Abstract A new genus and new species of caprellid, Parapseudaeginella n. gen., and Parapseudaeginella australiensis n. sp., is described from shallow water of Ningaloo Reef, south of Tantabiddy, reef front, Western Australia. The new genus is very similar to Pseudaeginella Mayer, 1890, but can be easily distinguished by the pereonites 6 and 7 being clearly fused (separated in Pseudaeginella) and by the absence of a pair of proximal grasping spines on the propodus of pereopods 5-7 (present in Pseudaeginella). The new species is characterised by acute dorsal projections on head, pereonite 1 and 2, and acute lateral projections near the coxa of gnathopod 2 in males. The new taxon has probably been overlooked in the past due to its tiny size. Further efforts to sample and describe the smaller caprellids is needed to fully understand the global diversity and relationships of caprellids.

El orden Amphipoda es uno de los más diversos dentro de los Peracáridos. Las investigaciones sobre este orden en el Mar Caribe se iniciaron a finales de los años 1800, incrementándose significativamente a partir de 1980. En este estudio se analizó la biodiversidad de los anfípodos (Caprellidea, Gammaridea, Hyperiidea e Ingolfiellidea) en el Mar Caribe, compilándose los registros de especies citadas en las diversas ecorregiones del área, tanto en publicaciones como a través de bases de datos (WoRMS y OBIS). Se listan un total de 535 especies pertenecientes a 236 géneros y 73 familias. La ecorregión del Caribe Occidental presentó la mayor riqueza específica (282), mientras que el Caribe Oriental presentó el menor valor (73). México y Venezuela presentaron el mayor número de especies registradas (266 y 206, respectivamente), mientras que doce países presentaron menos de 50. Los Gammaridea fueron el grupo más diverso con 387 especies, seguido de los Hyperiidea (116 especies). Hasta el presente, se han descrito 218 especies nuevas en aguas del Caribe, de las cuales 132 son endémicas. Las áreas con mayor diversidad de anfípodos se concentraron a lo largo del caribe Mexicano, Cuba y la costa norte de Sur-América (Venezuela-Colombia); sin embargo, este patron refleja más bien un mayor esfuerzo en la recoleccion de estos organismos y una mayor experticia taxonómica, que un patron específico de distribución del grupo. En general, el conocimiento del grupo se limita a las aguas someras, con muy poca información sobre zonas profundas. En este sentido, las prioridades de investigación regional en este grupo, debe enfocar un mayor esfuerzo en la costa de Centro América y las Antillas Mayores y Menores. Así mismo, es necesario aumentar las recolecciones en aguas profundas y otros ecosistemas particulares como los anquialinos. Por último, es importante aumentar las investigaciones taxonómicas y ecológicas de los taxones que presentan mayor diversidad.

The order Amphipoda is one of the most diverse within Peracarids, and comprises 6 950 described marine species. Amphipod research in the Caribbean Sea began in the late 1 800s, but has increased significantly since 1 980. In this study, we analized the amphipod biodiversity (Caprellidea, Gammaridea, Hyperiidea, and Ingolfiellidea) of the Caribbean Sea. For this, we compiled available data on species diversity of marine amphipods (data bases: WoRMS and OBIS and published species lists) into a comprehensive taxonomic list by country for the ecoregions of the Caribbean. Additionally, we analized the relative contribution of each country to regional diversity and the rate of discovery of new species. The Caribbean amphipod fauna is composed of 535 species within 236 genera and 73 families for the higher taxon. The Western Caribbean ecoregion holds the largest diversity (282 species), while the Eastern Caribbean recorded the lowest one (73). Mexico and Venezuela recorded the largest number of species with 266 and 206, respectively. Twelve countries had less than 50 species. The richest suborder is the Gammaridea with 381 species followed by the suborder Hyperiidea with 116. From the total of 535 amphipod species reported for the Caribbean region, 218 have the Caribbean as the holotype locality, and 132 are endemic (about 25% of the total). Areas of higher diversity seem to be concentrated along the Mexican Caribbean, Cuba and the Northern coast of South America (Venezuela-Colombia); however, such pattern is most likely reflecting local collection efforts and taxonomic expertise rather than actual distribution. Knowledge of amphipod species is mostly limited to shallow, near-shore waters, with little information available on the deep sea fauna. Regional research priorities for this group should be focused on completing shallow water coastal inventories of species in Central America and the Greater and Lesser Antilles. In addition, sampling the deep sea ecosystems should follow along with other particular habitats such as anchialine cave systems. It is also neccessary to increase ecological research efforts, mainly in some speciose suborders, including the Caprellidea and Hyperiidea, known to exhibit high diversity in other tropical localities. Rev. Biol. Trop. 61 (4): 1681-1720. Epub 2013 December 01.