Phymatoceros Stotler et al. (Anthocerotophyta) newly recorded from India with a new species, P. binsarensis

Abstract

ABSTRACT Introduction Phymatoceros Stotler et al., one of the 14 extant genera of hornworts, is known from only two species worldwide. During our studies of Indian hornworts, a distinctly variable population was found at Binsar, Uttarakhand, and sharing the same habitat as Phaeoceros himalayensis (Kashyap) Prosk. ex Bapna & G.G.Vyas and Phaeoceros laevis (L.) Prosk. Methods A critical study of the specimens housed at CSIR–NBRI, Lucknow (LWG) was conducted. An SEM study of spores was also carried out to examine their ultramorphological characters. Key results The plants were found to be remarkably characterised by a narrow thallus with prolific stalked tubers arising from the mid-ventral surface; female plants with short involucres; single rounded to irregular chloroplast per cell, without a pyrenoid; and spore distal face with a large, central, single, pitted central hump, and the proximal face with a distinct single dimple on each tetrahedral area between triradiate rays. A detailed morphotaxonomic account is presented, along with detailed SEM observations of spores of the Indian plants. Conclusion Our critical comparative study has revealed that the plants of the newly recorded population belong to the genus Phymatoceros and are distinct from hitherto known species. They are described here as a new species, Phymatoceros binsarensis A.K.Asthana, D.Shukla & Reesa Gupta, and are the first record of Phymatoceros in India. As such, they represent a remarkable and interesting disjunct occurrence of the genus in Asia, separate from its distribution in four other continents (Africa, Europe, and North and South America).