Mcvaughia sergipana Amorim & R.F.Almeida, Systematic Botany 40(2): 534. 2015

Almeida, Rafael F., Guesdon, Isabel R., Pace, Marcelo R. & Meira, Renata M. S., 2019, Taxonomic revision of Mcvaughia W. R. Anderson (Malpighiaceae): notes on vegetative and reproductive anatomy and the description of a new species, PhytoKeys 117, pp. 45-72 : 45

3. Mcvaughia sergipana Amorim & R.F.Almeida, Systematic Botany 40(2): 534. 2015 Figs 9 , 10 , 11

Type.

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!).

Description.

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.

Specimens seen.

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).

Distribution, habitat, and phenology.

Mcvaughia sergipana is known only from sandy restingas and coastal dunes within the Atlantic Forest Domain in the state of Sergipe, Brazil (Fig. 11 ). Flowering and fruiting from September to December.

Conservation status.

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.

Etymology.

The epithet refers to the distribution of M. sergipana , which is restricted to the state of Sergipe, Brazil.

Anatomical notes.

This species has an unusual distribution pattern of leaf glands (Fig. 3C ), in which all conspicuous glands are scattered throughout the leaf blade and visible to the naked eye. The basilaminar glands are generally positioned in pairs, varying from 2-8 glands. Several laminar glands are distally scattered throughout the blade, and one pair is positioned subjacent to the apical leaf tooth (Fig. 3G ). The outline of the anticlinal epidermal cell walls is straight on both adaxial and abaxial surfaces (Fig. 3N, P ). Leaf glands are yellow, and bracteole glands are green in secretory stage (Fig. 4A ), turning yellow at blooming. The basilaminar and laminar leaf glands were anatomically identified as sessile (Fig. 3F, K ), while the bracteole gland was recognized as subsessile (Fig. 4D ) and the sepal gland as short-stalked (Fig. 4I ). The bracteole gland shows a flattened secretory surface. Another important character that distinguishes M. sergipana is the distribution pattern of glands on the posterior petal. About five marginal petal glands are present on the proximal portion of the posterior petal in other Mcvaughia species, but only in M. sergipana do these glands extend the entire length of the petal margin (Fig. 4K, M–N ). The proximal petal glands are stalked, in contrast to the small glands distributed distally that are sessile (Fig. 4 R–T ).

Figures

Figure 3. 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).

Figure 4. 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).

Figure 9. 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.

Figure 10. Photograph of the isotype of Mcvaughia sergipana.

Figure 11. Distribution map of Mcvaughia: triangle - M. bahiana, circle - M. piauhiensis, and square - M. sergipana. Solid blue line in the center represents the Sao Francisco River today. Dotted blue line represents the past course of Sao Francisco River. Blue circle represents the Sao 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 Ceara, MA - state of Maranhao, PB - state of Paraiba, PE - state of Pernambuco, PI - state of Piaui, RN - state of Rio Grande do Norte, and SE - state of Sergipe.