FIGURES 20–28 in Ninastrelnikovia lateritica sp. nov., a new and rare freshwater diatom species from the rocky pools of the Western Ghats, India with a note on the genus Ninastrelnikovia Lange-Bertalot & A.Fuhrmann (Bacillariophyta)

FIGURES 20–28. Detail of the external views of Ninastrelnikovia lateritica sp. nov. frustules (SEM). 20 & 21. Apices showing distal raphe ends of terminal and intermediate valves respectively. 22. Girdle view of the apex of a frustule showing pseudospines (arrows), spatulate spines (arrowheads) with distal raphe end curving towards the mantle. 23. Middle part of the terminal valve showing fully developed raphe system. 24. Middle part of the intermediate valve showing rudimentary raphe. 25. Girdle view of the middle part of a frustule showing pseudospines (arrow), linking spines (arrowhead) and silica granules (round pointer). 26 & 27. Apices showing distal raphe ends of terminal and intermediate valves respectively. 28. Another broken frustule apex showing raphe slit (arrow). (All scale bars represent 1 μm).