Observations and remarks on the morphology and taxonomy of the diatom genera Gyrosigma Hassall and Pleurosigma W. Smith. V. Pleurosigma types of A. Mann (1925): a critical re-investigation

Abstract

Abstract Type specimens of the nine Pleurosigma taxa described by A. Mann (1925) from the Philippine Islands were critically re-investigated as a result of a loan of these slides held in the Albert Mann collection at the United States National Museum, Smithsonian Institution, Washington, D.C., (USNM). Improved photomicrographic documentation and more recent insights into the taxonomy of the genus Pleurosigma lead to some revision of Mann's views. Mann noted a similarity between his P. obtusum and P. prisma and these species are here synonymized under the former name. No specific differences can be demonstrated for P. exemptum and P. obesum and the latter is here synonymized under the former name. Although Mann noted some resemblance between specimens of P. falx and small specimens of P. decorum W. Smith, I have found that P. falx A.Mann, closely resembles specimens of P. normanii Ralfs in Pritchard. Because no specific differences have been detected by light microscopy (LM), P. falx is here synonymized wi...