Size at the onset of sexual maturity in Chasmagnathus granulata (Grapsidae, Sesarminae). A critical overall view about the usual criteria for its determination.

LÓPEZ GRECO, L.S.; RODRÍGUEZ, ENRIQUE M.

Proceedings of the Fourth International Crustacean Congress

Brill Academic Publishers

Año: 1999; p. 675 - 689

The size at the onset of sexual maturity was studied in the estuarine crab Chasmagnathus granulatus from Sambormbón Bay (36ª 18´S, 56ª 47´W), Argentina. Sexual maturity was determined according to three criteria: gonadal (from histology), allometric (size at the change in the allometric level of secondary sexual characters), and functional (size at which crabs reproduce). Related to these criteria, the concept of "puberty moult" is discussed. The results indicate that gonadal maturity occurred prior to allometric maturity for both sexes. Size at gonadal maturity for females was observed at a larger size than for males. For females, functional maturity was observed at a size similar to that of gonadal maturity, but it was statistically relevant (more than 5% of the frequency distribution of the ovigerous size) once the allometric size was attained. For males, the relationship between the three criteria was more complex. The functional maturity preceded the allometric size, but most matings were seen when males had a similar size to the allometric size of maturity of females. There was a clear "puberty moult" for both sexes. For females, it was related to the size of functional maturity, while for males, it occurred before the size at which they could mate was reached.