Ehretiaceae Mart., Nov. Gen. Sp. Pl. 2: 136, 138. 1827, 2023

Moonlight, Peter W. & Cardoso, Domingos Benicio Oliveira Silva, 2023, A taxonomic revision of Keraunea, including three new species and its phylogenetic realignment with Ehretiaceae (Boraginales), PhytoKeys 219, pp. 145-170 : 145

Ehretiaceae Mart., Nov. Gen. Sp. Pl. 2: 136, 138. 1827 nom. cons.

Type genus.

Ehretia P.Browne.

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 ).

Included genera.

The family includes the following eight genera: Bourreria , Cortesia , Ehretia , Halgania , Keraunea , Lepidocordia Ducke, Rochefortia and Tiquilia Pers. ( Luebert et al. 2016).

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 few-flowered inflorescences are present elsewhere in the Boraginaceae , Codonaceae and Wellstediaceae ( Luebert et al. 2016).

Figures

Figure 1. RAxML bootstrap tree based on nuclear ribosomal (ITS) and plastid (matK, rbcL, trnL-F) DNA sequence data resolving Keraunea within the Ehretiaceae. Node labels indicate nodes with bootstrap support values above 50. Inset phylogram (bottom left) indicates branch lengths. Outgroup taxa from representatives of other Boraginales families are in light grey. Illustrations are (top to bottom): Keraunea, Halgania, Ehretia, Bourreria, Rochefortia and Tiquilia.