Several specimens of Licmophoraflabellata (Carmichael ex Greville) C. Agardh from Bahia San
Antonio, Rfo Negro, Argentina, were examined using light and scanning electron microscopy.
There were several rimoportulae per valve, distributed one in the base and the others adjacent to
the axial area. Comparison with the type material of the species and with slides of the Tempere
and Peragallo Collection has allowed the specific diagnosis to be emended. Differences found
between the Licmophora species that have been studied by us and by other authors suggest that
Licmophora should be split into two. The distribution pattern of rimoportulae known up to the
present for the family Diatomaceae was enlarged.