Prosuberites geracei

Phylum Porifera
Class Demospongiae
Order Hadromerida
Family Suberitidae

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

Genus Range:

Bahama Islands: P. geracei van Soest & Sass, 1981
- San Salvador Island: P. geracei van Soest & Sass, 1981
Holland: P. epiphytum (Lamarck, 1813) reported in van Soest, 1977
United States:
- Florida: P. microsclerus de Laubenfels, 1936
West Indies: P. epiphytum (Topsent, 1933)

Species Range: Known only from Lighthouse Cave, San Salvador Island, Bahamas.

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

References:

de Lamarck, J.B.P.A. 1813-1817. Sur les polypiers empatees. Annls. Mus. Hist. nat. Paris, 20:294-312, 370-386, 432-458.
de Laubenfels, M.W. 1936. A discussion of the sponge fauna of the Dr Tortugas in particular, and the West Indies in general, with material for a revision of the families and orders of the Porifera. Publs. Carnegie Instn., 467 (Pap. Tortugas Lab., 30):i-iii, 1-225, pls. I-XXII.
van Soest, R.W.M. and D.B. Sass. 1981. Marine sponges from an island cave on San Salvador Island, Bahamas. Bijdragen tot de Dierkunde, 51(2):332-344, 4 figures, 2 tables.
Topsent, E. 1933. Eponges de Lamarck conservees au Museum de Paris. Fin. Archs. Mus. natn. Hist. nat Paris, 10(6):1-60, pls. I-III.