Hilsenbergia

Miller, James S., 2003, Classification of Boraginaceae subfam. Ehretioideae: Resurrection of the genus Hilsenbergia Tausch ex Meisn., Adansonia (3) 25 (2), pp. 151-189 : 153-154

HILSENBERGIA

The molecular data presently available are not comprehensive enough to resolve all of the problems of generic circumscription within Ehretioideae , but they do support several changes in generic delimitation and subfamilial placement that differ from what has recently been accepted (e.g. MILLER 1989). The analyses of G OTTSCHLING & H ILGER (2001) and GOTTSCHLING (pers. comm.) distinguish four clades within Ehretioideae . Tiquilia and Halgania are each distinct from the arborescent genera. A broad Ehretia clade also contains Carmona and Rotula and a broad Bourreria clade has Lepidocordia and Rochefortia as sister taxa. The broad Ehretia clade consists of three distinct lineages of Ehretia species and also includes Carmona and Rotula . The Ehretia I subclade includes African, Indian Ocean, and Asian species with endocarps that break into four single-seeded pyrenes at maturity. The Ehretia II subclade includes American and Asian species with endocarps that mature with two 2-seeded endocarps in each fruit and the third subclade consists of Ehretia longiflora (GOTTSCHLING pers. comm.), which has an endocarp that remains entire at maturity. Rotula is sister to the Ehretia I clade and Carmona may be as well, although its position is not entirely resolved. Based on these data, GOTTSCHLING & HILGER chose to accept a broadly defined Ehretia that included both Carmona and Rotula .

The Bourreria clade likewise contains three lineages. The first subclade includes Lepidocordia and Rochefortia , which are sister to one another and form a group that is in turn sister to the remaining species. These two genera are morphologically distinct as both are dioecious and Rochefortia differs further in possessing spines. The second subclade consists of New World Bourreria , with leathery, rotate to funnelform corollas, and the third comprises the African and Indian Ocean island species and their relatives in Madagascar, with fleshy, urceolate to campanulate corollas. The third subclade contains the group of species that THULIN (1987) included in Bourreria . Because each subclade is both morphologically and geographically coherent, maintaining them in a single, broadly-defined genus would unnecessarily obscure meaningful groups. The alternative approach, in which each subclade is treated as a separate, easily recognized genus, is considered more informative, and is adopted here. Thus Rochefortia and Lepidocordia are maintained, and Bourreria is restricted to the New World, with the Old World species comprising the genus Hilsenbergia .

This circumscription of genera differs from previous classifications (e.g. JOHNSTON 1949, 1951; MILLER 1989) so the following key is provided as a synopsis of the subfamily.