﻿A taxonomic revision of Keraunea, including three new species and its phylogenetic realignment with Ehretiaceae (Boraginales)

﻿Abstract Keraunea is an enigmatic genus of lianescent shrubs endemic to Brazil and found within the Caatinga and Mata Atlântica phytogeographic regions. When first published, Keraunea was included in the Convolvulaceae and there has been considerable recent disagreement about its true family placement on the Angiosperm tree of life. Based on further assessment of morphology and a new comprehensively-sampled combined phylogenetic analysis of nuclear and plastid genes from recently published DNA sequence data, we settle the position of the genus within the Ehretiaceae as sister to the Australian genus Halgania Gaudich. and provide an expanded family description. We recognize five species within Keraunea, three of them newly described here: K.brasiliensis Cheek & Simão-Bianchini, K.bullata Moonlight & D.B.O.S.Cardoso, sp. nov., K.capixaba Lombardi, K.confusa Moonlight & D.B.O.S.Cardoso, sp. nov. and K.velutina Moonlight & D.B.O.S.Cardoso, sp. nov. We also provide a full taxonomic revision of the genus, including a key, descriptions, map of geographical distribution and provisional IUCN threat assessments for all species.


Introduction
In spite of its short taxonomic history, the small Brazilian genus Keraunea Cheek & Simão-Bianchini (Cheek and Simão-Bianchini 2013) has caused considerable taxonomic confusion. In 2013, three specimens of lianescent shrubs with a highly unusual inflorescence structure were published as a new genus and species: Keraunea brasiliensis Cheek & Simão-Bianchini (Cheek and Simão-Bianchini 2013). The authors "confidently" placed the genus within the Convolvulaceae because its fruits (with the pedicels adnate to a large leaf-like bracteole) resembled the African lianas of the genus Neuropeltis Wall. Additional flowering, fruiting and vegetative characters were used to support this family placement (Cheek and Simão-Bianchini 2013). In 2014, a second species of Keraunea was described, K. capixaba Lombardi (Lombardi 2014). This was based upon four specimens, all collected after 2012 in Jaguaré and Sooretama municipalities, Espírito Santo, Brazil.
The first molecular phylogenetic study that sampled Keraunea was published in 2022 by authors working on the Convolvulaceae of the Americas (Muñoz-Rodríguez et al. 2022). The authors produced DNA sequence data for an isotype (Passos et al. 5263 [K]) and paratype (Lombardi & Salino 1819 [K]) of K. brasiliensis and a paratype of K. capixaba (Siqueira 893 [K]). Rapid phylogenetic inference was carried out with IQ-Tree (Nguyen et al. 2015), which conclusively demonstrated that all samples fell outside of the Convolvulaceae. More surprisingly, the isotype of K. brasiliensis was resolved within the Malpighiaceae while the paratype of K. brasiliensis and the paratype of K. capixaba was resolved within the Ehretiaceae. It is worth noting, however, that the primary motivation for this study was demonstrating that Keraunea does not belong within the Convolvulaceae, and the authors suggested further comprehensive studies were required to correctly place Keraunea in the right family (Muñoz-Rodríguez et al. 2022). The placements within the Malpighiaceae and Ehretiaceae were well supported but the authors did not formalise the taxonomic changes because of their conflicting results and the sparse phylogenetic sampling within the Ehretiaceae. The placement with Keraunea nested in Malpighiaceae has more recently shown to be erroneous, possibly caused by Muñoz-Rodríguez et al. (2022) extracting DNA from an errant Malpighiaceae leaf, likely Masgania cordifolia (A.Juss.) Griseb., found within the capsule of the Kew specimen of Passos et al. 5236 (de Almeida et al. 2023). While we note that Muñoz-Rodríguez et al. (2022) did re-extract and re-sequence the specimen Passos et al. 5236 (K), it is unclear whether this was from the same leaf sample.
During general collecting in the Caatinga of southwestern Bahia and northern Minas Gerais, the second author of this paper collected several specimens of two closely related species but was unable to determine them to family with confidence. These were identified subsequently as Keraunea with reference to the specimens in HUEFS but, like the authors of Muñoz-Rodríguez et al. (2022), we were unconvinced by placement in the Convolvulaceae. Furthermore, one of our yet undescribed species was a close match for the type of K. brasiliensis (Passos et al. 5263) but the second was a close match for a paratype of that species (Lombardi & Salino 1819). This led us to conclude that the original generic description and illustration of K. brasiliensis (Cheek and Simão-Bianchini 2013) were based upon two separate species, both of which were distinct from K. capixaba. We then conducted a thorough survey and revision of the material held in several Brazilian herbaria (ALCB, HUEFS, RB) and online during which we were able to recognise five species of Keraunea.
It came to our attention after the submission of our article that a preprint had been filed with bioRxiv, also placing Keraunea within the Ehretiaceae and providing a taxonomic revision of the group . While not effectively published, this article includes the description of "K. lombardiana Cheek", whose type specimen falls within our concept of K. confusa Moonlight & D.B.O.S.Cardoso but also includes material from our concept of K. bullata Moonlight & D.B.O.S.Cardoso (Rose & Russell 19979, Mori et al. 11534). The article also included "Keraunea sp. A" whose concept matches our K. velutina Moonlight & D.B.O.S.Cardoso, and "Keraunea sp. B" whose concept falls clearly within our concept of K. capixaba.
In this article we assemble a more comprehensive and taxonomically vetted molecular dataset based on four genes to settle the family-level placement and generic relationships of Keraunea. We also provide an expanded description of the Ehretiaceae and the genus Keraunea. We further provide a full taxonomic revision of the genus, including a key to all five species, and the publication of three undescribed species. For each species, we include a description, provisional IUCN Red List assessment, and identification notes.

Taxonomic treatment
We performed a thorough search of specimens available in several Brazilian herbaria (all herbarium acronyms follow Index herbariorum, Thiers 2016) supplemented with searches of the online databases CRIA Species Link (http://splink.cria.org.br/, February 2023) and Flora do Brasil (http://floradobrasil.jbrj.gov.br/reflora/herbarioVirtual/, February 2023). We searched for all Brazilian data of Keraunea and Ehretiaceae as well as undetermined material in the families Boraginaceae, Dichapetalaceae, and Nyctaginaceae (all families into which Keraunea specimens had previously been thought to belong). All descriptions are based upon direct measurements of herbarium specimens and our own field collections, with some macro-morphological characters measured from images of herbarium specimens using the ruler tool in Adobe Photoshop CS5 v.12.0 ×64.

Phylogenetic analyses
Previously published molecular phylogenetic analyses have suggested that the genus Keraunea is a member of the Boraginales and more closely related to the Ehretiaceae than to Malpighiacae (Muñoz-Rodríguez et al. 2022;de Almeida et al. 2023). As such, we assembled a new, more comprehensively-sampled combined molecular dataset of the plastid regions matK, rbcL and trnL-F and the nuclear ribosomal internal transcribed spacer (ITS), with focus on members of the Ehretiaceae. The molecular data were downloaded from the GenBank sequence repository (http://www.ncbi.nlm.nih. gov/Genbank), including one published Keraunea sample (Muñoz-Rodríguez et al. 2022). We supplemented these data with eight samples representing families in the Boraginales sensu Luebert et al. (2016). All sequences were retrieved with a custom R script using functions from ape package (Paradis and Schliep 2019). Details of all sequenced samples and their GenBank accession numbers are available in Table 1.
The individual DNA matrices were subjected to automatic multiple alignments in AliView v.1.26 (Larsson 2014), using the Muscle algorithm, but with subsequent manual editing to improve homology in more variable sites. Individual DNA alignments were combined into a concatenated dataset using the R package catGenes (https://github.com/DBOSlab/catGenes; Cardoso et al. 2020). The custom R script uses catGenes functions to automatically build the concatenated dataset by maximising the inclusion of taxa that are incomplete or with missing data (Wiens 2003(Wiens , 2006. A maximum likelihood (ML) phylogeny was inferred using RAxML (Stamatakis 2006) using the graphical user interface raxmlGUI v.2.0 (Edler et al. 2020), with the following settings: best-scoring ML tree starting with a random seed and utilizing the GTR + GAMMA nucleotide substitution model, with the gamma distribution and invariants sites estimated during the run; and 500 rapid bootstrap (BS) replicates to determine branch support. The phylogeny was rooted based on a clade including the Wellstediaceae, Boraginaceae s.str. and Codonaceae following Luebert et al. (2017).

Phylogenetic analyses
Our four-gene ML phylogenetic analysis resolve the genus Keraunea as nested within the Ehretiaceae sister to the Australian endemic genus Halgania Gaudich. (Fig. 1). This placement is well supported (BS: 94) and consistent with previous analyses placing samples of the genus as nested within the Ehretiaceae (Muñoz-Rodríguez et al. 2022;Cheek et al. 2023). The topology within the Ehretiaceae is largely congruent with that found in previous analyses (e.g. Luebert et al. 2017) and the monophyly of the Ehretiaceae, including Keraunea, is well supported (BS: 97). The Ehretiaceae is resolved as sister to the Lennoaceae (BS: 96).

Discussion
The phylogenetic realignment of the genus Keraunea as nested within the Ehretiaceae requires a slightly emended description of the family. Keraunea represents the first lianescent member of a family that otherwise includes trees, shrubs and perennial herbs (Luebert et al. 2016). The inflorescence structure of Keraunea is also unique not just within the Ehretiaceae but in the Boraginales as a whole. Keraunea does, however, present the only character believed to hold together the Ehretiaceae, bifid styles with two stigmatic branches (Luebert et al. 2016). We provide an emended family description below (see Taxonomic treatment) and a discussion of the unique inflorescence of Keraunea.  The placement of Keraunea as sister to the Australian endemic genus Halgania presents a biogeographical conundrum but is ecologically and morphologically coherent. Halgania is a dry adapted group (Holstein and Gottschling 2017), and Keraunea is primarily found in dry forest within the Caatinga phytogeographic domain or in and around rock outcrops in the Mata Atlântica phytogeographic domain. Insights from recent biogeographical studies with dated molecular phylogenies of transcontinentally disjunct plant clades have suggested that long distance dispersal and phylogenetic niche conservatism may explain why closely related lineages are ecologically confined to the same dry forest biome no matter how much geographic distance separates them (Gagnon et al. 2019;Ringelberg et al. 2020). An assessment of the diversification history of Ehretiaceae in the context of biome conservatism seems an important issue to explore in the future to better understand the evolution of the interesting geographical disjunction, yet similar ecologies of Keraunea and Halgania.
The flowers of Halgania are buzz-pollinated "solanum-type" flowers (Holstein and Gottschling 2018) that at first glance seem highly distinct from those of Keraunea (Fig. 1). The androecium of the two groups is very similar, with both genera having five stamens with short filaments fused at the base to the corolla tube, long anthers and conspicuous, extended connectives. The two genera differ in that the anthers of Halgania dehisce by opening into a small chamber formed by protrusions of the connective and appear to be poricidally dehiscent while those of Keraunea dehisce via longitudinal slits along the entire length of the anther, and in Halgania the anthers are held together in a cone by long, interlaced trichomes while in Keraunea they are held apart and are glabrous (Holstein and Gottschling 2018). Further, the fruits of the two genera are very similar. Cheek and Simão-Bianchini (2013) dissected a fruit of K. brasiliensis and characterised it as bilocular with four ovules, though two of those may be aborted. We characterise this fruit as a drupe, and bilocular, drupaceous fruits with four ovules are the most common character state in the Ehretiaceae (Luebert et al. 2016) and one shared with Halgania (Holstein and Gottschling 2018).

Taxonomic treatment
We recognise five species of Keraunea, which are all endemic to Brazil, including three newly described species. Description.
[differences from Luebert et al. (2016) in bold] Trees, shrubs, lianas, perennial herbs, rarely with thorns (Rochefortia Sw.); indumentum variable, hirsute to glabrescent. Leaves alternate, entire, petiolate; lamina variable in shape, strongly dissected in the halophytic Cortesia Cav. Inflorescences terminal or axillary thyrses, sometimes congested, or few-flowered corymbs (Keraunea). Flowers pentamerous, cosexual or unisexual and dioecious in Lepidocordia Ducke and Rochefortia, sometimes inserted on the centre of an accrescent bracteole (Keraunea); calyx lobes united in a tube or distinct nearly to the base, tubular to campanulate; aestivation imbricate (mostly quincuncial); corolla sympetalous, generally tubular with spreading lobes, rotate, or campanulate to urceolate, white, red or blue (Halgania, some species of Bourreria P.Browne); stamens 5, the filaments generally adnate to the corolla tube at least at the base, sometimes puberulent at the point of insertion, the anthers usually exerted; gynoecium bicarpellate, the ovary uni-to tetralocular from secondary subdivision, style terminal, the stigma clavate to capitate with 1(2) branches; nectar disc usually present at base of the ovary. Fruits drupaceous, often drying and separating into two two-seeded pyrenes, or 4 1-seeded pyrenes or schizocarps, or 4 nutlets.
Distribution. Ehretiaceae is a broadly distributed family found throughout tropical and subtropical Asia, Australia, sub-Saharan Africa. In the Americas, its distribution encompasses the eastern United States, Florida, Central America, the Caribbean, the Guyana shield and the Andes. In Brazil, the Ehretiaceae was previously only known from the single species Lepidocordia punctata Ducke (Stapf 2023), found in lowland Amazonian forests in Pará and Roraima states. Our treatment therefore represents new records of the family from the Caatinga and Mata Atlântica phytogeographic regions in Brazil, and from the states of Bahia, Minas Gerais, Espírito Santo and Rio de Janeiro (Fig. 1).
Notes. Our morphological concept of the Ehretiaceae is little changed from that of Luebert et al. (2016). The characters that differ are included in bold in the description above. The first of these is that the four species of Keraunea are the first lianescent species included within the family (versus perennial herbs, shrubs, or trees). Lianas are elsewhere found in the Boraginales in the Cordiaceae (Cordia L.) and Heliotropiaceae (Tournefortia L.). Secondly, we have expanded the concept of the Ehretiaceae to include species with a few-flowered corymb inflorescence structure and where the flower and later fruit are inserted at the centre of an accrescent bracteole. To our knowledge, these characters are unique among not just the Ehretiaceae but the Boraginales, whose members are known for their characteristic scorpioid cymose inflorescences. We suggest the few-flowered inflorescence of Keraunea is the result of secondary reduction rather than a retained ancestral form. Within the Boraginales, reductions to fewflowered inflorescences are present elsewhere in the Boraginaceae, Codonaceae and Wellstediaceae (Luebert et al. 2016). Description. Scandent shrubs or lianas. Stems woody, cylindrical, hollow, lacking lenticels. Stipules lacking. Leaves on the main stems alternate, simple, petiolate; margins entire; venation pinnate, camptodromous or brochododromous. Side shoots with 2-4 aborted leaves, then 2-6 progressively larger leaves along the shoot. Inflorescences terminal on side shoots, determinate, corymbose, with 3-6 flowers; bracteoles one per flower or rarely lacking, leaf-like, inserted halfway along the pedicel. Flowers 5-merous, cosexual. Calyx campanulate, fused at the base, alternating with the petals; aestivation imbricate. Corolla with the tube campanulate, fused at the base; aestivation imbricate. Stamens epipetalous, inserted at the base of the corolla tube, alternating with the petals; filaments free; anthers basifixed, introrse, dehiscing via lateral slits; connectives extended. Nectary disk present, at base of the ovary. Ovary superior, subglobose, 2-locular, the locules biovulate, each with one functional and one aborted ovule. Style single, with two apical stigmas. Fruit a dry, indehiscent drupe, usually inserted in the centre of the persistent and accrescent bracteole; calyx persistent; corolla caducous; style persistent.
Distribution. Keraunea is endemic to Brazil and thus far known from the states of Bahia (3 spp.), Espírito Santo (1 sp.), Minas Gerais (1 sp.) and Rio de Janeiro (1 sp.). Each of the species is restricted to a single state except for K. capixaba, which is found in both Bahia and Espírito Santo (Fig. 2).
Habitat. Two species are known from seasonally dry forest within the Caatinga domain (K. brasiliensis and K. confusa); two from humid forests within the Mata Atlântica domain (K. capixaba and K. velutina); and a fifth from transitional, semideciduous forests between the Caatinga and Mata Atlântica domains (K. bullata). The genus has a marked preference for rock outcrops or forest on rocky soils. Both K. brasiliensis and K. confusa are found mostly on karstic outcrops, while K. capixaba and K. velutina have both been collected at the base of granitic inselbergs.
Etymology. The epithet derives from the Greek, keraunos, or lightning bolt. This was intended to signify the unexpected but now disproven appearance of a neuropeltoid genus of the Convolvulaceae in the Americas. Notes.
Cheek and Simão-Bianchini (2013) treated the flower and fruit of Keraunea as being inserted at the centre of a large, leaf-like bract. This 'bract' is inserted halfway up and adnate to the pedicel, so we instead follow Lombardi (2014) and treat it as a bracteole rather than a bract.
Identification notes. Keraunea species are distinctive in being semi-scandent shrubs or lianas with simple, alternate, exstipulate leaves and inflorescences terminal on foliose side shoots. The flowers and fruits are highly unusual in being inserted at and appearing to arise from the centre of an accrescent bracteole.
Several specimens of Keraunea were erroneously identified as Bougainvillea Comm. ex Juss. (Nyctaginaceae), which is understandable, as both genera have exstipulate leaves, a semi-lianescent habit, and flowers and fruits associated with showy bracts or bracteoles. Keraunea spp. are however never spinescent, and the flowers and fruits are inserted directly onto the bract, whereas in Bougainvillea several flowers or fruits are clustered on a pedunculate inflorescence surrounded by two or more bracts. Description. Scandent shrub or liana, to 7 m tall. Stems cylindrical, hollow, 3-9 mm in diameter, frequently branching, sericeous-pubescent with silky hairs; internodes 0.7-11 cm long; side shoots 4-9 cm long, hirtellous-pubescent with minute, rigid hairs. Leaves of main stem with the blades 5.0-6.5 × 3.1-3.6 cm, ovate, hirtellous-pubescent with minute, rigid hairs, the venation pinnate, camptodromous, with 4-6 secondary veins; the base acute, the margins entire, ciliate, the apex obtuse; petioles of leaves on main stem ca. 8 mm long, distinctly curved to 90° ⅓ of the way along their length. Side shoots with 3-5 leaves, these progressively larger along the shoot; blades 5.1-7.2 × 2.3-3.9 cm, ovate, hirtellous-pubescent, the venation as on leaves of the main stem, the base acute, the margins entire, ciliate, the apex obtuse; petioles 5.7-6.1 mm long, straight, hirtellous-pubescent like the leaves. Inflorescence corymbose, with 2-4 flowers; free portion of the peduncle ca. 3.5 mm long, 2.5 cm long, the remainder adnate to the bracteole, hirtellous-pubescent; bracteole 5.1-8.1 × 2.4-3.8 cm, inserted ca. ¼ of the way along the pedicel, ovate, hirtellous-pubescent, the venation as the leaves, the base acute, the margins entire, ciliate, the apex obtuse. Flowers incompletely known, 5-merous. Calyx with the tube campanulate, ca. 3.5 mm long, the lobes ca. 12 × 1.5 mm, lanceolate, velutinous-pubescent. Corolla unknown; androecium and gynoecium unknown. Fruit inserted on the accrescent bracteole; calyx persistent, expanding to 14 mm long.

Key to the species of Keraunea
Distribution. Keraunea brasiliensis is endemic to Brazil and is known only from the state of Bahia (Coribe, São Félix do Coribe and Caetité municipalities) (Fig. 2).
Habitat. Keraunea brasiliensis has primarily been collected scrambling over exposed rocks and vegetation in karst formations supporting Caatinga seasonally dry tropical forest vegetation. The two most easterly collections of the species Passos et al. 5263) were collected in Caatinga vegetation but far from any known karst outcrops. Cheek and Simão-Bianchini (2013) as Endangered (EN B2 a b iii) under IUCN Criteria (IUCN 2019). We alter this assessment as it covered specimens now known to be of two different species. Our narrower concept includes plants from four localities and has an EOO of 4,550 km 2 . None of the known localities are in protected areas. Accordingly, we still assess K. brasiliensis as EN (EN B2 a b iii) under IUCN criteria (IUCN 2019).

Conservation status. Keraunea brasiliensis was provisionally assessed by
Etymology. Named for the country of Brazil. Notes. The protologue of K. brasiliensis cited individuals we now recognise as two different species and both paratypes collected in Minas Gerais fall under our circumscription of K. confusa. The authors of K. brasiliensis did, however, note the unusual intraspecific morphological variation within the species and speculated that the material collected in Bahia and Minas Gerais may have represented two different species. The original illustration in the protologue (Cheek and Simão-Bianchini 2013) included individuals of both of the species we recognise here so only the subfigures (B, H-I) represent K. brasiliensis. Muñoz-Rodríguez et al. (2022) also published sequence data for K. brasiliensis and K. confusa and a member of the family Malpighiaceae under the name K. brasiliensis.
Our emended description of K. brasiliensis reflects our much narrower circumscription of this species. The specimens we cite represent a morphologically homogenous group of specimens all collected at a similar phenological state, i.e. with fruits but lacking flowers. As such, our description lacks some floral traits. The floral description of K. brasiliensis provided by Cheek and Simão-Bianchini (2013) was made using a dissected bud from Lombardi & Salino 1819 (K), which we now consider as an isotype of K. confusa (see below).
Identification notes. Within its range, K. brasiliensis is most likely to be confused with K. confusa, but the two species can be distinguished with ease based entirely upon vegetative characters. The leaves of K. confusa are larger (to 18 × 12 cm versus to 7.5 × 4 cm) with brochidodromous venation and a rugose texture (versus camptodromous venation and smooth texture in K. brasiliensis). Keraunea brasiliensis is most similar to K. capixaba (though this species is also similar to K. velutina), from which it can be distinguished by its rugose stems (versus smooth) and membranous, dull green leaves (versus chartaceous, glossy green) with indistinct secondary veins (versus raised above the lower leaf surface).
Distribution. Endemic to the state of Bahia (Fig. 2). Habitat. Keraunea bullata is a species of forests in the transition from humid forests in the coastal Mata Atlântica phytogeographic domain and seasonally dry forests in the inland Caatinga domain. This forest is described on labels as "Caatinga arborea" (Guedes et al. 9176) and (Mori et al. 11534) as growing on rocky soils. This area has a metamorphic bedrock (often called crystalline in the literature, de Queiroz et al. 2017) and is quite edaphically distinct from the karstic outcrops that are home to K. brasiliensis and K. confusa.
Conservation status. Keraunea bullata is known from only three localities with a combined EOO of ca. 6,300 km 2 . We know of no specific conservation threats to this species so provisionally assess it as Vulnerable (VU D2) under IUCN Red List criteria (IUCN 2019).
Habitat. Collections of Keraunea capixaba have primarily been made in "mata tabuleiro" or flat, semi-deciduous forests found within the coast of the Mata Atlântica domain of Brazil. A more recent collection (Gurtler & Dutra 371) was made growing over rocks in forest understory at the base of a granitic outcrop. Specimen labels describe the species as scandent or lianescent.
Conservation status. Keraunea capixaba was provisionally assessed by Lombardi (2014) as Endangered because it was at that time known from four collections made within disturbed forest patches adjacent to the Sooterama Biological Reserve. We add five collections to the known distribution, including one collected within the Sooterama Biological Reserve (Covre s.n.), two collected at the base of inselbergs > 30 km from the reserve (Gurtler & Dutra 371,Demuner et al. 3799), and a gathering made a remarkable 500 km to the north near Ipauí, Bahia. The species is now known from six localities with a collective Extent of Occurrence (EOO) of ca. 11,000 km 2 . The species is known from < 10 localities and has a EOO of < 20,000 km 2 , so we assess K. capixaba as Vulnerable (VU B1 a b iii) under IUCN criteria (IUCN 2019).
Etymology. The epithet is an indigenous term referring to people or objects from Espírito Santo state.
Identification notes. Keraunea capixaba is most morphologically and ecologically similar to the newly described K. velutina, the two species of the genus that are associated with more humid settings in the Mata Atlântica phytogeographic region, yet they were never found growing sympatrically. Keraunea capixaba differs in lacking an indumentum on the stems, side shoots and lower leaf surface (versus a velutinouspubescent in K. velutina), and its ovate leaves on the side shoots (versus elliptic to narrowly-lanceolate). Its range is close to that of K. confusa, from which it is readily distinguished by its camptodromous venation (versus brochidodromous).  Description. Scandent shrub or liana, to 4 m tall. Stems cylindrical, hollow, 2-5 mm in diameter, rarely branching, sericeous-pubescent with silky hairs; internodes 3.8-16.5 cm long; side shoots 2.6-3.5 cm long, sericeous-pubescent. Leaves of the main stem with the blades 9.5-17 × 5.6-13.5 cm, ovate, velutinous-pubescent, the venation pinnate, brochidodromous, with 5-7 secondary veins, the base truncate to subcordate, the margins entire, ciliate, the apex attenuate to acute; petioles of leaves on main stem 10-16 mm long, distinctly curved to 90° ¼ of the way along their length. Side shoots with 2-5 leaves, these progressively larger along the shoot; blades 2.1-18 × 3.0-12 cm, velutinous-pubescent, the venation as on leaves of the main stems, the base rounded to truncate, the margins entire, ciliate, the apex obtuse; petioles 3-25 mm long, sericeous-pubescent. Inflorescence corymbose, with 2-4 flowers; free portion of the peduncle 5-13 mm long, 2.2-2.8 cm long, the remainder adnate to the bracteole, sericeous-pubescent; bracteole 4.9-5.6 × 2.7-5.1 cm, inserted ca. ⅓ of the way along the pedicel or rarely lacking, ovate, sericeous-pubescent, the venation as the leaves, the base short cuneate, the margins entire, ciliate, the apex attenuate. Flowers incompletely known, 5-merous. Calyx with the tube campanulate, ca. 1.5 mm long, the lobes ca. 7-9 × 1.5 mm, ensiform, sericeous-pubescent. Corolla unknown; androecium and gynoecium unknown. Fruit inserted on the accrescent bracteole; calyx persistent, expanding to 9 mm long.
Distribution. Keraunea confusa is endemic to Brazil and to the state of Minas Gerais (Fig. 2). Habitat. All collections of K. confusa are from karstic (limestone) areas, where plants have been collected growing over rocks and vegetation in the understory of Caatinga seasonally dry tropical forest vegetation.
Conservation status. Keraunea confusa is known from two localities and has an AOO of ca. 12 km 2 . Two of the known collections (Lombardi & Salino 1819, Lombardi 2107 were made within Parque Nacional Cavernas do Peruaçu, which includes extensive karst limestone habitat suitable for the species. We know of no specific threats to this species but provide a preliminary assessment as Vulnerable (VU D2) because of the species' few known localities (IUCN 2019).
Etymology. The epithet refers to the confusion that has surrounded the taxonomic history of this species, which was both included within the original circumscription of the type species and the placement of the genus in the wrong family by Cheek and Simão-Bianchini (2013).
Identification notes. Keraunea confusa is one of two species of the genus with brochidodromous venation, the other of which is K. bullata. It is distinguished from K. bullata by its generally bigger leaves measuring 9.5-17 cm long (versus 4.2-10.5 cm long), rugose (versus bullate) leaf texture and by the tertiary veins, which are plane to the lower leaf surface (versus raised).
Distribution. Keraunea velutina is endemic to Brazil and known only from the type from Cardoso Moreira municipality in the state of Rio de Janeiro (Fig. 2).
Habitat. The single specimen known of K. velutina was collected within a forest fragment around isolated inselbergs. Cardoso Moreira municipality includes several granitic inselbergs and deforestation appears reduced around these compared to the surrounding land. We suspect that, like the similar Keraunea capixaba, this species was collected scrambling over rocks at the base of an inselberg.
Conservation status. Keraunea velutina is known from a single specimen collected within a small forest fragment. Forest cover within Cardoso Moreira municipality declined from 5.2% in 1985 to 4.0% in 2012 before recovering to 4.6% by 2021 (Mapbiomas 2022). This picture is however complex, with Google Earth imagery showing that deforestation of primary forest is continuing in some areas, but forest is recovering in other areas (Google Earth Pro 2020). As such, due to single collection with imprecise locality information from a largely deforested municipality, we provisionally assess K. velutina as Critically Endangered (CR B1 B2 a b ii) under IUCN criteria (IUCN 2019).
Etymology. Named for the plant's velvety indumentum. Identification notes. Keraunea velutina is a distinct species easily distinguished from all others in the genus by the dense, velvety indumentum of the stems and lower leaf surfaces. It is also distinctive in its side shoots with more numerous leaves than other members of the genus (6-8 versus 2-5), which are almost all elliptic (versus variously ovate to broadly ovate). and Alex Zuntini for their enlightening insights into Keraunea; Geovane Siqueira for the field photos of K. capixaba; and Mariela Nuñez Florentin and Javier Elias Florentin for help during fieldwork. We acknowledge the Brazilian authorities for permission to export plant material (Material Transfer Agreement [Decree number 8772] under the SisGen number R87901F); curators of all herbaria for providing us access to specimens and images, and particularly Pedro Moraes (BHCB) for providing a high-resolution image of the holotype of K. confusa, and Maria Lenise Guedes, Angelis Farias, Cássia Sacramento, Jeanderson Jesus and Soliene Teixeira for helping with the image of the holotype of K. bullata. DCBOS's research on plant biodiversity is supported by CNPq (Research Productivity Fellowship grant no. 314187/2021-9). Finally, we thank three anonymous reviewers for their insightful comments.