Dasycaris ceratops; Dasycaris zanzibarica; Indo-Pacific; Pennatularia; symbioses; sexual dimorphism

The pontoniine shrimp Dasycaris ceratops is for the first time reported from Vietnam in the South China Sea. The hydroid Lytocarpia sp. occupied by some juvenile specimens is a new host for the species. The species is redescribed and illustrated here based on an adult male collected from the sea-pen Virgularia sp. The examination of the present male specimen of D. ceratops contributes to the knowledge on intraspecific variability of the rostral and carapacial teeth armament, and allows to report on previously undescribed structures, e.g., the anteroventral denticulation of the carapace, the fine denticulation of the cutting edges on the first pereiopods, the movable anteroventral lobe on the first abdominal pleurae and the unique subdivision of the first male pleopodal endopod. The colour in life and some morphological characters ofjuveniles are described. Dasycaris ceratops is compared with specimens of D. zanzibarica from Vietnam, Australia and Papua New Guinea.