Egg production in the porcellanid crab Pachycheles laevidactylus Ortmann, 1892 (Decapoda: Anomura: Porcellanidae) in southern Brazil

Abstract

Abstract We analysed the egg production of the porcellanid crab Pachycheles laevidactylus Ortmann, 1892 in two coastal locations (Tramandaí and Torres) in southern Brazil. The number of eggs and egg volume were analysed during one year and compared between locations and seasons. A total of 438 ovigerous females were collected from sand banks formed by the polychaete Phragmatopoma caudata Krøyer in Mörch, 1863. The eggs were measured, classified into three stages of development, and quantified. Females with stage-I eggs were more frequent than those with stages II and III, possibly because it is the longest-duration stage. A positive correlation between female body size and fecundity (stage I) was observed, represented by a power function. The ovigerous females of Tramandaí and Torres had the mean/median (Tramandaí) and the maximum (both locations) fecundity higher than previously recorded for the species, nevertheless they also reached the largest body sizes. Fecundity differences were found between locations and among seasons, all attributed mainly to female size, air exposure time, and temperature. Pachycheles laevidactylus did not follow the expected latitudinal pattern of fecundity. The volume of stage-I eggs fluctuated between seasons in Tramandaí only, showing a tendency to be smaller in the warmer seasons. Ovigerous females in Torres lost 36.8% of their eggs between stages II and III, whereas no egg loss was detected in Tramandaí. A similar increase in egg volume was found from stage I to III in both locations, 44.4% in Tramandaí and 41.2% in Torres.