Morphological characterization of Symbiodinium minutum and S. psygmophilum belonging to clade B

doi:2014.29.4.299

Algae > Volume 29(4); 2014 > Article

Algae 2014;29(4): 299-310. doi: https://doi.org/10.4490/algae.2014.29.4.299

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

*Corresponding Author

Email: hjjeong@snu.ac.kr

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.

Key words: dinoflagellate; Dinophyceae; eyespot; protist; Symbiodiniaceae; taxonomy