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Muricy, G.; Pearse, J.S. (2004). A new species of Oscarella (Demospongiae: Plakinidae) from California. Proceedings of the California Academy of Sciences. 55 (33): 598-612.
Muricy, G.; Pearse, J.S.
A new species of <i>Oscarella</i> (Demospongiae: Plakinidae) from California.
Proceedings of the California Academy of Sciences
55 (33): 598-612
We describe a new species of Oscarella Vosmaer, 1877 (Porifera: Homosclerophorida) from a rocky coast and marine aquariums in central California and analyze its spatial distribution and temporal fluctuations to determine if it is a non-indigenous species. We also compare the efficiency of two different fixatives, Bouin’s solution and glutaraldehyde in seawater, and found that glutaraldehyde is better for comparisons of anatomical and cytological characters that are important for species identification. This is the first record of the genus Oscarella from the Eastern Pacific. The new species is characterized by its light brown to rusty orange color, undulated appearance, bumpy, microlobate surface, soft, slimy consistency, two particular kinds of cells with inclusions, and occurrence in the intertidal high zone. It sometimes thrives in laboratory conditions, indicating that predators may limit its vertical distribution on the shore. The new species of Oscarella is clearly different in external morphology and cell content from all previously described species of Oscarella, thus giving low support to the hypothesis that it is an invasive species. Instead, it appears to have been previously overlooked because it is inconspicuous and relatively uncommon in the field, and because it could not be distinguished from Halisarca sacra de Laubenfels, 1930 or Halisarca sp. in keys to the West Coast sponge fauna. We present how it can be distinguished from Halisarca, and discuss the present knowledge of that genus in the northeast Pacific in comparison to Oscarella.
Pacific, North East (Warm + cold temperate (boreal))