Discovery of two new species of Crotalaria (Leguminosae, Crotalarieae) from Western Ghats, India

Abstract

Two new species of Fabaceae-Papilionoideae are described and illustrated. Crotalaria suffruticosa from Karul Ghat region of Maharashtra is morphologically close to C. albida and C. epunctata. C. multibracteata from Panhala region of Maharashtra resembles C. vestita. C. suffruticosa differs from C. albida and C. epunctata in its habit, leaf, inflorescence, callosity, keel type, stigma, style morphology and number of seeds/pod. To test if the new species differ from their morphologically most similar species, we measured various traits and performed a Principal Component Analysis (PCA). This analysis shows that the new species differs from similar species in gross morphology for several diagnostic traits and showed correlations between the variables or distance among groups and estimated the contribution of each character. Phylogenetic analyses were also conducted based on nuclear (ITS) and plastid (matK) markers. The analyses revealed nucleotide differences between the new species and their close allies attributing to their distinctiveness. A map and key including all species of Crotalaria from Maharashtra state are provided. Conservation status of the two new species have also been assessed.

Fig 1. Maximum likelihood tree of the genus Crotalaria, constructed using RAxML, with bootstrap support values and Bayesian posterior probabilities indicated above the branches.

Since Bayesian analyses resulted in almost the same topology, only the tree constructed from RAxML has been presented here. The new species are colored in red and blue.

Fig 2. Principal component analysis on morphological traits comparing the new species Crotalaria suffruticosa and morphologically most similar species C. albida and C. epunctata.

Fig 3. Principal component analysis on morphological traits comparing the new species Crotalaria multibracteata and morphologically most similar species C. vestita.

Fig 4

A–Y. Crotalaria suffruticosa. A. Habit. B. Plant twig showing leaves and flowers. C. Herbarium specimen of the new species. D. Close-up of the flower in field. E. Adaxial leaf surface with white sparse pubescent vestiture. F. Abaxial surface with pubescent vestiture. G. Close-up of abaxial leaf surface showing prominent hairs on the midrib region. H. Close-up of mucronulate leaf apex. I. Flower showing calyx, corolla and pedicel. J. Position of bract (base of pedicel) and bracteoles (middle of pedicel). K. Bi-lipped calyx with pubescent surface. L. Adaxial surface of standard. M. Abaxial surface of standard. N. Planar callosities. O. Close-up of silky pubescence on standard dorsal apex. P-Q. Wing petals. R. Close-up of cavae. S-T. Keel petals, angled with lower third curvature and ciliate glabrous vestiture. U. Anthers in 5 + 5 arrangement (one missing), with five carinal/basifixed/sagittate anthers and five small dorsifixed ovoid anthers. V. Gynoecium showing ovary, style and stigma. W. Close-up of style showing trichomes in two parallel rows(parallel) and brush type stigma. X. Fruit showing glabrous surface and prominent beak. Y. Cordiform seed, golden brown color. Scale bar 0.5 cm unless indicated otherwise.

Fig 5. Distribution map of all 37 Crotalaria species found in Maharashtra including the two new species Crotalaria suffruticosa and C. multibracteata.

The color and symbols specify the distribution of different species and the triangle (red: C. suffruticosa, yellow: C. multibracteata) designates the distribution of the new species.

Fig 6

A–R. Crotalaria multibracteata. A. Plant twig showing leaves and flowers. B-C. Adaxial and abaxial leaf surface with hirsute vestiture and ciliate margin. D. Flower showing pedicel, bracteoles and calyx with corolla inserted (all three with dense pubescence). E. Bilipped calyx with pubescent-densely ciliate surface. F. Both lips of calyx dissected show surface and bi-lipped condition. G. Adaxial surface of standard with pubescent apex. H. Abaxial surface of standard. I-J. Wing petals. K-L. Keel petals, sub-angled with below the middle curvature and lanate vestiture. M. Anthers in 5 + 5 arrangement (one missing), with five carinal/basifixed/sagittate anthers and five small dorsifixed ovoid anthers with their filaments fused to form a staminal sheath. N. Gynoecium showing ovary, style and stigma. O. Fruit showing glabrous surface, and densely pubescent calyx. P. Seed reniform, golden brown with smooth surface. Q. Close-up of lameliform callosities. R. Close-up of cavae.