YANA, Ekkachai, & Shigeki MAYAMA 2015 (Oct. 28) Two new taxa of Achnanthidium and Encyonema (Bacillariophyceae) from the Yom River, Thailand, with special reference to the areolae occlusions implying ontogenetic relationship Phycol. Research 63(4): 239-252, 64 figs., 2 tables Achnanthidium pseudoconspicuum var. yomensis, Encyonema yuwadeeanum |