The mantis shrimp Squilla biformis is the most conspicuous and abundant stomatopod captured during benthic trawling operations off the Pacific coast of Costa Rica. Due to its abundance, this species is considered a potential fisheries resource for the region. Nevertheless, its life history is practically unknown. The present study describes the population demography, spatial distribution and behaviour of S. biformis from Pacific Costa Rica. The population was principally composed of individuals between 20 and 32 mm carapace length (CL), forming 2 age groups. Individuals of 35 to 45 mm CL and > 45 mm CL were poorly represented. We assume that larger individuals are more frequent at greater depths (probably on the continental slope), thus out of the reach of the fishing vessels used in our study. Males outnumbered females, as observed in other stomatopods. Visual evidence of their behaviour demonstrates that the adults in this species possess a benthic and pelagic life style. Largest numbers of individuals (50% of the total) were found between 240 to 260 m, the same bathymetric range that was historically occupied by commercial shrimps. This shift may be related to intense fishing activities. We observed a synchronized moulting of females and males during less luminous (third and fourth) lunar phases. The evolutionary development of a group moulting system could confer advantages to S. biformis in comparison to other stomatopods whose moulting process is individual and asynchronous.Ristic AG (Oberferrieden, Germany)Universidad de Costa Rica[V.I. 111-A4-508]Universidad de Costa Rica[V.I. 808-A9-536]Universidad de Costa Rica[V.I. 808-A9-537]Consejo Superior Universitario Centroamericano (CSUCA)University of KasselDeutsche Gesellschaft fur Technische Zusammenarbeit (GTZ

SeveralSynalpheusspecies have been reported as hosts of bopyrid parasites; however, the impact of infestation on egg production is still unknown. Therefore, the present work studied reproductive aspects and the effect of parasitism on fecundity of the alpheid shrimpSynalpheus yanofrom Bocas del Toro, Caribbean coast of Panama. Un-infested females (N = 84) ranging from 3.7 to 9.6 mm carapace length, produced between 5 and 246 eggs (average: 98±64.6), and egg number increased significantly with female size. The eggs were relatively large (0.6–1.3 mm in diameter), but within the range of otherSynalpheusspecies, and egg size did not differ significantly between un-infested and infested females. Despite these large eggs, the morphological characteristics of hatching larvae indicate a planktotrophic development. During the incubation period, the egg volume increased from 0.100 to 0.218 mm³, representing an overall increase of 118%. A total of 18 females (16% of all ovigerous individuals) were infested, and the occurrence of parasitic infestation was more pronounced in larger females. Infested females ranging from 4.6 to 9.4 mm carapace length, produced between 22 and 166 eggs (average: 81±44.4). Egg-bearing females infested by parasitic bopyrids carried on average 41% fewer eggs than similar-sized females without parasites. The co-occurrence of parasites and developing eggs, however, indicates that the bopyrid parasite does not necessarily castrate its host. Therefore, we encourage more comparative intraspecific studies on egg production in infested and un-infested females to assess the impact of infestation on fecundity in caridean shrimp.

Freshwater crabs are an important component of the fauna of limnic environments, and out of the two true freshwater crab families present in the Neotropics, Pseudothelphusidae is the most diverse. Considering the lack of information regarding reproductive features of neotropical freshwater crabs, we studied, for the first time, the fecundity and the presence of juveniles carried by females of two pseudothelphusids from the Amazon region - Kingsleya latifrons (Randall, 1840) and Kingsleya ytupora Magalhães, 1986 - and one from Central America - Potamocarcinus magnus (Rathbun, 1896). The two Kingsleya species produced relatively few (56-114) and large eggs (1.9-3.7 mm), typical for species with an abbreviated or direct development. Recently produced eggs were substantially larger in K. latifrons (mean 2.83 mm) when compared to those of K. ytupora (mean 1.87 mm); however, at the end of the embryogenesis, mean egg diameter was similar in both species. Therefore, it is assumed that hatchlings in both species should have a similar size. A brief description of attached juveniles of K. ytupora is provided. The number of juveniles varied between 30 (K. ytupora) and 179 (P. magnus); two size groups of juveniles were found, which indicates that the offspring cling to their mother for a prolonged period of time. There was no significant loss of eggs and juveniles; it is assumed that parental care diminishes the loss of their offspring. We compiled the available information of reproductive aspects from freshwater crabs: egg diameter was in the range of 2-3 mm, independent of female size and fecundity, and reported egg number varied between 9 and 417 eggs.CNPqCONICITUniversidad de Costa Ric