Staurochlamys burchellii Baker (1889: 1825)

Bueno, Vinicius Resende, Dalastra, Claudenice Hilda & Buchoski, Monica Gomes, 2024, Staurochlamys (Neurolaeneae, Asteraceae): an endemic genus from Cerrado, Brazil, Phytotaxa 661 (2), pp. 157-168 : 160-165

Staurochlamys burchellii Baker (1889: 1825) .

Type:— BRAZIL. North Brazil [Tocantins]. Porto Real [Porto Nacional], W.J. Burchell 8679-6 (K [K000955642]!, lectotype designated here; isolectotypes GH [GH00549710], digital image!; GH [GH00012657], [fragment] digital image!; K [K000955643]!; NY [NY00260022]!; NY [NY00260024]!; NY [NY00260025]!; US [ US 00128687]!) .

Herbs, 0.15–0.5m tall; stems cylindrical, strigose to pubescent, olivaceous, internodes 1.2–4.5 cm long. Leaf arrangement opposite, sessile or petiolate, 0.8–2 mm long; blades 1.4–4 × 0.2–1.6 cm, lanceolate, base obtuse to attenuate, apex acute, venation acrodromous basal, margins serrate, revolute, abaxial surface sparsely puberulous to puberulous, densely glandular-punctate, adaxial surface puberulous to densely puberulous, sometimes glabrous to margins scabridulous, eglandular; membranaceous, concolorous, olivaceous. Capitulescence cymose dichasiform, terminal; peduncle 1.6–13 cm long, densely strigose to densely puberulous, eglandular. Capitulum heterogamous, radiate; involucre 5.9–8.9 × 5.6–8.2 mm, flattened. Phyllaries 3-seriate, margins entire, flat; outer series of phyllaries foliaceous, green, first series 3.3–5.6 × 2–3.4 mm, ovate, sometimes narrow ovate, obtuse, densely puberulous, glandular-punctate, inconspicuously 1–2-striate; second series 5.9–8.9 × 5.6–8.2 mm, orbiculate, sometimes suborbiculate, apex rounded, densely puberulous, eglandular, conspicuously 12–15-striate; innermost series scarious, greenish yellow, 4.1–5.2 × 1.2–1.6 mm, narrow elliptic, apex acute, glabrous, inconspicuously 2-striate; receptacle flat to slightly convex, holopaleaceous, 4.2–4.6 × 0.1–0.2 mm long, filiform, apex acuminate, flat, glabrous. Ray florets 4–5, pistillate, corolla 5.2–6 mm long, liguliform, tube 2.5–3.4 mm long, limb 2.5–2.7 × 1.5–2 mm, obovate to wide obovate, apex 3-lobed, 3-veined, glabrous, yellow; style arms 0.3–0.4 mm long, yellow, linear. Disc florets 10–12, bisexual, corolla 4.1–5.3 mm long, tubular, tube 2.1–2.7 mm long, lobes 1.7–2 mm long, flat, glabrous, yellow; anthers 1.5–1.9 mm long, light yellow, apical anther appendages ovate; style arms 0.7–0.9 mm long, yellow, linear. Cypselae 3.9–4 mm long, cylindrical, glabrous, black; pappus absent. Fig. 1 .

Diagnosis and Taxonomy:— Staurochlamys burchelii can be characterized by herbaceous habit, opposite leaves, flattened and 3-seriate involucre, 4–5 ray florets, 10–12 disc florets, cypselae glabrous, and pappus absent. Bueno (2023) associated Staurochlamys with Enydra Loureiro (1790: 590–591) and Greenmaniella Sharp (1935:141) based on the phylogenetic analyzes and morphological interpretations; the three species have opposite leaves, foliaceous outer series of involucre, and pappus absent or much reduced. The flattened involucre ( Fig. 1E ) individualized this genus, not only of these two genera, but also of Asteraceae , since this is a unique characteristic in this worldspread family.

Nomenclatural notes and Etymology:— Staurochlamys burchellii was described based on syntypes collected by W.J. Burchell 8679-6 deposited in GH, K and US. Therefore, it is necessary to lectotypify the species name by one of these specimens. As Baker worked at Kew, the lectotype was chosen based on the two syntypes from Kew; the material [K000955642] is in better condition with more stems, leaves, capitula and florets than [K000955643]. Thus , the specimens [K000955643]!, [GH00549710], [GH00012657], [NY00260022], [NY00260024], [NY00260025], US [ US 00128687] are considered isolectotypes.

Baker (1889) did not comment on the etymology of the genus or the species epithet. Probably the prefix “Stauro” comes from the Greek word “staurós” which means cross, “clamys” is also a term in Greek, which means mantle and is widely used in botany as a reference to the reproductive verticils (sepal and petal). Often, the involucral phyllaries of the Asteraceae specimens are misidentified as the sepals of a flower. Thus, Baker (1889) probably made this choice because the first series of bracts was positioned at about ninety degrees (when opened) from the peduncle and the second series of phyllaries—making a cross. The species epithet “ burchellii ” honors the botanist W. J. Burchell who collected the type material.

Habitat and Distribution:— Staurochlamys burchellii occurs in four Brazilian states: Goiás, Maranhão, Piauí, and Tocantins ( Fig. 2 ). Corroborating Roque & Barbosa (2024), this species is endemic of Cerrado ( Fig. 3 ), occurring both in areas of open formations and dense formations of Cerrado. As evidenced in Fig. 3 , there are two points of occurrence within the Caatinga, although these collection points are within the Parque Nacional de Sete Cidades (Seven Cities National Park), which has Cerrado enclaves within the Caatinga domain ( Matos & Felfili 2010). Staurochlamys burchellii was found in rocky or sandy soils associated with quartzite, often found in riverine vegetation.

Phenology:— Staurochlamys burchellii produces florets and cypselae from February until July. According to Fig. 3 , the peak of the reproductive phase is between the end of February and the beginning of April. Another interesting piece of information is that there is a north-south pattern to reproduction: collections made between February and March are primarily found to the south of the species’ distribution. Individuals reproducing after April are mostly found in the northern part of the species. The northernmost point of the species’ distribution reproduces between May and July. This pattern may contribute to future sampling efforts being more focused on the months when the species usually breeds in the region.

Conservation status:— Staurochlamys burchellii is here proposed as Endangered ( EN) (B2—cii, ciii). The Extent of Occurrence ( EOO) was calculated in 540,192.433 km ² and the Area of Occupancy ( AOO) in 96.000 km ². The criterion was adopted due the AOO that suggests the highest threat level and the extreme fluctuations in (ii) the area of occupancy and (iii) the number of subpopulations. Despite S. burchellii occurs in four protected areas in three States (Parque Nacional da Chapada das Mesas-MA, Parque Nacional de Sete Cidades-PI, Estação Ecológica de Uruçuí-UnaPI, Parque Nacional do Araguaia-TO), many populations are situated outside of protected areas, especially in Goiás State. The species is subject to general threats in the Cerrado domain, such as habitat loss due to anthropogenic fires and agriculture in the Cerrado sensu stricto and cerradão formations.

Ecological Niche Modelling:—Based on Ecological Niche Modeling ( ECM) for the current days made for the species ( Fig. 4C ), it can be seen that the most likely areas of occurrence (pink to red) occur from the northern portion of Goiás to the south of Maranhão and the west of Piauí, through the central and western portion of Tocantins state. When compared to the occurrence map ( Fig. 2 ), it is evident that there are no collections in the north of Tocantins, an area with high suitability for the species. As Tocantins is a state that has not yet been extensively collected in Brazil ( SpeciesLink 2024), there are great chances that more collections there will result in more occurrences of S. burchellii . The northernmost and westernmost points of occurrence are the only ones outside the probable areas for the present in the ENM.

In the LGM scenario ( Fig. 4B ), Staurochlamys burchelli presents a suitability similar to that of current time, however with the most probable areas with a narrower distribution in the same areas to the current. Fewer areas in red are seen compared to the present model. This shows that the species had its potential areas of occurrence reduced in the LGM compared to what is available for the current time. Compared to the occurrence map, the LGM model shows the same that was seen for the current model: the specimens sampled in the northernmost and westernmost points of occurrence are the only ones outside the probable areas. Ledru et al. (2001) studied sites to the north of Maranhão state; their results show that during the LGM there was no expansion of Cerrado into the area, which is corroborated by the results found here since S. burchellii retracts its occurrence to the north of its distribution ( Fig. 4B ). When compared to the occurrence map ( Fig. 2 ), it is noticed that the southernmost points of occurrence are only explained by the models for the LGM and current ENM.

In the LIG model ( Fig. 4A ), there are areas of lower suitability that are practically disjointed with the reduction of these areas in the state of Tocantins. Like the current time model, the areas in southern Maranhão and western Piauí have areas with greater suitability than in the LGM. What most differs in relation to the models for current time and LGM, is that in the LIG areas in the northeast of Mato Grosso, on the border with Tocantins and Pará, as well as areas in the north of Piauí appear with high suitability.

When this map ( Fig. 4 ) is compared to the occurrence map ( Fig. 2 ), it is evident that the northernmost and westernmost points of occurrence are probably relicts of the LIG ( Fig. 4A ). The northernmost point comes from the Parque Nacional de Sete Cidades (National Park of Sete Cidades). The occurrence of Staurochlamys in the park shows that during the LIG there was an expansion of this species, endemic to the Cerrado, to areas that today are Caatinga. This region is also considered a refuge for characteristic trees of the Cerrado ( Buzatti et al. 2017). The two species analyzed by Buzatti et al. (2017) show greater suitability in this region during LIG than in any other period—the same pattern seen for Staurochlamys . This could perhaps show the expansion of the Cerrado to this area that today belongs to the Caatinga domain.

The westernmost point of occurrence is in “ Ilha do Bananal” (Bananal fluvial island) are possibly also explained by the LIG expansion of Staurochlamys burchelli and it remains today as relicts of the LIG. Behling (2002) found evidence of savannah formations preceding the LGM at “Lagoa da Confusão” (Confusão lagoon), the point ever studied paleopalynologically closest to Bananal fluvial island. Therefore, this evidence suggests that savannahs likely covered most of the island. The records also show that there was probably a drier period in the region during the LGM ( Behling et al. 2005), which may explain the isolation of this population as a relict LIG.

The stable areas ( Fig. 5 ) show two main areas of long-term occurrence of S. burchellii that coincide with most of the occurrence points known today ( Fig. 2 ). These two areas are inserted with a similar altitude in distinct regions of Cerrado, in the south of Tocantins and in the south of Maranhão. A worrying fact for the conservation of this species is that the stable areas are not found in any current preservation area.

Bueno et al. (2017) studied only trees and found that the largest stable areas were located further south of the Cerrado in Minas Gerais, which is quite contrasting when compared to that found for S. burchellii ( Fig. 5 ). This pattern is related to the distribution of the species, but it may also indicate that herbaceous plants found stable areas in different regions during the Quarternary. As this is the first modeling study for herbaceous species in the Cerrado, further studies with herbs are needed to see if the pattern is confirmed.

Werneck et al. (2012) found a high climatic stability in the Cerrado throughout the Quaternary. The stable areas under the broad definition of the Cerrado ( Werneck et al. 2012) include the stable areas for S. burchellii ( Fig. 5 ). The refugial areas under narrow definition ( Werneck et al. 2012) do not include the stable areas for S. burchellii . This highlights the importance of expanding studies like this to better understand the flora of the Cerrado, to understand the sites most likely to have been Cerrado refuges and, therefore, to be areas of higher priority for preservation ( Werneck et al. 2012).

Specimens examined:— BRAZIL. GOIÁS: Colinas do Sul, GO-132, ca. 2.7 km do trevo GO-239, sentido Minaçu , e 50 m à esquerda, 7 April 2014, J. M. Mendoza F. 4241 ( CEN) ; Flores de Goiás, Ca. 2km do Trevo da BR-020 para Flores de Goiás , estrada anterior ca. 11km, Fazenda Jatobá , 21 March 2013, J. E. Q. Faria 3338 ( UB) ; Monte Alegre de Minas, Morro da cidade de Campos Belos , 16 April 2003, C. W. Fagg 1270 ( IBGE) ; Pirenópolis, Caminho da cachoeira do Abade , 05 March 1967, Irnaldo & G. M. Barroso s.n. (IAN, US). MARANHÃO: Carolina, Parque Nacional Chapada das Mesas, Acesso E no km 612 da BR-230, 20 km da estrada vicinal em direção à localidade Buenos Aires, Ribeirão das Lajes, 06 April 2016, M. F. Simon et al. 2735 (CEN, HUFU) ; Carolina, Parque Nacional Chapada das Mesas , cachoeira da Prata , 12 March 2017, F. C. Martins & I. Doihara 47 ( CCAA) ; Loreto, Ilha de Balsas , entre Balsas e o rio Parnaíba , ca. 5,5 km south of Loreto , 7 April 1962, G. Eiten & L. T. Eiten 4170 (K, RB, SP, US) ; Loreto, Ilha das Balsas, 5,5 Km sul de Loreto , ca. 3,5 Km sul de Rio Balsas , Caminho da Fazenda Aldeia , 11 April 1962, G. Eiten & L. T. Eiten 4248 (IAN, K, RB, SP, UEC, US) ; Loreto, Ilha das Balsas, 5,5 Km sul de Loreto, ca. 3,5 Km sul de Rio Balsas , Caminho da Fazenda Aldeia , 23 April 1962, G. Eiten & L. T. Eiten 4248 (K, UB, US). PIAUÍ: Baixa Grande do Ribeiro , Parque Nacional de Sete Cidades , 24 May 2000, R. Barros s.n. ( TEPB) ; Brasileira, Parque Nacional de Sete Cidades , 05 May 2000, R. Barros 643 ( HUFU) ; Piracuruca, Parque Nacional de Sete Cidades, Córrego Sambaíba , ponto 110, 24 July 2007, R. C. Mendonça et al. 6140 (HUFU, IBGE, UB) ; Piripiri, Parque Nacional de Sete Cidades, 18 May 2018, M. I. B. Loyola et al. 2735 ( EAC). TOCANTINS: Chapada da Natividade , estrada de terra para Pindorama , ca. 17km do entroncamento com a BR-010, 26 March 2011, J. B. A. Bringel Jr. & H. J. C. Moreira 721 (CEN, CESJ, IBGE, UB) ; Conceição do Tocantins, Rod. TO-050, Km 375, Fazenda São José , próximo do Rio Santa Isabel , 11 May 2000, G. Hatschbach et al. 70899 (MBM, US) ; Darcinópolis, margem direita do rio Curiaca , cachoeira fazenda do Sr. Marcelo, 17 April 2008, G. Pereira-Silva et al. 13026 (CEN, HUFU) ; Lagoa da Confusão, Parque Nacional do Araguaia ; Ilha do Bananal , cerca de 2,2 Km da sede do IBAMA ; morro pelado, 21 March 1999, F. R. Mendonça et al. 3943 (HUFU, IBGE, RB, US) ; Natividade, s.d., P. H. Labiak 5925 ( CEPEC) ; Paranã, Acesso ao eixo da barragem pela estrada da Vila Rosário , 24 March 2009, G. Pereira-Silva 11488 ( CEN) ; Paranã, margem do rio Urubuzão, estrada canteiro de obras— rio Custódio , km 7, 31 March 2009, G. Pereira-Silva 14183 ( CEN) ; Paranã, Fazenda São João, proprietário Aldair Freire. Sítio 3, 25 March 2004, G. Pereira-Silva 14183 ( CEN) ; Pindorama de Tocantins, Estrada de terra para Pindorama ca. de 17 Km do entroncamento com a BR 010, cerrado denso, 26 March 2011, J. B. A. Bringel Jr. 721 ( CEN) ; Porto Nacional , 07 February 1974, J. A. Rizzo 9573 ( UFG) .

Figures

FIGURE 1. Field photos of Staurochlamys burchellii Baker (Asteraceae). (A) Herbaceous habit; (B) Detail of inflorescences and ovate leaves; (C) Opposite, sessile, and narrow lanceolate leaves; (D) Dichasial cymose capitulescence; (E) Radiate capitulum with flattened involucre. Photos: M.F. Simon (A, B) and H.J.C. Moreira (C, D, and E).

FIGURE 2. Occurrence map of Staurochlamys burchellii (Neurolaeneae, Asteraceae) in Brazil. Brazilian states: BA—Bahia, GO— Goiás, MG—Minas Gerais, MA—Maranhão, MS—Mato Grosso do Sul, MT—Mato Grosso, PA—Pará, PI—Piauí, and DF—Distrito Federal. Ocean: AO—Atlantic Ocean.

FIGURE 3. Occurrence map of Staurochlamys burchellii (Neurolaeneae, Asteraceae) regarding phenological data and phytogeographic domains.Brazilian states: BA—Bahia, GO—Goiás, MG—Minas Gerais, MA—Maranhão, MS—Mato Grosso do Sul, MT—Mato Grosso, PA—Pará, PI—Piauí, and DF—Distrito Federal.

FIGURE 4. Species distribution models map of Staurochlamys burchellii (Neurolaeneae, Asteraceae) under three climate scenarios: Interglacial Maximum (A), Glacial Maximum (B), and current (C).

FIGURE 5. Stable areas map of Staurochlamys burchellii (Neurolaeneae, Asteraceae) considering the Interglacial Maximum, Glacial Maximum and current climate scenarios. Brazilian states: BA—Bahia, CE—Ceará, GO—Goiás, MG—Minas Gerais, MA—Maranhão, MS—Mato Grosso do Sul, MT—Mato Grosso, PA—Pará, PI—Piauí, PE—Pernambuco, and DF—Distrito Federal. Ocean:AO—Atlantic Ocean.