Phyllanthus longipetiolatus Marques-Torres & M. J. Silva, A. Habit. B. Cataphyll. C. Stipule. D. Leaf. E. Inflorescence 2022, sp. nov.
Creators: name: Torres, Alícia Marques
name: Silva, Marcos José Da
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Malpighiales
Phyllanthaceae
Phyllanthus
Phyllanthus longipetiolatus

description: Phyllanthus longipetiolatus Marques-Torres & M.J. Silva, sp. nov. (Figure 1)
Type:— BRAZIL. São Paulo: São Miguel do Arcanjo, Rodovia São Miguel do Arcanjo para Sete Barras, 28 September 1977, fl. fr., P. E. Gibbs, N.D. da Cruz, G. M. Felipe & W. M. Ferreira 6627 (holotype MBM!; isotypes F!, SP!).
Diagnosis:— Phyllanthus longipetiolatus differs from P. niruri by its leaves with long petioles (1.4–1.9 mm long versus less than 1 mm in P. niruri), staminate inflorescences in cincinni (vs. staminate inflorescences in cymule), staminate and pistillate flowers with pedicels measuring 3.8–4 mm long and 6.7–8 mm long, respectively (vs. 1.9–2.5 long and 3.8–4 mm long), as well as staminate disk and seeds smooth (vs. verruculose).
Description:—Subshrub 26–45 cm tall, monoecious, erect, caespitose, glabrous. Branching phyllanthoid; deciduous branchlets (5–8) 12–16 cm long, cylindrical or sometimes zig-zagged, smooth, grayish to reddish or brownish.Cataphylls 1–1.2 mm long, triangular to oval-triangular, apex acuminate, margin entire, scarious, brownish. Stipules 1–1.1 mm long, oval-triangular, apex acuminate, margin entire, scarious, brownish. Petiole 1.4–1.9 mm long, cylindrical, slender, glabrous; leaf blade 1–1.3 × 0.4–0.7 cm, membranous, elliptical, oblong-elliptic to oblong, strongly asymmetrical, obtuse; apex obtuse and mucronulate; discolor; upper surface dark green; lower surface grayish or glaucous; venation brochidodromous, the midrib and laterals raised and conspicuous, the tertiary veinlets forming a delicate reticulum on lower surface. Staminate inflorescences in cincinni with two flowers, one in maturity and the other in bud and solitary pistillate flower, distributed randomly along the branches, but concentered in the terminal portion. Staminate flowers with pedicel 3.8–4 mm long, filiform, glabrous; sepals 5, 1–1.1 × 0.9–1 mm, obovate, apex obtuse, midvein evident, greenish; disk with five segments obtriangular, surface strongly smooth, margin wavy; stamens 3, free, filaments slender; anther sacs globose, dehiscing horizontally, not emarginated. Pistillate flowers with pedicel 6.7–8 mm long, cylindric-clavate; sepals 5, 2–2.1 × 1.2–1.3 mm, obovate, apex acute, pinnate; disk patelliform, margin crenulate; ovary ca. 1.5 mm long, globose, glabrous; styles 3, up to 1 mm long, free, slightly ascending and curved, bifid; stigmas capitate. Capsule 1.9–2 × 1.9–2 mm, globose; fruiting pedicel 6.9–8 mm long; sepals and styles persistent. Seeds ca. 2 × 1 mm, trigonous, smooth.
Additional specimens examined (paratypes):— BRAZIL. São Paulo: São Miguel do Arcanjo, Carlos Botelho State Park, 04 October 1996, fl., P. L.R de Morais 1284 (ESA, SP); ibd., Carlos Botelho State Park, Núcleo Sete Barras, Trilha do Rio Taquaral 2, 24 April 2002, fl., fr., S. M. Gomes et al. 462 (ESA); ibd., Carlos Botelho State Park, 14 October 2004, fl., L. S. Kinoshita, C. Urbanetz, F. T. Farah & S. H. Obando-Polo 302 (UEC); Sete Barras, Reserva Florestal de Sete Barras, 2 April 1983, fl. fr., W. M. Ferreira, K. Yamamoto & A. Chautems 14592 (G).
Distribution and habitat:— Phyllanthus longipetiolatus is known from the state of São Paulo, Southeast region of Brazil (Fig. 2). The new species was collected mainly in the Carlos Botelho State Park which has an area of 37,644 ha covering the municipalities of Sete Barras, São Miguel Arcanjo, Capão Bonito and Tapiraí, in which the characteristic vegetation is the Montana and Submontana Dense Ombrophilous Forest. In addition, there are also smaller sections covered by Upper Montana Dense Ombrophilous Forest between 900–1000 m. a.s.l. and by “Campos de Altitude”, over shallow and stony soils (Lima et al. 2009). According with the vouchers analysed, P. longipetiolatus occurs in humid places in coastal rainforest and grows on clay soils covered by the leaf litter.
Phenology:—Collected with flowers in April and October and with fruits in April and September, but it must blossom throughout the year, similar to other herbaceous taxa of genus.
Preliminary conservation status:—We estimate an area of occupancy (AOO) of 12km 2 for P. longipetiolatus. The species is known from only two localities, both are within a protected area, the Carlos Botelho State Park, which can ensure the long-term stability of that population. Despite that, we assess the conservation status for P. longipetiolatus as Endangered (EN), under sub-criteria B2(a, b[iv]), due to the number of locations, and criterion D, due to the low number of known individuals.
Etymology:— The specific epithet refers to the long petiole of the species, unlike the other species in the subsection Phyllanthus.
Taxonomic considerations:— The new species is ascribed here in Phyllanthus sect. Phyllanthus subsect. Phyllanthus according to Bouman et al. (2022), which corresponds to P. sect. Phyllanthus subsect. Niruri in Webster’s concept (1955, 2002), because it has phyllanthoid branching, the leaf blades asymmetrical at the base, flowers in both sexes with five sepals, staminate flowers with three free stamens, and styles with capitate branches. P. sect. Phyllanthus subsect. Phyllanthus includes seven species, five of which occur in Brazil (four of them are endemic) (See Webster 2002, Silva 2009, Torres et al. 2020) and differs from the other co-subsections by including plants with asymmetrical leaves, flowers on both sexes with five sepals, 4-colporate pollen grains, capitate stigmas and verruculose seeds (Webster 1955, 2002).
Among the others Brazilian species of the Phyllanthus subsect. Phyllanthus, P. longipetiolatus is more similar to P. niruri by the branches distributed along the stem, oblong and membranous leaves and short styles (up to 1 mm long). However, it surely differs from P. niruri by the characters related to the length of the petiole and pedicel of flowers of both sexes, type of inflorescence staminate, ornamentation of the surface of the staminate disk and seeds, in according to Table 1.
Phyllanthus longipetiolatus has been identified in herborized collection of Brazil, as P. tenellus Roxburgh (1832: 668) [= Moeroris tenella (Roxb.) R.W. Bouman (2022: 30)], P. claussenii Müller Argoviensis (1863:40), and P. niruri. The mistaken identification with the first two is due to the fact that they share the oblong-elliptical leaves with the longer petiole, together with the long pedicel of the pistillate flowers, and was confused with P. niruri due to the asymmetry of the leaves and flowers with 5 sepals. However, the new species can be easily distinguished from M. tenella by the three stamens (versus five in M. tenella), from P. claussenii by the 5 sepals in both flowers (vs. 6 in P. claussenii) and of P. niruri by the features listed in Table 1.
Phyllanthus longipetiolatus now broadens the definition of the subsection Phyllanthus by adding staminate inflorescences in cincinni and smooth seeds. In the Phyllanthus subgenus, inflorescences in cincinni are often found in Phyllanthus sect. Choretropis Müller Argoviensis (1863: 52) (Santiago et al. 2006), while smooth seeds are found all sections, but they are less frequent in the section Phyllanthus, where the species often have verruculose, striate or puncticulate seeds (Webster 1956, 2002).
description: Published as part of Torres, Alícia Marques & Silva, Marcos José Da, 2022, Phyllanthus longipetiolatus (Phyllanthaceae), a new species from São Paulo State, Brazil, pp. 287-293 in Phytotaxa 567 (3) on pages 288-291, DOI: 10.11646/phytotaxa.567.3.8, http://zenodo.org/record/7156772