The sea anemone Exaiptasia diaphana (Actiniaria: Aiptasiidae) associated to rhodoliths at Isla del Coco National Park, Costa Rica / La anémona de mar Exaiptasia diaphana (Actiniaria: Aiptasiidae) asociada a rodolitos en el Parque Nacional Isla del Coco

Introduction: The sea anemones diversity is still poorly studied in Isla del Coco National Park, Costa Rica. Objective: To report for the first time the presence of the sea anemone Exaiptasia diaphana. Methods: Some rhodoliths were examined in situ in Punta Ulloa at 14 m depth, by SCUBA during the expedition UCR-UNA-COCO-I to Isla del Coco National Park on 24th April 2010. Living anemones settled on rhodoliths were photographed and its external morphological features and measures were recorded in situ. Results: Several individuals of E. diaphana were observed on rodoliths and we repeatedly observed several small individuals of this sea anemone surrounding the largest individual in an area (presumably the founder sea anemone) on rhodoliths from Punta Ulloa. Conclusions: The geographic distribution is extended as well as their bathymetric distribution from the intertidal to 14 m depth. The photographs provide evidence of clonal reproduction by pedal laceration.

Introducción: La diversidad de anémonas de mar en el Parque Nacional Isla del Coco, Costa Rica, está aún poco estudiada. Objetivo: Reportar por primera vez la presencia de la anémona de mar Exaiptasia diaphana. Métodos: Algunos rodolitos fueron examinados in situ en Punta Ulloa a 14 m. de profundidad mediante SCUBA durante la expedición UCR-UNA-COCO-I al Parque Nacional Isla del Coco el 24 de abril de 2010. Especímenes vivos fijados sobre rodolitos fueron fotografiados y sus medidas y carácterísticas morfológicas externas fueron registradas in situ. Resultados: Varios individuos de E. diaphana fueron observados sobre rodolitos y observamos repetidamente pequeños individuos rodeando a un individuo mayor (presumiblemente la anémona fundadora) sobre rodolitos de Punta Ulloa. Conclusiones: La distribución geográfica de esta especie es extendida, como así también su distribución batimétrica desde el intermareal hasta los 14 m de profundidad. Las imágenes obtenidas aportan evidencia de reproducción clonal por laceración pedal.

Cnidom variation through distinct developmental stages in the sea anemone Aulactinia marplatensis (Zamponi, 1977) (Cnidaria: Actiniaria).

The cnidae are the exclusive diagnostic structures of phylum Cnidaria. The inventory of all cnidae types of a particular species is called the cnidom. The study of cnidae has been widely addressed in all classes of cnidarians. Particularly in the order Actiniaria (sea anemones), the study of the composition, size and distribution of cnidae is essential to the identification and description of species. In the present study, we examine the cnidom of the sea anemone Aulactinia marplatensis in three different stages of development throughout its life cycle. We found that the composition and abundance patterns are very similar between the adult and juvenile stages, although significant differences in the size capsules were found between both stages and in all cnidae types observed, being bigger those from the adult forms. The planula larvae stage presents a less diverse cnidom in comparison to the juvenile and adult stages; however, it presents an exclusive cnidae type (the mesobasic p-mastigophore) which is the biggest in size of all the cnidae types observed in the species. These results highlight the importance of considering the stage of development when cnidae is used as a diagnostic character, and the particular relevance of the study of the cnidom in larval stages.

Cnidae sizes in the two morphotypes of the giant Caribbean anemone Condylactis gigantea (Actiniaria: Actiniidae) / Tamaños de cnidae en dos morfotipos de la anémona gigante del Caribe Condylactis gigantea (Actiniaria: Actiniidae)

Abstract The sea anemone Condylactis gigantea is an ecologically important member of the benthic community in coral reefs of the tropical Atlantic, and displays two morphotypes with respect to the color in their tentacular tips: the green tip morphotype and the pink/purple tip morphotype. Although some molecular and ecological differences have been found between these morphotypes, no other morphological distinctions have been reported, and currently both are still considered a single taxonomic species. In the present study, we perform an exploration on the variability in the size of cnidae between these two morphotypes and performed statistical analyses to compare the 10 categories of cnidae from specimens hosted in the Cnidarian Collection of Gulf of Mexico and Mexican Caribbean, of the Universidad Nacional Autónoma de México, which were previously collected in several coral reefs localities of the Yucatán Peninsula. Results reveal no significant variation in cnidae size between the two morphotypes, but significant variations were found within each morphotype. In addition, we update the composition of the cnidom of C. gigantea, and the utility of the size of cnidae to distinguish between morphotypes or closely related species is discussed. Rev. Biol. Trop. 66(3): 1055-1064. Epub 2018 September 01.

Resumen La anémona Condylactis gigantea es un miembro ecológicamente importante de la comunidad bentónica en arrecifes de coral del Atlántico tropical, y exhibe dos morfotipos con respecto al color de las puntas de sus tentáculos: el morfotipo de puntas verdes y el morfotipo de puntas rosadas/púrpuras. Aunque se han encontrado algunas diferencias moleculares y ecológicas entre estos morfotipos, no se han reportado otras distinciones morfológicas, y actualmente ambos siguen siendo considerados una sola especie taxonómica. En el presente estudio, realizamos una exploración sobre la variabilidad en el tamaño de los cnidocistos entre estos dos morfotipos y realizamos un análisis estadístico de 10 categorías de cnidocistos a partir de especímenes albergados en la Colección de cnidarios del Golfo de México y Caribe Mexicano, de la Universidad Nacional Autónoma de México, los cuales fueron previamente recolectados en varias localidades arrecifales de la Península de Yucatán. Los resultados no revelan variación significativa en el tamaño de los cnidocistos entre los dos morfotipos, aunque fueron encontradas variaciones significativas dentro de cada morfotipo. Adicionalmente, actualizamos la composición del cnidoma de C. gigantea, y discutimos sobre la utilidad de la talla de los cnidocistos para distinguir entre morfotipos o entre especies estrechamente relacionadas.