Stepanek and Kociolek 2013 Category: Asymmetrical biraphid
BASIONYM: Halamphora latecostata Stepanek and Kociolek 2013
REPORTED AS: Amphora acutiuscula (Patrick and Reimer 1975, pg. 77, Pl. 14, Figs. 9-10) | Halamphora acutiuscula (ANSP Image Database (IM000479, IM002259, IM002260))
Contributor: Ian Bishop - November 2015
Length Range: 16-50 µm
Width Range: 4.1-7.9 µm
Striae in 10 µm: 9-13 at dorsal center; 15-18 at dorsal apices; 19-20 ventral
Valves are semi-elliptical, with rounded dorsal margins and nearly straight ventral margins that vary from slightly concave to slightly convex. Apices are distinctly protracted, round and subcapitate to capitate. Dorsal striae are radiate throughout, increasing from 9-13 in 10 µm near the center to 15-18 in 10 µm at the apices. Ventral striae are shortened and radiate to parallel. The ventral striae are interrupted at the center and vary little from 19-20 in 10 µm across the valve. The axial area is linear. On the dorsal side, the axial area is narrow. On the ventral side, the axial area expands near the central area. The raphe is filiform. The proximal raphe ends are inflated and deflect slightly to the dorsal side of the valve. Areolae are not visible in LM.
Patrick and Reimer (1975) used the name Amphora acutiuscula in their volume, Diatoms of the United States, for a taxon conspecific with the specimens shown on this page. Like these illustrated specimens, the Patrick and Reimer material was also collected from the Sabine River, Texas. Patrick and Reimer did not, however, examine Kützing’s original material. Kützing’s type material was revisited by Levkov (2009, Pl. 265), but the type of Amphora acutiuscula varies considerably from the Patrick and Reimer concept. The species Halamphora latecostata described by Stepanek and Kociolek (2013) conforms to the taxon illustrated here, and also to the taxon to which Patrick and Reimer misapplied the name A. acutiuscula.
While Levkov (2009) imaged Kützing’s type material (Pl. 265, Figs. 12-15), he did not refer to this plate in his recombination of Halamphora acutiuscula, but instead referred to a Venezuelan population (Pls. 96, 109, 234) dissimilar to Kützing’s type. The comparison of H. latecostata to H. acutiuscula found on this page refers to the type images only (Pl. 265).
Basionym: Halamphora latecostata
Author: Stepanek and Kociolek 2013
Length Range: 25-40 µm
Width Range: 5.5-7.5 µm
Striae in 10 µm: 10 in the center (dorsal), 14-15 at the apices (dorsal), 18-22 on the ventral side
Kützing, F.T. (1844). Die kieselschaligen Bacillarien oder Diatomeen. Nordhausen. 152 pp., 30 pls.
Levkov, Z. (2009). Amphora sensu lato. In Diatoms of Europe, Volume 5. (H. Lange-Bertalot, ed). A.R.G. Gantner Verlag K.G. 916pp.
Patrick, R.M. and Reimer, C.W. (1975). The Diatoms of the United States, exclusive of Alaska and Hawaii, V. 2. Monographs of the Academy of Natural Sciences of Philadelphia 13.
Stepanek, J.G. and Kociolek, J.P. (2013). Several new species of Amphora and Halamphora from the western USA. Diatom Research. 10.1080/0269249X.2012.735205
The specimens shown on this page were collected by Ruth Patrick in 1952, from the epipsammon of the Sabine River, Texas.
This page was originally posted as Halamphora acutiuscula sensu Patrick and Reimer 1975. After this page was opened, however, the contributor became aware that this taxon conforms to H. latecostata Stepanek and Kociolek (2013). The name was changed as of the current date from Halamphora acutiuscula to Halamphora latecostata. - I. Bishop and S. Spaulding