An analysis of the body length distribution and correlation between the fecundity and body length was carried out in a population of the terrestrial amphipod Talitroides topitotum (Burt, 1934) from the neighborhood of Hydroelectric Plant of Guaricana, Serra do Mar, Guaratuba, State of Paraná, Brazil. The amphipods were collected with Malaise nets erected inside a Tropical Rain Forest, monthly, from June, 1985 to June, 1986. A total of 2191 amphipods were collected, from which 1626 females with oostegits but without eggs in the marsupium, 558 ovigerous females, 6 juveniles and an adult without any secondary sexual characters. No male was obtained. The eggs inside the female marsupium were counted. The body length of the amphipods was obtained through photographed images of the animals in lateral decubitus. Mature females summed 98.54% of the sampled population. The body length of the juveniles varied from 2.88 to 5.97 mm and that of mature females (including ovigerous ones) from 7.00 to 14.43 mm up to the present, this is the larger, with the modal class of the mature females in 8.50 mm class and that of ovigerous in 9.50 mm class. The non-ovigerous females presented shorter body length than the ovigerous ones. Ovigerous females were present all year round, which percentage ranged from 8 to 40%; four peaks were observed (July, October, and December, 1985, and March, 1986) in relative frequency distribution. Fecundity varied from 1 to 10 eggs per female; mean of 3.34 per female. In spite of the linear tendency of the regression between fecundity and body length the correlation was very weak (r = 0.5675, p < 0.05). The adult population of T. topitotum from Guaricana can be characterized by number of pulses (four) of ovigerous females during the year and by the absence of males.
Eggs; fecundity; terrestrial amphipod
