Tragia peltata Vellozo (1831b: 6)

Cordeiro, Wesley Patrício Freire De Sá, Melo, André Laurênio De, Sales, Margareth Ferreira De & Athiê-Souza, Sarah Maria, 2022, Unraveling Tragia peltata (Euphorbiaceae): taxonomy, morphology, distribution and conservation, Phytotaxa 570 (1), pp. 67-76 : 68-74

Tragia peltata Vellozo (1831b: 6) .

Lectotype (designated here):— BRAZIL. Rio de Janeiro: Paraty, Vellozo s.n. (illustration in the original manuscript of Flora Fluminensis in the Manuscripts Section of the National Library of Rio de Janeiro [cat. no.: mss1198659_010] and later published in Vellozo, Fl. Flumin. Icones 10: t. 6. 1831b). Figure 1 .

Subshrubs, scandent, glabrescent, stems 2–3 mm diam., internodes 1.5–8.5 cm long; internodes with rare stinging trichomes and dense simple non glandular trichomes. Stipules triangular, ca. 2–3(–4) × 1–2 mm, glabrescent, with rare stinging trichomes, deciduous. Leaves alternate, spirally arranged; petiole 20(–40) × 1–1.5 mm, cylindrical, hirsute; leaf blade 8.5–14.5 × 4–7 cm, peltate, attachment distance 1–10 mm, ovate or oblong, base emarginate to retusecordate, apex acuminate, margins sparsely serrated or subentire, teeth acuminate, starting from the mid-region of the leaf towards the apex, adaxial and abaxial faces glabrescent, with sparse stinging trichomes; primary basal nerves actinodromous, secondary nerves craspedodromous or brochidodromous, 5–8 pair. Inflorescences axillary, bisexual, racemiform thyrses, usually grouped in 2–4; axis 4–6.5 cm long, with short stipitate glandular trichomes, bracts 1- flowered, basal bract 1–1.5 mm long, 3-lobed, lobes triangular, apex acute, the other bracts ca. 1 × 0.5 mm, triangular, apex acute. Staminate flowers single per node, pedicel 2–3(–4.5) mm long, hispidulous, with stinging trichomes and short stipitate glandular trichomes; sepals 3–4, ca. 1–1.2 × 0.5–0.8 mm, elliptic, apex acute, adaxial face glabrous, abaxial face with rare stinging trichomes; stamens 2–3, filaments 0.5–0.8 mm long, with central gland, anthers oblong, ca. 0.3 mm long. Pistillate flowers solitary at the base of the inflorescence; pedicel 13–20 mm long, with hispidulous, sparse stinging trichomes, and abundant subsessile glandular trichomes; sepals 6(–8), ca. 2.5 × 1.2 mm, ovate, apex acuminate, apical gland present, margins ciliate with stipitate glandular trichomes, adaxial surface glabrous, abaxial surface hispidulous, with sparse stinging and more abundant glandular trichomes; ovary 0.5–0.7 × 1 mm, sessile, 3-lobed, each lobe 2-corniculated, hispidulous, covered with stinging trichomes, styles 1.2–2 mm long, joined for approximately 3/4 of their length, stigma smooth. Fruit ca. 6 × 10–15 mm, transversely ellipsoid, 3-lobed, lobes 2- corniculate, cornicles 3–5 mm long, hispid; peduncle 25–30 mm long. Seeds ca. 4.5 × 4 mm, globose, smooth, light brown spots formed by small elliptical papillae. Figure 2 .

Material examined:— BRAZIL. Bahia: Itamaraju , 16°59’48”S, 39°33’12”W, 5 May 1971, fl., fr., T.S. Santos 1551 (CEPEC) . Espírito Santo: Linhares , 19°23’28”S, 40°04’20”W, 13 November 2010, fl., D.A. Folli 6736 (SP) ; Linhares, 19°23’28”S, 40°04’20”W, 12 April 1993, fl., fr., D.A. Folli 1864 (CVRD, K) ; Linhares, 19°23’28”S, 40°04’20”W, 09 December 1993, fl., fr., D.A. Folli 2117 (CVRD, NY, SP) ; Linhares, 19°23’28”S, 40°04’20”W, 01 December 1998, fl., fr., D.A. Folli 3306 (CVRD, SP) ; Linhares, 19°23’28”S, 40°04’20”W, 15 October 2003, fl., fr., D.A. Folli 4631 (CVRD, SP) ; Linhares, 19°23’28”S, 40°04’20”W, 26 November 2004, fl., fr., D.A. Folli 4982 (CVRD, SP) ; Linhares, 19°23’28”S, 40°04’20”W, 09 December 1993, fl., D.A. Folli s.n. (IPA) ; Linhares, 19°23’28”S, 40°04’20”W, 15 October 2003, fl., fr., D.A. Folli 4632 (VALE) ; Linhares 19°23’28”S, 40°04’20”W, 26 November 2004, fl., fr., D.A. Folli 4982 ; Sooretama, 19°01’03”S, 40°08’43”W, 26 October 2012, fl., fr., G.O. Romão 1160 (MBML) . Rio de Janeiro: Angra dos Reis, 23°03’34”S, 44°18’51”W, 2–9 September 1980, fl., D. Sucre & J. Gomes 11277 (RB); unknown location, unknown date, fl., fr., Talbot s.n. (K 001205063) .

Taxonomic Considerations:— Tragia peltata was characterized in the literature as having peltate leaves, sparsely serrate, with teeth from the mid-leaf to the blade apex ( Vellozo 1831b, 1881, Müller Argoviensis 1866, 1874, Pax & Hoffmann 1919), although the morphological analyses performed here indicate previously unknown variations for this species.

The leaf is consistently peltate, but the distance between the base of the blade and the petiole insertion point is variable ( Fig. 3A, B, E ), giving the impression that some leaves are not peltate ( Fig. 3E ). The recognition of this character state is fundamental to the identification of T. peltata , as this character is unique among the South American species ( Pax & Hoffmann 1919). Sparsely serrated leaf margins occur only in specimens from Rio de Janeiro State ( Fig. 3 A, C ), while the margins of specimens from Bahia and Espírito Santo are predominantly subentire ( Fig. 3 D, F ). Additionally, the leaves of the specimens from Rio de Janeiro are membranous, while those of specimens from Bahia and Espírito Santo are chartaceous.

Tragia peltata is morphologically related to T. aurea Rusby (1907: 444) , T. giardelliae Gutiérrez de Sanguinetti & Múlgura de Romero (1986: 491) , T. hoffmanniae W.Cordeiro & M.F.Sales (in Cordeiro et al. 2020a: 841), and T. volubilis Linnaeus (1753: 980) ( Table 1 ). These species share an accrescent pedicel of the pistillate flower, which can attain the size of the axis of the inflorescence ( Cordeiro et al. 2020b). This is an important taxonomic feature that may aid in the systematics of the genus ( Cardinal-McTeague & Gillespie 2016). Despite having this characteristic in common with the abovementioned species, T. peltata can easily be recognized by its peltate leaf base ( Fig. 2 B ) and emarginate to retuse-cordate, pistillate sepals with apical glands and ciliate with glandular trichomes ( Fig. 2 I ) — an exclusive character combination among South American Tragia species.

Distribution and ecology:— Tragia peltata occurs in lowland evergreen forests in the Atlantic Forest biome ( Fig. 4 A ), in forest interiors, and along the edges of forests adjacent to areas that have suffered recent disturbances. Until recently, the species was considered endemic to Ilha Grande Bay in Rio de Janeiro State ( Secco et al. 2020), but new populations were found during this study in the northern region of Espírito Santo State and in the southern region of Bahia State, expanding its area of occurrence ( Fig. 4 A ).

The different regions where T. peltata occurs have different biogeographies. Fiaschi & Pirani (2009) divided the Atlantic Forest into two parts: a northern block (extending from latitude -5° in Rio Grande do Norte State to latitude -19° in northern Espírito Santo) in areas that share similarities with Amazonian vegetation; the southern block occurs from latitude -19° to latitude -29° (in Santa Catarina State) and shares similarities with the Andean subtropical flora.

As the two Atlantic Forest blocks are roughly divided by the Vale do Rio Doce region ( Fiaschi & Pirani 2009), T. peltata populations likewise appear to be separated by that geographic barrier. The role of the Rio Doce as a barrier between populations has been reported in the literature, and is sometimes considered a speciation mechanism ( Maciel et al. 2019, Santos et al. 2018). Additionally, although the known occurrences of T. peltata are in dense ombrophilous forest vegetation ( Fig. 4 B ), they are separated by the semideciduous seasonal forest that occurs from southern Espírito Santo to northern Rio de Janeiro ( Fig. 4 B ), which appears as another barrier between populations.

Phenology:— Tragia peltata was encountered flowering and fruiting in April and May and from September to December. Flower maturation apparently varies according to sex. The pistillate flowers of the inflorescence open while the staminate buds are still developing, and the staminate flowers open when fruits begin to develop, which sometimes creates an overlap. Due to this reproductive strategy, Vellozo (1881) and Müller Argoviensis (1874) had only fruiting material to describe T. peltata , making this the first description of staminate and pistillate flowers.

Conservation status:— Tragia peltata has an Area of Occupancy of 16,000 km 2 and an Extent of Occurrence 46,562.074 km ² which classifies it as Least Concern according to IUCN (2019). However, the conditions a(iii) and b (iii) of the B criteria may be applied. Most collections (10) of the T. peltata that was found on the Reserva Biológica de Sooretama (RBS) and Reserva Natural da Vale (RNV), which are two parts of a continuous forest among the municipalities of the Linhares and Sooretama on Espírito Santo state. Two other collections of T. peltata were made: a) on municipality of Itamaraju-BA, ca. 220 km from the forest of the RBS and RNV; b) on municipality of Angra dos Reis-RJ, ca. 620 km from the forest of the RBS and RNV ( Fig. 4 A ).

The populations of T. peltata occur in areas of Atlantic Forest that have suffered historical fragmentation processes. Currently, the Atlantic Forest only have 11.26% of the original cover ( SOS Mata Atlântica 2008), and 80% of the fragments occupy less than 50 ha. The maintenance of those fragments is important for reducing isolation between populations. However, recent studies have documented their continuing size reductions ( Ribeiro et al. 2009) – which can expose T. peltata to risk of extinction.

Typification:— The typification of Vellozo’s names based on exsiccates is often impossible due to the lack of information concerning the locations of type collections ( Kury 2015, Milward-de-Azevedo 2017). Therefore, in accordance with articles 9.3, 9.4 and 9.11 of the International Code of Nomenclature for Algae, Fungi and Plants ( Turland et al. 2018), the original illustration n. 6 ( Vellozo 1831b) ( Fig. 1 ) preserved in the Manuscript section of the Library of the National Museum of Rio de Janeiro [cat. no: mss1198659_010], and published in Vellozo, Fl. Flumin. 10, t. 6, 1831, iss selected as the lectotype.

Figures

FIGURE 1. Lectotype of Tragia peltata. Original plate of T. peltata (1831b) on Flora Fluminensis in the Manuscripts Section of the National Library of Rio de Janeiro (cat. no.: mss1198659_010).

FIGURE 2. Tragia peltata. A. Flowering branch, B. Abaxial leaf face, C. Basal bract of the inflorescence. D. Staminate bract, E‒F. Staminate flowers, G–H. Pistillate flowers, I. Pistillate sepal, detail of the apex and ciliate margins with stipitate glandular trichomes, J. Fruit, K. Seed. Illustrated by Regina Carvalho, from H.F. Talbot s.n. [K 001205063] (A, B), D.A. Folli s.n. [IPA 66670] (C‒K).

FIGURE 3. Leaf variability in Tragia peltata. Population from Rio de Janeiro state. A. Leaf blade, B. Leaf base on adaxial view, C. Leaf margin. Population from Bahia and Espírito Santo states. D. Leaf blade, E. Base of leaf blade with petiole insertion close to the margin, F. Leaf margin. A‒C from D. Sucre & J. Gomes 11277 (RB); D‒F from T.S. Santos 1551 (CEPEC). Scale = 1 cm (A‒B and D‒E) or 0.1 cm (C and F).

FIGURE 4. A. Geographic distribution of Tragia peltata in the Atlantic Forest in the states of Bahia (BA), Espírito Santo (ES), and Rio de Janeiro (RJ), Brazil. B. Spatial distribution of the Phytophisiognomies in the area of occurrence of T. peltata, stats of Bahia (BA), Espírito Santo (ES), Minas Gerais (MG), and Rio de Janeiro (RJ).

Tables

TABLE 1. Morphological differences among T. peltata and species with long pistillate pedicels.

		T. aurea	T. giardelliae	T. hoffmanniae	T. peltata	T. volubilis
General	Habit	Vine up to 2 m long	Vine up to 90 cm long	Vine, unknown length	Vine, unknown length	Subshrub volubilis up to 3 m long
aspect	Indument color in dry plants	Rust-coloured	White	White	White	White
	Size	1.5–3 × 0.4–0.5 mm	4–4.5 × 2–2.5 mm	3 × 0.5 mm	2–3(–4) × 1–2 mm	1–4 × 1–2 mm
Stipules	Shape	Narrowly triangular	Ovate	Narrowly triangular	Triangular	Triangular-ovate
	Persistence	Persistent	Deciduous	Deciduous	Deciduous	Persistent
	Petiole (length)	5 mm	(3–)4–11 cm	1–2 cm	2–4 cm	1–5 cm
	Leaf blade size	2.5–5 × 0.7–2 cm	(4–)7–15 × (3.5–)5– 11 cm	8–14 × 3.5–6 cm	8.5–14.5 × 4–7 cm	2–9 × 1–5.5 cm
	Leaf blade shape	Ovate	Broadly ovate	Elliptical or lanceolate	Ovate to oblong	Triangular-ovate, lanceolate or oblong
Leaves	Base shape	Slightly cordate	Deeply cordate	Cordate or rounded	Emarginate to retuse-cordate, peltate	Cordate, obtuse, truncate or rounded
	Apex shape	Acute or acuminate	Acuminate	Caudate	Acuminate	Acute or acuminate
	Leaf margin	Serrate	Dentate-acuminate	Entire	Sparsely serrate or subentire	Serrate or subentire
	Number of sepals	–	3	3	3 or 4	3
Staminate	Sepal length	–	1.2–1.6 mm	2.5–2 mm	1–1.2 mm	0.9–1.5 mm
flowers	Sepal shape	–	Subcircular	Ovate	Elliptical	Obovate or elliptical
	Number of stamens	–	2	3	2–3	2–3
	Number of sepals	5	6	5	6(–8)	6
Pistillate flowers	Number of sepal series Sepal length Sepal shape	1 1.5 mm Lanceolate, apex obtuse	2 3–3.5 mm Broadly elliptical, apex acute	1 2.5 mm Narrowly triangular, apex acute	1 2.5 mm Ovate, apex acuminate	1 1–2.5 mm Ovate or lanceolate, apex acute
	Apical gland	?	Absent	Absent	Present	Absent