103
Views
16
CrossRef citations to date
0
Altmetric
Articles

Diversity of the marine diatom Chaetoceros (Bacillariophyceae) in Thai waters – revisiting Chaetoceros compressus and Chaetoceros contortus

, &
Pages 161-175 | Received 12 Aug 2014, Accepted 14 Jan 2015, Published online: 21 Mar 2019
 

Abstract:

Chaetoceros is one of the most species-rich phytoplankton genera, and its known diversity can be expected to increase significantly when additional material from tropical and other less studied areas has been examined by a combination of molecular and morphological methods. We have succeeded in culturing and examining a pair of very characteristic Chaetoceros species, Chaetoceros compressus and Chaetoceros contortus, from a number of geographically separate localities. The pair is easily recognizable as such because of the heavy setae characteristic of the section Compressa but morphological similarities between the two species have caused considerable taxonomic confusion since the second species, C. contortus, was described nearly one hundred years ago. Critical studies exploring species delineation are therefore needed to determine whether C. compressus and C. contortus should be considered separate species. A combination of phylogenetic analyses based on large subunit rDNA and detailed morphological studies using light microscopy, scanning electron microscopy and transmission electron microscopy on strains of both species showed them to make up separate species and found that the variety C. compressus var. hirtisetus should be raised to species level as C. hirtisetus comb. & stat. nov. We describe two varieties of C. contortus: the temperate cf. var. contortus and the tropical var. ornatus var. nov. Characters for species delineation comprise a combination of light microscopically visible features, such as valve size and shape and number of chloroplasts. Furthermore, resting spore morphology and the number of labiate processes on the terminal valve seen in electron microscopy (EM) can be used to separate the two species, as well as molecular characters.

ACKNOWLEDGEMENTS

A.C. was supported by a PhD scholarship from the Royal Thai Government. N.L. was supported by a FREJA stipend of Faculty of Science, University of Copenhagen. Ines Sunesen, La Plata, Argentina is thanked for sharing unpublished information on resting spores of C. contortus and C. hirtisetus, and Jan Rines, Graduate school of Oceanography, Rhode Island, USA, for discussion on the taxonomy of the species. We thank the two reviewers for useful comments.

SUPPLEMENTARY DATA

Supplementary data associated with this article can be found online at http://dx.doi.org/10.2216/14-074.1.s1.

Log in via your institution

Log in to Taylor & Francis Online

PDF download + Online access

  • 48 hours access to article PDF & online version
  • Article PDF can be downloaded
  • Article PDF can be printed
USD 61.00 Add to cart

Issue Purchase

  • 30 days online access to complete issue
  • Article PDFs can be downloaded
  • Article PDFs can be printed
USD 283.00 Add to cart

* Local tax will be added as applicable

Related Research

People also read lists articles that other readers of this article have read.

Recommended articles lists articles that we recommend and is powered by our AI driven recommendation engine.

Cited by lists all citing articles based on Crossref citations.
Articles with the Crossref icon will open in a new tab.