A New Species and a New Record of the Diastylidae (Crustacea: Cumacea) from Korea

In this study, a new species, Dimorphostylis breviplicata n. sp. is described and illustrated on the basis of specimens collected from the shallow Korean waters. This new species is similar to Dimorphostylis brevicaudata (Zimmer, 1903), Dimorphostylis acroplicata Harada, 1960 and Dimorphostylis valida Gamo, 1962 in that the carapace has three pairs of oblique ridges on the surface. However, the new species is distinguished by the combination of the following features: the middle oblique ridge is short and not joined to the other oblique ridges; the transverse ridge is absent on the frontal lobe; the dorso-median process on the pereonite 5 is only barely visible; the male telson has no short stout seta on the both lateral margins; the length ratio of the first to remaining articles combined on the male uropod is 1 : 0.7. A key to the Korean Dimorphostylis species is provided. Also, Diastylis alaskensis Calman, 1912 is redescribed as a new recorded species of the Korean fauna.