Chengjiang arthropod Leanchoilia illecebrosa (Hou, 1987) reconsidered

摘要

The common Chengjiang arthropod Leanchoilia illecebrosa (Hou, 1987) has been restudied on the basis of more than 500 new specimens. Important news concern the eyes: (1) There is a pair of kidney-shaped compound eyes, or possibly two confluent eyes; (2) optical lobes appear to reach the eyes, leaving no space for any eye stalks. Important news on the ventral appendages include the presence of: (3) an ample, annulated body-basipod articulation membrane with two sclerotized folds; (4) a prominent basipod with a spinous medial edge; (5) an articulation between the two rami extending to the middle of the 3(rd) endopod podomere; (6) up to nine endopod podomeres; (7) a long spine forming the limb tip; and (8) an exopod composed of a sub-triangular proximal portion and a leaf-shaped distal portion, both with marginal setae. New reconstructions are presented. There is a notable intraspecific variability. We conclude that none of the additional proposed species of Chengjiang Leanchoilia can be positively identified as separate from L. illecebrosa (Hou, 1987). In the possession of pointed anterior and posterior body ends, all species of Leanchoilia differ from Alalcomenaeus Simonetta, 1970.