Vola | Glossary - Diatoms of North America

Vola

A vola is an extension of silica from the side of an areola. A vola may be simple (e.g., Thalassiosira decipiens) or branched (e.g., Arachnoidiscus ehrenbergii). From Latin for the palm of the hand, based on the first described shape (Cox 2004 p. 36). Plural is volae. This structure is visible only with electron microscopy. Several volae combine to occlude an areola.

See also occlusion (a general term for covering).

Citations

Anonymous (1975) Proposals for standardization of diatom terminology and diagnoses Nova Hedwigia, Beihefte 53: 323-354
Cox, E.J. (2004) Pore occlusions in raphid diatoms - a reassessment of their structure and terminology, with particular reference to members of the Cymbellales. Diatom 20: 33-46.

Publication Link: 10.11464/diatom1985.20.0_33
Idei M., Sato S. and Mann D.G. (2020) The Amazing World of Diatoms. Sogensha Publishers, Osaka, Japan, pp. 176.
Mann, D.G. (1981) Sieves and flaps: siliceous minutiae in the pores of raphid diatoms. Proceedings of the 6th Symposium on Recent and Fossil Diatoms (pp. 279-300). Koenigstein: O. Koeltz.
Ross, R., Cox, E.J., Karayeva, N.I., Mann, D.G., Paddock, T.B.B., Simonsen, R. and Sims, P.A. (1979) An amended terminology for the siliceous components of the diatom cell Nova Hedwigia, Beihefte 64: 513-533
Round, F.E., Crawford, R.M. and Mann, D.G. (1990) The Diatoms. Biology and Morphology of the Genera. Cambridge University Press, Cambridge, 747 pp.

A Crassipunctata Areola SEM — An areola of Aulacoseira crassipunctata with volae extending from its sides (SEM). Scale bar = 0.5 µm.

Arachnoidiscus ehrenbergii vola 1µm — An areola of Arachnoidiscus ehrenbergii (SEM), occluded by a complex vola extending from its sides. Dark areas of the vola are openings to the cell interior. Scale bar = 1 µm.

Thalassiosira decipiens Langwarder Groden2 18 1 — Center of valve face of Thalassiosira decipiens (SEM). Areolae have volae consisting of branches and bars. Scale bar = 1 µm.

Petroneis monilifera verdronken zwarte polder72 1 — Internal view of Petroneis monilifera with areolae occluded by volae (SEM). In this genus, a cribrum is attached to the outside of each vola. Scale bar = 0.5 µm.