A new species in the genus Salpa Forskål, 1775 (Tunicata, Thaliacea).

Salpa younti nov. spec. is described from the Bermuda area. The new species is also reported from the South Atlantic and the Pacific. Its systematic position within the genus Salpa is discussed and general remarks are made on the taxonomic status of the known taxa of this genus

Zoogeography and speciation in the Salpidae (Tunicata, Thaliacea).

This paper represents a general study of two major phenomena in the taxonomy of the lower taxa of the Salpidae and their bearing on theories about the origin of the recent species. Arguments are presented that point strongly to a specific status for closely related forms previously described as infraspecific by most authors. Latitudinalclinal variation, reported for the first time in salps in a previous paper of the present author, is now demonstrated to be a uniform trend in all species with a wide distribution into temperate waters. Some indications are found that support the assumption that the clinal forms represent separate populations with a small degree of genetic difference. Thalia democratica (Forskål, 1775) is divided into two formae, forma democratica, distributed over the whole of the Atlantic and the subtropical and temperate parts of the Indo-Pacific, and forma indopacifica nov., confined to the tropical parts of the Indo-Pacific. On the basis of the species distribution and the occurrence of clinal variation the surface waters of the world oceans are divided into 11 major biogeographic regions, largely conforming to similar divisions made on the basis of other holoplanktonic groups. Finally postulations are made about the most likely mode of speciation of the lower taxa in the Salpidae. Climatic deterioration and lowering of the sea surface temperatures during glaciations of the past four million years are thought to have caused isolation of salp populations in the Atlantic Ocean. This isolation presumably resulted in the present species diversity

Taxonomy of the subfamily Cyclosalpinae Yount, 1954 (Tunicata, Thaliacea) with descriptions of two new species.

The genera Cyclosalpa de Blainville, 1827 and Helicosalpa Todaro, 1902 are revised on the basis of material from all three oceans. Two new species, Cyclosalpa foxtoni and Cyclosalpa ihlei are described, and four taxa, formerly described as varieties or subspecies, are raised to specific rank. The existence of morphological groups of species within the genus Cyclosalpa is discussed

Observations on taxonomy and distribution of some salps (Tunicata, Thaliacea), with descriptions of three new species.

The Salp genera Traustedtia Metcalf, 1918, Weelia Yount, 1954 and Brooksia Metcalf, 1918 are revised, resulting in the conclusion that Traustedtia is a monotypical genus, and that Brooksia on the other hand, contains two taxa, one of which is newly described under the name B. berneri. Weelia shows a confusing variation, which must await further study. The variation in Ihlea punctata (Forskål, 1775) shows that there is no ground for the assumption that the species described as Ihlea asymmetrica (Fowler, 1896) is separate from I. punctata. Two undescribed taxa, reported upon in previous studies of the present author, are now fully described as new species: Cyclosalpa danae and Thalia rhinoceros

Diversity and spatial heterogeneity of mangrove associated sponges of Curaçao and Aruba

Sponges are major epibionts of mangrove roots in the Caribbean. Mangrove sponge communities in the Caribbean mainly consist of species that are typical to this habitat and community compositions often differ from those found on coral reefs nearby. Heterogeneity in species distributions between locations and within locations between roots is often reported. This study quantifies the diversity and abundance of mangrove associated sponges in the inner bays of Curaçao and Aruba and correlates variability of regional sponge diversity with environmental variables measured along the surveyed sites. Tannin concentrations vary between mangrove roots, and were correlated to sponge cover as a possible cause for habitat heterogeneity on a smaller scale. A total of 22 species was observed. Heterogeneity in species richness and abundance was apparent, and several sponge species were restricted in their depth of occurrence. Statistical data reduction suggests that sponge diversity may be partly explained by the distance towards adjacent reefs and to the degree of eutrophication, in which the latter is comprised of rate of planktonic respiration, total carbon and turbidity. Tannin concentrations did not determine within locality species heterogeneity as a priori postulated, but were positively related to sponge cover for reasons not yet elucidated