Species of Acetes Shrimps (Decapoda : Sergestidae) along the Coast of Rayong Province

Three species of Acetes shrimps viz., Acetes erythraeus Nobili, 1905, A . japonicus Kishinouye, 1905 and A vulgaris Hansen, 1919 were found from five different sites namely Pang Rad Estuary, Pra Sae Estuary, Laem Mae Pim beach, Suan Son beach and Pla beach in Rayong Province during June 2016 to August 2017.  Study on external morphology found that total length of all three species of Acetes shrimps were in the range of 2-3 centimeter.  Female Acetes shrimps of all three species are bigger than males.  Distinct taxonomic characteristics that can be used to clearly identified three species of Acetes shrimps were clasping spine of lower antennular flagellum of males and apex of telson in both males and females.  A. erythraeus and A. vulgaris have lower antennular flagellum with one clasping spine whereas A. japonicas have lower antennular flagellum with two clasping spines.   Both males and females of A. japonicas have apex of telson with round shapes whereas A. erythraeus and A. vulgaris have apex of telson with triangular shapes. Keywords : Acetes , species, Rayong  Province