Based upon the material from the Kii Strait, the taxonomy and biology of Metapenaeopsis palmensis (HASWELL) are presented. It is the fourth stridulating species in Japan and is separated from the three other species by having 6-12 ridges, the short inner intermediate strip of the petasma and a pair of large bosses on the sternite of fourth pereiopods in females. Sex ratio is approximately 1:1, and females are larger than males.
M. palmensis is abundant in shallow waters less than 30m of Tanabe-Bay, but becomes abruptly rare in deeper waters of the strait, as well as in the far north localities. This species seems to be well settled only in Tanabe-Bay and has the long- and short-term generations. The spawning season continues from June to September and new recruitments occur from July to November. It is one of the commercially important prawns and accounted for about 16-19% of the total catches of small-type trawl fisheries in 1972-1975.