Simbiontes associados a ascídias solitárias na costa brasileira

Abstract

This study evaluated the distribution and abundance of metazoan endosymbionts in the internal cavities of ascidians at two scales on the Brazilian coast. The first covering four species of solitary ascidians, namely: Phallusia nigra Savigny, 1816, Herdmania pallida (Heller, 1878), Microcosmus exasperatus Heller, 1878 and Styela plicata (Lesueur, 1823) in a tropical bay located in the south of the state of Rio de Janeiro, testing the hypothesis that each species has a unique symbiotic fauna, influenced by location and time of year. The second, specifically, evaluates the species Phallusia nigra, between the tropical and warm-temperate biogeographic domains, on the Southeast Atlantic coast, between latitudes 9°S and 23°S, testing the hypothesis that the taxonomic composition of the symbionts would be influenced by geographic location. In Ilha Grande Bay, was recorded the association of a total of 4034 symbionts, belonging to 26 taxa and the four species of ascidians. A total of 1377 individuals belonging to eight different taxa were recorded as symbionts of P. nigra on the Southeast Atlantic coast. The most abundant and frequent taxon was the amphipod genus Leucothoe (Class Malacostraca, Order Amphipoda), which was recorded in all body cavities of P. nigra, throughout the entire studied area. The other taxa were quite rare, but despite this, Tanaidacea, Copepoda and individuals of Polychaeta from the most diverse genera was recorded for the first time as endosymbionts of solitary ascidians on the Brazilian coast. We did not observe any latitudinal pattern for taxon richness, nor in the distribution of symbionts throughout the BIG, however, Leucothoe density varied between locations, regardless of the body size of the ascidians. The wide distribution of P. nigra in various oceans and the high abundance of symbionts observed in the present study may enable important biogeographic and environmental comparisons in the future.