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Developing a species complex, I mean, species concept

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16 November, 2015

Sarah Spaulding

EPA Taxon Page Workshop November 5-9, 2015 Academy of Natural Sciences of Drexel University, Philadelphia

Brave diatomists: Ian Bishop, David Burge, Gina LaLiberte, Melissa Vaccarino, Marina Potapova, Nina Desiante, Sylvia Lee, Meredith Tyree, Richard Mitchell, Jana Veselá, Kalina Manyolov, Sarah Spaulding

For the fall 2015 workshop, brave diatomists agreed to take on the challenge of several of the larger araphid “fragilarioid“ diatoms. This group of diatoms has been problematic for both taxonomists and analysts and has been noticeably neglected, until recently. “Fragilarioid“ diatoms are now slightly less ignored (see the list of citations below), but they are still a difficult to sort, polyglot of species complexes.

In this workshop, we set out to examine a number of taxa reported from North America. Thanks to the recent works by Tuji, Williams and others, many of the type specimens of species have been investigated and published. And for a number of taxa, we were able to resolve the morphological size series and taxon name. Taxon pages for the following species are now in progress on the Diatoms of the US website:

F. amphicephala
F. distans
F. pennsylvanica
F. saxoplanktonica
F. socia
Synedra goulardii
Ulnaria contracta
Ulnaria delicatisima

And updated genus descriptions for Fragilaria, Synedra and Ulnaria.

We were not, however, able to resolve other taxa by the same approach. These groups require additional work, as the circumscription of the species is not clear from the images and materials gathered this week. The group plans to take a novel approach to examining the remaining taxa. Stay tuned.

Fragilaria capucina
F. gracilis
F. pectinalis
F. perminuta
F. rhabdosoma
F. rumpens

Some useful references:

Lange-Bertalot H. and Ulrich S. 2014. Contributions to the taxonomy of needle-shaped Fragilaria and Ulnaria species. Lauterbornia 78: 1-73.

Morales et al. 2014 New epiphytic araphid diatoms in the genus Ulnaria (Bacillariophyta) from Lake Titicaca, Bolivia, Diatom Research, 29:1, 41-54.

Tuji A. 2004. Type examination of the ribbon-forming Fragilaria capucina complex described by Christian Gottfried Ehrenberg. In: Poulin, M. (ed.), Proceedings of the Seventeenth International Diatom Symposium. Ottawa, Canada, 25th-31st August 2002, Biopress Limited, Bristol, pp. 411-422.

Tuji A. 2007. Type examination of Fragilaria gracilis Østrup (Bacillariophyceae). Bulletin of the national museum of nature and science, Series B, Botany 33: 9-12.

Tuji A. and Williams D.M. 2006. Examination of the type material of Synedra rumpens-Fragilaria rumpens, Bacillariophyceae. Phycological Research 54: 99-103.

Tuji A. and Williams D.M. 2006. Typification of Conferva pectinalis O. F.Müll. (Bacillariophyceae) and the identity of the type of an alleged synonym, Fragilaria capucina Desm. Taxon 55: 193-199.

Tuji A. and Williams D.M. 2008. Examination of types in the Fragilaria pectinalis-capitellata species complex. In: Likhoshway, Y. (ed.), Proceedings of the Nineteenth International Diatom Symposium 2006, Listvyanka, Russia. Biopress Limited, Bristol, pp. 125-139.

Tuji A. and Williams D.M. 2013. Examination of types in the Fragilaria vaucheriae-intermedia species complex. Bulletin of the national museum of nature and science Series B, Botany, 39: 1-9.

Wetzel, C. and Ector, L. 2014. Taxonomy and ecology of F. microvaucheriae sp. nov. and comparison with the type materials of F. uliginosa and F. vaucheriae. Cryptogamie Algologie 36(3): 271-289.