Postabdominal claw with secondary tooth (2nd) in the middle Postabdominal claw without secondary tooth in the middle. Only one basal spine, in some cases it may be absent. If your organism has two basal spines click here to be redirected.   Taxonomy Phylum Arthropoda Subphylum Crustacea Class Branchiopoda Suborder Cladocera Family Chydoridae