Species diversity of the genusThalassiosira(Thalassiosirales, Bacillariophyta) in South Korea and its biogeographical distribution in the world

Abstract

Thalassiosira species are an important component of phytoplankton populations, and most species are considered cosmopolitan. Many authors have investigated the diversity of Thalassiosira species in order to understand their ecological roles in local areas. Our regional taxonomic study revealed the presence of 44 Thalassiosira species at 124 sites in Korean coastal waters. Of these, 14 species are newly reported in Korean waters and are described in detail with external and internal valve illustrations. Some morphologically confused taxa, such as the Thalassiosira s.s. group, T. curviseriata/T. tealata, T. simonsenii/Planktoniella blanda and T. proschkinae/T. spinulata, are clearly distinguished using additional morphological criteria. In addition, the full biogeographical distribution of Thalassiosira is described and compared with the Korean species. Korean waters seem to be the 'Maginot Line' for the cold-and warm-water Thalassiosira species. Knowledge of Thalassiosira species diversity will increase with more intensive work in relatively little-studied regions, such as the Indo-Pacific and tropical Atlantic Oceans.

Transfer of the small diatoms Thalassiosira proschkinae and T. spinulata to the genus Minidiscus and their taxonomic re-description

“…In the present study, T . spinulata had three satellite pores of marginal fultoportulae, it agreed to the previous description [ 14 ]. However, T .…”

“…However, T . proschkinae had two satellite pores in marginal fultoportula and sometimes rarely three reported by Park et al [ 14 ]. Despite of the number of satellite pore in marginal fultoportula in the thalassiosiroid diatoms is a stable characteristic, this structural variation in T .…”

“…Hasle & Syvertsen [ 11 ] also agreed to Makarova’s consideration and mentioned that the two species could not be distinguished by light microscopy. However, the taxonomic relationship between the species has been clarified by the differences of areola structure and valve silicification [ 12 – 14 ]. The taxonomic relationship between T .…”

“…Alverson et al [ 5 ] transferred 26 Thalassiosira species in subgroup B into the genus Shionodiscus , which is characterized by the rimoportula on the valve face and no extension of the processes externally. Since Thalassiosira species in subgroup B were transferred to the genus Shionodiscus , most Thalassiosira species have a rimoportula at the valve margin [ 14 ]. In addition to Shionodiscus , some genera have the rimoportula on the valve face in Thalassiosirales, namely, Minidiscus Hasle, Livingstonia Prasad, and Skeletonema Greville.…”

Newly Recorded Species of Diatoms in the Source of Han and Nakdong Rivers, South Korea

“…The FE-SEM was operated with an accelerating voltage of 5 kV with a 15 mm working distance. The cells were measured using the ImageJ v1.32 software (Schneider et al 2012, Park et al 2016. The terminology was according to that of Anonymous (1975), Ross et al (1979), and Round et al (1990).…”