Algae. 2014; 29(4): 299-310.
Morphological characterization of Symbiodinium minutum and S. psygmophilum belonging to clade B
Sung Yeon Lee1, Hae Jin Jeong1,*, Nam Seon Kang1, Tae Young Jang1, Se Hyeon Jang1 and An Suk Lim1
1School of Earth and Environmental Sciences, College of Natural Sciences, Seoul National University, Seoul 151-747, Korea
ABSTRACT
Dinoflagellates in the genus Symbiodinium are known as zooxanthellae and exist as either symbiotic or free-living forms. Among this genus, two species, Symbiodinium minutum and Symbiodinium psygmophilum, were recently established based on genetic characters. However, some critical morphological characters of these species, such as plate formulae and related diagnoses have not been provided yet. In this study, we analyzed the morphology of S. minutum and S. psygmophilum by scanning and transmission electron microscopy. The S. minutum had the Kofoidian plate formula consisting of a small plate (x), elongated amphiesmal vesicle (EAV), 4?, 5a, 8??, 7s, two cingulum rows, 18-20c, 6???, and 2????, while S. psygmophilum had x, EAV, 4?, 5a, 8??, 7-10s, two cingulum rows, 20-22c, 5-6???, and 1????. These plate formulae are different from any other reported Symbiodinium species. In addition, both species had a pentagonal 1a plate and a hexagonal 2a plate, while other known Symbiodinium species had a hexagonal 1a plate and a pentagonal 2a plate. Thus, we confirm the species status of S. minutum and S. psygmophilum based on morphological and genetic characters and report the detailed morphological characteristics of these two species.
Keywords :
dinoflagellate; Dinophyceae; eyespot; protist; Symbiodiniaceae; taxonomy
