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SUMMARY: Tunicotheres moseri (Rathbun, 1918) presents a rare case of post-hatching parental care not recorded previously among brachyuran decapods. The complete larval development takes place within a brooding enclosure of the parental female, formed by flexure of the broad abdomen against the sternum. The first crab instar is the earliest stage observed to leave this enclosure, doing so without active help from the parental female. The development of stages preceding the first crab was investigated by in vitro culture of eggs obtained from ovigerous crabs inhabiting the atrial cavity of the tunicate Phallusia nigra Savigny, 1816, in Venezuela. Eggs were hatched in the laboratory and reared through two zoeal stages and the megalopa. Additional samples of the larval stages were obtained directly from abdominal enclosures of aquarium-held females. All larval stages were described and illustrated in detail. Morphological comparisons were made between larvae from two different populations. Comparisons were also made with other previously described larvae of Pinnotherinae, which led us to conclude that Tunicotheres should not be assigned to the Pinnotherinae sensu stricto. Relationships between the three known disjunct populations assigned to T. moseri remain questionable, especially since the potential for larval dispersal appears to be very limited. (Rathbun, 1918) representa un caso raro de cuidado parental de los estadios posteriores a la eclosión larval, que no ha sido documentado con anterioridad en decápodos braquiuros. Todo el desarrollo larval transcurre en la cavidad comprendida entre el abdomen y la placa esternal de la hembra. El primer estadio juvenil es el primero que abandona la cavidad, y lo hace sin ayuda de un movimiento activo del abdomen por parte de la hembra. El desarrollo de los estadios previos al primer juvenil fue estudiado mediante cultivo in vitro de huevos extraídos de hembras ovígeras que habitan la cavidad atrial del tunicado Phallusia nigra Savigny, 1816, en Venezuela. Los huevos eclosionaron en el laboratorio y se obtuvieron dos estadios zoea y una megalopa. Muestras adicionales de todos los estadios larvales fueron obtenidas directamente de las cavidades formadas por el abdomen de hembras mantenidas en acuarios en el laboratorio. Todos los estadios larvales son descritos e ilustrados en detalle. La morfología de las larvas de dos diferentes poblaciones de esta especie fue comparada. También se hicieron comparaciones morfológicas con las larvas de otros Pinnotherinae previamente descritos, lo que nos permite concluir que Tunicotheres no debería ser asignado a los Pinnotherinae sensu stricto. Queda en cuestión que exista relación entre las tres poblaciones aisladas, reconocidas como pertenecientes a la especie T. moseri, debido especialmente a que su potencial para la dispersión larvaria parece ser muy limitado.

Resource-monopolization theory predicts the adoption of a solitary habit in species using scarce, discrete, and small refuges. Life-history theory suggests that temporarily stable parental dwellings favor extended parental care in species that brood embryos. We tested these two predictions with the symbiotic crab Tunicotheres moseri. This species exhibits abbreviated development and inhabits the atrial chamber of the scarce, structurally simple, long-lived, and relatively small ascidian Phalusia nigra in the Caribbean. These host characteristics should favor a solitary habit and extended parental care (EPC) in T. moseri. As predicted, males and females of T. moseri inhabited ascidians solitarily with greater frequency than expected by chance alone. The male-female association pattern and reverse sexual dimorphism (males < females) additionally suggests a promiscuous "pure-search" mating system in T. moseri. Also in agreement with theoretical considerations, T. moseri displays EPC; in addition to embryos, females naturally retain larval stages, megalopae, and juveniles within their brooding pouches. This is the first record of EPC in a symbiotic crab and the second confirmed record of EPC in a marine brachyuran crab. This study supports predictions central to resource-monopolization and life-history theories.

Charybdis hellerii is one of several poorly known non-indigenous crabs in the Caribbean. In this study we report on the reproductive dynamic of a shallow subtidal population that invaded Isla Margarita, Venezuela, south-eastern Caribbean Sea . 15 years ago and has persisted in the region up to date. Male and female crabs, both large and small, were found year-round at the study site. The size-frequency distribution indicated a lifespan of 2-3 years. Charybdis hellerii reproduces continuously but with very low intensity during the year. Small individuals (,25 mm carapace length) were uncommon and intermittently found during the study period. Sex-ratio varied between 0.1 and 0.65 (mean + SD ¼ of 0.46 + 0.14) and did not differ significantly from 1:1 ratio during most of the year. The size of the smallest brooding female was 36.81 mm carapace width (CW). Behavioural size at first maturity (movable abdomen) in males and females was estimated to be 22.39 mm CW (confidence limits: 18.35-24.72) and 37.43 mm CW (35.55-39.09), respectively. Reproductive output, estimated as the ratio of embryo to female body dry mass, varied between 0.052 and 0.084 (0.07 + 0.008). Also, reproductive output was sizedependent with large females allocating proportionally less resources to egg production than small females. The reproductive schedule here reported for C. hellerii disagrees with the generalized idea of exotic populations 'thriving' in an environment free of natural enemies (e.g. predators, competitors and diseases).

Recent studies based on morphological and molecular data provide a new perspective concerning taxonomic aspects of the brachyuran family Mithracidae. These studies proposed a series of nominal changes and indicated that the family is actually represented by a different number and representatives of genera than previously thought. Here, we provide a comparative description of the ultrastructure of spermatozoa and spermatophores of some species of Mithracidae in a phylogenetic context. The ultrastructure of the spermatozoa and spermatophore was observed by scanning and transmission electron microscopy. The most informative morphological characters analysed were thickness of the operculum, shape of the perforatorial chamber and shape and thickness of the inner acrosomal zone. As a framework, we used a topology based on a phylogenetic analysis using mitochondrial data obtained here and from previous studies. Our results indicate that closely related species share a series of morphological characteristics of the spermatozoa. A thick operculum, for example, is a feature observed in species of the genera Amphithrax, Teleophrys, and Omalacantha in contrast to the slender operculum observed in Mithraculus and Mithrax. Amphithrax and Teleophrys have a rhomboid perforatorial chamber, while Mithraculus, Mithrax, and Omalacantha show a wider, deltoid morphology. Furthermore, our results are in agreement with recently proposed taxonomic changes including the separation of the genera Mithrax (previously Damithrax), Amphithrax (previously Mithrax) and Mithraculus, and the synonymy of Mithrax caribbaeus with Mithrax hispidus. Overall, the spermiotaxonomy of these species of Mithracidae represent a novel set of data that corroborates the most recent taxonomic revision of the family and can be used in future taxonomic and phylogenetic studies within this family.

Crabs from the Mithrax-Mithraculus species complex are known for their diversity of lifestyles, habitats, and coloration. This group includes small, colourful, symbiotic species and much larger, reef-dwelling crabs targeted by fishermen. The evolutionary relationships between the species within this complex are not well-defined. Previous studies based upon morphological characters have proposed the separation of this complex into two genera (Mithrax and Mithraculus), but cladistic analyses based upon larval characters do not support this division. A molecular phylogeny of the group may help to resolve this longstanding taxonomic question and shed light on the ecological conditions driving the diversity of these crabs. Using a 550-bp alignment of the 16S rRNA mitochondrial DNA segment we examined the phylogenetic relationships between 8 species within the Mithrax-Mithraculus complex native to the Caribbean. The resulting phylogeny indicates that this complex is paraphyletic, as it includes the genus Microphrys. The analyses revealed a well-supported, monophyletic group containing four species of Mithraculus (M. cinctimanus, M. coryphe, M. sculptus and M. forceps) and supported one pair of sister species from the genus Mithrax (M. caribbaeus and M. spinosissimus). No complete segregation of species, according to genera, was evident, however, from tree topologies. Bayesian-factor analyses revealed strong support for the unconstrained tree instead of alternative trees in which monophyly of the two genera was forced. Thus, the present molecular phylogeny does not support the separation of the species within this complex into the genera Mithrax and Mithraculus. A review of the literature demonstrated considerable phenotypic variation within monophyletic clades in this group.

ine and 70% isopropyl alcohol. Dissections were carried out under an Olympus SZH10 stereoscopic microscope. Drawings were made with the aid of an Olympus U-IT120 camera lucida using an Olympus BMAX-50 compound microscope. Measurements were made with a calibrated ocular. At least three specimens of each zoeal stage from two or more females were measured, dissected, and analyzed. The females and specimens of their zoeal progeny are deposited in the collection of the Laboratory of Crustaceans at the Universidad de Oriente.The carapaces of both zoeal stages and of the megalopa were measured in the standard way for Porcellanidae (Gore, 1971(Gore, , 1973 Hernández et al., 1998 Hernández et al., , 2000. These measurements are expressed as the arithmetic average of the number of measured specimens and their standard deviation; the following abbreviations are used: CL = carapace length; CW = carapace width; RL = rostral length; LPS = length of posterior spines of the carapace. The distribution of the chromatophores and coloration of the specimens was determined on live specimens. The use of the term seta and the nomenclature for the different types of setae follows Hernández et al. (1998Hernández et al. ( , 2000. The counts and setal formulas assume a proximodistal arrangement. The dorsal setae on the endopodite of maxillipeds 1 and 2 and the apical setae of the scaphognathite were designated with roman numerals. RESULTSMegalobrachium roseum hatches as a prezoea which persists less than 120 minutes, and then molts through two subsequent zoeal stages which last 5-7 and 6-9 days, respectively, before the megalopa is reached. The duration of the megalopa was not recorded. First ZoeaSize.-CL = 1.00 ± 0.11 mm, range = 0.90-1.15 mm; RL = 2.64 ± 0.13 mm, rangeThe porcellanid crab genus Megalobrachium is represented in the Caribbean Sea by four species (Haig, 1956(Haig, , 1962Gore and Abele, 1976;Werding, 1977;Scelzo, 1982). One of them, Megalobrachium roseum (Rathbun, 1901), is quite abundant in rocky shores from the Caribbean Sea to São Paulo (Brazil) but is usually overlooked because of its small size, cryptic coloration, and thanatosis.Like larvae of other porcellanid crabs, those of M. roseum are significant in the bioenergetic cycles of the pelagos. Knowledge of the larval morphology of this species is important to make possible its identification in plankton samples.This study deals with the larval development of M. roseum. The zoeal and megalopal stages of this species are fully described and illustrated, and compared with those of M. soriatum (Say, 1818), M. poeyi (Guérin-Méneville, 1855), and M. pacificum Gore and Abele, 1974, for which the larval development has previously been described. MATERIALS AND METHODSLarvae from hatchings of four females of M. roseum, collected on the southwestern coast of Margarita Island, were incubated individually in 150 ml glass containers, with filtered and UV-sterilized sea water, at 25°C and 37‰ salinity. Larvae were fed daily with newly hatched nauplii of Artemia. The water was chan...

Lysmata udoi n. sp., a new peppermint shrimp, is described from Venezuela, southeastern Caribbean Sea. All individuals were collected from dens of the toadfish Amphichthys criptocentrus (Valenciennes, 1837) in the subtidal zone. This new species can be distinguished from other closely related species of Lysmata by the number of teeth, length and shape of the rostrum, the relative length of the antennular peduncle, and the number of carpal articles of the second pereiopod. The color pattern is distinctive. The fourth abdominal segment almost lacks color, but bears a posterior red thin line with three short forward projections. Morphological and molecular characters demonstrate that L. udoi n. sp. is most closely related to the Gulf of Mexico L. boggessi Rhyne and Lin, 2006 and the Caribbean L. rafa Rhyne and Anker, 2007 and L. ankeri Rhyne and Lin, 2006. Field observations suggest that L. udoi n. sp. is a protandric simultaneous hermaphrodite, with a primary male phase followed by a simultaneous hermaphrodite phase.