The presence of a male in a population of terrestrial isopods can accelerate the onset of female reproduction, a feature that has been suggested also to occur in bopyrid isopods. This paper aims to estimate the influence of the male presence on the ovarian maturation of Bopyrina abbreviata. Females of B. abbreviata of different sizes were collected at Términos lagoon, Campeche, Mexico. The organisms were morphometrically classified as immature or mature, the male presence or absence at female's marsupium was recorded, and the degree of ovarian development was determined histologically. The internal organization of B. abbreviata agrees with that described for bopyrids and isopods in general. The ovarian cells originate from a dorsal lamina germinal layer that extends horizontally. The ovarian development of lone and paired immature females was classified as incipient and medium, respectively. In mature females it was classified as advanced, in the paired females and in the one lone mature female studied. The lone mature female differed from paired mature females only in the presence of reabsorption process in some oocytes located closer to the ventral wall of the ovary. Morphology variations between lone and paired females suggests that the presence of a cryptoniscus larva or a male between the female's pleopods stimulates the onset of reproduction and accelerates the ovarian development of B. abbreviata.

The aim of this paper is to describe the population structure and some reproductive aspects of Hippolyte zostericola during an annual cycle. Samples were taken bimonthly, from June 2009 to April 2010, with a Colman–Seagrove sledge net on seagrass meadows located in the internal margin of Isla del Carmen, Campeche, Mexico. The population structure of H. zostericola was similar throughout the cycle analysed. The males, significantly smaller than females (0.57–1.8 and 0.55–3.52 mm carapace length (CL), respectively), were more frequent between 0.8 and 1.54 mm CL, whereas in larger size-classes (1.8–3.52 mm CL) only females were registered, ovigerous principally. The sex-ratio was always in favour of males, mean of 1.3 males per female. Size at maturity (CL50) was 2.28 ± 0.1 mm CL. Based on the presence of ovigerous females throughout the year it is considered that the reproduction of H. zostericola is continuous. The main breeding season and recruitment occurs during the first third of the year. The mean fecundity of the species was 144 ± 69 eggs and varies with female size. The higher egg loss occurred in larger females (37.3%) and the relationship between fecundity and female size was estimated as negative allometric, which suggests that age influences the fecundity of the species.