Abstract
New observations of Maeotias, Blackfordia, and Moerisia in low salinity waters of the San Francisco Bay estuary allow better understanding of the life cycles and natural history of these three genera of invading hydrozoans. Maeotias inexpectata Ostroumoff, 1896 is found to be a junior synonym of Maeotias marginata (Modeer, 1791). Moreover, M. inexspectata Ostroumoff, 1896b is an incorrect subsequent spelling of M. inexpectata Ostroumoff, 1896a. The clear presence of marginal statocysts in the medusa of this species places it back in the family Olindiidae of the Limnomedusae. Polyps previously attributed to Maeotias in San Francisco Bay are now known to belong to a Moerisia sp., whose medusa has also recently been found in the estuary system. Solitary Moerisia polyps have been found in the field amongst the general fouling fauna on floating docks in the Napa River. Small simple primary polyps of M. marginata were obtained in the laboratory. Polyps of Blackfordia virginica have been found in abundance in the field covering the valves of nonindigenous barnacles in the Napa River and laboratory-cultured colonies are pictured here along with their newly-released and juvenile medusae.
Highlights
Further observations in low salinity tributaries to San Francisco Bay of hydromedusae and their polyps in the genera Maeotias, Blackfordia, and Moerisia have revealed a number of errors in the Mills and Sommer (1995) paper, which first described the presence of two of these invasive species in California
Polyps previously attributed to Maeotias in San Francisco Bay are known to belong to a Moerisia sp., whose medusa has recently been found in the estuary system
Solitary Moerisia polyps have been found in the field amongst the general fouling fauna on floating docks in the Napa River
Summary
Further observations in low salinity tributaries to San Francisco Bay of hydromedusae and their polyps in the genera Maeotias, Blackfordia, and Moerisia have revealed a number of errors in the Mills and Sommer (1995) paper, which first described the presence of two of these invasive species in California. Polyps previously attributed to Maeotias in San Francisco Bay are known to belong to a Moerisia sp., whose medusa has recently been found in the estuary system. Polyps of Blackfordia virginica have been found in abundance in the field covering the valves of nonindigenous barnacles in the Napa River and laboratory-cultured colonies are pictured here along with their newly-released and juvenile medusae.
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