Two unusual species of Alpheidae (Decapoda : Caridea) associated with upogebiid mudshrimps in the mudflats of Taiwan and Vietnam

Descriptions are provided for Athanas dentirostris, new species, and Chelom alpheus crangonus, new species, two alpheid shrimps collected from the burr ows of the upogebiids Upogebia aff. takaoensis Sakai and Turkay, 1995, and Upogebia edulis Ngoc-Ho and Chan, 1992, respectively. Athanus dentirostris, known only from northern Vietnam, is unique among all Alpheidae in having the superior margin of the rostrum dentate. Adult males of C. crangonus are immediately recognizable by the peculiar, subcheliform first pereiopods, w hich show superficial resemblance to the chelipeds of Crangonidae.