Plaxiphora mercatoris Leloup, 1936 (Polyplacophora: Mopaliidae) de Isla de Pascua, Chile

A total 588 specimens of Plaxiphora mercatoris were analyzed, in terms of sizes and sex, registering sizes between 6 and 57 mm. P. mercatoris presents separate sexes, with no external sexual differences; no hermaphrodites were observed. The proportion of males versus females was 1.04: 0.89. Males differentiate sexually at 15.6 mm and females at 18.2 mm, and the maximum sizes registered were 53 mm and 57 mm respectively. P mercatoris is distributed only along the perimeter of the island. Its vertical distribution in the rocky system is from mid to low intertidal with densities between 1 and 8 individuals/m². The accompanying flora of this chiton presented some algae, calcareous algae being dominant: Mesophyllum siamense, Amphiroa yendoi and other Corallinaceae. The accompanying fauna is made by following species Chtamalus belyiaevi, Cypraea caputdraconis, Echinometra insularis, Nodilittorina pyramidalis pascua and Nerita morio.