Graeff, Kociolek and Rushforth 2013 Category: Symmetrical biraphid
BASIONYM: Envekadea vanlandinghamii Graeff, Kociolek and Rushforth 2013
REPORTED AS: Navicula pseudocrassirostris (Wachnicka et al. 2011) | Envekadea pseudocrassirostris (Lee et al. 2013)
Valves are linear, with a tumid center. The apices are protracted and rounded. The axial area is wide at the ends of the valve, but very narrow at the center. The central area is slightly raised above the rest of the valve face. The raphe is weakly lateral and straight except for at the apices, where it becomes sigmoid. External proximal raphe ends are widely T-shaped and terminate close to one another. External distal raphe ends are slightly expanded, positioned within a wide groove. The distal raphe ends are surrounded by a hyaline area, and are deflected to opposite sides. Internally, the raphe is straight. Internal proximal raphe ends are deflected to the same side. The internal distal raphe ends terminate in reduced helictoglossae.
Transapical striae are indistinctly puncate, strongly radiate in the center of the valve, and strongly convergent near the apices. Striae in the center of the valve are composed of interspersed short and long striae. Striae are continuous over the valve mantle. External striae are composed of irregularly formed, rectangular to polygonal areolae. Internally, the areolae are round and unoccluded.
Basionym: Envekadea vanlandinghamii
Author: Graeff, Kociolek and Rushforth 2013
Length Range: 32-67 µm
Width Range: 7-8.5 µm
Striae in 10 µm: 17-23
Valves linear, tumid in the center, with apices protracted, rounded (Figs 76–83). Length 32.0–67.0 µm, breadth 7.0–8.5 µm. Apical breadth 4.0–6.0 µm. Axial area wide at the ends of the valve, very narrow to the center where it is only slightly wider and bordered on either side by striae that are more coarse than the others and of various lengths. The raphe is weakly lateral with external proximal ends terminating close to one another and distal ends deflected in opposite directions (Figs 76, 79, 81). Striae are indistinctly punctate, strongly radiate around the center, strongly convergent towards the poles (Figs 79, 81). Striae 17–23/10 µm in the center, 27–29/10 µm at the ends.
In the SEM, the valve exterior is dominated by the striae with their volate occlusions (Fig. 85) and a sharp change in orientation from radiate at the center to convergent at the ends (Fig. 84). The raphe branches and axial area are S-shaped (Fig. 84). Proximal raphe ends are widely T-shaped (Fig. 86). The terminus of the axial area is wide and more developed on one side than the other (Fig. 85). Internally, the axial area is narrow and thickened (Fig. 87). Helictoglossae are fine, with the end pointed inward (Fig. 88). Proximal raphe ends terminate close to one another (Fig. 89).
Cite This Page:
Lee, S., and Van de Vijver, B. (2015). Envekadea vanlandinghamii. In Diatoms of the United States. Retrieved March 25, 2017, from http://westerndiatoms.colorado.edu/taxa/species/envekadea_pseudocrassirostris
Species: Envekadea vanlandinghamii
Reviewer: Sarah Spaulding
Gligorga, M., Kralj, K., Plenkovic-Moraj, A., Hinz, F., Acs, E., Grigorszky, I., Cocquyt, C. and Van de Vijver, B. (2009). Observations on the diatom Navicula hedinii Hustedt (Bacillariophyceae) and its transfer to a new genus Envekadea Van de Vijver et al. gen. nov. European Journal of Phycology 44(1): 123-138. 10.1080/09670260802389783
Graeff, C.L., Kociolek, J.P., and Rushforth, S.R. (2013). New and interesting diatoms (Bacillariophyta) from Blue Lake Warm Springs, Tooele County, Utah. Phytotaxa 153 (1): 1–38. 10.11646/phytotaxa.153.1.1
Hustedt, F. (1966). Die Kieselalgen Deutschlands, Österreichs und der Schweiz unter Berücksichtigung der übrigen Länder Europas sowie der angrenzenden Meeresgebiete. 3.Teil. Reprint 1977 by Otto Koeltz Science Publishers, Koenigstein, Germany. 816 pp.
Lee, S.S., Tobias, F.A.C., and Van de Vijver, B. (2013). Envekadea metzeltinii sp. nov., a new diatom (Bacillariophyta) species from the subtropical karstic wetlands of the Florida Everglades, U.S.A. Phytotaxa 115 (1): 15-24. doi:10.11646/phytotaxa.115.1.2
Wachnicka, A.H., Gaiser, E.E., and Boyer, J. (2013). Ecology and distribution of diatoms in Biscayne Bay, Florida (USA): Implications for bioassessment and paleoenvironmental studies. Ecological Indicators. doi:10.1016/j.ecolind.2010.08.008
Envekadea vanlandinghamii was described from the main basin of Blue Lake Warm Springs, Utah, with high conductance (9320 µS/cm) and close to neutral pH (7.6 pH).
Envekadea vanlandinghamii was found at low abundance (<1%) in a periphyton assemblage that included green algae and bladderwort. The site in Everglades National Park had 3900 µS/cm conductivity, 6.5 pH, and 270 µg/g total phosphorus. Other diatom taxa within the assemblage were E. metzeltinii, Fragilaria synegrotesca, Mastogloia lanceolata, and M. calcarea (Lee et al. 2013).