FIGURES 40–44 in Three new Psammothidium species from lakes of Olympic and Cascade Mountains in Washington State, USA

FIGURES 40–44: Psammothidium alpinum sp. nov., SEM. Figs 40–42. Type material, Snow Lake, sample ANSP WACA019 Fig. 40. External view of raphe valve. Fig. 41. Internal view of raphe valve. Fig. 42. External view of rapheless valve. Fig. 43. Internal view of rapheless valve, Hidden Lake NOCA, sample ANSP WACA018. Fig. 44. Areolae on the internal surface of the valve, Snow Lake, sample ANSP WACA001. Scale bars = 1 µm.