Artystone minima n. sp. (Isopoda, Cymothoidae) a body cavity parasite of the pencil fish (Nannostomus beckfordi Guenther) from the Brazilian Amazon.
Artystone minima sp. nov. from the body cavities of N. beckfordi is described. The infected fish were caught in backwaters of the upper Rio Negro, Amazonas State, Brazil. The new species is morphologically similar to A. trysibia, from which it differs in several important respects. A. minima is smaller (3.3-6.9 mm rather than 22-25 mm). The small body size of these parasites permits them to infect smaller fish hosts (3-4 cm instead of 15-30 cm). The small body size also limits to 13-15 the number of eggs in the marsupia of mature females (compared to 400 for A. trysibia). The lesions produced by this parasite in the fish show no evidence of inflammatory reaction or of secondary invasions by bacteria.