Publication Date:
2018-09-11
Description:
The recently established diatom genus Shionodiscus is characterized as possessing a labiate
process on the valve face and strutted processes with long internal and reduced, or no,
external extensions. Many Thalassiosira species with these features were transferred to this
new genus, as well as some with short internal, strutted process extensions. Examination of
samples from the Argentine continental shelf and slope waters, and from the Beagle
Channel, revealed the presence of a small centric diatom that formed an extensive bloom in
slope waters during spring 2005 and 2006. Analysis by light and electron microscopy
revealed high similarity to specimens previously referred as Thalassiosira bioculata var.
raripora. This name was never effectively published; nevertheless, the name has been
adopted and observations referring to it have been reported on several occasions. Here we
trace the usage of the (nomenclaturally invalid) name Thalassiosira bioculata var. raripora
in the literature, and formally describe the species as Shionodiscus gaarderae, based on our
observations and comparison with previous reports. A morphological comparison of this
and similar taxa is also provided. In addition, we offer an emended description of S.
bioculatus var. bioculatus from Ostenfeld material sampled from the "Färöer Island Naströ
Fjord Plankton (16.9.1902)”, held in the Hustedt collection. Finally, we propose the transfer
of Thalassiosira rosulata to Shionodiscus.
Repository Name:
EPIC Alfred Wegener Institut
Type:
Article
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isiRev
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