A taxonomic revision of Keraunea, including three new species and its phylogenetic realignment with Ehretiaceae (Boraginales)
Author
Moonlight, Peter W.
https://orcid.org/0000-0003-4342-2089
Botany Department, School of Natural Sciences, Trinity College Dublin, Dublin 2, Ireland
p.moonlight@rbge.ac.uk
Author
Cardoso, Domingos Benicio Oliveira Silva
https://orcid.org/0000-0001-7072-2656
Instituto de Pesquisas Jardim Botanico do Rio de Janeiro, Rio de Janeiro, Brazil & Universidade Federal da Bahia, Salvador, Bahia, Brazil
text
PhytoKeys
2023
2023-02-20
219
145
170
http://dx.doi.org/10.3897/phytokeys.219.101779
journal article
http://dx.doi.org/10.3897/phytokeys.219.101779
1314-2003-219-145
A2ECEB672C4D5027A90252D384FB1795
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
Para
and Roraima states. Our treatment therefore represents new records of the family from the Caatinga and Mata
Atlantica
phytogeographic regions in Brazil, and from the states of Bahia, Minas Gerais,
Espirito
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
).