Analysis of the type material of Achnanthidium lanceolatum BRÉBISSON ex KÜTZING (Bacillariophyta) with the description of two new Planothidium species from the Antarctic Region
Abstract
The type material of Achnanthidium lanceolatum (transferred in 1999 to the genus Planothidium) is investigated to reveal the identity of several Planothidium populations from the Antarctic Region. The morphology and the ultrastructure was analysed using light and scanning electron microscopy.
The results of this analysis revealed the presence of two so far undescribed Planothidium species in the investigated Antarctic material and were described as new to science: P. rostrolanceolatum Van de Vijver, Kopalová et Zidarova sp. nov. and P. subantarcticum Van de Vijver et C.E.Wetzel sp. nov. The new species can be differentiated based on differences in valve outline and the shape and size of the central area.
Planothidium lanceolatum is formally lectotypified. Notes on the ecology and distribution of the new Antarctic species are added.