MIDDLE TRIASSIC LOBSTERS FROM THE LUOPING BIOTA IN CHINA: MORPHOLOGICAL INNOVATIONS PROVIDE NEW PERSPECTIVES ON PHYLOGENY AND EVOLUTION

The Luoping biota in Yunnan Province, southwestern China, has recently been recognized as a remarkably varied Anisian (middle Triassic) association including a diverse assemblage of invertebrates as well as vertebrates and plants. Among them, decapod crustaceans are represented by over 100 specimens of lobsters and shrimp. The lobsters, representing at least three genera, are notable in being well preserved, often nearly complete, and relatively abundant. Over 40 specimens have been studied and illustrated. Among them, one of the taxa represents the oldest palinurid (spiny lobster) known to date. It bears all the essential morphological features of the carapace and antennal array to confirm that the group arose in the middle Triassic. Previously, the oldest occurrence was from the Norian (late Triassic) of Europe. The other two species are tentatively assigned to the Infraorder Glypheoidea Winckler, 1883, based upon characters of the cephalothorax and pleon. However, they exhibit features of the appendages that have been previously unrecognized in Glypheoidea or any other macruran group. The claws of one of the species have occlusal surfaces that are nearly perpendicular to the long axis of a club-shaped propodus; those of the other species have a pseudochelate closure with at least two spines on the terminus of the propodus. More remarkably, both species have chelate or pseudochelate closures on pereiopods 2-4, a feature only known previously in the Eryonoidea de Haan, 1841. This feature calls into question the widely accepted utility of placing decapod taxa within superfamilies based upon the architecture of closures of pereiopods 2-5. The variation on style of closure of the pereiopods suggests that the organisms were adapted to different manners of food capture and grooming which documents early niche diversification within the lobsters. Thus, the Luoping decapod fauna provides significant new information regarding the evolutionary history of lobsters as well as confirming the importance of continued work on the decapods of China; only six species have been described previously from the country. This work was supported in part by the Chengdu Institute of Geology and Mineral Resources, Chengdu, China.