Taxonomic Studies on the Diatom Genus DiploneisI. Fine Structure on Hustedt's VI Group

Algae > Volume 7(1); 1992 > Article

Algae 1992;7(1): 63-78.

Noh, Jae Hoon, Joong Ki Choi

Department of Oceanography, Inha University

ABSTRACT

The fine structures of several Diploneis species, collected from 15 marine stations of Korea, have been investigated using light and electron microscopy. We studied fine stuctures of 6 species classified as VI group by Hustedt (1937), 1 variety, 1 unclassified species and some modified speciments. These species are as following: Diploneis bombus, D. bombus var. bombiformis, D. weissflogi, D. chersonensis, D. bomboides, D. splendida, D. diplosticta, D. sp. and some modified specimens. All observed Diploneis taxa have chambers which are formed by crossing of transapical and longitudinal costae. Valve outline in these species also shows similar shapes of panduliform. These species are differentiated into two groups by internal pores on the inside of the longitudinal canal. Diploneis bombus, D. bombus var. bombiformis. D. sp. D. weissflogi and D. chersonensis have no internal pores. Diploneis bombus, D. weissflogi and D. sp. have very similar morphological features. D. chersonensis and D. bomboides are also similar features. And there are intermediate forms between these two species. The number of longitudinal costae, elongated slits and the slit-like openings were useful morphological features in differentiating D. bombus var. bombiformis from the D. bombus. According to these morphological features, specimens with two longitudinal costae should be classified as D. bombus var. bombiformis. The fine structures of outer walls are useful in defining the species and lower taxonomic levels, while the internal pores may be useful in defining the species or subgeneric level.

Key words: Diploneis, VI group, internal pore, intermediate form