Algae World: Phycological Research

Holotype of Cymbellonitzschia minima

type specimen of Cymbellonitzschia minima


Scale bar = 10 µm


differential interference contrast optics

Ringed specimen on Hustedt slide 224/75 (Alfred Wegener Institut, Bremerhaven). This frustule was shown to be the type of Cymbellonitzschia minima by R. Simonsen (1987) and was reexamined during work by Trobajo et al. (submitted).

There are several frustules of Cymbellonitzschia minima on the type slide, including some that are hantzschioid while others are nitzschioid. Frustules lying in girdle view can be quite easily confused with frustules of Nitzschia epiphyticoides, also present on slide 224/75, also exhibiting hantzschioid and nitzschioid symmetries, and also with low striation densities (c. 20-24 in 10 µm). However, the two species can be distinguished in girdle view by careful focusing, which reveals the dissimilar (strongly convex and flat) sides of the frustule in Cymbellonitzschia, but similar and only slightly convex sides in N. epiphyticoides. Here we illustrate a nitzschioid frustule of C. minima.


References:

Trobajo, R., Mann, D.G. & Cox, E.J. (submitted). Studies on the type material of Nitzschia abbreviata (Bacillariophyta).

Simonsen, R. (1987). Atlas and catalogue of the diatom types of Friedrich Hustedt, 3 vols. J. Cramer, Berlin & Stuttgart.

David Mann & Rosa Trobajo
Royal Botanic Garden Edinburgh
December 2010

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