FIGURES 37–42 in Achnanthidium lucectorii sp. nov. and A. enigmaticum sp. nov., novel diatoms (Bacillariophyta, Achnanthidiaceae) from Texas, U.S.A.

FIGURES 37–42. Achnanthidium lucectorii sp. nov. (SEM) from type material. 37–39. RV in external view. Striae are more densely packed toward valve apices (open arrows in 38), Figure 39 shows straight distal ends of raphe extending beyond the striation region (white arrows). 40. Internal view of RV showing small capitate termini of proximal raphe ends (white arrows) and valve apex low thickening attached to low helictoglossum (black arrow). 41, 42. External view of RV and internal view of SV. Figure 42 shows internal view of SV. Scale bars = 5 μm.