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.
Basionym: Punctastriata mimetica
Author: Morales 2005
Length Range: 7-22 µm
Width Range: 5-7 µm
Striae in 10 µm: 9-11
Frustula aspectu cingulari rectangularia in catenis cum marginibus spiniferis. Valvae heteropolares cruciform-rhomboid, extremiis acuminat-subrostratis. Longitudo 7–22 mm, latitudo 5–7 mm, striae 9–11 per 10 mm (n = 50). Sternum linearum vel lanceolatum. Striae parallelae aut aliqua tulus radiatae. Areolae compositio multiposthoc singulari ordinis. Volae nullae. Costae elevare crassae cum spinae bifurcate, areae porellum ad apices distincta. Valvocopulae maior quam alias elementa.
Cite This Page:
Morales, E., Rosen, B., and Spaulding, S. (2013). Punctastriata mimetica. In Diatoms of the United States. Retrieved December 21, 2014, from http://westerndiatoms.colorado.edu/taxa/species/punctastriata_mimetica
Species: Punctastriata mimetica
Reviewer: Sam Rushforth
Morales, E.A. (2005). Observations of the morphology of some known and new fragilarioid diatoms (Bacillariophyceae) from rivers in the USA. Phycological Research 53: 113-133.
Siver, P.A., Hamilton, P.B., Stachura-Suchoples, K. and Kociolek, J.P. (2005). Diatoms of North America. The Freshwater Flora of Cape Cod. Iconographia Diatomologica 14: 1-463.
Significant populations of P. mimetica were found in alkaline water (pH = 8.2) of moderately low conductivity (179 mS/cm) and moderate concentrations of P (orthophosphate) and total N (0.129 mg/L and 0.437 mg/L, respectively).