Envekadea vanlandinghamii

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).

• Author
  Graeff, Kociolek and Rushforth 2013
• Length Range
  32-67 µm
• Width
  7-8.5 µm
• Striae in 10µm
  17-23