A revised circumscription of the species in Bracteatae complex (section Calycinae) in the genus Crotalaria L.: evidence from nuclear and chloroplast markers

Abstract

The existing sectional classification of the genus Crotalaria has merged the Indian sections Calycinae and Crotalaria under the section Calycinae Wight & Arn. emend. M.M.Le Roux & B.-E.van Wyk. Crotalaria subsection Bracteatae is re-evaluated to ascertain its position in the Calycinae clade. Evidences from morphological and molecular sequence data (ITS and trnL-F regions) are used to assess the subsectional position of Bracteatae. Within the recognized 12 species in the subsection, the morphological characters currently used to distinguish these species, are insignificant and overlapping and do not merit diagnostic characters of the species. Examination of the types and vouchers at different herbaria and specimens collected during field trips enabled us for a new interpretation of the existing circumscription of the species. Further, pod anatomical and molecular sequence data were also used for the delimitation of the species. Based on the results of the above studies, a new circumscription has been formalized here and contains five recognized species in the Bracteatae clade, viz., C. berteroana DC., C. longipes Wight & Arn., C. paniculata Willd., C. pulchra DC. and C. pellita DC. of the section Calycinae emend. M.M.Le Roux & B.-E.van Wyk. Crotalaria subsection Bracteatae appeared to be a well supported monophyletic group, but nested within the Calycinae clade. In order to maintain the monophyly of Crotalaria section Calycinae, Bracteatae is synonymized with the former.