AMERICANARUM DIATOMARUM EXSICCATA: CANA, VOUCHER SLIDES FROM EIGHT ACIDIC LAKES IN NORTHEASTERN NORTH AMERICA

Abstract

Ninety-eight slides from eight lakes in the Adirondack Mountains of the northeastern United States have been distributed as an exsiccata to 16 museums and collections around the world. The slides were prepared from sediment cores representing microfloras dating from 1830 to 1983. Lake size varies from small ponds (1.0 ha) to large lakes (520.5 ha). Present pH levels range from 4.26 to 7.05, with all the lakes having low to negative alkalinity levels. A total of 279 taxa have been identified, with 80 unknowns catalogued and photographed. to 1983. Lake size varies from small ponds (1.0 ha) to large lakes (520.5 ha). Present pH levels range from 4.26 to 7.05, with all the lakes having low to negative alkalinity levels. A total of 279 taxa have been identified, with 80 unknowns catalogued and photographed…The most common taxa are Asterionella ralfsii var. americana Körner, Anomoeoneis serians var. brachysira (Bréb. ex Rabenh.) Hust. (= Brachysira brebissonii Ross), Tabellaria flocculosa (Roth) Kütz. strains III & IV, Tabellaria quadriseptata Knudson, Fragilaria acidobiontica Charles (= Fragilariforma acidobiontica (Charles) Williams & Round), Frustulia rhomboides var. saxonica (Rabenh.) DeToni, and Cyclotella stelligera (Cleve & Grun.) V.H. Several new combinations are made: Brachysira serians var. acuta (Hust.) Hamilton; Brachysira zellensis f. difficilis (Grun. in V.H.) Hamilton; Diademsis contenta var. biceps (Grun. in V.H.) Hamilton; Fragilariforma constricta f. stricta (A. Cleve) Poulin, f. tetranodis (A. Cleve) Poulin and var. trinodis (Hust.) Hamilton; Fragilariforma hungarica (Pant) Hamilton and var. tumida (Cleve-Euler) Hamilton; Fragilariforma virescens var. exigua (Grun. in V.H.) Poulin; Staurosira construens var. binodis (Ehrenb.) Hamilton and var. venter (Ehrenb.) Hamilton