Skaracardia, a new order of Crustacea from the Upper Cambrian of Västergötland, Sweden

Skara Müller 1983, has been re-examined on the basis of more than 120 specimens. The body has two tagmata: a cephalon with five pairs of appendages, and a trunk composed of one pedigerous, 10 apodous ring-shaped and conical segments, telson and furca. The head shield is small and does not overhang the body on any side. The forehead extends from the shield terminating in a tubular dorsofrontal process which may represent a sensory organ. Eye structures are absent. The labrum is prominent, nose-shaped and posteroventrally directed. The antennal gland exits at its sides, in front of the bases of the antennae. The antennulae are uniramous and tubular. Antennae and mandibulae assisted locomotion and trophie functions. The two pairs of maxilIes and the pairs of maxillipeds are biramous and of the same design. All postantennular limbs participated in a short cephalic filter apparatus. The material proved to consist only of adults, but belonging to two almost equally represented size groups of a similar gross morphology. The large-sized group is represented by the holotype of Skara anulata Müller, 1983. Differences in size as well as various details led to the establishment of a new species, Skara minuta n.sp., for the smaller type. The two species most probably inhabited distinet ecological niches, feeding on particles of different size. Skara was a soft-integumented, marine filter-feeding crustacean. Its well developed setose antennal and mandibular exopods as well as the plumose, paddle-shaped exopods of the postmandibular limbs suggest that they were nectobenthic, most probably in a soft-bottom environment which was rich in detrital matter. Skara is a true crustacean showing affinities to Recent Maxillopoda, but differences between this genus, now with two speeces, and all known taxa motivates the erection of a new order.