Tethya

Abstract: A new species of Tethya Lamarck, 1815 is described from a depth of 1000 m on the continental slope of the Great Australian Bight (GAB), southern Australia. The GAB slope was explored as part of sys ...

Abstract: Sponges (phylum Porifera) are ubiquitous inhabitants of marine ecosystems and have been shown to provide substantial ecosystem services. Despite this ecological importance, the sponge fauna in California has received little study. Here I use a collection of kelp forest sponges to describe the diversity of the order Tethyida in California. This order contains the genus Tethya, which has been included in long-term ecological monitoring projects. I show that Tethya vacua is a junior synonym of Tethya californiana, and thus all Tethya populations known in California belong to a single species. Genetic data from California's only Timeidae, Timea authia, indicate that this species is in fact in the Tethyidae and is the third known member of the genus Tethytimea. I also describe the first member of the family Hemiasterellidae from the Eastern Pacific, Galaxia gaviotensis gen. nov. sp. nov. By combining field photographs, morphological taxonomy, and phylogenetic analysis of these samples, this work will facilitate future efforts to understand the evolution of this order and the ecological role of sponges in the California kelp forest.

Abstract: The sexual and asexual phases of reproductive cycles of two sponges, Tethya citrina and T. aurantium, living sympatrically in a Mediterranean coastal lagoon (Stagnone di Marsala, NW Sicily) were studied from samples collected over an 18-mo period. Both species are oviparous and gonochoric. They have a summer, partially overlapping, period of oocyte production, although T. citrina appear to mature earlier. No males were found, possibly due to the very short period of spermatogenesis. Both species produce asexual buds during the autumn/winter months. However, they seem to follow different reproductive strategies, with T. citrina showing a significantly lower production of buds than T. aurantium; by contrast, egg production is significantly lower in the latter species. The difference in the reproductive resource allocation is consistent with data reported in the literature on the anatomy features, genetic population structure and ecological distribution.

Abstract: In Tethya seychellensis (Wright), a demosponge collected on the coral reef of the Maldive Islands, algal filaments of the syphonaceous chlorophyte Ostreobium sp. were seen to penetrate deep into the sponge body. The filaments were in close association with the sponge skeleton, which consists of siliceous spicules. Filaments were arranged around the spicular bundles radiating from the central core of the sponge body into the outermost cortical region. In sponges like Tethya, which is characterized by a massive globular shape and radial structure, spicular tracts may represent a system to entrap and guide light toward the center of the sponge body. In such conditions, algal filaments develop in a n environment otherwise prohibitive for autotrophic organisms. These data suggest that sponges could use spicules as a natural p~pellne for light, a natural condition similar to modern fibre-optic systems.