Figure 5
LM and SEM images of Paralia guyana ‘smooth’ valves. (A,B) SV7. Light micrographs. (A) Holotype specimen of P. guyana, CANA 107802. Smooth valve face sibling separation valves. (B) A chain of live cells. (C-I) Scanning electron micrographs. Isotype specimens of P. guyana B40 0040793. (C,D) Valve face of intercalary (C; EC112-3) and separation (D; EC106-1) valves with arrows marking central baculiform elevations and noduliform central protrusions, respectively. (E) EC105-2. Mantle view of relatively weakly silicified and slightly separated sibling intercalary valves with unobscured fenestrae. Black arrow indicates long, capitate marginal linking spines. Black arrowheads point to external pores of rimoportulae. Siliceous outcropping (white arrow) and pore (white arrowhead) in basal silica layer are also evident. Parenthesis indicates cingulum. (F) YH1. Marginal linking spine (arrow) with slit at its apex (arrowhead). (G) EC109-2. Notches (arrow) between the short, blunt, squared-shoulder spines in relief intercalary valve. (H) Van4B3. Mantle view of interlocked sibling intercalary valves with arrow denoting shallow depressions in the siliceous covering of fenestrae. (I) GA3. Internal view of valve showing slit of rimoportulae (arrow) and striae pores (arrowhead). Scale bars = 2 μm (A-D), 1 μm (E,G,H), 0.5 μm (F,I).