Ludwigia octovalvis P. H. Raven
Creators: name: Rocha, Amanda Macêdo
name: Melo, José Iranildo Miranda de
Publisher: name: Zenodo
Year: 2020
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Myrtales
Onagraceae
Ludwigia
Ludwigia octovalvis

description: Ludwigia octovalvis (Jacq.) P.H.Raven
Figs 5b, 7 d–h, 8a–g
Material examined
BRAZIL – Paraíba • Alagoa Nova, Fazenda Capim-Açú; 6 Mar. 2012; fl.; E. Melo et al. 10941; HUEFS • Araruna; 19 Dec. 2016; bud, fl. and fr.; A.M. Rocha 08; HACAM • Areia, Mata do Pau Ferro; 2 Dec. 2016; fl. and fr.; A.M. Rocha 05; HACAM • Bananeiras, Mata de Goiamunduba; Dec. 2012; fl.; E.C.S. Costa, L.B.S. Pereira & J.I.M. Melo 202; HACAM • Cabedelo; 5 Apr. 1992; fl.; L.P. Felix et al. 4819; EAN • Cajazeiras, Açude Lagoa de Arroz; 21 Dec. 2013; H.O. Machado-Filho 536; IPA • Campina Grande, district Catolé; 8 Sep. 1989; fl.; I.C. Dantas s.n.; HACAM 332 • Conde, Rio Gramame; May 2013; H.O. Machado-Filho s.n.; IPA[88439] • Cruz do Espírito Santo, Fazenda Massangana; 3 Nov. 1987; fl.; L.P. Felix & E.C. Silva 1866; EAN • João Pessoa, riparian vegetation of the river Cuiá; 20 Jan. 2011; fl.; L.A. Pereira 135; JPB • Lagoa Seca, Pinga waterfall; 11 Jul. 2017; fl. and fr.; A.M. Rocha 23; HACAM • Mataraca; 1 Nov. 2017; bud, fl. and fr.; A.M. Rocha 28; HACAM • Monteiro; 27 Jun. 2017; fl. and fr.; A.M. Rocha 20; HACAM • Patos, Barragem da Farinha; 14 May 2012; C. Torres 299; CSTR • Pombal, Sítio Maniçoba II; 27 Mar. 2011; fl. and fr.; I.S. Queiroga 29; CSTR • Remígio; 19 Jul. 1972; fr.; V. Perazzo Barbosa 66; JPB • Riachão; 30 May 2001; fr.; M. Costa-Santos 60; JPB • Rio Tinto; 6 Apr. 1989; fl.; L.P. Felix 3569; EAN • Santa Luzia; 20 Apr. 2017; fl.; A.M. Rocha 18; HACAM • Santa Teresinha, Fazenda Tamanduá; 1 Mar. 2009; fr.; B. Laine & J. Cortez 05; IPA • São Bento, Sítio Várzea da Serra, river Piranha; 17 Jan. 2015; F.G.Silva et al. 82; CSTR • São João do Cariri; 15 Jun. 2001; fl.; P.C. Gadelha-Neto et al. 639; JPB • São João do Rio do Peixe, Balneário de Brejo de Freiras; 31 Jul. 1974; fr.; L.P. Xavier s.n.; JPB[3593] • São Mamede, Fazenda Verdes Pastos; s.d.; fl. and fr.; R.C. Vila 04; CSTR • Serraria; 28 Nov. 1942; M.C. Espínola s.n.; JPB[1217] • Sousa, Fazenda Jangada; 25 Jun. 1995; fl.; P.C. Gadelha-Neto 221; JPB.
Description
Herbs to subshrubs, 0.3–1.65 m high, erect; branches cylindrical, subglabrous to pubescent. Leaves subsessile; blade 3.7–14.1 × 1.1–3.3 cm, with entire margin, membranous, lanceolate-linear to oblonglanceolate, with acute apex and obtuse base, subglabrous to pubescent. Flowers tetramerous, sessile; bracteoles 2, near the base of hypanthium, less than 1 mm long; sepals 1.2–5 × 6 7 mm, green, ovate, with acute apex, external face hirsute to pubescent; petals 13–19 × 9–14 mm, golden yellow, obovoid, with emarginate apex; hypanthium ca 2–2.7 cm long, 4-locular; style ca 1.5–2 mm long, stigma globose to ovoid; stamens 8, anthers globose; convex nectariferous disk with depressed nectaries, glabrous to densely pilose, surrounding the base of each epipetalous stamens. Capsule 3.5–57 × 3.3–3.4 mm, cylindrical, internally non-dimorphic, subglabrous to pubescent. Seeds less than 1 mm long, globoid, pluriseriate, not embedded in the endocarp, raphe inflated, equal in size to the body of the seed.
Distribution
Ludwigia octovalvis is widely distributed in tropical regions, although it is mainly found in the Americas (Raven 1963; Grillo & Giulietti 2004). In Brazil, it occurs in the North (AC, AM, PA, RR, TO), Northeast (AL, BA, CE, MA, PB, PE, PI, RN, SE), Center-West (DF, GO, MS, MG), Southeast (ES, MG, RJ, SP) and South (PR, SC) Region, associated with virtually all phytogeographic domains, excepting the Pampas domain (Vieira 2015).
Habitat and phenology
Ludwigia octotvalvis is well-distributed throughout the Paraíba State, associated with banks of dams and humid or prone to flooding sites. Flowers may be harvested throughout the year and fruits are collected in March, May, June and December.
Conservation status (Paraíba State, Brazil)
The extent of occurrence (EOO) of Ludwigia octovalvis in the Paraíba State is 44 771.860 km 2, exceeding the upper limit for Vulnerable status under the criterion B1. The species has an area of occupancy (AOO) of 120 km 2, within the limit for Endangered status under the criterion B2. However, due to its EOO greater than 40 000 km², it does not fall within the threatened category. It is currently placed on the Near Threatened (NT) list.
Note
This species is mainly differentiated from other representatives of the genus in the study area by its seeds with inflated raphe with diameter equal to or greater than the body of the seed, a typical feature of
Ludwigia sect. Macrocarpon (Zardini & Raven 1992). Furthermore, it has petals with emarginated apex, 8-ribbed capsules, and pluriseriate seeds in the locule and not embedded in the endocarp.
According to Raven (1963), the species has a complex morphological variation. Specimens may be found varying in size, shape of leaf blades, density of branch and leaf indumentum, and in petal and fruit length (Duarte & Esteves 2001). Precisely for this reason, Raven (1963) acknowledged two subspecies for South America: Ludwigia octovalvis subsp. octovalvis (Jacq.) P.H.Raven and Ludwigia octovalvis subsp. sessiliflora (Micheli) P.H.Raven. However, Raven & Tai (1977) recognize only as a single species, since specimens of the two subspecies may be found on the same site. Thus, it is usual to find both populations with typical individuals and populations with individuals intermediate in morphological characteristics between the two subspecies. Differences are maintained by autogamy (Raven & Tai 1977). In the study area, morphologically variable individuals were found. In this paper, the two distinct populations are treated as a single species, as suggested by Raven & Tai (1977).
description: Published as part of Rocha, Amanda Macêdo & Melo, José Iranildo Miranda de, 2020, Diversity and distribution of Ludwigia (Onagraceae) in Paraíba State, Northeastern Brazil, pp. 1-24 in European Journal of Taxonomy 639 on pages 18-21, DOI: 10.5852/ejt.2020.639, http://zenodo.org/record/3786601