Syngonanthus incurvifolius M.T.C.Watan. & Echternacht, 2015

Syngonanthus incurvifolius M.T.C.Watan. & Echternacht View in CoL , sp. nov.

Type:— BRAZIL. Goiás: Alto Paraíso de Goiás, ca. 15 km south of Veadeiros, road to São João da Aliança , cerrado on outcrops, in wet sand, adjacent campo, 1000 m alt., 19 March 1969, H. S. Irwin, R. Reis dos Santos, R. Souza & S. F. da Fonseca 24648 (Holotype UB! , Isotypes F! , MO! , NY! RB! ). Figures 2 A–G View FIGURE 2 & 3 View FIGURE 3 .

Syngonanthus incurvifolius differs from all other New World species of Syngonanthus by the rosette leaves incurved from the middle to the apex. It differs from Syngonanthus arenarius , the most similar species, by pistillate flowers with cream sepals and adpressed trichomes on the leaves. Syngonanthus incurvifolius is also similar to Syngonanthus densifolius var. majus but differs by pistillate flowers with pilose petals, sepals cream with a light castaneous longitudinal band, and individuals smaller.

Perennial herbs, 7.5–18.0 cm tall. Roots 0.75–1.4 mm in diameter, cream-colored, spongy. Rosettes 1.7–3.4 cm in diameter. Rhizome 1.0–2.5(–5) cm × 2.5–7.5 mm, horizontal to oblique, often branched, tomentose to villous, with white, dense and interwoven trichomes ca. 1 cm long; each branch giving rise to a rosette of leaves, each rosette bearing 1–5 synflorescences. Leaves 0.5–2.0 cm × 0.75–1.20 mm, linear, flat to semi-terete, apex acute to round, base truncate, sinuous, recurved at base, becoming incurved from the middle to the apex, firm to rigid, striate adaxially with 3-veins prominent, or only the midvein perceptible in young leaves; densely pilose adaxially, glabrescent to pilose abaxially, with adpressed trichomes, and patent, simple trichomes ca. 0.5 mm long; basal sheath not enlarged. Synflorescences with a primary axis bearing a lax umbel of 1–18 inflorescences at the apex. Synflorescence axes 2–8 cm long, 0.2–1.0 mm in diameter, emerging from the center of the rosette, erect to curved, brown, sometimes with a dark-reddish tinge, glabrescent to pilose with simple filamentous trichomes ca. 0.3 mm long. Bracts of synflorescence axis restricted to the apex, 0.2–3.0 cm × 0.5 mm, whorled and numerous, patent, progressively elongating from the outer toward the inner series, linear to narrowly lanceolate, apex acute, erect to uncinate, pubescent on both surfaces with adpressed trichomes, and patent, capitate and simple, filamentous trichomes, capitate trichomes mostly on abaxial surface, simple trichomes concentrated at margins. Inflorescences composed of a closed spathe subtending a scape with a capitulum at the apex. Spathes 1–4 cm long, chartaceous, cylindrical, lax at apex, obliquely opened, apex acute to obtuse, erect to recurved, tip erect to uncinate, margin entire, not involute, glabrous adaxially, pubescent abaxially with capitate and simple, filamentous trichomes. Scapes erect, 3–12 cm long, green to straw-colored with age, 3-costate, pilose, pubescent near the apex with erect to patent, simple and capitate trichomes. Capitula 4–8 mm in diameter, radiate. Involucral bracts in 5–7 series, castaneous, reddish-brown to brown, sometimes with a lighter stramineous longitudinal band in the middle and on the margins, glabrous on adaxial surface, pilose to glabrescent abaxially, ciliate, with simple filamentous trichomes, rarely also capitate trichomes, these concentrated at the apex, ca. 0.3 mm long; external series 1.0–1.8 × 0.5–0.8 mm, triangular to ovate, apex acute, progressively longer toward the internal series, middle series 2.5–3.0 × 0.9–1.2 mm, obovate, apex acute to obtuse, internal series 2.5–3.0 × 0.3–0.7 mm, equaling the flower height, elliptic to slightly oblanceolate, apex acute to obtuse, sometimes membranous, lighter-colored than the external series; receptacle obconic, pilose. Floral bracts absent. Flowers 3-merous, 40–100 per capitulum, the staminate and pistillate generally equal in number, with contrasting colors, staminate flowers darker and concentrated at the border of the capitulum or mixed. Staminate flowers with pedicels 0.5–1.0 mm long, pilose in the bottom part of pedicel with simple trichomes ca. 1 mm long; sepals 1.5–2.0 mm long, coppery brown, shortly fused at base, concave, membranous, the sepals slightly different from each other, or two sepals similar to each other and a third different, falcate-asymmetrical, oblanceolate, elliptic or irregular-subspathulate, apex mucronate, cuspidate, rounded or obtuse to acute, glabrous adaxially, pubescent abaxially, especially at apex and margin, with simple filamentous trichomes ca. 0.4 mm long; petals 1–2 mm long, hyaline, membranous, fused, tubulose, lobes obtuse to rounded, involute after anthesis, glabrous; stamens adnate to the petals at base, anthers ca. 0.3 mm long, cream to yellowish; anthophore ca. 0.3 mm long; pistillodes 3, ca. 0.3 mm long, clavate, papillose at apex. Pistillate flowers 2–3 mm long, including pedicels; pedicels 0.4–1.0 mm long, with filamentous trichomes at insertion with receptacle, actinomorphic; sepals equaling the petal height, 1.2–2.0 mm long, oblong to widely ovate, concave, apex acute, base thickened, free, white with a light castaneous longitudinal band, adaxially glabrous, abaxially pubescent near the apex, ciliate, with simple filamentous trichomes up to 0.5 mm long; petals about equaling the sepals, 1–2 mm long, linear to oblong, fused at the upper half, free at base and at the very top, lobe triangular, apex acute, membranous, white to hyaline when hydrated, pilose with simple filamentous trichomes up to 0.5 mm; gynoecium ca. 2 mm long; ovary 0.4–0.6 mm long; style column ca. 0.2 mm long, cream-colored to castaneous; appendages ca. 0.4 mm long, the glandular apex capitate; stigmatic branches simple, ca. 1.5 mm long. Seed 0.4–0.6 × 0.2–0.3 mm, ellipsoid, brown-colored.

Etymology:— The specific epithet refers to the orientation of the rosette leaves, which are curved inward and upward at the distal middle, a unique feature within Brazilian Syngonanthus . Only Syngonanthus wahlbergii Ruhland (1903:247) in Africa has leaves like this.

Notes and taxonomic affinities:— Several species share a similar architecture with Syngonanthus incurvifolius , including: a rhizome with apical rosettes of leaves, bearing synflorescences with verticillate bracts at the apex and scapes arranged in lax umbels. The following taxa also share dark and pilose involucral bracts ( Fig. 3H View FIGURE 3 ), usually with a lighter longitudinal band abaxially: Syngonanthus arenarius (Gardner) Ruhland (1903:260) , S. densifolius var. brachyphyllus Moldenke (1984: 372) , S. densifolius var. majus Moldenke (1972:499) , and S. vittatus , the new species described here below. Syngonanthus densifolius var. majus and S. densifolius var. brachyphyllus , actually do not belong to S. densifolius , which possess golden to cream, glabrous involucral bracts, and shall be elevated to species status (Echternacht et al. in prep.). We consider these five taxa to form a cohesive morphological group due to the characters mentioned above. All of them, except S. arenarius , occur in Chapada dos Veadeiros and they are possibly sympatric.

Syngonanthus incurvifolius also shares with these four taxa an unusual floral trait: sepals of staminate flowers are always clearly asymmetrical ( FIG. 3D; 3F View FIGURE 3 ). The three sepals might differ in form and curvature or two might be similar and the third different.

Syngonanthus incurvifolius differs from the congeneric species that have synflorescences by the remarkable form of the rosette leaves, which are recurved at base and incurved at the upper half. This feature persists even after diaphanization. Syngonanthus densifolius var. brachyphyllus can be easily distinguished from S. incurvifolius by its broader leaves (ca. 2–5 vs. 0.5–2 mm), with arachnoid trichomes on the adaxial surface (vs. not arachnoid), which is reticulate (vs. striate), and leaf bases achlorophyllous and pale (vs. chlorophyllous and green) ( FIG. 3C View FIGURE 3 ). Syngonanthus densifolius var. majus differs by pistillate flowers with glabrous petals (vs. pilose), and darker sepals, light-brown at the upper half ( FIG. 3G; 3J View FIGURE 3 ) (vs. cream with a longitudinal light castaneous band); moreover, individuals are bigger than S. incurvifolius and the rosette leaves are erect and flexuous. Syngonanthus arenarius var. arenarius shares with S. incurvifolius the small size and pilose petals of pistillate flowers ( FIG. 3E; 3I View FIGURE 3 ); it differs by the cup-shaped bracts of the synflorescence (equal size), which are fewer (vs. progressively elongating from the outer toward the inner series and more numerous), and pistillate flowers with sepals cream at base and dark reddish-brown on the upper half (vs. cream with a longitudinal light castaneous band). Syngonanthus incurvifolius also differs from S. vittatus by the synflorescence axis bearing bracts only at the apex (vs. tiny bracts scattered along axis), the petals of the pistillate flowers pilose (vs. glabrous), and the involucral bracts of the middle series obovate (vs. narrow-elliptic).

Syngonanthus incurvifolius has been determined as S. densifolius var. pilosior Silveira (1928:320) in some herbaria. Actually, S. densifolius var. pilosior is probably a synonym of S. anthemiflorus var. similis (Ruhland) L.R. Parra & Giulietti (1997:228) ( Echternacht 2012), which can be easily distinguished from S. incurvifolius by the involucral bracts surpassing the capitulum disc (vs. not surpassing), the outer series golden to straw-colored and the internal series cream (vs. all series castaneous to reddish-brown). Furthermore, the distributions of these taxa do not overlap, as S. anthemiflorus is restricted to the Espinhaço Range in Minas Gerais State.

Phenology:— The flowering season of Syngonanthus incurvifolius is somewhat different from congeneric sympatric species. Most species of Syngonanthus bloom during the dry season but the blooming period of S. incurvifolius recorded in herbaria is between February and May (the rainy season). Exceptions are S. densifolius var. majus and S. densifolius var. brachyphyllus , whose records also attest for a blooming in the first semester of the year. Flowers of S. incurvifolius are in anthesis from February to April, corresponding to the latter half of the rainy season in the region. Fruits were observed only in herbarium specimens collected in May, suggesting that seeds are dispersed during the dry season.

Habitat and distribution:— Records for this species have only been reported from the municipality of Alto Paraíso de Goiás, along a small stretch of GO-118 highway, that connects Alto Paraíso de Goiás and São João da Aliança, between 5–15 km south of Alto Paraíso de Goiás. According to herbarium labels, S. incurvifolius occurs on campos rupestres within the Cerrado biome, over quartzitic sandy soils and in wet meadows, typical habitats at the border of the highway at the described locality. Field observations (King & Bishop 8900, MO) reported the species to be locally abundant. However, we have done fieldwork in Chapada dos Veadeiros over a large area and we did not find the reported population neither did we see any other subpopulation. This fact indicates that the populations probably occupy narrow areas. The roadside along GO-118 northwest of Alto Paraíso de Goiás belongs to the Parque Nacional da Chapada dos Veadeiros (PNCV); roads to the south and northeast are privately owned, used for cattle grazing and farming, fragmenting the original campo rupestre habitat. Syngonanthus incurvifolius is registered southward, outside the PNCV and therefore might be threatened by human activities.

Conservation status:— Syngonanthus incurvifolius is known from a stretch no longer than 10 km along GO-118 highway, where the natural habitat is severely fragmented. The species is not recorded from a protected area and the region is affected by fire, pasturage and farming, with great impact on natural habitats. As it has not been collected since 1994 and there was no success to find it in recent fieldwork, the species could be classified as extinct in the nature. However, the region is still poorly collected and a careful search might discover new populations. Because there is reasonable doubt that the last individual has died, a more thorough check of expected habitat of this species is needed to confirm it. CNCFlora (Brazilian National Center for Plant Conservation, cncflora.jbrj.gov.br) evaluated the species threatened status, following the criteria of the IUCN Red List ( IUCN 2001, 2015). Syngonanthus incurvifolius has an area of occupancy of 8 km 2, which tend to contract and deteriorate in quality. According to criteria A2ac and B2ab(i,ii,iii) this species is currently considered critically endangered (Negrão 2014a).

Additional specimens examined:— BRAZIL. Goiás: Alto Paraíso de Goiás, Region of the Chapada dos Veadeiros at 14°30’ S 47°30’ W, 7 km south of Veadeiros, wet meadowland below sandstone outcrop 7, 24 May 1956, Y. Dawson 14639 ( LL) GoogleMaps ; Rod. GO-12, km 5–10 ao Sul de Alto Paraíso , campo arenoso, 26 May 1975, G. Hatschbach 36814 ( C, LL, MBM) ; 5–12 km S of Alto Paraíso de Goiás, mostly E of road to São João da Aliança , 3300–3800 feet, 8 February 1981, L. R. M. King & L. E. Bishop 8900 ( MO, UB) ; 10 km S of Alto Paraíso de Goiás (GO-118) heading for Brasília, adjacent to Chapada dos Veadeiros , 14°30’S, 47°30’W, 23 February 1990, J. Saunders, L. Breyer & G. Eiten 3020 ( LL) GoogleMaps ; Rod. GO-118, 10 km S de Alto Paraíso , campo rupestre, solo arenoso úmido, 1150 m, 10 February 1994, G. Hatschbach, M. Hatschbach & J. M. Silva 60290 ( F, MBM) .