The reproductive cycle of Limnoperna fortunei (Dunker, 1857) (Mytilidae) from a neotropical temperate locality

Limnoperna fortunei is a dioecious, freshwater mytilid native to Asia. The reproductive biology of this invasive species is analyzed for the first tim e in its neotropical habitat. About 35 specimens were processed monthly usi ng standard histological techniques (sections similar to 6 mu m thick). The size of mussels at sexual maturity varied seasonally. From June to October , sex differentiated at 5-6 nlm shell length (SL), and from March to May at 7-10 mm SL. Adult males contained mature sperm throughout the year. Mature oocytes measured 70-100 mu m. Three main spawning events occurred in May t o July 1993, April to May 1994, and October 1994. Two partial spawnings wer e observed in September to October 1992 and December 1992 to January 1993. No spawnings were recorded from October 1993 to February 1994 and from June to October 1994. Oocyte proliferation was continuous and immature oocytes were recorded throughout the year. The population appears to have continuou s reproduction with peaks of maturing activity related to temperature chang es.