Wedelia tenuinervia Bringel & Alves

Bringel Jr, João Bernardo De A., Alves, Maria & Roque, Nádia, 2024, Taxonomic studies in Wedelia (Asteraceae, Heliantheae) reveal a new species for the Brazilian Cerrado, Phytotaxa 647 (2), pp. 177-188 : 178-184

Wedelia tenuinervia Bringel & Alves , sp. nov. ( Figs. 1 , 2 )

Type:— BRAZIL. Goiás: Parque Nacional Chapada dos Veadeiros, porteira 25 km W de Alto Paraíso em direção a S. Jorge , 1 km N, 14º07’37’’ S, 47°44’00’’ W, elevation 1195 m, 14 November 2017, M. F. Simon et al. 3191 (holotype CEN barcode 00105341 !, isotypes ALCB!, HUFU!, RB!) .

Wedelia tenuinervia is morphologically similar to W. foliacea but differs from the latter by the leaf with brochidodromous venation, pistillate ray flowers, glandular trichomes on the abaxial surface of the leaf blade, corolla lobes and apical anther appendages; phyllaries abaxial surface strigillose, 6–8 ray flowers; corolla limb of the ray flowers 8–11 mm length and disc cypselae, 4–5-angled, keeled at the angles, without basal scars or elaiosomes, carpopodium inconspicuous (vs. acrodromous venation, neuter ray flower, abaxial surface of the leaf blade, corolla lobes and apical anther appendage lacking glandular trichomes; phyllaries abaxial surface setose or glabrescent, 8–15 ray flowers, corolla limb of the ray flowers 11–32 mm length and disc cypselae biconvex, not keeled, with basal scars or elaiosomes, carpopodium in two plates or one shallowly lobed).

Cespitose subshrub 7.5–22 cm tall, xylopodium napiform, 5–20 cm diam., multiple aerial stems ca. 1 mm diam., dense to sparsely strigillose, internodes 1.3–4.7 cm long. Leaves opposite, sessile or petiolate, petiole 0.5–1.5 mm long, leaf blade simple, membranaceous, 11–25 × 3–9 mm, ovate, elliptic, narrowly elliptic or obovate, apex acute to obtuse, base cuneate, margin entire to slightly serrulate on the upper 1/2, flat, abaxial and adaxial surfaces strigillose, abaxial surface densely covered with glandular trichomes, venation brochidodromous, with slender secondary veins, slightly discolored. Capitula radiate, heterogamous, solitary on terminal peduncle, peduncle 1.5–9 cm long; involucre campanulate, 2-seriate, 7–11 mm diam.; phyllaries subequal, green, outer phyllaries 6–8 × 2.5–5 mm, ovate, obovate when fruiting, apex acute or obtuse, abaxial surface strigillose, covered with glandular trichomes; inner phyllaries 5–7 × 2.5–4.2 mm, ovate to elliptic or widely elliptic when fruiting, apex acute or obtuse, abaxial surface strigillose, covered with glandular trichomes; receptacle paleaceous, paleas 5.6–6 mm long, oblong to narrowly oblanceolate, slightly conduplicate, yellow with a dark-red spot at apex, apex acute to acuminate, straight or slightly inflexed, abaxial surface sparsely setose at apex or glabrescent. Ray flowers 6–8 per capitula, pistillate, corolla liguliform, yellow, tube ca. 0.8 mm long, glabrescent, limb 10–11 × 4–6 mm, abaxial surface sparsely pubescent, covered with glandular trichomes, style shaft ca. 2 mm long, style branches ca. 1.2 mm long, apex acute, glabrous. Disc flowers 29–30 per capitula, corolla yellow, 3.7–4.6 mm long, 1.4–2 mm diam., tube 1–1.3 mm long., outside sparsely pilose to glabrescent, limb narrowly campanulate to cylindric, 2–2.5 mm long, glabrous or with glandular trichomes at apex; lobes reflexed at anthesis, 0.7–0.8 mm long, outer surface with glandular trichomes, inner surface papillose at margin; stylopodium ca. 0.4 mm long, shortly cylindrical, slightly constricted at base, style shaft ca. 3 mm long; style branches ca. 1.2 mm long, recurved, pubescent at abaxial surface, apex acuminate; anthers 2–2.3 mm long, blackened, apical appendages yellow, ovate, ca. 0.3 mm long, slightly concave, with glandular trichomes on abaxial surface. Cypselae obovoid, 3.2–4.3 × 1.9–3 mm, inconspicuously rostrate, rostrum 0.1–0.2 mm long, 3–4(5)-angled in the ray ones, 4–5 angled in the disc ones, keeled at the angles, sparsely setose at apex, base obtuse to cuneate, lacking elaiosomes or scars, carpopodium inconspicuous; pappus coroniform, fimbriate, 0.4–0.8 mm long, sometimes with irregular and elongate paleaceous segments ca. 1 mm long; with glandular trichomes sparsely scattered along all the pappus.

Etymology: —The specific epithet refers to the slender secondary veins that make up the brochidodromous venation of the leaf, an unusual venation for Wedelia species that are mostly trinervate (acrodromous or actinodromous venation).

Distribution, habitat, and conservation status:— Wedelia tenuinervia is restricted to the northeastern portion of Goiás state, within the Chapada dos Veadeiros highlands ( Fig. 3 ). It grows at elevations above 1,000 m, in grassland or shrubby-grassland vegetation, on soils with quartz gravel, and blooming after fire.

According to the IUCN (2012, 2019) criteria of geographic range (B1,2ab(ii,iii)), W. tenuinervia is considered vulnerable (VU), since it counts six different locations known, covering an area of occupancy of 24 km 2 and an extent of occurrence of 110.29 km 2. Although W. tenuinervia grows in the National Park of Chapada dos Veadeiros, which is a federal conservation park spreading over nearly 2,406 km 2, it was recently observed that anthropogenic pressure has increased between Alto Paraíso city and São Jorge village, near some of its occurrence points. This species is recorded with flowers between June and November, usually after burning. Recently (November 2022), W. tenuinervia was seen in the field without signs of fire, appearing with more spreading stems and with cypselae already dispersed ( Fig. 2E ).

Additional specimens examined (paratypes):— BRAZIL. Goiás. Alto Paraíso de Goiás: Chapada dos Veadeiros , Divisa do Parque Nacional da Chapada dos Veadeiros , on road GO-118, 13°57’30’’ S, 47°28’45’’ W, 27 June 2014, R. D. Sartin et al. 620 ( CEN) ; Estrada para Vila de São Jorge, próximo ao Jardim de Maytrea , J. Paula-Souza et al. 8601 ( SPF) ; GO-118 de Alto Paraíso de Goiás a Teresina de Goiás, 14.8 km N de Alto Paraíso, 14º01’24’’ S, 47º31’43’’W, 06 June 2011, J. B. Bringel & H. J. C. Moreira 817 ( CEN, UB) ; GO -118 sentido Alto Paraiso de Goiás — Teresina de Goiás, 11 November 2011, J. B. Bringel et al. 861 ( CEN, UB) ; Parque Nacional da Chapada dos Veadeiros, ao norte do Morro da Baleia , 14º05’46.1’’ S, 47°40’32.2’’ W, 16 November 2021, S. R. Silva & J. B. A. Bringel 3197 ( CEN) ; Parque Nacional Chapada dos Veadeiros, Alto Paraiso-Cruzeiro, 28 September 1995, M. L. Fonseca 654 ( IBGE, US [image]) ; Chapada dos Veadeiros, 23 October 1965, A. P. Duarte 9434 ( CEN, RB) ; Parque Nacional da Chapada dos Veadeiros, Pouso Alto, BR 010 sentido Teresina de Goiás e Cavalcante , lado esquerdo da estrada, estrada de terra para as Cabeceiras do Rio Preto , guarita abandonada, 13º58’26’’ S, 47°29’55’’ W, 26 November 2014, P. Eduardo et al. 148 ( CEN, RB) .

Discussion:— Wedelia tenuinervia can be morphologically related to W. foliacea ( Aspilia foliaceae in Flora e Funga do Brasil, Fig. 4 ), due to similar vegetative traits. Both species are cespitose subshrubs, with many aerial stems arising from the xylopodium, usually with no more than 30 cm high, heads solitary and leaf blades similar in shape. However, accurate analysis showed W. tenuinervia differs from W. foliacea by the leaves with brochidodromous venation, pistillate ray flowers, glandular trichomes on the abaxial surface of the leaf blade, corolla lobes and apical anther appendages; phyllaries abaxial surface strigillose, 6–8 ray flowers; corolla limb of the ray flowers 8–11 mm length and disc cypselae 4–5-angled, keeled at the angles, carpopodium inconspicuous, without basal scars or elaiosomes (vs. acrodromous venation, neuter ray flower, abaxial surface of the leaf blade, corolla lobes and apical anther appendage lacking glandular trichomes; phyllaries abaxial surface glabrescent to setose, 8–15 ray flowers, corolla limb of the ray flowers 11–32 mm length and disc cypselae biconvex, not keeled, carpopodium in two plates or one shallowly lobed with basal scars or elaiosomes) ( Table 1 ).

Although W. foliacea is a vegetatively polymorphic species, the differential reproductive characteristics mentioned above are also invariable in all previously analyzed specimens (Robinson1984, Strother 1991, Santos 2001, Alves & Roque 2016, Alves & Bringel 2024). Among the set of differential traits, we highlight the venation, the sexuality of ray flowers (pistillate), cypselae and the pappus morphology as a strong taxonomic signal to corroborate the new taxon here proposed.

Among Brazilian species with pistillate ray florets, W. tenuinervia is morphologically similar to W. oligocephala Baker (1884: 182 , Fig. 5), since both have the cespitose habit with a xylopodium, leaf blades with entire to slightly serrate margins and small capitula. However, W. tenuinervia differs by membranaceous leaf blades with flat margins and brochidodromous venation, solitary capitula, ray cypselae 3–4(5)-angled, and disc cypselae 4–5-angled, keeled at the angles (vs. subcoriaceous leaf blades with revolute margins and acrodromous venation, capitula in dichasia, ray cypselae 3-angled, and disc cypselae 4-angled to biconvex, never keeled in W. oligocephala ).

Based on the morphology of cypselae, W. tenuinervia is related to the Brazilian species included by Baker (1884) in W. sect. Cyathophora Candolle (1836: 538) , which have an inconspicuous or lenticular carpopodium that is lacking basal elaiosomes or scars. However, only a comprehensive phylogenetic study in Wedelia could confirm this placement.

Figures

FIGURE 1. Wedelia tenuinervia. A. Cespitose habit. B. Leaf blade abaxial surface. C. Detail of leaf blade abaxial surface with glandular trichomes. D. Capitulum (with two ray flowers removed). E. Outer phyllary. F. Inner phyllary. G. Receptacle pale. H. Disc flower. I. Ray flower. J. Anthers. K. Style and nectary of disc flower. L. Capitulum with cypsela. M–P. Cypsela from ray flowers. Q–R. Cypsela from disc flowers. Drawn by Gustavo Surlo.

FIGURE 2. Wedelia tenuinervia. A. Specimens scattered on the grass layer. B. Detail of cespitose habit. C. Aerial branch showing the solitary capitula. D. Details of the head and subequal phyllaries. E. Xylopodium and aerial stems. F. Aerial branch showing details of leaf with slender veins and six ray flowers. G. Capitula showing six ray flowers and detail of disc flowers. Photo’s authors: A–D. Henrique Moreira; E. J. Bringel; G. Marcelo Simon. Herbarium specimens:A, B, F. Bringel & Moreira 861; C–D. Bringel & Moreira 817; E. Silva & Bringel 3197; G. Simon et al. 3191.

FIGURE 3. A. Distribution map of Wedelia tenuinervia. A. Map of South America highlighting the state of Goiás (yellow) B. Occurrence map of Wedelia tenuinervia in Goiás state.

FIGURE 4. A–F.Wedelia foliacea.A. Blooming of yellow flower after fire incidence on cerrado vegetation.B–D.Corolla colour variations of specimens of different populations. E. Corolla collor variation from the same population. F. Leaf. G–H. Wedelia oligocephala. G. Capitulum showing ten ray flowers. H. Involucre with peduncle and adjacent leaves. Photo’s authors: A–F. Henrique Moreira; G–H. J. Bringel. Herbarium specimens: G–H. Bringel & Borges 1032.