The epi- and mesopelagic shrimps of the genus Sergestes (Decapoda： Sergestidae) in the waters around Taiwan

Abstract

Eight species, totaling some 500 specimens, of the genus Sergestes (Decapoda:Sergestidae) were collected from the Taiwanese waters, namely S. armatus Krfyer, 1855; S. orientalis Hansen, 1919; S. pectinatus Sund, 1920; S. sagassi Ortmann, 1893; S. seminudus Hansen, 1919; S. similis Hansen, 1903, and S. formosus sp. nov. All these are new records of the Taiwan fauna. They were taken both in the daytime and night by various collecting devices in the Taiwan Strait and the open sea off eastern Taiwan, at depths ranging from surface to 1,000 metres. This genus is characterized by the presence of specialized luminescent modification of the gastrohepatic gland, i.e. the organs of Pesta. In different species of the genus, the organs of Pesta differ not only in number but also in shape and location. A key to the eight species is given. Besides the luminescet organs, other morphological characteristics of each species are given and illustrated. Geographical and vertical distributions of the speciesn are also discussed.