We describe one new species from Ceará state, Brazil: Wedelia figueiredoana. It is morphologically associated with W. bonplandiana, but distinguished by 0.25–1.05 cm leaf blade width (vs. 1.5–2.6 cm), linear to narrow oblong leaf blade (vs. elliptic to spatulate), 3-seriate involucre (vs. 2-seriate), and cypselae 3.9–4 mm long (vs. 6–7 mm). An anatomical analysis of cypselae is provided, and we propose a more accurate terminology to describe similar wings to Wedelia species. We also provide a scientific illustration of the new species, photos of habitat, a map of its geographic occurrence, and its taxonomic affinities are discussed with a taxonomic key to the Wedelia species with the apically pronounced wings in the cypselae.

Auricular projections, Cerrado, Compositae, fruit anatomy

Wedelia Jacq. is inserted in Heliantheae Cassini. This genus occurs mainly in the Neotropics (Strother 1991; Panero 2007), and occasionally in the south USA and Tropical Africa (Strother 1991). We adopted the Wedelia circumscription of Turner (1992), which includes Aspilia Thouars as its synonym. Brazil is the most rich-species country of the world for the genus with the occurrence of 89 species, 56 of them endemic (Flora e Funga do Brasil 2024).

Wedelia can be characterized by herbaceous or shrubby habit, opposite leaves, blades lanceolate to ovate, oval or elliptic; capitula solitaires or in cymes, radiate, rarely discoid; 2–4-seriate involucre, paleaceous receptacle; pistillate or sterile ray florets, yellow or yellow to orange corolla; bisexual disc florets, yellow to orange corolla; black anthers, yellow styles arms; black cypselae, winged or no-winged, coroniform pappus, 0–3 awns (Panero 2007).

During field expeditions in the municipality of Graça, Ceará state, Brazil in February 2023, specimens with yellow florets of Asteraceae were found. After extensive literature review, morphological analysis of specimens from herbaria, and anatomical studies led to the conclusion that this is a new species with unusual cypselae structures, when compared with the Brazilian Wedelia species. Thus, we propose here a new species of Wedelia for the Brazilian flora. We provide morphological description, an illustration plate, photos and information on the habitat, distribution map, preliminary data on its conservation status, taxonomic key to the Brazilian Wedelia species with winged cypselae, and the morphological relationship with the most similar species is discussed. In addition, an anatomical plate is provided and the taxonomic implications for Wedelia of its results are discussed.

Herbarium specimens from BHCB, BHZB, CEN, HUFU, ICN, R, RB, SPF (acronyms according to Thiers 2024) were analyzed. Several online herbarium databases were consulted, including the following: C. V. Starr Herbarium Virtual (https://sweetgum.nybg.org/science/vh/), Reflora (http://reflora.jbrj.gov.br/reflora/), Smithsonian Virtual Herbarium (https://collections.si.edu/search/), SpeciesLink (https://specieslink.net/), and Tropicos (https://tropicos.org). The types of numerous Wedelia species were consulted for taxonomic comparisons. The literature of Wedelia was reviewed (Baker 1884; Turner 1988, 1992, 2004; Strother 1991; Pruski and Robinson 2018; Bueno et al. 2019; Bueno and Nakajima 2020; Remor et al. 2022; Flora e Funga do Brasil 2024).

The morphological description was based on vegetative and reproductive material from herbaria specimens, for which a stereomicroscope was used to perform the measurements with a caliper rule. The vegetative structures were described from dried material, whereas reproductive structures were characterized after rehydration, immersing the structure in warm water for 1 minute at 100 °C. The outliers of measures were based on calculation of medians, quartiles, and interquartile deviations. “Rarely” is applied for characters that occur in up to 10% of the specimens studied; “sometimes” is adopted for features that occur in between 10.01% and 25% of the specimens analyzed; “often” is used for the characters that occur between 25.01% and 40% of the specimens studied; and “Or” is applied for traits that occur between 40% and 60% of the specimens (Bueno and Heiden 2022).

The general morphological terminology follows Hickey (1973), Ellis et al. (2009), and Beentje (2016). The specialized Compositae terminology follows Funk et al. (2009), and specific literature about the terminology of receptacle (Bueno et al. 2022) and pappus (Bueno and Heiden 2022). Although Bueno and Heiden (2022) proposed the terminology of pappus based on pappus scales, they refer to the size of pappus scales and the frequency of different lengths in the same heads. We believe that this terminology contributes to the description of the aristate pappus of Wedelia. The GeoCAT analysis (Bachman et al. 2011) and IUCN guidelines (2022) were used for preliminary conservation status assessment. The distribution maps were prepared in QGIS v. 3.0 (QGIS Development Team 2015).

We used a technique for scanning electron microscopy (SEM) to observe the details of the surface of the cypsela. Mature ray and disk cypsela were placed on aluminum stubs and then covered by gold old using a sputter coater (Leica EM SCD050). Pictures of the cypsela were taken from a SEM (Tescan VEGA 3 LMU). Anatomical studies were made from exsiccatae, therefore, the cypselae were rehydrated in a solution containing 5% NaOH for four hours (Anderson 1963 modified). After that time, the material was washed with distilled water for 24 hours, and dehydrated in an increasing ethylic series. Dehydrated cypsela was included in historesin (Leica®) following the manufacturer protocol. The material was 8–10 μm thick on a rotary microtome and the sections obtained were stained in toluidine blue at pH 4.7 with acetate buffer (O’Brien et al. 1964 modified). Finally, the sections were mounted in synthetic resin and images were taken using a light microscope (Olympus BX51). The anatomical terminology pericarp follows Roth (1977).

The herbaceous habit, decussate leaves, monocephalous heads, overlapped phyllaries in the involucre, and the neutral ray florets resembles the Wedelia foliacea group: Wedelia foliacea (Sprengel) B.L. Turner, W. montevidensis (Sprengel) B.L.Turner, and W. riedelii (Baker) B.L.Turner. However, W. figueiredoana can be differentiated from this group by the 3-seriate involucre (vs. 2-seriate, rarely 3-seriate), second series of phyllaries hirsute (glabrous, rarely pilose), and pronounced apically winged cypselae (vs. wings absent).

Wedelia figueiredoana, W. bonplandiana (Gardner) B.L.Turner, Wedelia brachylepis Griseb., and Wedelia rudis (Baker) H.Rob. are the unique Brazilian Wedelia species with winged cypselae. Wedelia figueiredoana and W. bonplandiana have neutral ray florets, while W. brachylepis and W. rudis have pistillate ray florets. Wedelia figueiredoana and W. bonplandiana are the only two species from Brazil with a pronounced apically winged cypselae, they also share more characters as the herbaceous and prostrate habit, sessile leaves, both surfaces with strigose indumentum, solitaries capitula, and paleae about 7 mm long (Santos 2001). Nevertheless, W. figueiredoana can be individualized from W. bonplandiana by 0.25–1.05 cm leaf blade width (vs. 1.5–2.6 cm), linear to narrow oblong leaf blade (vs. elliptic to spatulate), 3-seriate involucre (vs. 2-seriate), and cypselae 3.9–4 mm long (vs. 6–7 mm).

Blake (1931) was the first author who described “auriculate” projections to the Wedelia cypselae for W. penninervia S.F.Blake. Strother (1991) described three taxa with the same projections: W. acapulcencis var. hispida (Kunth) Strother, W. greenmanii B.L.Turner, and W. strigosa Hook. & Arn. The same terminology was applied by Pruski and Robinson (2018) to describe the cypselae of Wedelia filipes Hemsl. Until then, these were the only known Wedelia species with such structures described. The theoretically same structure can be seen in the cypselae of W. bonplandiana (Gardner) B.L.Turner. In the first moment of the morphological descriptions, it was believed to be the same projections in the cypselae of W. figueiredoana.

Strother (1991) and Pruski and Robinson (2018) made the distinction between species with winged cypselae and cypselae with auriculate projections. Our anatomical results found internal tissues in the supposed projections so we will treat these projections as wings. Based on this, we hypothesize that the species aforementioned with such projections also have winged cypselae, but further studies will elucidate this. We propose that this specific type of wing, described here for W. figueiredoana, be treated as “apically pronounced wings” to differentiate them from the wings that are more developed and that can be easily seen along the cypselae commonly found in Wedelia species, such as the wings described by Strother (1991).

Elaiosomes are more common in seeds but can be found in fruits of Asteraceae, such as Centaurea (Roth 1977). For Wedelia, elaiosomes proved to be very important for new classification of this genus, proposed by Alves (2019). In this classification, Wedelia now includes the genera Aspilia, Coronocarpus Schumach. & Thonn., Oyedaea DC., Steiractinia S.F. Blake, Zexmenia La Llave, Zyzyxia Strother, and two species of Elaphandra Strother (Alves 2019). According to Alves (2019), clades within Wedelia that do not present elaiosomes are considered as a derived character state. The anticlinal projections present in the outermost layer of the median mesocarp of W. figueiredoana were also described for Clibadium, Desmanthodium, Ichthyothere (Stuessy and Liu 1983) and Calea (Marques et al. 2022).

Special thanks to all the staff at the Herbarium HUFU for the infrastructure provided to proceed with the analysis. We thank the staff at the Laboratório Multiusuário de Microscopia Eletrônica da Faculdade de Engenharia Química (UFU) for their support with SEM. LSR thanks to the State Environmental Superintendence of Ceará for the field support. We also thank Dr. Rosa and the other reviewer for the suggestions, which helped improve this paper.