Davilla pygmaea M. J. Silva, 2022

Silva, Marcos José Da & Santos, Igor Soares Dos, 2022, A remarkable new species of Davilla Vand. (Dilleniaceae, Dolicocarpoideae) from the Brazilian Savanna supported by morphological and anatomical data, Phytotaxa 560 (2), pp. 186-208 : 188-195

Davilla pygmaea M. J. Silva , sp. nov. ( Figs 1 , 2 )

Type:— BRAZIL. Goiás: Niquelândia, Reserva Particular de Desenvolvimento Sustentável Legado Verdes do Cerrado, Núcleo Engenho , Área do Mirante , cerca de 600 metros a leste do Mirante , campo limpo, 14°39’52”S 48°27’54”W, 690 m, 18 February 2021, fl., M. J. Silva , I. S. Santos & B. R. Pereira 11815 (holotype UFG!) .

Diagnosis:— Decumbent subshrubs with a woody underground system; stem with one or two branches 0.7–1 m long and 20–30 cm above ground level. Leaves (6.5) 10–14 cm long, alternate distichous; petiole (0.6) 1.5–1.8 cm long, with two conspicuous lateral and upward-oriented extensions; blade (5) 7.5–13 × (1) 1.7–3.2 cm, coriaceous, elliptic, oblanceolate, veins hispid on both surfaces, inflorescence 3–5 cm long, (2)4–6 flowers, unbranched, or with only one basal branch; flowers 1.7–2.2 cm long, glabrous with spatulate-obovate petals, external and internal sepals glabrous; androecium with 126–131 stamens and two free carpels, follicles indehiscent when young, ca. 0.6 × 4.1 mm long.

Description:— Subshrubs, decumbent with a woody underground system; main stem with one or two tillers 0.7–1 m long and 20–30 cm tall above ground level; adult branches cinereous, bark peeling off in plates near the base, and sparsely hispid; young branches brown or slightly vinaceous scabridulous, especially near the base. Leaves (6.5) 10–14 cm long, alternate, distichous; petiole (0.6) 1.5–1.8 cm long, green or brownish, scabridulous, with two conspicuous lateral extensions with flat margins, oriented upwards; leaf blades (5) 7.5–13 × (1) 1.7–3.2 cm, coriaceous, elliptic, oblanceolate, primary and secondary veins hispid on both surfaces, trichomes hyaline, base attenuate, apex obtuse and mucronate, margins flattened, sparsely dentate from the lower third, ciliate; bifacial, adaxial surface dark green, glossy, abaxial surface opaque green; venation eucamptodromous, midrib impressed on adaxial surface; secondary and tertiary veins prominent on both surfaces, the former arranged in 8–9 pairs, ascending at an acute angle>90º, the latter reticulate; Inflorescence 3–5 cm long, (2)4–6 flowers, terminal or less frequently axillary, racemose with a single main axis, or with only basal branching, vinaceous, hirsute, trichomes golden; floral bud dark green, glabrous. Flowers 1.7–2.2 cm long, pedicel 0.9–1.5 cm long, scabridulous, vinaceous; basal bracts 9–12 × 3.8–4 mm, caducous, sparsely hispid externally, glabrous internally, oblong-elliptic, oblanceolate, margins entire, ciliate on upper third, apex shortly acuminate; sepals 5, three outer sepals smaller and two inner larger; outer sepals widely ovate or suborbicular, crustaceous, glabrous, smooth on both surfaces, ciliate on the margins, unequal in size, the external ones 4–4.1 mm diam. when flowering and 4.9–5 mm diam. when fruiting, the median sepal 6.9–7 mm diam. when flowering and 6.6– 6.7 mm diam. when fruiting, the internal sepals 7.7–7.8 mm diam. when flowering, 7.8–7.85 mm diam. when fruiting; inner sepals orbicular, crustaceous, glabrous on both surfaces, and shiny internally, non-ciliate along the margins, equal in size, 8.6–8.7 mm diam. when flowering and 10.9–11 mm diam. when fruiting, the innermost sepals with a reflexed margin, and the outermost sepals superimposed on the inner ones; petals 5, 17–18 × 10–11 mm, 2.5-2.7 mm wide at the base, and 10–10.1 mm wide in the middle third, deciduous, membranous, spatulate-obovate, glabrous on both faces, not ciliate on the margins, emarginate at the apex, yellow; stamens 126–131, arranged in a circle surrounding the carpels, exserted, filaments 3.7–4.3 × 0.1–0.2 mm, cylindrical to clavate, glabrous; anthers 0.9–1 × 0.6–0.7 mm, basifixed, oblong, glabrous, longitudinally dehiscent; carpels 2, free; ovary 1–1.1 × 1.1–3 mm, globose, glabrous with 2 basal ovules 0.6–0.7 × 0.4–0.5–mm; styles 5.4–5.5 × 0.2–0.3 mm, straight, glabrous, stigma capitate, discoid, verrucose. Fruit an indehiscent follicle, ca. 0.6 × 4.1 mm long when young; seed not seen.

Paratypes:— BRAZIL. Goiás, Cavalcante, RPPN Serra do Tombador, 3 km da sede da reserva, em direção a Cavalcante , 13º38’13’’S, 47º49’11’’W, 870 m, 06 March 2017, fl., M . F . Simon , A . T . Fidelis & L . M . Borges 3022 ( CEN); Niquelândia, RPDS Legado Verdes do Cerrado, Núcleo Engenho, Área do Mirante , cerca de 300 metros a leste do Mirante na borda da floresta estacional, 14º39’50’’S, 48º27’30’’W, 692 m, 21 January 2020, fl., M . J . Silva , I . S . Santos & B . R . Pereira 10574 ( UFG); ibd., ca. 250 metros a leste do Mirante , na parte inferior do morro em sua lateral, campo sujo, 14°39’50”S 48°27’37”W, 685 m, 18 February 2021, fl., M . J . Silva , I . S . Santos & B . R . Pereira 11804 ( UFG), 11805 ( UFG), 11806 ( UFG), 11807 ( UFG), 11807 ( UFG), 11808 ( UFG); cerca de 600 metros do a leste do Mirante, campo limpo, 14°39’52”S 48°27’54”W, 690 m, 18 February 2021, fl., M . J . Silva 11813 ( UFG), 11814 ( UFG) .

Distribution and habitat:—Species probably endemic to Goiás State, Brazil; was found in the northern and northeastern portions of that state, in the municipalities of Cavalcante and Niquelândia respectively growing in “campos limpos” or “ campos sujos” and in “cerrado rupestre” on sandy-stony, clayey-sandy soils, or stony-clayey soils in undulating or flat landscapes, between 685 and 870 m elevation.

Phenology:—Collected with flowers and fruits from January to March.

Etymology: — The specific epithet “pygmaea” is derived from the Latin meaning “dwarf”, alludes to the fact that the species is a dwarf subshrub habit.

Preliminary conservation status: — Species classified as Critically Endangered, having an estimated Extent of Occurrence (EOO) of 38,875 km 2. It grows, however, in protected areas such as the Legado Verdes do Cerrado Private Sustainable Development Reserve and in mountainous areas in the municipality of Cavalcante.

Identity, systematic position, and morphological relationships:— Davilla pygmaea can be recognized by having a decumbent subshrub habit, terminal or less often axillary racemose inflorescences 3–5 cm long, with (2)4–6 flowers, and a single main axis or only one basal branch, flowers glabrous with spatulate-obovate petals, androecium with 126–131 stamens, and two free carpels. By having margins of the innermost sepals reflexed, not alate, and the innermost sepals overlapped by the adjacent inner sepals, the species described here can be assigned to D. sect. Davilla , a section proposed by Kubitzki (1971) and recently reviewed by Fraga (2012) with 11 assigned species, four of which [ D. elliptica August Saint-Hilaire (1825: 17), D. grandiflora August Saint-Hilaire & Tulasne (1842: 131), D. lacunosa Martius (1838: 49) , and D. nitida ( Vahl, 1794: 70) Kubitzki (1971: 95) ] are found in Goiás State, especially in Cerrado vegetation, with D. lacunosa Martius and D. nitida having monocarpellary flowers, and, therefore, differentiated from the new species, which has bicarpellary flowers, a characteristic shared with D. elliptica and D. grandiflora .

In terms of the latter two species, D. elliptica can be easily recognized by its shrub habit, erect or lianescent (vs. subshrub and decumbent in D. pygmaea ), inflorescences 7–26 cm long, 3–12 lateral branches, and 3–37 flowers (vs. 3–5 cm long, with single main axis or with only one basal branch, and (2) 4–6 flowers). D. grandiflora shares with the new species a glabrous or glabrescent stem, petioles with reflexed wings, venation eucamptodromous with tertiary veins reticulated, as well as basal bracts, petals and carpels glabrous. It differs by having an erect shrub habit, or rarely lianescent (vs. subshrub and decumbent in D. pygmaea ), leaves 2–18.5 × 1.5–15 cm, elliptic-lanceolate, elliptic, ovate, or orbicular (vs. (5) 7.5 –13 × (1) 1.7–3.2 cm, always elliptic or oblanceolate), branching inflorescence (vs. nonbranching, or with only one basal branch), basal bracts 4.3–8.2 mm long (vs. 9–12 mm long), pedicel 5.5–16 cm long (vs. 0.9–1.5 cm long), in addition to petals 10.5–12 mm long, spatulate, with apex emarginate (vs. 17–18 mm long, spatulate-obovate and bifid), and androecium with 110–126 stamens (vs. 126–131).

In the consultation of the herbaria of the Brazilian midwestern region (CEN, COR, IBGE, UB and UFG) it was verified that Davilla specimens are usually unidentified or wrongly identified. For this reason, we provide the key below and some images as a tool to identify the species of Davilla from the state of Goiás.

Figures

FIGURE 1. Davilla pygmaea M. J. Silva. a habit. b detail of adaxial surface of the leaves showing the venation, apex, and margins. c detail of abaxial surface of the leaves showing the venation, apex, and margins. d and e bracts on ventral side, note the indumented upper third. f inflorescence. g flower. h frontal view of a flower, with one inner sepal removed. i-k external sepals. l and m internal sepals. n petals. o stamen. p dorsal surface of the anthers. q detail of one of the carpels. r stigma detail. (Images by Cristiano Gualberto, from the holotype).

FIGURE 2. Davilla pygmaea M. J. Silva. a habit. b detail of an inflorescence. c general aspect of the plant in frontal view, note the ascending leaves. Images a and b provided by Marcelo F. Simon, c, by M.J. Silva.