Porophyllum spathulatum C.R.Carneiro & A.A.Schneid., 2014

Carneiro, Camila Rezendo, Schneider, Angelo Alberto & Ritter, Mara Rejane, 2014, Porophyllum spathulatum (Asteraceae: Tageteae), a new species from the southern Brazilian coast, Phytotaxa 173 (2), pp. 157-162 : 157-161

Porophyllum spathulatum C.R.Carneiro & A.A.Schneid. , sp. nov. ( Figs. 1 and 2 )

Inter species generis Porophylli habitu decumbenti, foliis spathulatis, capitulis ultra 50-floris, corolla albo-lutea, pedunculis apice dilatatis ab aliis recedens.

Porophyllum spathulatum differs from the other species of the genus by the combination of its decumbent habit along with the spatulate shape of the leaves, the large heads with more than 50 light-yellow florets, and the swollen upper part of peduncles.

Type:— BRAZIL. Rio Grande do Sul: Santa Vitória do Palmar, Hermenegildo Beach , 0 m elev., 33º40ʹ21ʺ S, 53º16ʹ11ʺ W, 17 November 2013, C. R . Carneiro 73 (holotype ICN!; isotypes: K!, LP!, RB!) .

Decumbent, gynodioecious, glaucous and glabrous perennial subshrubs, ascending branches 10–20 cm tall, deep taproot. Stems terete, 1.5–3 mm in diam., branched and brown, reddish in herbaceous younger portions, nodes conspicuous. Leaves entire, alternate or opposite, pseudopetiolate, pseudopetioles 2.2–3.6 mm long, spatulate, 14–20 × 2.4–4.2 mm, with a pair of linear translucent oil glands at the base, a solitary drop-shaped or short-linear gland near the apex and eventually one or few ones irregularly scattered along the margin, 0.4–0.9 mm long; apex rounded, margins entire, base attenuated, internodes 2.3–14.8 mm long. Heads homogamous discoid, solitary, 16–24 × 9–15 mm, florets 52–66; florets and pappus bristles exserted. Peduncles 28–48(60) mm long, apex obconical, enlarged beneath the head, 3.3–4.3 mm wide, 0.8–1.2 mm wide basally. Receptacle flat, 2.25–4.6 mm in diam., naked, alveolate. Phyllaries 5, free, uniseriate, 12.2–16 × 3.7–5.4 mm, oblong with mucronate apex, pruinose, glaucous to slightly wine-tinged, fleshy with hyaline margins, with two irregular rows of longitudinal glands 0.5–4 mm long each. Bisexual florets tubulose, 7.7–12.3 mm long, light yellow, corolla base inflated, 0.6–0.7 mm in diam., middle slender, 0.3–0.45 mm in diam., with sparse short hairs, apex 1.3–2 mm in diam., expanded and divided into 5 lobes, acute, glabrous, 1.5–1.7 × 0.5 mm each; anthers exserted, 2.6–3 mm long, yellow, apical appendages acute, 0.6 mm long, basal appendages shortly sagittate; style 13.2–14.6 mm long, style branches 2–2.2 mm long, curvate, subulate and papillose. Pistillate florets tubulose, 8.6–10.7 mm long, light yellow, corolla base inflated, 0.6–0.7 mm in diam., middle slender, 0.3–0.4 mm in diam., apex 1.3–2 mm in diam., expanded and divided into 5 lobes, acute, glabrous, ca. 1.7 × 0.6 mm each; stamens reduced to staminodes (5), ca. 2 × 0.2 mm, filiform, apex lanceolate; style 10.7–11.2 mm long, style branches 1.6–2 mm long, curvate, subulate and papillose. Cypselae cylindrical, 6.3–9.3 × 0.45–0.6 mm, ribbed, dark brown, with sparse short and stiff hairs (puberulent to glabrescent), carpopodium conspicuous, 0.3–0.45 mm long; pappus 1-seriate, 8–9.5 mm long, bristles light yellow, barbellate.

Distribution and Habitat:— Porophyllum spathulatum was only found in Balneário Hermenegildo,a neighborhood of Santa Vitória do Palmar municipality in Rio Grande do Sul State, southernmost Brazil ( Fig. 3 ). The occurrence area is situated in the Pampas, characterized by subtropical lowland grasslands and presenting continuous floristic and structural identity with Uruguay and Argentina ( Boldrini et al. 2010). The species occurs in semi-consolidated dunes along with native grasses such as Panicum racemosum ( Palisot de Beauvois 1812: 168) Sprengel (1824: 313) , sedges as Androtrichum trigynum ( Sprengel 1824: 216) Pfeiffer (1937: 10) , other composites as Sommerfeltia spinulosa ( Sprengel 1826: 510) Lessing (1832: 190) , members of other families as Hydrocotyle bonariensis Lamarck (1789: 153) and, also, exotic species such as Acacia longifolia ( Andrews 1802: 207) Willdenow (1806: 1052) .

Phenology:— Porophyllum spathulatum flowers and set fruits from November to February.

Conservation Status:—Critically Endangered:CR B1ab(iii) + 2ab(iii), D ( IUCN 2013). Porophyllum spathulatum presents a low extent of occurrence (<100 km 2) and low area of occupancy (<10 km 2); number of locations “1”; decline of quality of habitat, due to the presence of exotic species and also due to environmental degradation (houses built near and over the dunes, garbage and sewage dumping). The beach is almost desert in the winter, but it receives a lot of vacationers along summer, which represents a risk to species of rare occurrence such as P. spathulatum . Moreover, the only population known is composed of 21 individuals.

Etymology: —The species name reflects the shape of its leaves.

Additional specimens examined (paratypes): — BRAZIL. Rio Grande do Sul: Santa Vitória do Palmar, Hermenegildo, 17 km ao norte do Chuí , February 1978, fl., Pfadenhauer 671 ( ICN); idem, December 1987, fr., C . Costa s.n. ( ICN 86371); ibidem, 33º39ʹ26.2ʺ S, 53º14ʹ50.2ʺ W, 3 May 2013, st., C. R . Carneiro 62 ( ICN); ibidem, 33º40ʹ21ʺ S, 53º16ʹ11ʺ W, 16 November 2013, fl., C. R . Carneiro 72 ( ICN) .

Figures

FIGURE 1. Porophyllum spathulatum C.R.Carneiro & A.A.Schneid. A. Habit. B. Leaf. C. Head. D. Phyllary. E. Bisexual floret. F. Stamens. G. Style. H. Pistillate floret. I. Pistillate floret open showing staminodes (one lobe removed). J. Cypsela and pappus. (A, B, C, D, E, F, G and J from C.R. Carneiro 73, ICN; H and I from C.R. Carneiro 72, ICN). Drawings by Márcia Vignoli da Silva.

FIGURE 2. Porophyllum spathulatum C.R.Carneiro & A.A.Schneid. A. Habitat. B. Habit. C. Habit showing the taproot. D. Detail of the leaves. E. Bisexual heads showing the enlarged peduncle. F. Pistillate head. G. Bisexual floret (on the left) and pistillate floret (on the right). H. Bisexual floret showing the anthers (on the left) and pistillate floret open, showing staminodes (on the right). I. Cypsela and pappus. Photo credits:A–F by C.R. Carneiro and G–I by A.C.O. da Costa and C.R. Carneiro.

FIGURE 3. Map showing the occurrence area of Porophyllum spathulatum in southernmost Brazil.