Species diversity of the genus Protoperidinium, section Oceanica, (Dinophyceae, Peridi-niales) from Vietnamese waters, with description of a new species - P. larsenii sp. nov.

12 September 2016

Phan, Luom; Nguyen, Lam; Doan, Hai; Larsen, Jacob; Raine, Robin

Protoperidinium is one of the most important genera of armoured marine dinoflagellates. Despite its importance and many previous studies on this genus, the descriptions of many species are incomplete, their diagnostic features not properly described and illustrated and most species have been illustrated, if at all, only by line drawings and not documented by micro-photography. Examinations of about 600 phytoplankton net samples collected from Viet Nam and adjacent coastal waters over the last decade, revealed about 100 species of Protoperidinium, ten of which belong to the section Oceanica and this paper is the first in a series describing all species of Protoperidinium found in Vietnamese waters. The Oceanica species are described and illustrated by light and for some also by scanning electronic microscopy. The species are: Protoperidinium claudicans, P. depressum, P. depressum var. claudicanoides, P. larsenii sp. nov., P. murrayi, P. oceanicum f. bisintercalares, P. oceanicum var. tenellum, P. paraoblongum, P. venustum, and P. venustum var. facetum. Protoperidinium larsenii L. Phan Tan, L. Nguyen-Ngoc, and H. Doan-Nhu is new to science. It was found in the coastal waters of Rach Gia in Kien Giang Province, western part of South Viet Nam (Gulf of Thailand). The new species is characterized by its broad shape, conical epitheca and short, non-divergent antapical horns; the 1’ plate is asymmetrical, there are 3 anterior intercalary plates, the 2a plate is quadra; and the sutures connecting the 6” plate with the 4’ plate and the 7” form an almost straight line. By these features P. larsenii differs from the similar species P. claudicans and P. latidorsale.