Punctastriata mimetica

Valves with rostrate to cuneate ends, or broadly rounded in smaller specimens. The central area is expanded laterally. The valve face is undulate due to raised costae. The valve face/mantle junction forms a sharp angle. The abvalvar edge of the mantle is parallel to the valve face/mantle junction. In girdle view, frustules are rectangular with raised central area. Cells form short ribbon-like colonies, joined by linking spines. The axial area is narrowly lanceolate. Striae are distinct, composed of up to four rows of round areolae, which converge into a single row at the axial area and valve mantle. Striae terminate sharply at axial area. Striae extend continuously from valve face to mantle. Costae are wider than the striae. Spines are spatulate and sometimes expose laminar ligulae projected downwards to the valve mantle. Spines are present along the valve face edge, except at the apices, and are located on the striae. Small, ocellulimbus type, apical pore fields with round poroids are present on both valve apices, but are more developed at foot pole than at the head pole. Pore fields are located on the junction between the valve face and mantle. Rimoportulae are absent. Copulae, or girdle bands, are open and not perforated. Valvocopulum (first girdle band) is wider than the rest of the girdle elements and presents well-developed fimbriae.