Diploneis abscondita

Valves elliptical to linear–elliptical with bluntly rounded ends. Only central parts of the valve face are almost flat, whereas marginal parts become arcuate as they gently merge into the poorly differentiated mantle. Length 18–40 µm, breadth 8–15 µm. Length– to–breadth ratio 1.8–2.7. Raphe filiform, straight, with slightly expanded central endings which are moderately widely spaced; longer terminal fissures bent onto the same side of the valve mantle. Axial area narrow but expanded lanceolate towards the centre. Central area rather small with variable outlines, often apically elliptical, but clearly separated in all cell–cycle stages. H–shaped appendices barely developed. Axial internal canals are marked outside by transapical striae composed of three or four areolae, altogether forming a conspicuous rhombical–lanceolate area being softly arched around the central nodule. Adjacent regular striae radiate throughout, 13–15 in 10 µm, uniseriate but becoming biseriate near the valve margins onto the mantle. The areolae are opposed, not alternating, appearing here as single puncta in LM (cf. SEM Figs 106–107). Number of areolae in 10 µm is 13–18. SEM external view see Figs 106–108. Note in particular the raphe central and distal endings and the arrangement of cribrate areolae gradually cleaved with opposed parts.

• Author
  Lange-Bert. and Fuhrmann 2016
• Length Range
  18-40 µm
• Width
  8-15 µm
• Striae in 10µm
  13-15