A fascia is an area of thickened silica extending from the central area of pennate diatoms. A transverse fascia is formed by secondary deposition of silica into former depressions (Cox 2012). Also see definition for ‘stauros’. A number of genera possess a transverse fascia, including Luticola and Staurophora.
Cox, E.J. (2012). Ontogeny, homology, and terminology - wall morphogenesis as an aid to character recognition and character state definition for pennate diatom systematics . J. Phycol. 48: 1–31. 10.1111/j.1529-8817.2011.01081.x
Image Credit: Loren Bahls
The fascia of Staurophora is the thickened, unornamented area near the central nodule. Note that SEM images such as this one only show the surface features of the silica, so it is difficult to discern that the unornamented area is greater in thickness.
Image Credit: Pat Kociolek
Caloneis silicula has a fascia that often includes lunate markings.