Checklist and illustration of diatoms in the Hii River

Abstract

The freshwater diatom flora of the Hii River in Western Japan is studied. In December 1999,27 samples examined were collected from cobbles, pebbles and sands at ten sampling stations situated at almost regular intervals along the main course of Hii River. In total 180 diatom taxa belonging 58 genera were identified, and were illustrated together with 20 unidentified ones. Encyonema incurvatum Krammer was separated from Encyonema silesiacum (Breisch) D. G. Mann by the relationship between length and width, in addition to the density of areolae. Gomphonema tetrastigmatum Horikawa et Okuno, Ceratoneis arcus var. hattoriana F. Meister and Navicula aequatorialis Heiden are respectively transferred taxonomically suitable genera as follows: Gomphoneis tatrastigmata comb. nov., Hannaea arcus var. hattoriana comb. nov. and Luticola aequatorialis comb. nov. Because the type of Navicula exigua (W. Greg. ) Grunow has not been confirmed, N. exigua var. elliptica Hust. and N. exigua fo. undulata Hust. are raised to independent species, with transfer to the genus Placoneis Mereschk., i. e. Placoneis elliptica comb. nov. et stat. nov. and Placoneis paraundulata nom. nov.