New and Known Species of Tardigrada from the Coast of Vietnam.

Abstract

Four species of tardigrades have been found in the meiofauna communities of the seagrass meadows and adjacent areas off the coast of Vietnam. For two of them, Batillipes binhdinhicus sp. nov. and Batillipes ampullus sp. nov., integrative descriptions are presented. Batillipes binhdinhicus sp. nov. belongs to the B1 subgroup of species by having toe 3 shorter than toe 4 on legs IV, while Batillipes ampullus sp. nov. with toes 3 and 4 on legs IV of equal length belongs to the A group of species. Batillipes binhdinhicus sp. nov. can be distinguished from all previously described species by a set of features: very long cephalic cirri and leg sensory spines, both with swollen tips, presence of a single pair of conical lateral body projections between all pairs of legs and simple triangular caudal appendage. The distinctive features for Batillipes ampullus sp. nov. are short sensory organs on the fourth pair of legs, which consists of two parts and have swollen tips with a tuft of additional sensory filaments that are structurally similar to those found on the cephalic appendages. In addition, Batillipes ampullus sp. nov. does not have noticeable lateral body projections between the legs, and the body ends in a semi-circular tail appendage. Based on the obtained data on the nucleotide sequences of 18S rDNA and 28S rDNA, the distinction between the new species was confirmed.