Hohenbergia erecta (Bromeliaceae: Bromelioideae), a New Once-branched Species from Chapada Diamantina, Bahia State, Brazil

Hohenbergia is one the most diverse genera in Bahia state, and inhabits almost all regions of the state. As a result of ongoing studies on Hohenbergia in Bahia, Brazil, here we describe and illustrate Hohenbergia erecta, endemic to the municipality of Mucugê, at Chapada Diamantina. Hohenbergia erecta differs from its morphologically related, H. catingae, by an elongated tubular rosette (vs short stem with a crateriform rosette), and a once-branched cylindrical inflorescence (vs 2–3-branched pyramidal inflorescence), with branches congested at the apex (vs branches laxly arranged). Due to a small distribution area in the Caatinga forest and based on a spatial analysis we categorized it as Endangered (EN), following the IUCN criteria. Hohenbergia erecta is endemic to the central region of Chapada Diamantina, dominant in the area, where no other known Hohenbergia species have been found sympatrically. It is important, however, that new field expeditions are conducted in the region to observe the richness of the genus at Chapada Diamantina.


Introduction
Hohenbergia Schult & Schult.f is a bromeliad genus centered in Brazil, mainly in the Atlantic Forest (Benzing 2000;Aguirre-Santoro et al. 2016;Cavalcante et al. 2017). Most of the species occur in the State of Bahia (44 spp.), where most of them are endemic or found in a single population patch (microendemic), with at least 13 Hohenbergia species occurring at Chapada Diamantina as microendemic (Baracho 2004;Gonçalves-Oliveira et al. 2020).
Currently, this genus includes a single subgenus, Hohenbergia subg. Hohenbergia Mez, but in the past subg. Wittmackiopsis was also included, now being recognized as the genus Wittmackia, both being segregated only by their geographical occurrences (Caribbean versus Brazilian) and the chalazal appendage in the ovule (Baracho 2004). It is remarkable that their morphological traits do not seem phylogenetically constrained, showing a strong niche conversion, even comparing the two geographically disjuncted subgenera mentioned above, which were segregated only in a more recent phylogeny (Aguirre-Santoro et al. 2016). However, comparing just the current Hohenbergia, that morphological convergence appears strongly linked with the environment, such as the Atlantic Forest species near the coast, presenting open rosette and lax pyramidal inflorescence, or Drylands species, more inland, with a narrow tubular rosette and cylindrical sessile inflorescence. These species show more morphological similarities among themselves than when compared with their closest phylogenetic relatives, creating a convergent morphological pattern (Baracho 2004;Oliveira 2016a, b;Cavalcante et al. 2020a).
Hohenbergia species in the Atlantic Forest (mesic environment) are mainly epiphytic plants, with long leaves (> 100 cm long) and brownish leaf sheaths with a similar width to the leaf blade, forming a deep funnelform rosette; plants bearing a prominent 2-5-branched and laxly arranged inflorescence, with long branches; flowers with purple, yellow or, rarely, white petals (Baracho 2004;Cavalcante et al. 2020b). Hohenbergia species in dryland environments (Campos Rupestres and Caatinga) form another morphological group, which is characterized by a saxicolous life form, or growth in sandy soil banks, shorter leaves (blades commonly smaller than the sheaths in both length and width) with well developed sheaths that form the tank, resulting in a narrow rosette (lageniform or tubular), with a great capacity of storing water; sub-cylindrical inflorescence, two or three times higher than the rosette; and short pedunculate lateral branches with flowers bearing purple petals (Baracho 2004;Oliveira 2016a, b;Cavalcante et al. 2018).
Considering the peculiarities of these two morphological groups, Hohenbergia may be recognized by the welldeveloped rosette, forming a large water-tank, and a welldeveloped inflorescence (representing up to 2/3 of the total plant height when flowering), which is covered by a dense lanate indument, presenting strobilate spikes bearing small flowers (shorter than 45 mm), the ovaries are ventrally flattened and covered by spinescent floral bracts (Baracho 2004). Moreover, these are traits we might find in several tank-form species at Brazilian environments, which only the dorsiventrally flatten flowers with a pungent ovaltriangular floral bracts who completely concealed the ovary can be raised as a 100% certain feature to properly identify those species (Baracho 2004;Cavalcante et al. 2021a, b;Cavalcante et al. 2022).
As a result of at least ten years of field and herbarium studies with Hohenbergia in the State of Bahia, six new species have been discovered, (Leme and Kollmann 2011;Leme 2012;Maciel and Louzada 2014;Oliveira and Wanderley 2017;Cavalcante et al. 2020b), including the new species described here, which is illustrated and compared with its morphologically similar species. In addition, its conservation status, blooming period, and taxonomic comments and notes are provided. Hohenbergia erecta is closely related to H. catingae, but they differ on vegetative propagation (stolon vs short basal shoots), tubular rosette (vs crateriform rosette), linear-lanceolate leaves with erect and caudate apices (vs linear leaves with acuminate apices), sheaths wider than the leaf blades (vs sheaths and blades of the same width), once-branched inflorescence (vs 2-3-branched inflorescence) covered by a brownish indument (vs whitish indument), petals with rounded apices (vs petals with acuminate apices), and included stigma (vs exserted stigma).
Etymology The specific epithet refers to the erect and elongated aspect of the rosette and inflorescence.
Phenology The beginning of flowering was not observed, but blooming individuals were found in May until July.

Distribution and Habitat
Hohenbergia erecta has been found growing in sandy soils in Caatinga vegetation of Chapada Diamantina (Bahia), near rocky fields, along an unnamed road that connects the municipality of Mucugê to Brejo de Cima, and it is sympatric with other bromeliads, such as species of Ortophytum sp., Encholirium sp., and Neogloziovia variegata. No other Hohenbergia species was observed at this location. The region is a Dryland Forest with altitudinal Caatinga vegetation, with a few trees, large to medium sized shrubs, herbs and a great number of rocks. The climate

Conservation Status
The type locality is an extensive Caatinga forest close to a small community (Brejo de Cima) in the municipality of Mucugê and signs of illegal collections were observed in the area. In addition, it grows in a region that is being affected by deforestation events for road construction. When we plot the known occurrences of this species in Geocat software (Visualization and Analysis Systems Technologies 2019), the estimated extent of occurrence was 0.385 km 2 , while the area of occupancy is estimated as 8000 km 2 . Given these areas, the conservation status suggested was Critically Endangered (CR), however the area of occurrence of the species is a vast area of Caatinga, making it difficult to accurately estimate the total area of its distribution. Nonetheless, considering the impacts observed and projected for the area, we place this new species as Endangered (EN), according to the IUCN definition (IUCN 2021).

Discussion
Hohenbergia erecta has a "caulescent" habit, even in ramets growing from the plants in a greenhouse, a unique feature for the genus. The older leaves commonly remain attached to the rosette base by the sheaths -this resembles a stem (pseudostem) and assists in the species identification in combination with the once-branched and very narrow cylindrical inflorescence. Hohenbergia correia-araujoi Pereira & Moutinho and H. lanata Pereira & Moutinho, occurring in the Caatinga forests (Baracho 2004) as well, also presents a tubular rosette, but lack the caulescent habit.
Hohenbergia erecta bears some affinity with H. catingae by their habitat (both growing on sand soil banks) in Inflorescence spike with one flower at anthesis addition to their long and thin leaves with prominent apices; long reddish peduncle, covered by a dense indumentum; green floral bracts with brownish and papyraceous apices; and flowers with purple petals. It is important to highlight that all these features are uncommon for species of Hohenbergia that grow in Campos Rupestres and Caatinga.
Comparing both species (Table 1), H. erecta is easily identified by its appearance (caulescent habit with a tubular rosette and a cylindrical once-branched inflorescence), but other features may also be considered to facilitate its recognition. These features include the width of the rosette (ca. 35 cm diam. in H. erecta vs 100 cm diam. in H. catingae), the color of the indument of the inflorescence (brown-lanate indument in H. erecta vs white-lanate in H. catingae), and the height of the peduncle (80 cm in H. erecta vs 60 cm in H. catingae) -although the height of the peduncle is longer in H. erecta, the total length of the inflorescence is longer in H. catingae. Given the elegant aspect of the rosette with its marcescent and erect leaves, we believe this species will be of horticultural and landscaping interest, particularly for xeriscape gardens.
About 51 species of Hohenbergia are known from Latin America, most of them from the state of Bahia, and in the last years, many species were described from Chapada Diamantina, showing the taxonomic potential of the region. Hohenbergia erecta is endemic to the central region of Chapada Diamantina, being described as dominant in the area, where no other Hohenbergia species have been found. New field expeditions should be conducted

Methods
Our collection expeditions through the State of Bahia have been carried out over the past three years and the morphological studies have been performed based on living materials under natural conditions as well as studying images of herbarium specimens available on-line. Specimens of the new species were taken to a greenhouse for cultivation and observation of possible structural variations in plant architecture (Silva et al. , 2020; these specimens were deposited in the germplasm bank of bromeliads (BGB Bromélias) of Embrapa Mandioca e Fruticultura, located in Cruz das Almas, Bahia, Brazil, and Centro de Energia Nuclear na Agricultura, Universidade de São Paulo, in Piracicaba, São Paulo, following the guidelines recommended by the article 9 of the Convention on Biological Diversity (1993) for ex situ conservation.
The taxonomic description and illustrations were based on living plants, dissected samples and herbarium specimens using a stereomicroscope (Leica EZ4E). The descriptive terminology follows Smith and Downs (1979), with the modifications suggested by Scharf and Gouda (2008). The type specimen was deposited at Herbário do Recôncavo da Bahia (HURB), Cruz das Almas, Bahia.
The conservation status was inferred based on the occurrence of the species in the GeoCAT program (http:// geocat. kew. org/) following the categories and criteria of the IUCN (2021).