Cocconeis molesta Kütz., C. diaphana W.Sm. and C. dirupta W.Greg. (Bacillariophyta): type material, ambiguities and possible synonymies

  • Catherine Riaux-Gobin CRIOBE-USR 3278 CNRS-EPHE-UPVD, 66000 Perpignan
  • Pierre Compère Botanic Garden Meise, Domein van Bouchout, 1860 Meise
  • Richard W. Jordan Department of Earth & Environmental Sciences, Yamagata University, Yamagata 990-8560
  • Michel Coste RSTEA, 50 avenue de Verdun, Cestas
  • Jovita C. Yesilyurt The Natural History Museum, Department of Life Sciences, Cromwell Rd, SW7 5BD, London
Keywords: Cocconeis molesta, Cocconeis diaphana, Cocconeis dirupta, synonymies, types


F.T. Kützing introduced Cocconeis molesta with only an uninformative description and a poor illustration: C. molesta has small, oblong valves and is an epiphyte. Another species, Cocconeis diaphana, described by William Smith, is said to have larger valves than C. molesta, with frustules that are relatively oblong. Smith described two forms: one with a distinct fascia on its raphe valve (var. β), the other without this feature. A third species, Cocconeis dirupta was described by Gregory, who expressed doubts that it differed from C. diaphana. Finally, Cocconeis molesta var. crucifera Grunow was first introduced in Van Heurck’s Atlas but was subsequently treated by Van Heurck as a synonym of C. molesta. No previous account has examined the type material of these species. In this paper, we undertake that task and examine type slides and raw material in order to discriminate these different taxa. We conclude by recognizing three species: Cocconeis molesta Kütz., C. diaphana W.Sm. and C. dirupta W.Greg. Cocconeis diaphana var. β is considered to be a synonym of C. dirupta and C. molesta var. crucifera is considered to be a synonym of C. molesta. Lectotypes are designated for C. diaphana and C. dirupta.


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How to Cite
Riaux-Gobin, C., Compère, P., Jordan, R. W., Coste, M., & Yesilyurt, J. C. (2016). Cocconeis molesta Kütz., C. diaphana W.Sm. and C. dirupta W.Greg. (Bacillariophyta): type material, ambiguities and possible synonymies. European Journal of Taxonomy, (204).