Postmarsupial development of Armadillidium granulatum Brandt, 1833 (Isopoda, Oniscidea): description of the manca stages.

The postmarsupial development of the manca stages of Armadillidium granulatum Brandt, 1833 was studied in detail. Ovigerous females were reared separately under controlled conditions, allowing us to follow the stages of development, from the release of the marsupium until the development of the seventh pair of pereopods. Then, each newborn was individually followed in order to record the subsequent moults. The manca stage M I had a duration of 5.7 hours (± 0.55 SD); M II of 14.69 days (± 2.59 SD); M III of 32.31 days (± 2.54 SD). The cephalothorax width was calculated in order to have a growth measure of each stage with the mean values of 0.512 mm for M I, 0.677 mm for M II, and 1.194 mm for M III. The morphological modifications in the three postmarsupial manca stages (M I–M III) are described, the body parts are illustrated with drawings and SEM photographs. The distinguishing characteristics among the different manca stages and between these and the adults are discussed, and comparisons with manca stages of other terrestrial isopods species are given.