Cocconeis dapalistriata, first described as a member
of the genus Cocconeis, is re-examined due to its unique
ultrastructure. Both valvocopulae of this taxon show
significant differences compared to those found in the genus
Cocconeis. They are expanded and show some similarities
with those found in Amphicocconeis. On the other hand,
terminal parts of the raphe valve (RV) in C. dapalistriata
are simple and the raphe valve (RV) striae are composed of
small round areolae with a hymenate occlusion with radial
slits, similar to those observed in Cocconeis. Campyloneis
and Xenococconeis also have expanded valvocopulae but
with numerous morphological differences compared to
those found in C. dapalistriata. Furthermore, the areolae of
the sternum valve (SV) in C. dapalistriata are occluded by a
concave velum with no apparent internal slits, and externally
ornamented with irregular silica crystals. Upsilococconeis
Riaux-Gobin, Witkowski & Risjani gen. nov. is proposed to
accommodate the latter taxon. First described from the
Western Indian Ocean (Mascarenes), it was subsequently
listed from the Western Pacific Ocean (Guam), the South
Pacific Ocean (French Polynesia and New Caledonia) and
from the Eastern Indian Ocean (Indonesia), and thus may
qualify as pantropical.