Chitons (Mollusca: Polyplacophora) of Hainan Island and vicinity, South China Sea.

The chiton fauna of Hainan Island and its vicinity is poorly known. In this contribution, we present the first comprehensive account of the living chitons from this area. The present compilation is based on the study of historical collections housed in Qingdao (China), Saint Petersburg (Russia), new samples from Hainan Island and data from literature. Six species (Rhyssoplax venusta, Lucilina lamellosa, L. tenuicostata, L. tilbrooki, Onithochiton stracki and Acanthochitona intermedia) are reported for the first time from this area. Three species (Acanthochitona achates, A. britayevi and A. lanae) are re-identified on the basis of descriptions, drawings and photographs in old articles. We now know a total of 30 species (belonging to 18 genera in seven families) from the vicinity of Hainan Island. While examining material of Lucilina lamellosa, we found two forms: L. lamellosa forma typica and the new form L. lamellosa forma costata. Both forms differ from each other in the structure of the tegmentum of the pleural areas.