Guatemala

Guatemala (gt)

Lake Petén-Itzá, Department of Petén

F. Sylvestre

2006-2

16° 15' 50.004'' N ; 89° 15' 0'' O

16.26389 ; -89.25

Elliptically shaped valves, diameter 24–46 μm along major axis and 18–30 μm along minor axis. Central area elliptical, slightly transversally undulated with scattered punctae (10 to 25) corresponding to the external opening of central fultoportulae. Central fultoportulae formed by a tube surrounded by two to three satellite pores. Marginal area about one third of valve surface circumferentially undulated with coarse to very coarse striae. Striae of unequal length and density: along major axis 8–12 st/10μm, along minor axis 6–9 st/10μm longer, more outspread and sometimes dichotomous. Striae formed by four to six rows of small rounded areolae (30 in10 μm). Mantle fultoportulae present on nearly each costa and composed of one tube and three satellite pores. Rimoportula inserted on a costa within the ring of mantle fultoportulae. External openings of mantle fultoportulae and rimoportula in a ring at some distance from the valve margin