Silurian calcareous algae, cyanobacteria, and microproblematica from the Alexander terrane, Alaska

Limestones of Silurian age (late Llandovery–Ludlow) from the Heceta Formation of southeastern Alaska (Alexander terrane) yield a diverse assemblage of calcified microbial organisms. Fourteen taxa are described, including the cyanobacteria Girvanella and ?Hedstroemia, possible cyanobacteria Epiphyton, Ludlovia, and Renalcis, three species of “Solenopora,” and microproblematica Rothpletzella and Wetheredella. Diagnoses and descriptions are also given of the new epiphytacean genus Hecetaphyton n. gen. and new microproblematica genera Tuxekanella n. gen. and Sphaerina n. gen.