Portulaca goiasensis 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 : 109

Portulaca goiasensis T.A.S.Vieira & A.A.O.P.Coelho , sp. nov. Fig. 1 , 3–5 .

Type: — BRAZIL. Goiás: São João d’Aliança, 3km de Alto Paraíso (Sul), 14º42’30S. 47º31’17”W, 12 March 2007, J.F.B. Pastore et al. 1788 (holotype HUEFS!).

Diagnosis: — Portulaca goiasensis differs from P. hirsutissima and P. giuliettiae in having the seeds covered by grayish and granulated wax only at the basis of the cell relief, the outline corrugated in “U”, bifurcated, the cells with convex projections; pollen grains pantocolpate, synaperturate, colpes arranged in a spiral.

Description: —Herb succulent, decumbent (rarely erect), 7.0 − 10 cm tall, stem branched, green to purplish; axillary trichomes overlying the entire stem, abundant and conspicuous, whitish, wooly. Leaves sessile, leaf blades 0.5 − 1 cm × 0.2 − 0.4 mm, oblong-linear, sometimes purplish, adaxial surface flat, the abaxial convex, midrib not evident, base rounded, apex acute, margin entire, trichomes covering both surfaces. Inflorescence a terminal capitulum, 3 − 7- flowered, the flowers open one at a time. Flowers sessile, sepals 0.4 − 1.0 cm long, with hirsute trichomes along the margins and abaxial surface, concave, apex acute; petals 5, obcordate, apex emarginate, yellow; style and filaments yellow, stamens numerous, anthers yellow; pollen grains pantocolpate, synaperturate, colpes arranged in spiral, exine spiny with annulate perforations. Fruit capsule sessile, 2.0 − 2.5 × ca. 2.0 mm, base conical 0.5 − 1.0 mm length, operculum ovoid 2.0 × 2.5 mm; seeds reniform, more than 100 per fruit, 0.2 − 0.4 mm length, black, covered by grayish and granulated wax only at the basis of the cell relief, the outline corrugated in “U”, bifurcated, the cells with convex projections.

Etymology: —The epithet refers to the geographical distribution of this new species, here considered as endemic to the Chapada dos Veadeiros, Goiás, in central Brazil ( Fig. 5 ).

Taxonomical notes: — Portulaca goiasensis ( Fig. 3A ‒ C ) is similar to P. giuliettiae and P. hirsutissima , based on macromorphological characters, both vegetative and floral. The few specimens known have exclusively yellow corolla ( Fig. 3E and 4D ). The new species can be clearly separate by its micromorphology, such pollen grains are pantocolpate and have synaperturate colpes in a spiral ( Fig. 3D and 4C ), represents a peculiar feature which is not been registered for Portulaca until now ( Carolin 1987). The seeds of P. goiasensis are covered by grayish and granulated wax only at the basis of the cell relief, being the outline corrugated in “U”, bifurcated, and the cells with convex projections, which are also important features to distinguish this new species ( Fig. 3F ).

Distribution, habitat and conservation: —We considered Portulaca goiasensis as a endemic spcies to cerrado and campo rupestre vegetations in Goiás State (central Brazil). The individuals were found in dirty fields near streams and rocky soils in three municipalities from the Chapada dos Veadeiros region (Cristalina, São João d’Aliança and Serra dos Cristais) ( Fig. 5 ). Lacking further data, this species si to be considered as DD (Deficient Data) according to the IUCN criteria ( IUCN 2012).

Paratypes: — BRAZIL: Goiás: Serra dos Cristais, 3 March 1964, Irwin 13362 (RB). Cristalina, Irwin 12643 (NY).

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 3. Portulaca goiasensis. A. Habit. B. Fruit. C. Hirsute leaf blade. D. Pollen grain. E. Seed. F. Seed detail (Pastore et al. 1788).

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.