Hydroxypipecolic acids and hydroxyprolines as chemical characters in Aphanocalyx, Bikinia and Tetraberlinia (Leguminosae: Caesalpinioideae): support for the segregation of Monopetalanthus

The presence or absence of hydroxypipecolic acids and hydroxyprolines in leaves of members of the former genus Monopetalanthus Harms was generally found to support the recent segregation of species into Aphanocalyx Oliver, Bikinia Wieringa and Tetraberlinia (Harms) Hauman. The species transferred to Aphanocalyx were found to lack these non-protein amino acids, like species traditionally placed in that genus, while most of the species reclassified into the new genus Bikinia accumulated hydroxypipecolic acids and hydroxyprolines (the exceptions were B. aciculifera Wieringa, B. coriacea J. Morel ex Aubrév. and B. durandii F. Hallé & Normand). All seven known species of Tetraberlinia, including T. longiracemosa (A. Chev.) Wieringa, which was formerly placed in Monopetalanthus, also contained one or both types of compounds. In species of Bikinia and Tetraberlinia the hydroxypipecolic acids accumulated included trans-4-hydroxypipecolic acid, trans-4-trans-5-dihydroxypipecolic acid and cis-4-cis-5-dihydroxypipecolic acid. All except T. moreliana Aubrév. and T. korupensis Wieringa also accumulated N-methyl-trans-4-hydroxyproline and both of these species and T. bifoliolata (Harms) Hauman accumulated an epimer of N-methyl-4,5-dihydroxypipecolic acid. These chemical groupings of Tetraberlinia species are generally in accordance with those based on morphology