Taxonomia de Diadumene Stephenson, 1920 (Cnidaria, Actiniaria) no Brasil

Abstract

The genus Diadumene (order Actiniaria) comprises some sea anemones with expressive bioinvasive potential in several countries. The high tolerance to fluctuations in temperature, salinity and desiccation, combined with high periodic rates of asexual reproduction, contribute to the capacity of the species to colonize practically any type of habitat and substrate, being found even in considerably polluted port areas. Since they are benthic organisms, but with dispersion mediated by ships, the species are continually cited as new occurrences for places beyond their region of origin. Brazil has 4 valid species for the genus and recent studies exhibits an increasing number of records, mainly for estuarine zones. In this work, through collections in estuarine and port regions in the states of Maranhão, Ceará and Pernambuco, Northeast region of Brazil, we analyze individuals associated with rocks, bridges and mangrove roots, collected at low tide in the intertidal zone. In laboratory, the specimens were anesthetized, dissected, preserved in 4% formalin and observed for the external and internal organization of taxonomically relevant structures. Small tissue fragments were prepared in paraffin for the elaboration of histological slides, stained with Hematoxylin/Eosin. Cnidom data were obtained through squash preparations, and visualized with the aid of an optical microscope with 100X ocular magnification. As a result, we describe two new species, Diadumene sp. n. 1 and Diadumene sp. n. 2, we report new occurrences for the species Diadumene paranaensis, Diadumene leucolena, and discuss about the variety of morphotypes of Diadumene lineata found in the country. The descriptions presented here increase the number of Diadumene species in Brazil to 6, and to 14 in the world, demonstrating a great diversity of the group in the country for estuarine or port areas.