Prosuberites geracei van Soest & Sass, 1981
Taxonomic Characterization: Superficially smooth. Blue or grayish blue in color. Lateral expansion indefinate. Ecotsome is thin, organic, microhispid with single, projecting spicules. No evident oscules (van Soest & Sass, 1981).
Disposition of Specimens: National Museum of Natural History, Smithsonian Institution, catalog numbers USNM 31746; and Zoological Museum Amsterdam catalog number POR 4580
Ecological Classification: Stygobitic
Size: Spicule size 190-340.5-555 by 3.5-8.5-18 micrometers.
Number of Species in Genus: Three, all marine
Species Range: Known only from Lighthouse Cave, San Salvador Island,
Closest Related Species:
Habitat: Anchialine limestone caves
Ecology: Found encrusting calcareous rocks and limestone cave walls that are barely covered at low tide by fully marine salinity waters. Found with two other marine sponges, Pellina pencilliformis van Soest & Sass, 1981 and Cinachyra subterranea Van Soest & Sass, 1981. In addition, Lighthouse Cave is inhabited by species of cirolanid isopods, phoronid worms, ostracods, gastropods, amphipods and more. Requires a vegetation of fucoid algae.
Evolutionary Origins: It is believed that this species of sponge originated from a marooned population of a marine shallow-water species at least 23,000 years ago. Such a rate of speciation seems quite high, when compared to the evidence of slow evolution in tropical sponges. On the other hand, the cave situation very likely speeded up the development of morphological changes due to inbreeding (van Soest & Sass, 1981).
Conservation Status: Restricted to a single anchialine cave
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