(Kützing) Grunow 1867 Category: Monoraphid
BASIONYM: Stauroneis inflata Kützing 1844
Contributor: David R.L. Burge - July 2012
Length Range: 32-59 µm
Width Range: 13.5–21.1 µm
Striae in 10 µm: 11
Frustules are heterovalvar with a raphe valve and a rapheless valve. The valves are triundulate with the central valve margin wider than the apices, which are broadly rounded and capitate. Both valves are symmetric about the apical and transapical axes. The raphe valve face is concave about the transapical axis. On the raphe valve, the axial area is centered on the apical axis. The axial area is linear but narrows at the distal ends. A distinct transverse fascia is present in the central area. The raphe is slightly reverse lateral with expanded proximal ends. The proximal ends are unilaterally deflected. The distal raphe ends are deflected in the opposite direction. The distinctly uniseriate, punctate striae on the raphe valve are slightly radiate throughout and evenly spaced, 11 in 10 µm. The rapheless valve is convex about the transapical axis and does not have a fascia. On the rapheless valve, the narrow sternum is eccentric and positioned on the margin except where the valve center is expanded. The striae on the rapheless valve are distinctly punctate and have the same density as on the raphe valve. The rapheless valve striae are mostly parallel, tending to convergent and curved near the apices. Areolae on both valves are coarse and distinct, 11-12 in 10 µm. As a result of the concave and convex valve faces, the girdle view of A. inflata gives a recurved shape where the raphe valve valve fasica is on the inside of the curve.
Basionym: Stauroneis inflata
Author: Kützing 1844
Length Range: µm
Striae in 10 µm:
Kützing, F.T. (1844). Die kieselschaligen Bacillarien oder Diatomeen. Nordhausen. 152 pp., 30 pls.
Patrick, R.M. and Reimer, C.W. (1966). The Diatoms of the United States exclusive of Alaska and Hawaii, V. 1. Monographs of the Academy of Natural Sciences of Philadelphia 13.
Achnanthes inflata was common in epidendric samples from the woody plants Nyssa aquatica and Taxodium distichum (Figs 1 & 2). The trees were sampled in an ephemeral wetland along the Cache River in northeast Arkansas. Other common species in the collection were Eunotia monodon, Eunotia pectinalis var. undulata, and Luticola mutica.
Water chemistry for the site: 22.5C, pH 7.28, conductivity 375 µS, NTU 8.63, dissolved oxygen 5.08 mg/L, NO3 0.345 mg/L, NO2 0.069 mg/L, orthophosphate 0.172 mg/L.
Frustule in girdle view with two chloroplasts visible. Scale bar = 10 µm
Credit/Source: David Burge
Sample site and substrates in the Cache River, Arkansas, where Achnanthes inflata was collected.
Credit/Source: David Burge
Image added and text size range expanded to incorporate specimens sampled from Lake Catherine State Park, AR