Morphology and molecular phylogeny of the marine diatom &lt;i&gt;Nitzschia dentatum&lt;/i&gt; sp. nov. and &lt;i&gt;N. johorensis&lt;/i&gt; sp. nov. (Bacillariophyceae) from Malaysia

G Usup,S.N.P Suriyanti

doi:10.3329/bjpt.v24i2.35114

Morphology and molecular phylogeny of the marine diatom <i>Nitzschia dentatum</i> sp. nov. and <i>N. johorensis</i> sp. nov. (Bacillariophyceae) from Malaysia

G Usup, S.N.P Suriyanti

Open Access

https://doi.org/10.3329/bjpt.v24i2.35114

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Abstract

The marine diatom Nitzschia dentatum sp. nov. isolated from seawater samples of Kudat and N. johorensis sp. nov. isolated from beach sand samples of Sibu Island, Malaysia, have been described in this paper. Morphological identification, molecular phylogeny and toxin analyses were executed on the pure non-axenic algal cultures designated as KD89 and PS8, respectively. The main distinguishing feature of N. dentatum sp. nov. compared to other species is the jaggedcingulum structure which is only unique to this species. Meanwhile, N. johorensis sp. nov.is strongly characterized by the ‘hantzschioid’and ‘nitzschioid’ symmetry dimorphisms; a common diagnostic feature but rarely described in other Nitzschia species. Identification of both strains was made based on the frustule diagnostic features and verified using the partial large ribosomal subunit DNA sequences. The results have confirmed that these two speciesare independent entities and novel species that have not been documented elsewhere. A notable finding from the Maximum Likelihood (ML), Maximum Parsimony (MP) and Bayesian Index (BI) analyses have also revealed that Nitzschia species that have indentation in the middle of valves have been consistently grouped as same clade with high bootstrap values. The extracts of both species did not show detectable amount of domoicacid and have therefore, been classified as non-toxic. This discovery contributes to the documentation of Nitzschia species worldwide.Bangladesh J. Plant Taxon. 24(2): 183–196.

Highlights

Nitzschia Hassall is represented by 1,405 diatom species worldwide comprising the freshwater, brackish water and marine environments, with only half of it been accepted taxonomically (Guiry and Guiry, 2017)
A notable finding from the Maximum Likelihood (ML), Maximum Parsimony (MP) and Bayesian Index (BI) analyses have revealed that Nitzschia species that have indentation in the middle of valves have been consistently grouped as same clade with high bootstrap values
All cultures were grown in silica-enriched media modified from SWII (Iwasaki, 1961) concoction adjusted to 30 Practical Salinity Unit (PSU)and maintained at 26 °C under 12:12 hour light : dark photo cycle

Summary

Introduction

Nitzschia Hassall is represented by 1,405 diatom species worldwide comprising the freshwater, brackish water and marine environments, with only half of it been accepted taxonomically (Guiry and Guiry, 2017). A notable finding from the Maximum Likelihood (ML), Maximum Parsimony (MP) and Bayesian Index (BI) analyses have revealed that Nitzschia species that have indentation in the middle of valves have been consistently grouped as same clade with high bootstrap values.

Results

Conclusion