Abstract
Codonaceae (Boraginales) is here proposed as a novel segregate family from Boraginaceae, based on Boraginaceae subfamily Codonoideae. The family consists of a single genus, Codon (2 species, Southwest Africa) which is traditionally considered as the only African representative of the predominantly New World family Hydrophyllaceae. Recent molecular studies clearly indicated that it is more closely allied to Boraginaceae s. str. ("herbaceous" Boraginaceae), than to Hydrophyllaceae, however, Codon is morphologically highly aberrant for both families with its polymerous perianth and androecium, style inserted on the apex of an ovoidal ovary, many-seeded, sub-bilocular, loculicidal capsules, endospermous seeds with a very irregularly reticulate testa, and peculiar spines with a multicellular pedestal and unicellular apex. The genus was therefore recently placed into a monotypic subfamily Codonoideae in a broadly defined Boraginaceae s.l. (i.e., including Heliotropioideae, Hydrophylloideae, Cordioideae as subfamilies). We advocate the recognition of the morphologically well-differentiated clades of Boraginales at family rather than subfamily level and therefore propose the recognition of Codonaceae as a novel segregate family. Boraginales then consists of a total of seven families: Boraginaceae s. str., Codonaceae, Cordiaceae, Heliotropiaceae, Hydrophyllaceae, Lennoaceae and Wellstediaceae.
