Morphometrics and molecular systematics of the genus Afgekia Craib (FABACEAE)

Abstract

Afgekia Craib is a small genus of the tribe Millettieae in the family Fabaceae. According to the recent classification system, there are three species within this genus. They are A. sericea Craib, A. mahidolae Burtt et Chermsirivathana and A. filipes (Dunn) Geesink. Afgekia sericea and A. mahidolae are morphologically similar, while A. filipes, is rather different. In addition, this species also has some characters similar to those found in its closely related genus of Afgekia, i.e. Callerya Endl.. These discrepancy leads to uncertain taxonomic status and unsuitability of species treatment in this genus. Therefore, this research aims to explore the taxonomic status of the species in the genus Afgekia based on morphological and molecular data, which obtained from morphometrics, RAPD and DNA sequencing analyses in nuclear ITS and chloroplast trnL-F IGS repectively. In morphometrics study, 29 quantitative and 1 qualitative characters were analyzed by means of Cluster Analysis and Canonical Discriminant Analysis. The result showed that at average taxonomic distance 0.76, A. sericea and A. mahidolae were placed in the same group. While A. filipes was distinctly separated into another group. From the result of Canonical Discriminant Analyses, A. sericea and A. mahidolae were placed in the same groups on canonical axis 1 and separated from A. filipes. Likewise, the results of molecular systematics from both RAPD and DNA sequencing analysis agreed with the result from morphometric study. A close genetic similarity between A. sericea and A. mahidolae was observed. These two species were sister taxon which derived from the same ancestor. In contrast, A. filipes, is not in a section of Afgekia and should not belong to this genus. The most suitable genus to place A. filipes is likely to be Callerya. However, the genus Callerya itself requires further investigation for clearer delimitation and proper definition of the genus.