Morphology and occurrence of two epibiotic marine gomphonemoid diatoms in China

Abstract

Gomphonemoid diatoms exist in both freshwater and marine environment, but marine gomphonemoid taxa are morphologically different from Gomphonema. Although the marine gomphonemoid group has been expanded with many new taxa in recent years, only the genus Gomphonemopsis was described from Chinese seas. The present study reports on species diversity and classification of marine epiphytic diatoms on seaweeds and epizoic diatoms on animals collected from several stations in the South Yellow Sea and East China Sea. Two marine gomphonemoid diatoms, Pseudogomphonema kamtschaticum and Gomphoseptatum aestuarii, were observed and identified by light and electron microscopy, representing the first record in China of these two species and genera. Our observations matched the basic features of original species descriptions. Except that we observed in P. kamtschaticum showed various areolae shapes (e. g., slit-like, "I"-like, "C"-like and circular), and ornamented macroareolae with small warts were observed in G. aestuarii. Both P. kamtschaticum and G. aestuarii were epiphytic on the seaweed Sargassum hor neri, and P. kamtschaticum was found as epizoic on an ophiuroid species of the Ophiura genus. Therefore, we have increased the records of and knowledge about marine gomphonemoid diatoms to three genera with four species in China, including Gomphonemopsis.