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A second species of Microtabella (Grammatophoraceae, Bacillariophyta) from Guam

Published online by Cambridge University Press:  20 October 2015

Christopher S. Lobban
Christopher S. Lobban*
Affiliation:
Division of Natural Sciences, University of Guam, Mangilao, GU 96923, USA
*
Correspondence should be addressed to: C.S. Lobban, Division of Natural Sciences, University of Guam, Mangilao, GU 96923, USA email: clobban@uguam.uog.edu
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Abstract

One species of Microtabella, Microtabella interrupta, is widespread and has been known since the 19th Century but it has a convoluted taxonomic history leaving it presently the only species in the genus. The name interrupta derives from the chain-forming habit and the plastids being confined to a portion of the cell by a set of distinctively distended septa. This character makes it very easy to identify and very easy to overlook similar species, especially because the tabulate frustules are most often seen in girdle view. I found specimens of a new taxon that had these characters and was distinguished with difficulty in girdle view by the coarser striae on the copulae and the recurved edges of the septa. However, in valve view Microtabella rhombica n. sp. has a much broader, rhombic outline. Ultrastructural differences include a more elongated apical pore field with a prominent spine, biseriate striae on the copulae and a different form of the ligule (a raised bar on the last copula). Like Microtabella interrupta, the mature epitheca of Microtabella rhombica comprises numerous copulae with nearly flat septa, two copulae with distended septa and four hyaline pleurae that lack septa. This species could well be widespread but, as with other monospecific genera in which there is a strong distinguishing character, care must be taken to look beyond the outstanding feature.

Keywords

araphid pennate diatombiodiversitycoral reefsGrammatophoraceaemonospecific generatropical diatomswestern Pacific
Type
Research Article
Information
Marine Biodiversity Records , Volume 8 , 2015 , e151
Copyright
Copyright © Marine Biological Association of the United Kingdom 2015 

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References

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