Ouratea cauliflora Fraga & Saavedra, 2014

Fraga, Claudio Nicoletti De & Saavedra, Mariana Machado, 2014, A new cauliflorous white-flowered species of (Ochnaceae) from the Brazilian Atlantic Forest, Phytotaxa 167 (1), pp. 119-126 : 120-124

Ouratea cauliflora Fraga & Saavedra , sp. nov. ( Figures 1 , 2 )

Species nova Ouratea verticillata (Vell.) Engl. affinis, sed inflorescentia cauliflora ramifloraque, plus ramosa, floribus quaquaversum dispositis, thyrsis manifeste geniculatis, sepalis apice unguiculatis, petalis albis, gynophoris roseis minoribus differt.

Type: — BRAZIL. Espírito Santo: Viana, São Paulo de Viana, Propriedade do Waltinho, divisa com a Reserva Biológica de Duas Bocas , 20 o 18’23” S, 40 o 32’30” W, 700 m elev., 19 January 2009 (fl), C.N. Fraga, A.P. Fontana, R. Goldenberg, R.C. Forzza & L. Kollmann 2340 (holotype RB! , isotypes CEPEC! , MBML! , UPCB! ).

Treelet 1.8–2.7 m tall; stem erect, unbranched or with short and patent branches, glabrous, dark brown at the base and light brown at the apex, consisting of two regions, one leafless, fistulose, smooth when young and then rugose, 5–12 cm long, the other region with two to five clustered leaves, later with scars left by the fallen leaves, internodes 1–6 mm long, this last one also with brachyblasts. Stipules 10–22 × 5–8.5 mm, caducous in the older leaves, triangular, margins revolute. Leaves spirally alternate to subverticillate, clustered in groups of 8–35; petiole 8.5–21 mm long, canaliculate; leaf blade (15–)30–52 × (2–) 4–7.4 cm, chartaceous, oblanceolate, base attenuate, margins entire at the base and serrate at the apex, slightly revolute and undulate, apex acuminate, adaxial surface dark green, with midvein sulcate, secondary veins impressed, abaxial surface light-green, midvein and secondary veins prominent, tertiary veins inconspicuous and glabrous on both surfaces, secondary veins 16–23, curving strongly near the margin and continuing almost as submarginal veins. Inflorescence cauliflorous or emerging from short and patent brachyblasts on the stem or rarely subterminal at the distal leaf axils, thyrses 3–6.5 cm long, pendent, smooth, glabrous, densely grouped in clusters; basal bracts similar to the stipules, distichous and imbricate, unequal, the outer 1.5–3 mm long, ovate, the innermost 5–9.5 mm long, narrowly triangular, margins revolute, persistent, brown; bracts of branchlets 3, two lateral in pairs, 5–7 mm long, narrowly triangular to lanceolate, brown, one dorsal, 7.5–12 mm long, brown; bracteoles 3, narrowly triangular to linear, the two lateral in pairs, 1.5–2.8 mm long, the dorsal isolated, 2–5.8 mm long, both brown. Flowers with pedicels 5–8 mm long, straight to curved, smooth, glabrous, buds cream; sepals 5, 4.3–5.1 × 1.8–2.4 mm, imbricate, elliptic, concave, adaxially smooth, abaxially thick in the middle, margin hyaline, apex uncinate, smooth, white to cream on both surfaces; petals 5, 5.2–5.7 × 2.4–3 mm, obovate, sometimes somewhat thick at the base and along the central vein, base attenuate to unguiculate, apex reflexed and rounded with irregular margin, notched, glabrous, white; stamens 10, arranged in a circle around the ovary, anthers 3–3.7 mm long, erect, subsessile, transversely rugulose, poricidal, yellow; gynophore 0.8–1 × 0.8–0.9 mm, cylindrical, columnar, thickening near the apex, pink; gynoecium superior, 5-carpellate, fertile units 5, 0.8–1 × 1.2–1.4 mm, oblong, cream, style 1.5–1.7 mm long, single, erect, filiform, gynobasic, stigma punctiform, light green. Fruit with a carpophore of 4.4–6 × 4.5–6.2 mm, globose, rugose near the base, salmon pink in the ripe fruit; mericarp 1, 5–6.3 × 3.5–4.9 mm, ellipsoid, clavate, erect or obliquely disposed on the carpophore head, inflate, pericarp thin, greenish; seed ca. 3.8 × 2.7 mm, testa membranaceous, slightly rugose, embryo ellipsoid, cotyledons convex, hypocotyl strap-shaped, perpendicular to the cotyledon.

Etymology:— The specific epithet of this new species refers to the character of the cauliflorous inflorescence, which is unique in Ouratea .

Distribution, habitat and ecology: — Ouratea cauliflora is known from four collections in only one locality of the Atlantic Rain Forest in the state of Espírito Santo, Southeastern Brazil. It occurs in the Duas Bocas Biological Reserve ( Fig. 2 ), with 2,910 ha, and in a few other forest fragments around this Reserve, near the borders between the municipalities of Cariacica, Viana, Santa Leopoldina, and Domingos Martins. It has been collected in areas at 600–700 m above sea level ( Fig. 3 ), with flowers from January to May and fruits in July. These remnants of Atlantic Forest are highly species rich, with several other endemic species of Ochnaceae ( Fraga & Saavedra 2006) and other plant families ( Alves et al. 2002, Sousa 2004, Camargo & Goldenberg 2011, Kollmann & Peixoto 2012).

Conservation:— Ouratea cauliflora is endemic to only one locality in Espírito Santo and its populations are very restricted with few and scattered individuals, ranging less than 20 km 2. Hence, it is prone to the effects of stochastic events within a very short time period in an uncertain future. Ouratea cauliflora should be regarded as Vulnerable [VU: D2], according to the criteria of the IUCN (2001).

Additional apecimens examined (paratypes):— BRASIL. Espírito Santo: Cariacica, Pau Amarelo, ex. Condomínio Rural Cantinho do Céu, divisa com a Reserva Biológica de Duas Bocas , 20 o 16’42”S, 40 o 32’26”W, 619 m, 06 May 2008 (fl), A.M. Amorim, A.P. Fontana, C.N. Fraga, R. Goldenberg, W.M. São-Mateus & M.M. Saavedra 7398 ( CEPEC!, MBML!, RB!, UPCB!) ; same locality, 20 o 16’00”S, 40 o 32’00”W, 619 m, 12 April 2009 (fl), A.P. Fontana, C.N. Fraga, R. Goldenberg, L. Kollmann, A.M. Amorim, L. Daneu, J. Meirelles 5875 ( CEPEC!, MBML!, RB!). Cariacica, Alegre, Reserva Biológica de Duas Bocas, trilha do Pau-Oco , 20 o 17’29”S, 40 o 31’10”W, 600 m, 22 July 2008 (fr), A.M. Amorim, R.C. Forzza, R. Goldenberg, P. Labiak, C.N. Fraga, J.L. Paixão & L.C. J. Gomes 7650 ( MBML!, RB!) .

Affinities:— Ouratea cauliflora has two rare morphological features within the genus: the white flowers and the cauliflorous inflorescences in an otherwise predominantly yellow and terminal- or axillary-flowered genus. The white flowers are also present in Ouratea cassinifolia ( Candolle 1811: 421) Engler (1876: 329) , while the cauliflorous inflorescences are new to the genus. The new species resembles Ouratea verticillata ( Vellozo 1829: 222) Engler (1876: 349) , due to its erect and unbranched stem with two to five groups of subverticillate leaves in its apex, leaf blades longer than 30 cm and oblanceolate, with an attenuate base, acuminate apex, the midvein sulcate on the adaxial surface and secondary veins impressed on the adaxial surface and prominent on the abaxial surface.

The architectural model of the new species and of Ouratea verticillata is similar to Chamberlain’s Model as described by Hallé et al. (1978), which is characterized by the modular architecture and consisting of a linear sympodium, an apparently unbranched axis and a monocaulous physiognomy. The modules are all equivalent and usually orthotropic; each one is hapaxanthic, because of terminal flowering, and produces a subsequent module from a meristem in the axil of one of the distal leaves. Meanwhile, Ouratea cauliflora and O. verticillata never have terminal inflorescence: the inflorescences emerge from the stem (cauliflorous) or from short and patent branches on the stem or subterminal at the distal leaf axils, in all cases derived from a lateral bud.

However, in addition to the white flowers in cauliflorous inflorescences, O. cauliflora may be distinguished from O. verticillata by its chartaceous leaves, pendant thyrse with smooth branchlets, flowers with smooth pedicels, white to cream sepals that are externally smooth and uncinate at the apex, petals reflexed only at the apex, and the pink, 0.8–1 mm long gynophore. In contrast, O. verticillata has coriaceous leaves, erect thyrses with rugose branchlets, flowers with rugose pedicels, green-yellowish sepals that are externally rugose in the middle and not uncinate at the apex, petals strongly revolute, and a white, 1.2–1.4 mm long gynophore. The geographic distributions of these species do not overlap: O. cauliflora was collected at a locality in the central region of Espírito Santo, in elevations of 600–700 m ( Fig. 3 ), while O.verticillata occurs in the southern coast of the state of Rio de Janeiro and São Paulo, near the border between the two states, from 70 to 300 m above sea level ( Table 1 ).

Figures

FIGURE 1. Line drawing of Ouratea cauliflora Fraga & Saavedra. A. Habit and inflorescences. B. Detail of the stipules and leaf base. C. Detail of the apex and adaxial side of the leaf. D. Cauliflorous and ramiflorous inflorescences. E. Branchlets, bracteoles and flower bud and open flower in side view. F. Flower, from above. G. Flower, from below. H. Sepal, adaxial view. I. Petal, adaxial view. J. Pedicel, stamens, and side view of the gynoecium with sepals (petals and five stamens removed). K. Stamens, side view. L. Gynoecium, side view. M. Ovary, transverse section. N. Fruit, side view (A–M after Fraga et al. 2340; N after Amorim et al. 7650).

FIGURE 2. Vegetation physiognomy of the type-locality and morphology of Ouratea cauliflora: A. General view from Atlantic Forest and artificial lake at Duas Bocas Biological Reserve, Cariacica, Espírito Santo, Brazil. B. Forest interior in the Pau Oco trail. C. Habit and inflorescences.D. Stem subdivided in alternate leaf and leafless regions: (α) leaf region with clustered leaves and brachyblasts, (β) leafless regions aphyllous and (γ) leaf region aphyllous with scars left by the fallen leaves with brachyblasts. E. Cauliflorous and ramiflorous inflorescences in the apex of the brachyblasts. F. Axillar thyrse and flowers. G. Details of buds, and open flowers. H. Fruits and Ouratea verticillata: I. Habit. J. Axillar and erect thyrse. K. Details of buds, and open flowers (C–G after Fraga 2340; H after Amorim 7650; I–K after Cardoso 1009). All photos of the Ouratea cauliflora by C. N. Fraga and O. verticillata by L. J. T. Cardoso.

FIGURE 3. Map showing the geographical distribution of Ouratea cauliflora (black dots) in the state of Espírito Santo, Brazil.