Portulaca giuliettiae T.A.S.Vieira & A.A.O.P.Coelho, 2016

Santos, Thaíla Vieira A., Paes Coelho, Alexa Araújo De O., Dórea, Marcos Da Costa, Dos Santos, Francisco De Assis R., Leite, Kelly Regina B. & Oliveira, Reyjane Patrícia, 2016, Micromorphological features revealing two new species of Portulaca (Portulacaceae) from Brazil, segregated from P. hirsutissima, Phytotaxa 270 (2), pp. 103-115 : 106-109

Portulaca giuliettiae T.A.S.Vieira & A.A.O.P.Coelho , sp. nov. ( Fig. 1 ‒ 2 , 4 ‒ 5 ).

Type: — BRAZIL. Bahia: Mulungu do Morro, estrada de Segredo para Bonito, 810 m, 12° 0’ 23.00” S, 41° 32’ 4.99” W, 30 August 1999, Carneiro-Torres 123 (holotype HUEFS!).

Diagnosis: — Portulaca giuliettiae differs from P. hirsutissima in having seeds covered by grayish and granulated wax throughout the relief, the outline irregular or corrugated in “U” or “T”, not bifurcated, the cells without convex projections; pollen grains pantocolpate, synaperturate, clypeate, the colpes arranged in pentagons.

Description: —Herb succulent, decumbent (rarely erect), 5.0 − 28.0 cm tall, stems branched, green to purplish; axillary trichomes overlying the entire stem, abundant and conspicuous, whitish, wooly. Leaves sessile, leaf blades 0.5 − 1.4 cm × 0.3 − 0.6 mm, oblong-linear, sometimes purplish, adaxial surface flat, the abaxial one convex, midrib not evident, base rounded, apex acute, margin entire, trichomes covering both surfaces. Inflorescence as a terminal capitulum 3 − 9-flowered, the fowers open one at a time. Flowers sessile; sepals 0.5 − 1.0 cm long, concave, apex acute, with hirsute trichomes along the margins and on the abaxial surface; petals 5, obcordate, yellow, pink or magenta apex emarginate; style and filaments yellow or pink; stamens numerous, anthers yellow; pollen grains pantocolpate, clypeate, synaperturate, colpes organized in pentagons, exine spiny with annulate perforations. Fruit capsule sessile, 2.5 − 5.0 × 2.0–3.0 mm, base conical, 0.3 − 0.5 mm length, operculum ovoid 1.5 − 3.0 × 1.0 − 3.0 mm; seeds reniform, more than 100 per fruit, 0.3 − 0.5 mm length, black, seeds covered by grayish and granulated wax throughout the relief, the outline irregular or corrugated in “U” or “T”, not bifurcated, the cells without convex projections.

Etymology: —The epithet honors Dr. Ana Maria Giulietti Harley, an important Botanist who encouraged taxonomic studies on various plant families in Brazil, including Portulacaceae .

Taxonomical notes: — Portulaca giuliettiae ( Fig.2A ‒ C ) can be easily distinguished from P. hirsutissima mainly by micromorphological characters, including pollen grains pantocolpate clypeate, such colpes are organized in pentagons, the exine spiny with annulate perforations ( Fig. 2D and 4A ). The seeds ( Fig. 2E–F and 4B ) are also distinct, covered by grayish and granulated wax throughout the relief, the outline irregular or corrugated in “U” or “T”, not bifurcated, and such cells have not convex projections.

On the other hand, the corolla coloration in this new species appears to be very variable, occurring in a gradient between magenta or intermediates ( Figs. 1 , and 1D) to yellowish ( Fig. 1E ), mainly in individuals from Bahia. We noted that the specimens collected in rocky habitat of campo rupestre vegetation from Chapada Diamantina region show often a yellowish coloration, while corolla pink to magenta frequently occur in plants growing on sandy soils at the same locality. These features were seen in individuals only a few meters away and molecular analyses could be useful to correctly interpret this morphological variation.

Distribution, habitat and conservation: — Portulaca giuliettiae occurs in Eastern Brazil, from Pernambuco to Rio de Janeiro, excluding Alagoas and Sergipe States ( Fig. 5 ). It can be usually found in restinga, campo rupestre vegetation, as well as in open and ruderal places often growing on sandy, rocky or calcareous soils. According to the IUCN criteria ( IUCN 2012), this species is here considered as NT (Near Threatened).

Paratypes: — BRAZIL. Bahia: Palmeiras , 29 January 2015, Vieira 147, 150 ( HUEFS) ; Morro do Chapéu, 15 January 2014, Vieira 5, 9 ( HUEFS). Espírito Santo: Barra do Jacu , 12 February 2013, Sucre 4611 ( RB) ; Nova Venécia , 14 January 2009, Fontana 578 ( RB) ; Vitória, 24 January 1985, Heleodoro 265 ( RB). Paraíba, Mata Redonda, 15 November 1954, Falcão 1130 ( RB). Pernambuco, Serra do Catimbau , 11 November 2003, Souza 397 ( HUEFS). Rio de Janeiro, Rio de Janeiro, 6 June 2003, Calvente 40 ( RB) ; 13 November 2003, Braga 7265 ( RB) ; 18 February 1951, Brade 20587 ( RB) .

Figures

FIGURE 1. Morphological features of individuals previously identified as Portulaca hirsutissima. A. Abundant hairs in the leaf axils (Vieira et al. 147). B. Hirsute trichomes covering all surfaces of leaves (Vieira et al. 150). C‒E. Species collected in Bahia (Vieira et al. 150). F. Species collected in Goiás (Zannate 1093). G‒H. Species collected in Minas Gerais (Cardoso et al. 3784).

FIGURE 2. Portulaca giuliettiae. A. Habit. B. Fruit; C. Hirsute leaf blade. D. Pollen grain. E. Seed. F. Seed detail (Carneiro-Torres 123).

FIGURE 4. Micromorphological characters of pollen grains and seeds. A‒C. P. giuliettiae (Carneiro-Torres 123). D‒F. P. goiasensis (Pastore et al. 1788). G‒I. P. hirsutissima (Cardoso et al. 3784). Bar = 10μm, except B, E, H bar = 100μm

FIGURE 5. Distribution map of Portulaca hirsutissima and related species in Brazil.