The identity of Peliosanthes mantegazziana with respect to P. teta

It is remarkable that Peliosanthes mantegazziana was initially described as a variety of P. teta (Pampanini 1904), and P. graminea was in a similar manner diagnosed by Ridley (1911) from P. teta var. angustifolia Ridley (1911: 207). Furthermore, the type of P. mantegazziana originates from the same area as one of the syntypes of P. teta var. angustifolia.

Ridley (1911) considered Peliosanthes graminea to differ from P. teta var. angustifolia in usually shorter raceme, in shape and size of the leaves, flower colouration, obtuse tepals, and the androecium completely adnate to the tepals. Notably, he assigned all the material of P. teta from the Malay Peninsula to P. teta var. angustifolia, and assumed P. teta var. teta to be an Indian endemic (see Ridley 1924). As it follows from the morphological variation of P. mantegazziana outlined above and the available data on P. teta (Andrews 1810, Ker Gawler 1810, Redouté 1812 –1813, Kunth 1850, Baker 1879, Hooker 1892, Ridley 1898, 1911, 1924, partly summarised by Kroupsky et al. 2023), P. mantegazziana differs from P. teta only in the width of the leaf blade (6.5–20(28) mm vs. 25–66(76) mm) and perianth colouration (entirely light green vs. violet to purple or blue, often with green, or even green tinged with violet/blue). The treatment of P. teta by Rodriguez (1934) is also in agreement with this assumption, although Rodriguez considered P. teta to include P. violacea Wall. ex Baker (1879: 504) as its synonym, whereas currently the latter species is accepted as a distinct one (Tanaka 2018).

One can argue that the delimitation of Peliosanthes mantegazziana and P. teta is not clear enough. Indeed, their widths of the leaf blade overlap (although this is only due to a single gathering by L. M. Osinovetz, and otherwise the width does not exceed 20 mm in the former species), and the perianth colouration appears to be quite similar. At the same time, our preliminary phylogenetic findings based on entire plastid genomes indicate that the two species are well-segregated and are even not closely related to each other (Nuraliev et al. 2024). This issue is to be further clarified through extension of the sampling in both morphological and molecular analyses. Given the existing morphological differences and the preliminary phylogenetic data, we currently recognise P. mantegazziana as a distinct species.