- Ostracoda
Common names: seed shrimps, ostracods
Probability of encounter: high, at least in moist products (e.g. mosses, plants with phytotelmata, rainforest litter).
Quarantine importance: no known importance.
Similarity to mites: small size and obscured structure. Most likely to be confused with a ptychoid oribatid mite (box mites), but the latter do not have a bivalved carapace. May also be confused with small clams. Another aquatic crustacean group, the clam shrimp (Conchostraca), have an even more clam-like carapace, but a trunk with 10-32 pairs of appendages.
Normal adult length: <3 mm in length
Body tagmata: head and reduced trunk covered by bivalved carapace
Eyes: naupliar eye (black spot under carapace hinge in live animals)
Antennae: antennules and antennae
Mouthparts: mandibles; 2 pairs of maxillae
Legs: antennae, mandibular palps and caudal furca function as legs
Respiration: cuticular
Gonopore: between last pair of appendages
Distinguishing features: bivalved carapace
Comments: The bivalved carapace of ostracods is distinctive, and often has dense setae in terrestrial forms. Terrestrial cypridoid ostracods have robust appendages that allow them to plow through the leaf litter. A dorsal anterior eyespot (under joint of valves) is visible in life. Ostracods are normally considered aquatic organisms and would be expected primarily in wet intercepts (e.g. bromeliads); however, some are inhabitants of humus.