Two new haplosclerid sponges from Caribbean Panamá with symbiotic filamentous cyanobacteria, and an overview of sponge-cyanobacteria associations

Abstract

Two new species of the order Haplosclerida from open reef and mangrove habitats in the Bocas del Toro region (Panama) have an encrusting growth form (a few mm thick), grow copiously on shallow reef environments, and are of dark purple color from dense populations of the cyanobacterial symbiont Oscillatoria spongeliae. Haliclona (Soestella) walentinae sp. nov. (Chalinidae) is dark purple outside and tan inside, and can be distinguished by its small oscules with radial, transparent canals. The interior is tan, while the consistency is soft and elastic. The species thrives on some shallow reefs, profusely overgrowing fire corals (Millepora spp.), soft corals, scleractinians, and coral rubble. Xestospongia bocatorensis sp. nov. (Petrosiidae) is dark purple, inside and outside, and its oscules are on top of small, volcano-shaped mounds and lack radial canals. The sponge is crumbly and brittle. It is found on live coral and coral rubble on reefs, and occasionally on mangrove roots. The two species have three characteristics that make them unique among the families Chalinidae and Petrosiidae: filamentous, multicellular cyanobacterial symbionts rather than unicellular species; high propensity to overgrow other reef organisms and, because of their symbionts, high rate of photosynthetic production. These are the first descriptions of West Atlantic haplosclerid species associated with an Oscillatoria-type symbiont; all previous records of haploscleridcyanobacteria associations were of symbioses with unicellular cyanobacteria. High rates of photosynthetic production of Oscillatoria spongeliae could explain the abundance and overgrowth capability of the two host sponges in the region's reef environments. An overview of associations between sponges and cyanobacteria is presented.