Abstract. To better understand the mating systems of majoid crabs, we studied the functional anatomy of the female reproductive systems of the spider crabs Leurocyclus tuberculosus and Libinia spinosa, comparing them with those of other Majoidea. Adult females were measured and dissected, and their reproductive systems described macroscopically and histologically. In females of both species, the seminal receptacles are paired globular structures of ecto-mesodermal origin. The mesoderm-derived region is lined by a stratified epithelium. The anchoring, proliferative, and secretory strata are clearly recognizable. The ectodermderived region is lined by a simple cylindrical epithelium underlying a cuticle that increases in thickness toward the vagina. The transition between the ectoderm and mesoderm-derived regions is abrupt, with differences between the studied species: Li. spinosa has a "velum," whereas Le. tuberculosus presents prominent "folds." In both species, the position in which the oviduct is connected to the seminal receptacles is intermediate between the dorsal and ventral types previously described in other eubrachyurans. The seminal receptacles of the studied species show four different conditions, which can be distinguished macroscopically based on their shape and amount of sperm stored. We compare our data with those from other Majoidea in an attempt to determine whether the morphology of the seminal receptacles is related to different mating strategies or behaviors.Additional key words: reproductive anatomy, histology, crustacean, decapod Studies of reproductive morphology in a phylogenetic framework can answer questions about the coevolution of anatomy, mating behaviors, and fertilization mechanisms (Wortham-Neal 2002). In many species, including some crustaceans, there is a correlation between the morphology of the sperm-storage chambers and the pattern of sperm precedence (last/ first mate) at fertilization, the arrangement of stored ejaculates within the seminal receptacles (SR), and the molt status of females at mating (Parker 1970; Diesel 1991;Sainte-Marie 2007).The female genital ducts of eubrachyuran crabs extend from the ovary to the vulva (Hartnoll 1968). The ovary releases the oocytes into the oviducts, which lead them to the SR. Each SR connects ventrally with a vagina, which opens to the exterior through the sternal vulva (Hartnoll 1968; Diesel 1991;Guinot & Quenette 2005). The SR are classified into two types according to the position in which the oviducts are connected to them: the dorsal type (dorsal-type SR) and the ventral type (ventral-type SR) (Diesel 1991). In the dorsal-type SR, the opening of each oviduct is located more or less dorsal to the seminal receptacle, and the vagina lies ventrally (e.g., Portunidae and Xanthidae: Diesel 1991). In the ventral type, both oviduct and vagina open into the ventral region of the SR, close to each other (e.g., Calappidae, Geryonidae, Leucosiidae, Parthenopidae, Parathelphusidae, Corystidae, Ocypodidae, and some species of Majoidea: Diese...

No abstract

An integrative analysis of sexual maturity associated with growth was developed for the spider crab Leurocyclus tuberculosus (H. Milne Edwards and Lucas, 1842). Sexual maturity was characterized based on gonadal, morphological, morphometric, and functional sexual maturity. Progress in sexual maturation was described through 13 growth stages (instars) detected by the examination of size (carapace width) frequency distributions. Mature females displayed mature ovaries, developed vaginae, open gonopores, allometric changes in the abdomen, and ovigerous stage in the transition from instar IX to instar X. Sexually mature males presented spermatophores in the distal vasa deferentia and allometric changes in several measurements of the right chela in the transition from instar X to instar XI. However, two prepubertal phases were recognized in both sexes separated from each other by a prepubertal critical molt. Preceding the second critical molt, gonopores were sealed and vasa deferentia showed no spermatophores, and therefore neither sex was able to mate. The integrated analysis of size at maturity and size frequency distributions showed that in both sexes molt to gonadal, morphological, morphometric, and functional sexual maturity occurred in advance of the terminal molt, in contrast with patterns observed in other Majoidea.

RESUMEN. El objetivo de esta nota es reportar la presencia del cangrejo verde europeo, Carcinus maenas en el Golfo Nuevo, en Chubut, Argentina. Este hallazgo extiende su rango de distribución 250 km al norte del primer reporte en el Golfo San Jorge, en las costas patagónicas. C. maenas es una de las especies invasoras acuáticas más exitosas del mundo, con poblaciones establecidas en todos los continentes. Es un depredador voraz, por lo que su presencia representa una amenaza para la integridad de los ecosistemas costeros del sur de Sudamérica y para las economías de las comunidades pesqueras de la región.