Monday, November 11, 2019

[Botany • 2019] Coccoloba gigantifolia (Polygonaceae) • A New Species of Coccoloba P. Browne from the Brazilian Amazon with Exceptionally Large Leaves

Coccoloba gigantifolia E. Melo, C.A. Cid Ferreira & R. Gribel

in Melo, Cid Ferreira & Gribel, 2019. 

We describe and illustrate a new species of Coccoloba (Polygonaceae), named Coccoloba gigantifolia, from the Brazilian Amazon. It resembles Coccoloba mollis Casar, but differs from the latter species by its much larger leaves in the fertile branches. The species has only been recorded in the Madeira River basin, in the states of Amazonas and Rondônia, in the central and southwestern Brazilian Amazon. The description was based on herbarium material, cultivated plants, and individual trees in their natural habitat. We provide illustrations, photographs, and an identification key with morphological characteristics that distinguish the new taxon from the other two related taxa of the Coccoloba sect. Paniculatae, as well as comments on the geographic distribution and conservation status of the species.

KEYWORDS: taxonomic botany; Amazon rainforest; geographic plant distribution; Paniculatae

Figure 2 A. Individual of Coccoloba gigantifolia about 15 m high in its natural environment, reaching the sub-canopy of a secondary forest in the Jamarí National Forest (Rondônia state, Brazil); B. Individual in the collection process; C. Trunk of a cultivated adult plant; D. Details of the trunk showing two transverse rings; E. Leaf of a young cultivated plant; F. Leaf sample collected in the Jamarí National Forest (Rondônia state, Brazil), 2.15 m long and 1.38 m wide (abaxial view); G. Adaxial view of the same leaf; H. View of the petiole articulation at ochrea base in a young branch; I. Inflorescence; J-K. Mature fruits 
(photos: A-G and I-K: C.A. Cid Ferreira and R. Gribel, H: E. Melo). 

Coccoloba gigantifolia E. Melo, C.A. Cid Ferreira & R. Gribel sp. nov. (Figures 1-3)

Type material: Brazil. Rondônia. Floresta Nacional do Jamari, Serra da Onça, 2 km from the residential village, .... 05.ix.2008 (fr.), C.A. Cid Ferreira et al. 11211 (Holotype: INPA 258.437).

Trees 10-15 m high, polygamous-dioecious, with a straight, segmented trunk that occasionally sprouts at the base with transverse rings distanced about 10 cm, with thin branches of whitish bark restricted to the apex. The trees also have young, pubescent branches and ferruginous trichomes (Figures 2a-d). Leaves are alternate, spiral, and petiolate. Leaf blades measure 0.6 - 2.5 × 0.5 - 1.4 m and are elliptic, with acute or acuminate apex, base obtuse, subcordate, subtruncate, entire margin, wavy, coriaceous or subcoriaceous, discolor, pubescent glabrescent, pubescent adaxial face with ferruginous trichomes concentrated in the veins when young, pubescent abaxial face with ferruginous trichomes, brochidodromous venation, 16-45 pairs of lateral veins, flat on the adaxial side and prominent on the abaxial face (Figure 2e); petiole is 5-10 cm long, inserted at the base of the ochrea and articulated to it (Figure 2f), older leaves are completely glabrous or puberule; ochrea is 5-10 cm long, persistent at base, coriaceous, pubescent ferruginous, apex with acuminate edge, scariose and deciduous. Inflorescence a branched thyrse, paniculate, 40-80 cm in length (Figure 2g), rachis pubescent or puberulent, glabrescent, triangular bracts, 0.2-0.3 mm, coriaceous, puberulent or pubescent; ochreola campanulate, 0.5-10 mm, membranaceous, puberulent or pubescent with bilobed edge, persistent and lacerated after fruit maturation (Figure 3a). Flowers 1-2 mm in length, greenish-white; staminate flowers with campanulate hypanthium and vestigial pistil, stamens excluded, filaments fused at the base to form a bulbous, nectariferous tissue, covered with whitish papillae (Figure 3b), pistillate flowers with campanulate hypanthium, reduced stamens, reduced and sterile anthers, ovary ovoid, three glabrous styles, stigmas capitate papillose. Anthocarps 5-8 mm long, globose (Figure 3c-d), pubescent or puberulent, red, vinaceous or purple when mature (Figure 2h-i); globose nucules, smooth, slightly grooved, apex acute or pyramidal (Figure 3e), seeds with ruminate endosperm (Figure 3f); fruit pedicels 2-5 mm long, not thickened.

Geographic distribution and habitat: Coccoloba gigantifolia is endemic to the Madeira River basin. So far, individuals have been recorded in the states of Amazonas and Rondônia (Figure 1). At present, individuals have been collected in the wild only in the middle (Jamari and Samuel) and lower (Autazes and Borba) stretches of the Madeira River basin. The distance between the sampled populations of the middle and low Madeira River is of approximately 600 km, which may indicate a disjunct distribution restricted to the Madeira River basin. The scarcity of botanical collections in the region, however, does not allow to draw reliable conclusions about the distribution of the species. Coccoloba gigantifolia grows in open, ombrophylous forests, secondary forests, and in early successional stages (capoeira, in Portuguese), in altitudes of 20-100 m a.s.l., in areas of flat relief, on sandy or clayey, humid soils. Cultivated trees in Manaus bloomed from March to June and exhibited mature fruits in September.

Etymology: The specific epithet of C. gigantifolia is given in reference to its leaves presenting unusual proportions.

We describe a new species of Coccoloba (Polygonaceae), named Coccoloba gigantifolia from the Madeira River basin, in the Brazilian Amazon region. The species is very distinct, mainly due to the large size of the leaf blade, and is further differentiated by the petiole inserted at the base of the ochrea and articulated to it, inflorescence in panicles, campanulate ochreola with bilobate border, globose anthocarps and globose nucules, slightly grooved with an acute or pyramidal apex.

Efigenia de MELO, Carlos Alberto CID FERREIRA and Rogério GRIBEL. 2019. A New Species of Coccoloba P. Browne (Polygonaceae) from the Brazilian Amazon with Exceptionally Large Leaves [Uma nova espécie de Coccoloba P. Browne (Polygonaceae) da Amazônia brasileira com folhas excepcionalmente grandes]Acta Amazonica. 49(4); Epub Nov 04, 2019. DOI: 10.1590/1809-4392201804771

RESUMO: Uma nova espécie de Coccoloba (Polygonaceae) da Amazônia brasileira, denominada Coccoloba gigantifolia, é descrita e ilustrada. É semelhante a Coccoloba mollis Casar. mas difere desta espécie por ter folhas muito maiores nos ramos férteis. A espécie foi registrada apenas na bacia do Rio Madeira, nos estados do Amazonas e Rondônia, no centro e sudoeste da Amazônia Brasileira. A descrição foi feita a partir de material de herbário, plantas cultivadas e observações de campo de indivíduos em seu habitat natural. São apresentadas pranchas ilustrativas, fotografias e uma chave de identificação com caracteres morfológicos que distinguem o novo táxon de outras duas espécies de Coccoloba sect. Paniculatae, bem como, comentários sobre a distribuição geográfica e conservação da espécie.
PALAVRAS-CHAVE: botânica taxonômica; floresta amazônica; distribuição geográfica de plantas; Paniculatae