 (ASE); fl. fr., 9 May 2013, G.M.A. Matos 270 (ASE, CEPEC); fl. fr., 24 Sep 2015, I.R. Guesdon 305, 306 (VIC).
Mcvaughia sergipana is known only from sandy restingas and coastal dunes within the Atlantic Forest Domain in the state of Sergipe, Brazil (Fig.
Mcvaughia sergipana shows an extent of occurrence of 49.735 km2 and an area of occupancy of 12.000 km2. Its restricted distribution and accelerated degradation of habitat categorizes it as Critically Endangered (CR). Even though the populations of M. sergipana are scattered within two municipalities in the state of Sergipe, Brazil, some of them are located within the limits of Santa Isabel Biological Reserve.
Distribution map of Mcvaughia: triangle – M. bahiana, circle – M. piauhiensis, and square – M. sergipana. Solid blue line in the center represents the São Francisco River today. Dotted blue line represents the past course of São Francisco River. Blue circle represents the São Francisco paleo lake. Light green – Atlantic Forest domain, dark green – Amazon Forest domain, orange – Cerrado domain, and yellow – Caatinga domain. AL – state of Alagoas, BA – state of Bahia, CE – state of Ceará, MA – state of Maranhão, PB – state of Paraíba, PE – state of Pernambuco, PI – state of Piauí, RN – state of Rio Grande do Norte, and SE – state of Sergipe.
The epithet refers to the distribution of M. sergipana, which is restricted to the state of Sergipe, Brazil.
This species has an unusual distribution pattern of leaf glands (Fig.
Mcvaughia can be characterized by very hard woods, narrow vessels in a radial arrangement, scanty axial parenchyma, heterocellular mixed rays, and large prismatic crystals in ray cells. The bark can be characterized by scattered fiber-sclereids, axial parenchyma in lines filled with druse crystals, intercalating with sieve tubes. Mcvaughia has various features similar to other Malpighiaceae, such as the narrow vessels in radial arrangement, simple perforation plates and simple sieve plates, minute vestured pits, parenchyma strands of 2–4 cells, heterocellular rays, and prismatic crystals in wood and druse crystals in the bark (
Glandonia species also show leaf glands varying from two to four basilaminar and a few to several laminar glands, which can be conspicuous or inconspicuous to the naked eye (
The glands of the posterior petal provide promising floral characters for taxonomic studies in Malpighiaceae (Guesdon pers. com.). Previous studies in Mcvaughia (
The results presented in this study are the second step towards a complete taxonomic revision of the Mcvaughioid clade using several additional methods in biosystematics, initiated by
This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior-Brazil (CAPES, Finance Code 001). We would like to thank the curators and staff of visited herbaria for their support with herbarium specimens and images, and Marco Octávio de Oliveira Pellegrini for his valuable comments on an early version of the manuscript. RFA thanks Capes for his postdoctoral fellowship at UFMG. IRG thanks Capes, and Fundação de Amparo à Pesquisa do Estado do Amazonas (Fapeam/Programa Rh-Interiorização) for her Ph.D. fellowships. RMSAM thanks CNPq for her productivity grant (DEB #307762/2016-5). MRP was sponsored by a Peter Buck fellowship at the NMNH, Smithsonian Institution and from the Programa de Apoyo a Proyectos de Investigación e Innovación Tecnológica (PAPIIT IA200319 – Mexican government). Field trips and herbarium visits were sponsored by a CNPq Universal grant (DEB #422747/2016-5) and by Fundação de Amparo à Pesquisa do Estado de Minas Gerais (Fapemig) (Universal APQ-00383-16).